EP0220495A2

EP0220495A2 - Composite material including alumina-silica short fiber reinforcing material and aluminum alloy matrix metal with moderate copper and silicon contents

Info

Publication number: EP0220495A2
Application number: EP86113099A
Authority: EP
Inventors: Masahiro Kubo; Tadashi Dohnomoto; Atsuo Tanaka; Hidetoshi Hirai
Original assignee: Toyota Motor Corp
Current assignee: Toyota Motor Corp
Priority date: 1985-09-30
Filing date: 1986-09-23
Publication date: 1987-05-06
Also published as: AU587283B2; EP0220495A3; JPS6277433A; AU6306486A

Abstract

A composite material is made from alumina-silica type short fibers embedded in a matrix of metal. The metal is an alloy consisting essentially of between approximately 1.5% to approximately 6% of copper, between approximately 0.5% to approximately 2% of silicon, and remainder substantially aluminum. The short fibers may be all alumina short fibers, or may be all amorphous alumina-silica short fibers, or may have a substantial proportion of the mullite crystalline form included in them. The fiber volume proportion of the alumina-silica type short fibers may desirably be between approximately 5% and approximately 50%, and may more desirably be between approximately 5% and approximately 40%. And, in the desirable case that the fiber volume proportion of the alumina-silica type short fibers is between approximately 5% and approximately 20%, then the copper content of said aluminum alloy matrix metal is desired to be between approximately 2% and approximately 6%.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a composite material made up from reinforcing fibers embedded in a matrix of metal, and more particularly relates to such a composite material utilizing alumina-silica type short fiber material as the reinforcing fiber material, and aluminum alloy as the matrix metal.
The present invention has been described in Japanese Patent Application Serial No. 60-217489 (1985), filed by an applicant the same as the entity assigned or owed duty of assignment of the present patent application; and the present patent application hereby incorporates into itself by reference the texts of said Japanese Patent Application and the claims and the drawings thereof; a copy is appended to the present application. Further, the present inventors wish hereby to attract the attention of the examining authorities to copending Patent Applications Serial Nos. ............................ and .............................., which may be considered to be material to the examination of the present patent application.
In the prior art, the following aluminum alloys of the cast type and of the wrought type have been utilized as matrix metal for a composite material:

Cast type aluminum alloys

JIS standard AC8A (from about 0.8% to about 1.3% Cu, from about 11.0% to about 13.0% Si, from about 0.7% to about 1.3% Mg, from about 0.8% to about 1.5% Ni, remainder substantially Al)
JIS standard AC8B (from about 2.0% to about 4.0% Cu, from about 8.5% to about 10.5% Si, from about 0.5% to about 1.5% Mg, from about 0.1% to about 1% Ni, remainder substantially Al)
JIS standard AC4C (Not more than about 0.25% Cu, from about 6.5% to about 7.5% Si, from about 0.25% to about 0.45% Mg, remainder substantially AI)
AA standard A356 (from about 6.5% to about 7.5% Si, from about 0.25% to about 0.45% Mg, not more than about 0.2% Fe, not more than about 0.2% Cu, remainder substantially Al)
Al - from about 2% to about 3% Li alloy (DuPont)

Wrought type aluminum alloys

JIS standard 6061 (from about 0.4% to about 0.8% Si, from about 0.15% to about 0.4% Cu, from about 0.8% to about 1.2% Mg, from about 0.04% to about 035% Cr, remainder substantially Al)
JIS standard 5056 (not more than about 03% Si, not more than about 0.4% Fe, not more than about 0.1% Cu, from about 0.05% to about 0.2% Mn, from about 4.5% to about 5.6% Mg, from about 0.05% to about 0.2% Cr, not more than about 0.1% Zn, remainder substantially Al)
JIS standard 7075 (not more than about 0.4% Si, not more than about 0.5% Fe, from about 1.2% to about 2.0% Cu, not more than about 0.3% Mn, from about 2.1% to about 2.9% Mg, from about 0.18% to about 0.28% Cr, from about 5.1% to about 6.1% Zn, about 0.2% Ti, remainder substantially Al)
Previous research relating to composite materials incorporating aluminum alloys as their matrix metals has generally been carried out from the point of view and with the object of improving the strength and so forth of existing aluminum alloys, and therefore these aluminum alloys conventionally used in the manufacture of such prior art composite materials have not necessarily been of the optimum composition in relation to the type of reinforcing fibers utilized therewith to form a composite material, and therefore, in the case of using such conventional above mentioned aluminum alloys as the matrix metal for a composite material, it has not heretofore been attained to optimize the mechanical characteristics, and particularly the strength, of the composite materials using such aluminum alloys as matrix metal.

SUMMARY OF THE INVENTION

The inventors of the present application have considered the above mentioned problems in composite materials which use such conventional aluminum alloys as matrix metal, and in particular have considered the particular case of a composite material which utilizes alumina-silica type short fibers as reinforcing fibers, since such alumina-silica type short fibers, among the various reinforcing fibers used conventionally in the manufacture of a fiber reinforced metal composite material, have particularly high strength, and are exceedingly effective in improving the strength of the composite material. And the present inventors, as a result of various experimental researches to determine what composition of the aluminum alloy to be used as the matrix metal for such a composite material is optimum, have discovered that an aluminum alloy having a content of copper and a content of silicon within certain limits, and containing substantially no magnesium, nickel, zinc, and so forth is optimal as matrix metal, particularly in view of the bending strength characteristics of the resulting composite material. The present invention is based on the knowledge obtained from the results of the various experimental researches carried out by the inventors of the present application, as will be detailed later in this specification.
Accordingly, it is the primary object of the present invention to provide a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which enjoys superior mechanical characteristics such as bending strength.
It is a further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which is cheap.
It is a further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which, for similar values of mechanical characteristics such as bending strength, can incorporate a lower volume proportion of reinforcing fiber material than prior art such composite materials.
It is a further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which is improved over prior art such composite materials as regards machinability.
It is a further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which is improved over prior art such composite materials as regards workability.
It is a further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which has good characteristics with regard to amount of wear on a mating member.
It is a yet further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which is not brittle.
It is a yet further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which is durable.
It is a yet further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which has good wear resistance.
It is a yet further object of the present invention to provide such a composite material utilizing alumina-silica type short fibers as reinforcing material and aluminum alloy as matrix metal, which has good uniformity.
According to the most general aspect of the present invention, these and other objects are attained by a composite material, comprising a mass of alumina-silica short fibers embedded in a matrix of metal, said matrix metal being an alloy consisting essentially of between approximately 1.5% to approximately 6% of copper, between approximately 0.5% to approximately 2% of silicon, and remainder substantially aluminum. Preferably, the fiber volume proportion of said short fibers may be between approximately 5% and approximately 50%; and more preferably the fiber volume proportion of said short fibers may be between approximately 5% and approximately 40%. Even more preferably, the fiber volume proportion of said short fibers may be between approximately 5% and approximately 20%, in which case the copper content of said aluminum alloy matrix metal should be between approximately 2% and approximately 6%. The short fibers may be substantially all composed of alumina, which may be delta alumina; or, alternatively, substantially all said short fibers may be composed of amorphous alumina-silica; or, alternatively, said short fibers may have a substantial mullite crystalline content.
According to the present invention as described above, as reinforcing fibers there are used alumina-silica type short fibers which have high strength, and are exceedingly effective in improving the high temperature stability and strength of the resulting composite material, and as matrix metal there is used an aluminum alloy with a copper content of from approximately 1.5% to approximately 6%, a silicon content of from approximately 0.5% to approximately 2%, and the remainder substantially aluminum, and the volume proportion of the alumina-silica short fibers is desirably from approximately 5% to approximately 50%, whereby, as is clear from the results of experimental research carried out by the inventors of the present application as will be described below, a composite material with superior mechanical characteristics such as strength can be obtained.
Also according to the present invention, in cases where it is satisfactory if the same degree of strength as a conventional alumina-silica type short fiber reinforced aluminum alloy is obtained, the volume proportion of alumina-silica type short fibers in a composite material according to the present invention may be set to be lower than the value required for such a conventional composite material, and therefore, since it is possible to reduce the amount of alumina-silica short fibers used, the machinability and workability of the composite material can be improved, and it is also possible to reduce the cost of the composite material. Further, the characteristics with regard to wear on a mating member will be improved.
As will become clear from the experimental results detailed hereinafter, when copper and silicon are added to aluminum to make the matrix metal of the composite material according to the present invention, the strength of the aluminum alloy matrix metal is increased and thereby the strength of the composite material is improved, but that effect is not sufficient if the copper content is less than 15%, whereas if the copper content is more than 6% the composite material becomes very brittle, and has a tendency rapidly to disintegrate. Therefore the copper content of the aluminum alloy used as matrix metal in the composite material of the present invention is required to be in the range of from approximately 1.5% to approximately 6%. Furthermore, as will also become clear from the experimental results detailed hereinafter, with regard to the silicon which as specified above is to be added to the aluminum to make the matrix metal of the composite material according to the present invention, the strength of the aluminum alloy matrix metal is thereby increased and thereby the strength of the composite material is improved, but that effect is not sufficient if the silicon content is less than 0.5%, whereas if the silicon content is more than 2% the composite material becomes very brittle, and has a tendency rapidly to disintegrate. Therefore the silicon content of the aluminum alloy used as matrix metal in the composite material of the present invention is required to be in the range of from approximately 0.5% to approximately 2%.
It should be noted that, in the article entitled 'The fabrication and properties of metal matrix composites based on aluminum alloy infiltrated alumina fiber preforms" by M. G. Bader, T. W. Clyne, G. R. Cappleman, and P. A. Hubert published in 1984 in "Materials Science & Engineering", Vol. 65 No. 3, a composite material is described in which as matrix metal is used an aluminum alloy having a composition of 10 to 13% Si, 0.7 to 1.5% Cu, 0.7 to 1.5% Mg, 1.5% Ni, and remainder substantially aluminum. Furthermore, in Japanese Patent Application Sho 60-193416 (1985) and Japanese Patent Application Sho 60-193415 (1985), which are applications made by an applicant the same as the applicant of the Japanese Patent Application which is the parent of the present patent application and of which priority is claimed in the present patent application, and which are coowned or are subject to obligations of coassignment together with the present patent application and its said parent Japanese Patent Application, there are disclosed respectively a composite material in which the reinforcing fibers are silicon carbide short fibers or silicon nitride short fibers and the matrix metal is .an aluminum alloy having a copper content of 2 to 6%, a silicon content of 0.5% to 3%, and the remainder substantially aluminum, and a composite material having alumina-silica type short fibers as reinforcing fibers, and an aluminum- copper alloy as matrix metal, such that if the volume proportion of the short fibers is X (expressed in %) and the copper content is Y (expressed in %), then the following equations hold:

(where X is between 5% and 50%)
However, it is not hereby intended to admit any of the above identified documents as prior art to the present patent application except to the extent in any case mandated by applicable law.
Furthermore, in a composite material with an aluminum alloy of the above composition as matrix metal, as also will become clear from the experimental researches given hereinafter, if the volume proportion of the alumina-silica type short fibers is less than 5%, a sufficient strength cannot be obtained, and if the volume proportion of the alumina-silica type short fibers exceeds 40% and particularly if it exceeds 50% even if the volume proportion of the alumina-silica type short fibers is increased, the strength of the composite material is not very significantly improved. Also, the wear resistance of the composite material increases with the volume proportion of the alumina-silica type short fibers, but when the volume proportion of the alumina-silica type short fibers is in the range from zero to approximately 5% said wear resistance increases rapidly with an increase in the volume proportion of the alumina-silica type short fibers, whereas when the volume proportion of the alumina-silica type short fibers is in the range of at least approximately 5%, the wear resistance of the composite material does not very significantly increase with an increase in the volume proportion of said alumina-silica type short fibers. Therefore, according to one characteristic of the present invention, the volume proportion of the alumina-silica type short fibers is required to be in the range of from approximately 5% to approximately 50%, and preferably is required to be in the range of from approximately 5% to approximately 40%.
Furthermore, according to the results of experimental researches carried out by the inventors of the present application, when the volume proportion of the alumina-silica type short fibers is in a relatively low portion of the abovementioncd range, that is to say is between approximately 5% and approximately 20%, it is preferable that the copper content should be between approximately 2% and approximately 6%. Therefore, according to the above mentioned particular detailed characteristic of the present invention, the volume proportion of the alumina-silica type short fibers is desired to be between about 5% and about 20%, and the copper content is desired to be between about 2% and about 6%.
If, furthermore, the copper content or the silicon content of the aluminum alloy used as matrix metal of the composite material of the present invention has a relatively high value, if there are unevennesses in the concentration of the copper or the silicon within the aluminum alloy, the portions where the copper concentration or the silicon concentration is high will be brittle, and it will not therefore be possible to obtain a uniform matrix metal or a composite material of good and uniform quality. Therefore, according to another detailed characteristic of the present invention, in order that the concentrations of copper and silicon within the aluminum alloy matrix metal should be uniform, such a composite material is subjected to liquidizing processing for from about 2 hours to about 8 hours at a temperature of from about 480°C to about 520°C, and is preferably further subjected to aging processing for about 2 hours to about 8 hours at a temperature of from about 150°C to 200°C.
Further, the alumina-silica short fibers used in the composite material of the present invention may either be alumina non continuous fibers or may be alumina continuous fibers cut to a predetermined length. These alumina-silica short fibers, also, may be either alumina short fibers having a composition of from about 80% to about 100% A1₂0₃ and remainder substantially Si0₂, or may be crystalline or amorphous alumina-silica short fibers having a composition of not less than about 35% and not more than about 80% Al₂O₃ and remainder substantially Si0₂. In the case that the alumina-silica short fibers arc alumina short fibers, the crystalline structure of the Al₂O₃ may be any one of the alpha, the gamma, or the delta crystalline structures. Also, the fiber length of the alumina-silica type short fibers is preferably from approximately 10 microns to approximately 7 cm, and particularly is from approximately 10 microns to approximately 5 cm, and the fiber diameter is preferably from approximately 1 micron to approximately 30 microns, and particularly is from approximately 1 micron to approximately 25 microns.
Particularly in the case that as the alumina-silica type short fibers are used crystalline alumina-silica short fibers (alumina-silica short fibers including mullite crystals), then in the case that the matrix metal is an aluminum alloy of the composition described above, even in the case that the mullite crystalline amount has a relatively low value, as will be shown by the results of some of the experimental researches to be detailed hereinafter, the bending strength of the composite material has a relatively high value, and the variation in the bending strength of the composite material with variation in the mullite crystalline amount is relatively small, as a result of which it is considered that the mullite crystalline amount of the crystalline alumina-silica short fibers may have any value, in the composite material of this invention.
It should be noted that in this specification all percentages, except in the expression of volume proportion of reinforcing fiber material, are percentages by weight, and in expressions of the composition of an aluminum alloy, "substantially aluminum" means that, apart from aluminum, copper and silicon, the total of the inevitable metallic elements such as silicon, iron, zinc, manganese, nickel, titanium, and chromium included in the aluminum alloy used as matrix metal is not more than about 1%, and each of said elements individually is not present to more than about 0.5%. Further, in expressions relating to the composition of the alumina-silica type short fibers, the expression "substantially Si02" means that, apart from the Al₂O₃ and the Si0₂ making up the alumina-silica short fibers, other elements are present only to such extents as to constitute impurities. It should further be noted that, in this specification, in descriptions of ranges of compositions, temperatures and the like, the expressions "at least", "not less than", "at most", "no more than", and "from - to -" and so on are intended to include the boundary values of the respective ranges.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with respect to the preferred embodiments thereof, and with reference to the illustrative drawings appended hereto, which however are provided for the purposes of explanation and exemplification only, and are not intended to be limitative of the scope of the present invention in any way, since this scope is to be delimited solely by the accompanying claims. With relation to the figures, spatial terms are to be understood as referring only to the orientation on the drawing paper of the illustrations of the relevant parts, unless otherwise specified; like reference numerals, unless otherwise so specified, denote the same parts and gaps and spaces and so on in the various figures relating to one preferred embodiment, and like parts and gaps and spaces and so on in the figures relating to different preferred embodiments; and:

Fig. 1 is a set of graphs in which copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the first set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing delta type alumina short fiber material was approximately 40%), each said graph showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage silicon content of in the matrix metal of the composite material;
Fig. 2 is a set of graphs, similar to Fig. 1 for the first set of preferred embodiments, in which copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the second set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing delta type alumina short fibers was approximately 30%), each said graph showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 3 is a set of graphs, similar to Fig. 1 for the first set of preferred embodiments and Fig. 2 for the second preferred embodiment set, in which copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the third set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing delta type alumina short fibers was approximately 20%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 4 is a set of graphs, similar to Figs. 1, 2, and 3 for the first through the third sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the fourth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing delta type alumina short fibers was now approximately 10%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 5 is a set of graphs, similar to Figs. 1, 2, 3, and 4 for the first through the fourth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the fifth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing delta type alumina short fibers was now approximately 5%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 6 is a set of graphs, similar to Figs. 1 through 5 for the first through the fifth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the sixth set of preferred embodiments of the material of the present invention (in which the volume proportion of, this time, reinforcing crystalline alumina short fibers was now approximately 40%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 7 is a set of graphs, similar to Figs. 1 through 6 for the first through the sixth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the seventh set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing crystalline alumina short fibers was now approximately 30%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 8 is a set of graphs, similar to Figs. 1 through 7 for the first through the seventh sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the eighth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing crystalline alumina short fibers was now approximately 20%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 9 is a set of graphs, similar to Figs. 1 through 8 for the first through the eighth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the ninth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing crystalline alumina short fibers was now approximately 10%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 10 is a set of graphs, similar to Figs. 1 through 9 for the first through the ninth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the tenth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing crystalline alumina short fibers was now approximately 5%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 11 is a set of graphs, similar to Figs. 1 through 10 for the first through the tenth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the eleventh set of preferred embodiments of the material of the present invention (in which the volume proportion of, this time, reinforcing amorphous alumina-silica short fibers was now approximately 40%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 12 is a set of graphs, similar to Figs. 1 through 11 for the first through the eleventh sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the twelfth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing amorphous alumina-silica short fibers was now approximately 30%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 13 is a set of graphs, similar to Figs. 1 through 12 for the first through the twelfth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the thirteenth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing amorphous alumina-silica short fibers was now approximately 20%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 14 is a set of graphs, similar to Figs. 1 through 13 for the first through the thirteenth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the fourteenth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing amorphous alumina-silica short fibers was now approximately 10%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 15 is a set of graphs, similar to Figs. 1 through 14 for the first through the fourteenth sets of preferred embodiments respectively, in which again copper content in percent is shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for the fifteenth set of preferred embodiments of the material of the present invention (in which the volume proportion of reinforcing amorphous alumina-silica short fibers was now approximately 5%), each said graph similarly showing the relation between copper content and bending strength of certain composite material test pieces for a particular fixed percentage content of silicon in the matrix metal of the composite material;
Fig. 16 is a set of three graphs relating to three sets of tests in which the fiber volume proportions of reinforcing alumina-silica short fiber materials of three different types were varied, in which said reinforcing fiber volumes in percent are shown along the horizontal axis and bending strength in kg/mm² is shown along the vertical axis, derived from data relating to bending strength tests for certain ones of a sixteenth set of preferred embodiments of the material of the present invention, said graph showing the relation between volume proportion of the reinforcing alumina-silica short fiber material and bending strength of certain test pieces of the composite material;
Fig. 17 is a graph, in which mullite crystalline content in percent is shown along the horizontal axis and bending strength in kg/mm is shown along the vertical axis, derived from data relating to bending strength tests for various composite materials having crystalline alumina-silica short fiber material with varying amounts of the mullite crystalline form therein as reinforcing material and an alloy containing approximately 3% of copper, approximately 2% of silicon, and remainder substantially aluminum as matrix metal, and showing the relation between the mullite crystalline percentage of the reinforcing short fiber material of the composite material test pieces and their bending strengths;
Fig. 18 is a perspective view of a preform made of alumina-silica type short fiber material, with said alumina-silica type short fibers being aligned substantially randomly in two dimensions in the planes parallel to its larger two faces while being stacked in the third dimension perpendicular to said planes and said faces, for incorporation into composite materials according to various preferred embodiments of the present invention;
Fig. 19 is a perspective view, showing said preform made of alumina-silica type non continuous fiber material enclosed in a stainless steel case one end at least of which is open, for incorporation into said composite materials; and:
Fig. 20 is a schematic sectional diagram showing a high pressure casting device in the process of performing high pressure casting for manufacturing a composite material with the alumina-silica type short fiber material preform material of Figs. 18 and 19 being incorporated in a matrix of matrix metal.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described with reference to the various preferred embodiments thereof. It should be noted that all of the four tables referred to in this specification are to be found at the end of the specification and before the claims thereof: the present specification is arranged in such a manncr in order to maximize ease of pagination.

THE FIRST SET OF PREFERRED EMBODIMENTS

In order to assess what might be the most suitable composition for an aluminum alloy to be utilized as matrix metal for a contemplated composite material of the type described in the preamble to this specification, the reinforcing material of which is to be, in this case, alumina short fibers, the present inventors manufactured by using the high pressure casting method samples of various composite materials, utilizing as reinforcing material alumina short fiber material of type "Saffil RF' (this is a trademark) made by ICI K.K., which had composition about 95% delta Al₂O₃ and remainder substantially Si0₂, with the content of non fibrous particles of diameter more than about 150 microns being about 0.5%, and which had average fiber length about 2 cm and average fiber diameter about 3 microns, and utilizing as matrix metal Al-Cu-Si type aluminum alloys of various compositions. Then the present inventors conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of aluminum alloys designated as A1 through A64 were produced, having as base material aluminum and having various quantities of silicon and copper mixed therewith, as shown in the appended Table 1; this was done by, in each case, combining an appropriate quantity of substantially pure aluminum metal (purity at least 99%), an appropriate quantity of a mother alloy of approximately 50% aluminum and approximately 50% copper, and an appropriate quantity of a mother alloy of approximately 75% aluminum and approximately 25% silicon. And an appropriate number of alumina short fiber material preforms were made by, in each case, subjecting a quantity of the above specified alumina short fiber material to compression forming without using any binder. Each of these alumina short fiber material preforms was, as schematically illustrated in perspective view in Fig. 18 wherein an exemplary such preform is designated by the reference numeral 2 and the alumina-silica short fibers therein are generally designated as 1, about 38 x 100 x 16 mm in dimensions, and the individual alumina-silica short fibers 1 in said preform 2 were oriented as overlapping in a two dimensionally random manner in planes parallel to the 38 x 100 mm plane while being stacked in the direction perpendicular to this plane. And the fiber volume proportion in each of said preforms 2 was approximately 40%.
Next, each of these alumina-silica short fiber material preforms 2 was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through Λ64 described above, in the following manner. First, the preform 2 was was inserted into a stainless steel case 2a which was about 38 x 100 x 16 mm in dimensions and had at least one of its ends open. After this, each of these stainless steel cases 2a with its preform 2 held inside it was heated up to a temperature of approximately 600°C, and then said preform 2 was placed within a mold cavity 4 of a casting mold 3, which itself had previously been preheated up to a temperature of approximately 250°C. Next, a quantity 5 of the appropriate one of the aluminum alloys A1 to Λ64 described above, molten and maintained at a temperature of approximately 710°C, was relatively rapidly poured into said mold cavity 4, so as to surround the preform 2 therein, and then as shown in schematic perspective view in Fig. 20 a pressure plunger 6, which itself had previously been preheated up to a temperature of approximately 200°C, and which closely cooperated with the upper portion of said mold cavity 4, was inserted into said upper mold cavity portion, and was pressed downwards by a means not shown in the figure so as to pressurize said molten aluminum alloy quantity 5 and said preform 2 to a pressure of approximately 1000 kg/cm². Thereby, the molten aluminum alloy was caused to percolate into the interstices of the alumina-silica short fiber material preform 2. This pressurized state was maintained until the quantity 5 of molten aluminum alloy had completely solidified, and then the pressure plunger 6 was removed and the solidified aluminum alloy mass with the stainless steel case 2a and the preform 2 included therein was removed from the casting mold 3, and the peripheral portion of said solidified aluminum alloy mass and also the stainless steel case 2a were machined away, leaving only a sample piece of composite material which had alumina-silica short fiber material as reinforcing material and the appropriate one of the aluminum alloys Al through A64 as matrix metal. The volume proportion of alumina-silica short fiber material in each of the resulting composite material sample pieces was approximately 40%.
Next, the following post processing steps were performed on the composite material samples. First, they were subjected to liquidizing processing at a temperature of approximately 510°C for approximately 8 hours, and then they were subjected to artificial aging processing at a temperature of approximately 160°C for approximately 8 hours. Then, from each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of length approximately 50 mm, width approximately 10 mm, and thickness approximately 2 mm, with the planes of random fiber orientation extending parallel to the 50 mm x 10 mm faces of said test pieces, and for each of these composite material bending strength test pieces a three point bending strength test was carried out, with a gap between supports of approximately 40 mm. In these bending strength tests, the bending strength of the composite material bending strength test pieces was measured as the surface stress at breaking point M/Z (M is the bending moment at the breaking point, while Z is the cross section coefficient of the composite material bending strength test piece).
The results of these bending strength tests were as shown in the last or rightmost column of the appended Table 2, and as summarized in the line graphs of Fig.1. This rightmost column of Table 2 shows, for this case of 40% volume proportion of the reinforcing alumina-silica fiber material, the values of the bending strength (in kg/mm²) for each of the test sample pieces. And each of the line graphs of Fig. 1 shows the relation between copper content (in percent) and the bending strength (in kg/mm²) shown along the vertical axis of certain of the composite material test pieces having as matrix metals aluminum alloys with percentage content of copper as shown along the horizontal axis and with percentage content of silicon fixed along said line graph, and having as reinforcing material the alumina-silica fibers specified above.
From Table 2 and from Fig. 1 it will be understood that, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 05%, approximately 1%, and approximately 2%, except in the extreme case that the copper content was approximately 6%, the bending strength of the composite material was the same or higher than the bending strength of a composite material in which the silicon content was substantially 0%, and, except for the case that the copper content was in the range of approximately 1% or less, was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly along with an increase in the copper content in the ranges of approximately 1% to approximately 3.5%, approximately 1% to approximately 2.5%, and approximately 1% to approximately 3%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 4%, approximately 3.5%, and approximately 3%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5%; and, yet further, in the particular cases that the copper content was approximately 6% or was approximately 6.5%, the bending strength of the composite material test sample pieces had substantially the same value, as when the copper content was approximately 1.5% or approximately 1%, respectively.
It will be further seen that the values in Fig. 1 are generally higher than the typical bending strength of approximately 50 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar alumina short fiber material as reinforcing material in a volume proportion of approximately 40%. Further, it will be seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values are between approximately 1.14 and approximately 1.54 times said typical bending strength of approximately 50 kg/mm² attained by the above mentioned conventional composite material.
From the results of these bending strength tests it will be seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material alumina short fibers in a volume proportion of approximately 40% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Λl-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6% while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE SECOND SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, again utilizing as reinforcing material the same alumina short type fiber material, and utilizing as matrix metal substantially the same sixty four types of Al-Cu-Si type aluminum alloys, but this time employing a fiber volume proportion of only approximately 30%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first set of preferred embodiments were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of alumina short type fiber material preforms were as before made by the method disclosed above with respect to the first set of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 30%, by contrast to the first set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first set of preferred embodiments.
Next, substantially as before, each of these alumina short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had alumina short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through Λ64 as matrix metal. The volume proportion of alumina short type fibers in each of the resulting composite material sample pieces was thus now approximately 30%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the first set of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the penultimate column of Table 2 and as summarized in the graphs of Fig. 2; thus, Fig. 2 corresponds to Fig. 1 relating to the first set of preferred embodiments. In the graphs of Fig. 2, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 2 and from Fig. 2 it will be again similarly understood that, in this case that the volume proportion of the reinforcing alumina short fiber material was approximately 30%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or higher than the bending strength of a composite material in which the silicon content was substantially 0%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly along with an increase in the copper content in the range of approximately 1% to approximately 1.5%; and said bending strength attained a substantially maximum value when the copper content was approximately 4%, approximately 3.5% to approximately 4%, and approximately 3%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular cases that the copper content was approximately 6% or was approximately 6.5%, the bending strength of the composite material test sample pieces had substantially the same value, as when the copper content was approximately 1.5% or approximately 1%, respectively.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.21 and approximately 157 times the typical bending strength of approximately 47 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar alumina short fiber material as reinforcing material in a similar volume proportion of approximately 30%.
From the results of these bending strength tests it will be seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material alumina short fibers in a volume proportion of approximately 30% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6% while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE THIRD SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same alumina short type fiber material, and utilizing as matrix metal substantially the same sixty four types of Al-Cu-Si type aluminum alloys, but this time employing a fiber volume proportion of only approximately 20%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the previously described sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of alumina short type fiber material preforms were as before made by the method disclosed above with respect to the previously described sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 20%, by contrast to the first and second sets of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first and second sets of preferred embodiments.
Next, substantially as before, each of these alumina short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had alumina short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of alumina short type fibers in each of the resulting composite material sample pieces was thus now approximately 20%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the first and second sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the central column of Table 2 and as summarized in the graphs of Fig. 3; thus, Fig. 3 corresponds to Fig. 1 relating to the first set of preferred embodiments and to Fig. 2 relating to the second set of preferred embodiments. In the graphs of Fig. 3, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 2 and from Fig. 3 it will be again similarly understood that, in this case that the volume proportion of the reinforcing alumina short fiber material was approximately 20%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximately 6%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%, except for those of the test pieces which had copper content less than approximately 1%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1% to approximately 3%, approximately 1.5% to approximately 2.5%, and approximately 1.5% to approximately 3%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5% to approximately 5%, and approximately 3.5%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 6.5%, the bending strength of the composite material test sample pieces had substantially the same value, as when the copper content was approximately 1%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.07 and approximately 1.65 times the typical bending strength of approximately 43 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar alumina short fiber material as reinforcing material in a similar volume proportion of approximately 20%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material alumina short fibers in a volume proportion of approximately 20% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Λl-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6% and more desirably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE FOURTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same alumina short type fiber material, and utilizing as matrix metal substantially the same sixty four types of AI-Cu-Si type aluminum alloys, but this time employing a fiber volume proportion of only approximately 10%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the third sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of alumina short type fiber material preforms were as before made by the method disclosed above with respect to the first through the third sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 10%, by contrast to the first through the third sets of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the third sets of preferred embodiments.
Next, substantially as before, each of these alumina short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had alumina short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of alumina short type fibers in each of the resulting composite material sample pieces was thus now approximately 10%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the second column of Table 2 and as summarized in the graphs of Fig. 4; thus, Fig. 4 corresponds to Figs. 1 through 3 relating to the first through the third sets of preferred embodiments, respectively. In the graphs of Fig. 4, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 2 and from Fig. 4 it will be again similarly understood that, in this case that the volume proportion of the reinforcing alumina short fiber material was approximately 10%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximately 6%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%, except for those of the test pieces which had copper content less than approximately 1%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1.5% to approximately 5%, approximately 1.5% to approximately 4.5%, and approximately 1.5% to approximately 4%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5%, and approximately 4%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 6.5%, the bending strength of the composite material test sample pieces had a lower value than when the copper content was approximately 1.5%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.08 and approximately 1.74 times the typical bending strength of approximately 38 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar alumina short fiber material as reinforcing material in a similar volume proportion of approximately 10%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material alumina short fibers in a volume proportion of approximately 10% and having as matrix metal an Λl-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6% and more desirably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE FIFTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same alumina short type fiber material, and utilizing as matrix metal substantially the same sixty four types of Al-Cu-Si type aluminum alloys, but this time employing a fiber volume proportion of only approximately 5%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the fourth sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of alumina short type fiber material preforms were as before made by the method disclosed above with respect to the first through the fourth sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 5%, by contrast to the first through the fourth sets of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the fourth sets of preferred embodiments.
Next, substantially as before, each of these alumina short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had alumina short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of alumina short type fibers in each of the resulting composite material sample pieces was thus now approximately 5%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the first column of Table 2 and as summarized in the graphs of Fig. 5; thus, Fig. 5 corresponds to Figs. 1 through 4 relating to the first through the fourth sets of preferred embodiments, respectively. In the graphs of Fig. 5, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 2 and from Fig. 5 it will be again similarly understood that, in this case that the volume proportion of the reinforcing alumina short fiber material was approximately 5%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximately 6%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1.5% to approximately 5%, approximately 1.5% to approximately 3.5%, and approximately 1.5% to approximately 2.5%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5%, and approximately 4%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 6.5%, the bending strength of the composite material test sample pieces had a lower value, than when the copper content was approximately 1.5%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.06 and approximately 1.60 times the typical bending strength of approximately 35 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar alumina short fiber material as reinforcing material in a similar volume proportion of approximately 5%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material alumina short fibers in a volume proportion of approximately 5% and having as matrix metal an AI-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6% and more desirably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said AI-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

COMMENTS ON THE FIRST THROUGH THE FIFTH SETS OF

PREFERRED EMBODIMENTS

From the first through the fifth sets of preferred embodiments disclosed above, it will be understood that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material alumina short fibers and having as matrix metal an Al-Cu-Si type aluminum alloy, irrespective of the particular volume proportions of the short fibers, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6% while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%; and, particularly in the particular case that the fiber volume proportion of the alumina short fibers is in the range of from approximately 5% to approximately 20%, it is preferable that the copper content of said AI-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 2% to approximately 6%.

FURTHER VARIANT EMBODIMENTS

Further, although the details are not disclosed in this specification in the interests of brevity of description, in fact, bending strength tests in the same manner and under the same conditions as in these first through the fifth sets of preferred embodiments were conducted, except that as alumina - silica type short fibers there were used alumina short fibers obtained by cutting alumina continuous fiber material of the type "Sumika Alumina Fibers" manufactured by Sumitomo Kagaku Kogyo K.K., which were composed approximately of 85% gamma type A1₂0₃ and which had average fiber diameter approximately 17 microns, to a length of approximately 1 cm. The results of these tests showed a similar trend to that of the results for the first through the fifth sets of preferred embodiments detailed above and shown in Figs. 1 through 5. From these tests it could be discerned that, also in the case that such alumina short fibers having their main constituent being gamma type Al_z0₃ were used as the alumina - silica type short reinforcing fiber material for the composite material of the present invention, the copper and silicon content required to obtain a composite material of superior bending strength was substantially as detailed above. Yet further, although again the details are not disclosed in this specification in the interests of brevity of description, in fact, bending strength tests in the same manner and under the same conditions as in these first through the fifth sets of preferred embodiments were conducted, except that as alumina - silica type short fibers there were used alumina short fibers obtained by cutting continuous alumina short fiber material of the type "FP fiber" manufactured by Dupont, which were composed approximately of 99.5% alpha type A1203 and which had average fiber diameter 20 microns, to a length of approximately 1 cm. Again, the results of these tests showed a similar trend to that of the results for the first through the fifth sets of preferred embodiments detailed above and shown in Figs. 1 through 5. From these tests it could be discerned that, also in the case that such alumina short fibers having their main constituent being alpha type Al₂O₃ were used as the alumina - silica type short reinforcing fiber material for the composite material of the present invention, the copper and silicon content required to obtain a composite material of superior bending strength was substantially as detailed above.

THE SIXTH SET OF PREFERRED EMBODIMENTS

For the sixth set of preferred embodiments of the present invention, a different type of reinforcing fiber was chosen. The present inventors manufactured by using the high pressure casting method samples of various composite materials, utilizing as matrix metal Al-Cu-Si type aluminum alloys of various compositions, and utilizing as reinforcing material crystalline alumina-silica short fiber material, formed by subjecting a quantity of amorphous alumina-silica type short fiber material of the type "KaoWool" (this is a trademark) made by Isolite Babcock Taika K.K., which was a material composed of approximately 49% Alz03 and remainder substantially SiO₂, and having average fiber diameter about 3 microns and average fiber length about 1 mm, and with its content of non fibrous particles with particle diameter at least 150 microns being about 0.7%, to heat processing, so that the mullite crystalline amount included in said alumina-silica short fibers was raised to approximately 60%. Then the present inventors conducted evaluations of the bending strength of the various resulting composite material sample pieces.
In detail, first, a set of aluminum alloys the same as those designated as A1 through A64 for the first five sets of preferred embodiments were produced in the same manner as before, and the same number of fiber material preforms were then made by applying compression forming to masses of the above described crystalline alumina-silica short fiber material, without using any binder, in substantially the same way as in the first set of preferred embodiments described above. Each of the resulting crystalline alumina-silica fiber material preforms had dimensions and three dimensional fiber orientation characteristics substantially as in the first through the fifth sets of preferred embodiments, and said preforms all had a volume proportion of the crystalline alumina-silica short fibers of approximately 40%.
Next, substantially as before, each of these crystalline alumina-silica fiber material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as in the first set of preferred embodiments. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass, along with the stainless steel case utilized, was machined away, leaving, in each case, only a sample piece of composite material which had crystalline alumina-silica fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of crystalline alumina-silica fibers in the resulting composite material sample pieces was thus now approximately 40%. And post processing steps of liquidizing processing and artificial aging processing were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions substantially as before. And then, for each of these composite material bending strength test pieces, a bending strength test was carried out, again substantially as before and utilizing the same operational parameters.
The results of these bending strength tests were as shown in the last column of Table 3 and as summarized in the graphs of Fig. 6; thus, Fig. 6 corresponds to Figs. 1 through 5 relating to the first through the fifth sets of preferred embodiments, respectively. In the graphs of Fig. 6, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 3 and from Fig. 6 it will be again similarly understood that, in this case that the volume proportion of the reinforcing crystalline alumina-silica short fiber material was approximately 40%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or higher than the bending strength of a composite material in which the silicon content was substantially 0%, and, except for those of the test pieces which had copper content less than approximately 1% or greater than approximately 6%, was the same as or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1% to approximately 2.5%, approximately 1% to approximately 2.5%, and approximately 1% to approximately 3%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 4%, approximately 3.5%, and approximately 3%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5%; and, yet further, in the particular case that the copper content was approximately 6%, the bending strength of the composite material test sample pieces had a value substantially the same, as when the copper content was approximately 15%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.15 and approximately 1.62 times the typical bending strength of approximately 47 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar crystalline alumina-silica short fiber material as reinforcing material in a similar volume proportion of approximately 40%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material crystalline alumina-silica short fibers in a volume proportion of approximately 40% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6%, while the silicon content of said AI-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE SEVENTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same crystalline alumina short type fiber material as utilized in the sixth set of preferred embodiments described above, and utilizing as matrix metal substantially the same sixty four types of AI-Cu-Si type aluminum alloys as utilized in the previously described embodiments, but this time employing a fiber volume proportion of only approximately 30%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the sixth sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of crystalline alumina short type fiber material preforms were as before made by the method disclosed above with respect to the sixth set of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 30%, by contrast to the sixth set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the sixth sets of preferred embodiments.
Next, substantially as before, each of these crystalline alumina short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had crystalline alumina short type fiber material as reinforcing material and the appropriate one of the aluminum alloys Al through A64 as matrix metal. The volume proportion of crystalline alumina short type fibers in each of the resulting composite material sample pieces was thus now approximately 30%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the penultimate column of Table 3 and as summarized in the graphs of Fig. 7; thus, Fig. 7 corresponds to Figs. 1 through 6 relating to the first through the sixth sets of preferred embodiments, respectively. In the graphs of Fig. 7, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 3 and from Fig. 7 it will be again similarly understood that, in this case that the volume proportion of the reinforcing crystalline alumina short fiber material was approximately 30%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximately 5.5%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1% to approximately 3.5%, approximately 1% to approximately 3%, and approximately 1% to approximately 3%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 4%, approximately 3.5%, and approximately 3%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5%; and, yet further, in the particular case that the copper content was approximately 6.5%, the bending strength of the composite material test sample pieces had a value approximately the same, as when the copper content was approximately 1%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.14 and approximately 1.61 times the typical bending strength of approximately 44 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar crystalline alumina short fiber material as reinforcing material in a similar volume proportion of approximately 30%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material crystalline alumina short fibers in a volume proportion of approximately 30% and having as matrix metal an AI-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 15% to approximately 6%, while the silicon content of said AI-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE EIGHTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same crystalline alumina short type fiber material as utilized in the sixth and seventh sets of preferred embodiments described above, and utilizing as matrix metal substantially the same sixty four types of Al-Cu-Si type aluminum alloys as utilized in the previously described embodiments, but this time employing a fiber volume proportion of only approximately 20%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the seventh sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of crystalline alumina short type fiber material preforms were as before made by the method disclosed above with respect to the sixth and seventh sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 20%, by contrast to the seventh set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the seventh sets of preferred embodiments.
Next, substantially as before, each of these crystalline alumina short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had crystalline alumina short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of crystalline alumina short type fibers in each of the resulting composite material sample pieces was thus now approximately 20%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the central column of Table 3 and as summarized in the graphs of Fig. 8; thus, Fig. 8 corresponds to Figs. 1 through 7 relating to the first through the seventh sets of preferred embodiments, respectively. In the graphs of Fig. 8, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 3 and from Fig. 8 it will be again similarly understood that, in this case that the volume proportion of the reinforcing crystalline alumina short fiber material was approximately 20%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or considerably higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximately 6%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%, except for those of the test pieces which had copper content less than approximately 1%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1% to approximately 3.5%, approximately 1.5% to approximately 3%, and approximately 1.5% to approximately 3%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5%, and from approximately 3.5% to approximately 4%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 55%; and, yet further, in the particular case that the copper content was approximately 6%, the bending strength of the composite material test sample pieces had a value approximately the same, as when the copper content was approximately 1%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.10 and approximately 1.66 times the typical bending strength of approximately 41 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar crystalline alumina short fiber material as reinforcing material in a similar volume proportion of approximately 20%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material crystalline alumina short fibers in a volume proportion of approximately 20% and having as matrix metal an AI-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6%, and particularly more preferably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE NINTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same crystalline alumina short type fiber material as utilized in the sixth through the eighth sets of preferred embodiments described above, and utilizing as matrix metal substantially the same sixty four types of Al-Cu-Si type aluminum alloys as utilized in the previously described embodiments, but this time employing a fiber volume proportion of only approximately 10%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the eighth sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of crystalline alumina short type fiber material preforms were as before made by the method disclosed above with respect to the sixth through the eighth sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 10%, by contrast to the eighth set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the cighth sets of preferred embodiments.
Next, substantially as before, each of these crystalline alumina short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had crystalline alumina short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of crystalline alumina short type fibers in each of the resulting composite material sample pieces was thus now approximately 10%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the second column of Table 3 and as summarized in the graphs of Fig. 9; thus, Fig. 9 corresponds to Figs. 1 through 8 relating to the first through the eighth sets of preferred embodiments, respectively. In the graphs of Fig. 9, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 3 and from Fig. 9 it will be again similarly understood that, in this case that the volume proportion of the reinforcing crystalline alumina short fiber material was approximately 10%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or considerably higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximately 6%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1.5% to approximately 2.5%, approximately 1.5% to approximately 2.5%, and approximately 1.5% to approximately 3%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5%, and approximately 4%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 6.5%, the bending strength of the composite material test sample pieces had a value substantially lower than when the copper content was approximately 1%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.03 and approximately 1.56 times the typical bending strength of approximately 39 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar crystalline alumina short fiber material as reinforcing material in a similar volume proportion of approximately 10%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material crystalline alumina short fibers in a volume proportion of approximately 10% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Λl-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6%, and particularly more preferably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE TENTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same crystalline alumina short type fiber material as utilized in the sixth through the ninth sets of preferred embodiments described above, and utilizing as matrix metal substantially the same sixty four types of Al-Cu-Si type aluminum alloys as utilized in the previously described embodiments, but this time employing a fiber volume proportion of only approximately 5%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the ninth sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of crystalline alumina short type fiber material preforms were as before made by the method disclosed above with respect to the sixth through the ninth sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 5%, by contrast to the ninth set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the ninth sets of preferred embodiments.
Next, substantially as before, each of these crystalline alumina short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys A1 through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had crystalline alumina short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of crystalline alumina short type fibers in each of the resulting composite material sample pieces was thus now approximately 5%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the first column of Table 3 and as summarized in the graphs of Fig. 10; thus, Fig. 10 corresponds to Figs. 1 through 9 relating to the first through the ninth sets of preferred embodiments, respectively. In the graphs of Fig. 10, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 3 and from Fig. 10 it will be again similarly understood that, in this case that the volume proportion of the reinforcing crystalline alumina short fiber material was approximately 5%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or considerably higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximatcly 6%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1% to approximately 5%, approximately 1.5% to approximately 2.5%, and approximately 1.5% to approximately 2.5%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5%, and approximately 4%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 6.5%, the bending strength of the composite material test sample pieces had a value substantially lower than when the copper content was approximately 1%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.03 and approximately 1.54 times the typical bending strength of approximately 35 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar crystalline alumina short fiber material as reinforcing material in a similar volume proportion of approximately 5%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material crystalline alumina short fibers in a volume proportion of approximately 5% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6%, and particularly more preferably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said AI-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

COMMENTS ON THE SIXTH THROUGH THE TENTH SETS OF

PREFERRED EMBODIMENTS

From the sixth through the tenth sets of preferred embodiments disclosed above, it will be understood that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material crystalline alumina-silica short fibers and having as matrix metal an Al-Cu-Si type aluminum alloy, irrespective of the particular volume proportions of the crystalline alumina-silica short fibers, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6% while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%; and, particularly in the particular case that the fiber volume proportion of the crystalline alumina-silica short fibers is in the range of from approximately 5% to approximately 20%, it is preferable that the copper content of said AI-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 2% to approximately 6%.

THE ELEVENTH SET OF PREFERRED EMBODIMENTS

For the eleventh set of preferred embodiments of the present invention, a different type of reinforcing fiber was chosen. The present inventors manufactured by using the high pressure casting method samples of various composite materials, utilizing as matrix metal Al-Cu-Si type aluminum alloys of various compositions, and utilizing as reinforcing material amorphous alumina-silica short fiber material of the type "KaoWool" (this is a trademark) made by Isolite Babcock Taika K.K., which was a material composed of approximately 49% Al₂O₃ and remainder substantially Si0₂, and having average fiber diameter about 3 microns and average fiber length about 1 mm, and with its content of non fibrous particles with particle diameter at least 150 microns being about 0.7%. Then the present inventors conducted evaluations of the bending strength of the various resulting composite material sample pieces.
In detail, first, a set of aluminum alloys the same as those designated as A1 through A64 for the first five sets of preferred embodiments were produced in the same manncr as before, and the same number of fiber material preforms were then made by applying compression forming to masses of the above described amorphous alumina-silica short fiber material, without using any binder, in substantially the same way as in the first set of preferred embodiments described above. Each of the resulting amorphous alumina-silica fiber material preforms had dimensions and three dimensional fiber orientation characteristics substantially as in the previously described sets of preferred embodiments, and said preforms all had a volume proportion of the amorphous alumina-silica short fibers of approximately 40%.
Next, substantially as before, each of these amorphous alumina-silica fiber material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys Al through A64 described above, utilizing operational parameters substantially as in the first set of preferred embodiments. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass, along with the stainless steel case utilized, was machined away, leaving, in each case, only a sample piece of composite material which had amorphous alumina-silica fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of amorphous alumina-silica fibers in the resulting composite material sample pieces was thus now approximately 40%. And post processing steps of liquidizing processing and artificial aging processing were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions substantially as before. And then, for each of these composite material bending strength test pieces, a bending strength test was carried out, again substantially as before and utilizing the same operational parameters.
The results of these bending strength tests were as shown in the last column of Table 4 and as summarized in the graphs of Fig. 11; thus, Fig. 11 corresponds to Figs. 1 through 10 relating to the first through the tenth sets of preferred embodiments, respectively. In the graphs of Fig. 11, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 4 and from Fig. 11 it will be again similarly understood that, in this case that the volume proportion of the reinforcing amorphous alumina-silica short fiber material was approximately 40%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5_%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or higher than the bending strength of a composite material in which the silicon content was substantially 0%, and was the same as or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1% to approximately 2.5%, approximately 1% to approximately 2.5%, and approximately 1% to approximately 3%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 4%, approximately 3.5%, and approximately 3%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 6%, the bending strength of the composite material test sample pieces had a value substantially the same, as when the copper content was approximately 1.5%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.15 and approximately 1.61 times the typical bending strength of approximately 46 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar amorphous alumina-silica short fiber material as reinforcing material in a similar volume proportion of approximately 40%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material amorphous alumina-silica short fibers in a volume proportion of approximately 40% and having as matrix metal an AI-Cu-Si type aluminum alloy, it is preferable that the copper content of said Λl-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE TWELFTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same amorphous alumina-silica short type fiber material as utilized in the eleventh set of preferred embodiments described above, and utilizing as matrix metal substantially the same sixty four types of Al-Cu-Si type aluminum alloys as utilized in the previously described embodiments, but this time employing a fiber volume proportion of only approximately 30%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the eleventh sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of amorphous alumina-silica short type fiber material preforms were as before made by the method disclosed above with respect to the eleventh set of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 30%, by contrast to the eleventh set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the eleventh sets of preferred embodiments.
Next, substantially as before, each of these amorphous alumina-silica short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys Al through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had amorphous alumina-silica short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through Λ64 as matrix metal. The volume proportion of amorphous alumina-silica short type fibers in each of the resulting composite material sample pieces was thus now approximately 30%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the penultimate column of Table 4 and as summarized in the graphs of Fig. 12; thus, Fig. 12 corresponds to Figs. 1 through 11 relating to the first through the eleventh sets of preferred embodiments, respectively. In the graphs of Fig. 12, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 4 and from Fig. 12 it will be again similarly understood that, in this case that the volumr proportion of the reinforcing amorphous alumina-silica short fiber material was approximately 30%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same as or higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximately 6%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1% to approximately 2%, approximately 1% to approximately 2.5%, and approximately 1% to approximately 3.5%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 4%, approximately 3.5%, and approximately 3%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5%; and, yet further, in the particular case that the copper content was approximately 6%, the bending strength of the composite material test sample pieces had a value approximately the same, as when the copper content was approximately 1.5%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.12 and approximately 1.53 times the typical bending strength of approximately 43 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar amorphous alumina-silica short fiber material as reinforcing material in a similar volume proportion of approximately 30%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material amorphous alumina-silica short fibers in a volume proportion of approximately 30% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE THIRTEENTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same amorphous alumina-silica short type fiber material as utilized in the eleventh and twelfth sets of preferred embodiments described above, and utilizing as matrix metal substantially the same sixty four types of Al-Cu-Si type aluminum alloys as utilized in the previously described embodiments, but this time employing a fiber volume proportion of only approximately 20%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the twelfth sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of amorphous alumina-silica short type fiber material preforms were as before made by the method disclosed above with respect to the eleventh and twelfth sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 20%, by contrast to the twelfth set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the twelfth sets of preferred embodiments.
Next, substantially as before, each of these amorphous alumina-silica short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys Al through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had amorphous alumina-silica short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of amorphous alumina-silica short type fibers in each of the resulting composite material sample pieces was thus now approximately 20%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the central column of Table 4 and as summarized in the graphs of Fig. 13; thus, Fig. 13 corresponds to Figs. 1 through 12 relating to the first through the twelfth sets of preferred embodiments, respectively. In the graphs of Fig. 13, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 4 and from Fig. 13 it will be again similarly understood that, in this case that the volume proportion of the reinforcing amorphous alumina-silica short fiber material was approximately 20%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, the bending strength of the composite material was the same or considerably higher than the bending strength of a composite material in which the silicon content was substantially 0%, except for those of the test pieces which had copper content exceeding approximately 65%, and was the same as or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 1.5% to approximately 3%; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5%, and approximately 4%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 65%, the bending strength of the composite material test sample pieces had a value approximately the same, as when the copper content was approximately 1%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.08 and approximately 1.68 times the typical bending strength of approximately 40 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar amorphous alumina-silica short fiber material as reinforcing material in a similar volume proportion of approximately 20%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material amorphous alumina-silica short fibers in a volume proportion of approximately 20% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6%, and particularly more preferably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE FOURTEENTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same amorphous alumina-silica short type fiber material as utilized in the eleventh through the thirteenth sets of preferred embodiments described above, and utilizing as matrix metal substantially the same sixty four types of AI-Cu-Si type aluminum alloys as utilized in the previously described embodiments, but this time employing a fiber volume proportion of only approximately 10%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the thirteenth sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of amorphous alumina-silica short type fiber material preforms were as before made by the method disclosed above with respect to the eleventh through the thirteenth sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 10%, by contrast to the thirteenth set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the thirteenth sets of preferred embodiments.
Next, substantially as before, each of these amorphous alumina-silica short fiber type material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloys Al through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had amorphous alumina-silica short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of amorphous alumina-silica short type fibers in each of the resulting composite material sample pieces was thus now approximately 10%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the second column of Table 4 and as summarized in the graphs of Fig. 14; thus, Fig. 14 corresponds to Figs. 1 through 13 relating to the first through the thirteenth sets of preferred embodiments, respectively. In the graphs of Fig. 14, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 4 and from Fig. 14 it will be again similarly understood that, in this case that the volume proportion of the reinforcing amorphous alumina-silica short fiber material was approximately 10%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, except for those of the test pieces which had copper content exceeding approximately 6%, the bending strength of the composite material was the same or considerably higher than the bending strength of a composite material in which the silicon content was substantially 0%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the ranges of approximately 15% to approximately 3.5%, approximately 1.5% to approximately 3%, and approximately 1.5% to approximately 3%, respectively; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5%, and approximately 4%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 6.5%, the bending strength of the composite material test sample pieces had a value substantially lower than when the copper content was approximately 1.5%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.05 and approximately 1.61 times the typical bending strength of approximately 38 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar amorphous alumina-silica short fiber material as reinforcing material in a similar volume proportion of approximately 10%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material amorphous alumina-silica short fibers in a volume proportion of approximately 10% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 15% to approximately 6%, and particularly more preferably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

THE FIFTEENTH SET OF PREFERRED EMBODIMENTS

Next, the present inventors manufactured further samples of various composite materials, this time again utilizing as reinforcing material the same amorphous alumina-silica short type fiber material as utilized in the eleventh through the fourteenth sets of preferred embodiments described above, and utilizing as matrix mctal substantially the same sixty four types of Al-Cu-Si type aluminum alloys as utilized in the previously described embodiments, but this time employing a fiber volume proportion of only approximately 5%. Then the present inventors again conducted evaluations of the bending strength of the various resulting composite material sample pieces.
First, a set of sixty four quantities of aluminum alloy material the same as those utilized in the first through the fourteenth sets of preferred embodiments detailed above were produced in the same manner as before, again having as base material aluminum and having various quantities of silicon and copper mixed therewith. And an appropriate number of amorphous alumina-silica short type fiber material preforms were as before made by the method disclosed above with respect to the eleventh through the fourteenth sets of preferred embodiments, each of said alumina short type fiber material preforms now having a fiber volume proportion of approximately 5%, by contrast to the fourteenth set of preferred embodiments described above. These preforms had substantially the same dimensions as the preforms of the first through the fourteenth sets of preferred embodiments.
Next, substantially as before, each of these amorphous alumina-silica short fiber type material preforms was subjected to high pressure casting together with an appropriatc quantity of one of the aluminum alloys Al through A64 described above, utilizing operational parameters substantially as before. The solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and the peripheral portion of said solidified aluminum alloy mass and the stainless steel case were machined away, leaving only a sample piece of composite material which had amorphous alumina-silica short type fiber material as reinforcing material and the appropriate one of the aluminum alloys A1 through A64 as matrix metal. The volume proportion of amorphous alumina-silica short type fibers in each of the resulting composite material sample pieces was thus now approximately 5%. And post processing steps were performed on the composite material samples, substantially as before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was cut a bending strength test piece of dimensions and parameters substantially as in the case of the previously described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before.
The results of these bending strength tests were as shown in the first column of Table 4 and as summarized in the graphs of Fig. 15; thus, Fig. 15 corresponds to Figs. 1 through 14 relating to the first through the fourteenth sets of preferred embodiments, respectively. In the graphs of Fig. 15, there are again shown relations between copper content and the bending strength (in kg/mm²) of certain of the composite material test pieces, for percentage contents of silicon fixed along the various lines thereof.
From Table 4 and from Fig. 15 it will be again similarly understood that, in this case that the volume proportion of the reinforcing amorphous alumina-silica short fiber material was approximately 5%, substantially irrespective of the silicon content of the aluminum alloy matrix metal of the bending strength composite material test pieces, except for those of the test pieces which had substantially zero percent silicon content and had copper content approximately 6.5%, when the copper content was either at the low extreme of approximately 1% or less, or was at the high extreme of approximately 6% or more, the bending strength of the composite material pieces had a relatively low value; and, when the silicon content was one of the lower values of approximately 0.5%, approximately 1%, and approximately 2%, except for those of the test pieces which had copper content exceeding approximately 6%, the bending strength of the composite material was the same or considerably higher than the bending strength of a composite material in which the silicon content was substantially 0%, and was the same or much higher than the bending strength of a composite material in which the silicon content was substantially 3%. Further, it will be seen that, when the silicon content was approximately 0.5%, approximately 1%, or approximately 2%, the bending strength of the composite material test pieces increased relatively rapidly and substantially linearly along with an increase in the copper content in the range of approximately 1.5% to approximately 3%; and said bending strength attained a substantially maximum value when the copper content was approximately 5%, approximately 4.5%, and approximately 4%, respectively; and, further, said bending strength decreased relatively rapidly along with an increase in the copper content when the copper content was in the range exceeding about 5.5%; and, yet further, in the particular case that the copper content was approximately 6.5%, the bending strength of the composite material test sample pieces had a value substantially lower than when the copper content was approximately 1.5%.
It will be further seen that, for the particular above described types of such composite material using aluminum alloy as matrix metal with a copper content of from approximately 1.5% to approximately 6% and with a silicon content of from approximately 0.5% to approximately 2%, the bending strength values attained by the composite material test sample pieces are between approximately 1.03 and approximately 1.62 times the typical bending strength of approximately 34 kg/mm² attained in the conventional art for a composite material using as matrix metal a conventionally so utilized aluminum alloy of JIS standard AC4C and using a similar amorphous alumina-silica short fiber material as reinforcing material in a similar volume proportion of approximately 5%.
From the results of these bending strength tests it will be again seen that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material amorphous alumina-silica short fibers in a volume proportion of approximately 5% and having as matrix metal an Al-Cu-Si type aluminum alloy, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6%, and particularly more preferably should be in the range of from approximately 2% to approximately 6%, while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%.

COMMENTS ON THE ELEVENTH THROUGH THE FIFTEENTH SETS

OF PREFERRED EMBODIMENTS

From the eleventh through the fifteenth sets of preferred embodiments disclosed above, it will be understood that, in order to provide for a good and appropriate bending strength for a composite material having as reinforcing fiber material amorphous alumina-silica short fibers and having as matrix metal an Al-Cu-Si type aluminum alloy, irrespective of the particular volume proportions of the amorphous alumina-silica short fibers, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 1.5% to approximately 6% while the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%; and, particularly in the particular case that the fiber volume proportion of the amorphous alumina-silica short fibers is in the range of from approximately 5% to approximately 20%, it is preferable that the copper content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 2% to approximately 6%.

THE SIXTEENTH SET OF PREFERRED EMBODIMENTS

Variation of fiber volume proportion

Since from the above described first through the fifteenth sets of preferred embodiments the fact has been amply established and demonstrated that it is preferable for the copper content of the Al-Cu-Si type aluminum alloy matrix metal to be in the range of from approximately 1.5% to approximately 6%, and that it is preferable that the silicon content of said Al-Cu-Si type aluminum alloy matrix metal should be in the range of from approximately 0.5% to approximately 2%, it next was deemed germane to provide a set of tests to establish what fiber volume proportion of the reinforcing alumina-silica type short fibers is most appropriate. This was done, in the sixteenth set of preferred embodiments now to be described, by varying said fiber volume proportion of the reinforcing alumina-silica type short fiber material while using an Al-Cu-Si type aluminum alloy matrix metal which had the proportions of copper and silicon which had as described above been established as being quite good, i.e. which had copper content of approximately 3.5% and also silicon content of approximately 1% and remainder substantially aluminum. In other words, an appropriate number (in fact six in each case) of preforms made of the delta type alumina short fiber material used in the first through the fifth sets of preferred embodiments detailed above, the crystalline type alumina short fiber material used in the sixth through the tenth sets of preferred embodiments detailed above, and the amorphous alumina-silica short fiber material used in the eleventh through the fifteenth sets of preferred embodiments detailed above, hereinafter denoted respectively as Bl through B6, Cl through C6, and Dl through D6, were made by subjecting quantities of the appropriate short fiber material to compression forming without using any binder in the same manner as in the above described fifteen sets of preferred embodiments, the six ones in each said set of said alumina-silica type fiber material preforms having fiber volume proportions of approximately 5%, 10%, 20%, 30%, 40%, and 50%. These preforms had substantially the same dimensions and the same type of two dimensional random fiber orientation as the preforms of the above described fifteen sets of preferred embodiments. And, substantially as before, each of these alumina-silica type short fiber material preforms was subjected to high pressure casting together with an appropriate quantity of one of the aluminum alloy matrix metals described above, utilizing operational parameters substantially as before. In each case, the solidified aluminum alloy mass with the preform included therein was then removed from the casting mold, and as before the peripheral portion of said solidified aluminum alloy mass was machined away along with the stainless steel case which was utilized, leaving only a sample piece of composite material which had alumina-silica type short fiber material as reinforcing material in the appropriate fiber volume proportion and the described aluminum alloy as matrix metal. And post processing and artificial aging processing steps were performed on the composite material samples, similarly to what was done before. From each of the composite material sample pieces manufactured as described above, to which heat treatment had been applied, there was then cut a bending strength test piece, each of dimensions substantially as in the case of the above described sets of preferred embodiments, and for each of these composite material bending strength test pieces a bending strength test was carried out, again substantially as before. Also, for reference purposes, a similar test sample was cut from a piece of a cast aluminum alloy material which included no reinforcing fiber material at all, said aluminum alloy material having copper content of about 3.5%, silicon content of about 0.5%, and balance substantially aluminum, and having been subjected to post processing and artificial aging processing steps, as well as heat treatment, similarly to what was done before. And for this comparison sample a bending strength test was carried out, again substantially as before. The results of these bending strength tests were as shown in the three graphs of Fig. 16, respectively for the delta type alumina short reinforcing fiber material, the crystalline type alumina short reinforcing fiber material, and the amorphous alumina-silica type reinforcing fiber material. Each of these graphs shows the relation between the volume proportion of the alumina-silica type short reinforcing fibers and the bending strength (in kg/mm²) of the composite material test pieces, for the appropriate type of reinforcing fibers.
From Fig. 16, it will be understood that, substantially irrespective of the type of reinforcing alumina-silica short fiber material utilized: when the volume proportion of the alumina-silica type short reinforcing fibers was in the range of up to and including approximately 5% the bending strength of the composite material hardly increased along with an increase in the fiber volume proportion, and its value was close to the bending strength of the aluminum alloy matrix metal by itself with no reinforcing fiber material admixtured therewith; when the volume proportion of the alumina-silica type short reinforcing fibers was in the range of 5% to 40% the bending strength of the composite material increased greatly; and, when the volume proportion of the alumina-silica type short reinforcing fibers increased above 40%, the bending strength of the composite material did not increase very much even with further increase in the fiber volume proportion. From these results described above, it is seen that in a composite material having alumina-silica type short fiber reinforcing material and having as matrix metal an Al-Cu-Si type aluminum alloy, said Al-Cu-Si type aluminum alloy matrix metal having a copper content in the range of from approximately 1.5% to approximately 6%, a silicon content in the range of from approximately 0.5% to approximately 2%, and remainder substantially aluminum, it is preferable that the fiber volume proportion of the alumina-silica type short fiber reinforcing material should be in the range of from approximately 5% to approximately 50%, and more preferably should be in the range of from approximately 5% to approximately 40%.

THE SEVENTEENTH SET OF PREFERRED EMBODIMENTS

Variation of mullite crystalline proportion

In the particular case that crystalline alumina-silica short fiber material is used as the alumina-silica type short fiber material, in order to assess what value of the mullite crystalline amount of the crystalline alumina-silica short fiber material yields a high value for the bending strength of the composite material, several samples of the amorphous alumina-silica type short fiber material used in the eleventh through the fifteenth sets of preferred embodiments above were subjected to heat treatment under various conditions not particularly detailed here because they are per se known in the art, whereby crystalline alumina-silica type short fiber material samples were formed with mullite crystalline amounts of 0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, and 65%, and then, from each of these crystalline alumina-silica type short fiber material samples, a preform with a fiber volume proportion of approximately 15% was formed in the same manner and under the same conditions as in the sixth through the tenth sets of preferred embodiments detailed above, and then, using as matrix metal each such preform as a reinforcing fiber mass and an aluminum alloy of which the copper content was approximately 3%, the silica content was approximately 2%, and the remainder was substantially aluminum, various composite material sample pieces were manufactured in the same manner and under the same conditions as in the sixth through the tenth sets of preferred embodiments detailed above, the various resulting composite material sample pieces were subjected to liquidizing processing and artificial aging processing in the same manner and under the same conditions as in the various sets of preferred embodiments detailed above, from each composite material sample piece a bending test piece was cut in the same manner and under the same conditions as in the various sets of preferred embodiments detailed above, and for each bending test piece a bending test was carried out, as before. The results of these bending tests are shown in Fig. 17. It should be noted that in Fig. 17 the mullite crystalline amount (in percent) of the crystalline alumina-silica short fiber material which was the reinforcing fiber material is shown along the horizontal axis .
From Fig. 17 it will be seen that, in the case that such an aluminum alloy as detailed above is utilized as the matrix metal, even when the mullite crystalline amount included in the reinforcing fibers is relatively low, the bending strength of the resulting composite material has a relatively high value, and, whatever be the variation in the mullite crystalline amount included in the reinforcing fibers, the variation in the bending strength of the resulting composite material is relatively low. Therefore it will be seen that, in the case that crystalline alumina-silica short fiber material is used as the alumina-silica short fiber material for reinforcing the material of the present invention, it is acceptable for the value of the mullite crystalline amount therein to be more or less any value.

Wear tests

It should be noted that it was confirmed, although the details thereof are not laid out specifically herein in the interests of brevity of description, that for the composite materials of each of the above preferred embodiments, by comparison with composite materials having as reinforcing fibers ordinary alumina-silica short fibers, crystalline alumina-silica short fibers, and amorphous alumina-silica short fibers, and having contents of approximately 7%, 5%, and 7% respectively of non fibrous particles incorporated therein with particle diameter being 150 microns or more, their own wear resistance characteristics, as well as the frictional wear characteristics of members mating therewith, were found to be excellent.
Although the present invention has been shown and described in terms of the preferred embodiments thereof, and with reference to the appended drawings, it should not be considered as being particularly limited thereby, since the details of any particular embodiment, or of the drawings, could be varied without, in many cases, departing from the ambit of the present invention. Accordingly, the scope of the present invention is to be considered as being delimited, not by any particular perhaps entirely fortuitous details of the disclosed preferred embodiments, or of the drawings, but solely by the scope of the accompanying claims, which follow after the Tables.

Claims

1. A composite material, comprising a mass of alumina-silica short fibers embedded in a matrix of metal, said matrix metal being an alloy consisting essentially of between approximately 1.5% to approximately 6% of copper, between approximately 0.5% to approximately 2% of silicon, and remainder substantially aluminum.

2. A composite material according to claim 1, wherein substantially all said short fibers are composed of alumina.

3. A composite material according to claim 1, wherein substantially all said short fibers are composed of delta alumina.

4. A composite material according to claim 1, wherein said short fibers have a substantial crystalline content.

5. A composite material according to claim 1, wherein said short fibers have a substantial mullite crystalline content.

6. A composite material according to claim 1, wherein substantially all said short fibers are composed of amorphous alumina-silica.

7. A composite material according to claim 1, wherein the fiber volume proportion of said short fibers is between approximately 5% and approximately 50%.

8. A composite material according to claim 1, wherein the fiber volume proportion of said short fibers is between approximately 5% and approximately 40%.

9. A composite material according to claim 1, wherein the fiber volume proportion of said short fibers is between approximately 5% and approximately 20%, and the copper content of said aluminum alloy matrix metal is between approximately 2% and approximately 6%.