Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
  • C22C47/02—Pretreatment of the fibres or filaments
  • C22C47/06—Pretreatment of the fibres or filaments by forming the fibres or filaments into a preformed structure, e.g. using a temporary binder to form a mat-like element
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
  • C22C47/02—Pretreatment of the fibres or filaments
  • C22C47/06—Pretreatment of the fibres or filaments by forming the fibres or filaments into a preformed structure, e.g. using a temporary binder to form a mat-like element
  • C22C47/062—Pretreatment of the fibres or filaments by forming the fibres or filaments into a preformed structure, e.g. using a temporary binder to form a mat-like element from wires or filaments only
  • C22C47/068—Aligning wires
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D19/00—Casting in, on, or around objects which form part of the product
  • B22D19/14—Casting in, on, or around objects which form part of the product the objects being filamentary or particulate in form
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
  • C22C47/08—Making alloys containing metallic or non-metallic fibres or filaments by contacting the fibres or filaments with molten metal, e.g. by infiltrating the fibres or filaments placed in a mould
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C47/00—Making alloys containing metallic or non-metallic fibres or filaments
  • C22C47/08—Making alloys containing metallic or non-metallic fibres or filaments by contacting the fibres or filaments with molten metal, e.g. by infiltrating the fibres or filaments placed in a mould
  • C22C47/12—Infiltration or casting under mechanical pressure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D55/00—Brakes with substantially-radial braking surfaces pressed together in axial direction, e.g. disc brakes
  • F16D2055/0004—Parts or details of disc brakes
  • F16D2055/0016—Brake calipers
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D2200/00—Materials; Production methods therefor
  • F16D2200/0004—Materials; Production methods therefor metallic
  • F16D2200/0026—Non-ferro
  • F16D2200/003—Light metals, e.g. aluminium
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D2200/00—Materials; Production methods therefor
  • F16D2200/0034—Materials; Production methods therefor non-metallic
  • F16D2200/0039—Ceramics
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
  • F16D2200/00—Materials; Production methods therefor
  • F16D2200/006—Materials; Production methods therefor containing fibres or particles

Definitions

• the present invention relates to metal comprising inserts for reinforcing a metal matrix composite article and metal matrix composite articles reinforced with an insert(s).
• Ceramic materials used for reinforcement include particles, discontinuous fibers (including whiskers) and continuous fibers, as well as ceramic pre-forms.
• ceramic material is incorporated into a metal to provide metal matrix composites (MMC) having improved mechanical properties compared to the article made of the metal without the ceramic material.
• MMC metal matrix composites
• conventional brake calipers for motorized vehicles e.g., cars and trucks
• brake calipers are typically made of cast iron.
• brake calipers for motorized vehicles (e.g., cars and trucks) are typically made of cast iron.
• brake calipers are typically made of cast iron.
• One technique for aiding in the design of MMCs including placement of the ceramic oxide material and minimizing the amount of ceramic oxide material needed for the particular application, is finite element analysis.
• a brake caliper made of cast aluminum would be about 50% by weight lighter than the same (i.e., the same size and configuration) caliper made of cast iron.
• the mechanical properties of cast aluminum and cast iron are not the same (e.g., the Young's modulus of cast iron is about 100-170 GPa, while for cast aluminum it is about 70-75 GPa; the yield strength of cast iron is 300-700 MPa, while for cast aluminum it is 200-300 MPa).
• a brake caliper made from cast aluminum has significantly lower mechanical properties such as bending stiffness and yield strength than the cast iron caliper.
• the mechanical properties of such an aluminum brake caliper are unacceptably low as compared to a cast iron brake caliper.
• a brake caliper made of an aluminum metal matrix composite material that has the same configuration and at least the same (or better) mechanical properties, such as bending stiffness and yield strength, as a cast iron brake caliper is desirable.
• An aluminum metal matrix composite material e.g., aluminum reinforced with ceramic fibers
• One consideration for some MMC articles is the need for post-formation machining (e.g., adding holes or threads, or otherwise cutting away material to provide a desired shape) or other processing (e.g., welding two MMC articles together to make a complex shaped part).
• Many conventional MMCs typically contain enough ceramic reinforcement material to make machining or welding impractical or even impossible. It is desirable, however, to produce "net-shaped" articles that require little, if any, post- formation machining or processing.
• MMCs Another consideration in designing and making MMCs is the cost of the ceramic reinforcement material.
• the mechanical properties of continuous polycrystalline alpha- alumina fibers such as that marketed by the 3M Company, St. Paul, MN, under the trade designation "NEXTEL 610", are high compared to low density metals such as aluminum.
• the cost of ceramic oxide materials such as the polycrystalline alpha-alumina fibers, is substantially more than metals such as aluminum.
• the present invention provides a metal matrix composite article comprising a first metal and an insert (in some embodiments at least two, three, or more inserts) reinforcing the first metal, wherein the first metal is selected from the group consisting of aluminum, alloys thereof, and combinations thereof, wherein the insert comprises substantially continuous ceramic oxide fibers and a second metal selected from the group consisting of aluminum, alloys thereof, and combinations thereof, wherein the second metal secures the substantially continuous ceramic oxide fibers in place, wherein the second metal extends along at least a portion of the length of the substantially continuous ceramic oxide fibers, wherein there is an interface layer between the first metal and the insert, and wherein there is an interface layer peak bond strength value between the first metal and the insert of at least 100 MPa (in some embodiments, at least 125 MPa, 150 MPa, 175 MPa, or even at least 200 MPa.
• the interface layer is preferably free of oxygen.
• the present invention provides in one embodiment a method of making a metal matrix composite article according to the present invention, the method comprising: positioning an insert in a mold, the insert comprising substantially continuous ceramic oxide fibers and first metal selected from the group consisting of aluminum, alloys thereof, and combinations thereof, wherein the first metal secures the substantially continuous ceramic oxide fibers in place, and wherein the first metal extends along at least a portion of the length of the substantially continuous ceramic oxide fibers, the first metal having an outer surface, and a second metal (e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof) on the outer surface of the first metal, and the second metal having a thickness of at least 5 micrometers (in some embodiments, preferably at least 10 micrometers, at least 15 micrometers or even at least 20 micrometers; more preferably, in the range from 5 to 20 micrometers); providing molten third metal selected from the group consisting of aluminum, alloys thereof, and combinations thereof into the mold; cooling the molten third metal to provide an article;
• casting can be conducted in air, in some embodiments, it may be preferable to be conducted in an atmosphere comprising argon (e.g., at least 90% (at least 95%, 99%, or even 100%) by volume Ar, based on the total volume of the atmosphere; typically not greater than 10%, 5%, 1%, or even 0% by volume O 2 , based on the total volume of the atmosphere).
• argon e.g., at least 90% (at least 95%, 99%, or even 100%
• the present invention provides a method of making a metal matrix composite article according to the present invention, the method comprising: positioning an insert in a mold, the insert comprising substantially continuous ceramic oxide fibers and first metal selected from the group consisting of aluminum, alloys thereof, and combinations thereof, wherein the first metal secures the substantially continuous ceramic oxide fibers in place, and wherein the first metal extends along at least a portion of the length of the substantially continuous ceramic oxide fibers; providing molten third metal selected from the group consisting of aluminum, alloys thereof, and combinations thereof into the mold, wherein an atmosphere comprising at least 90% (at least 95%, 99%, or even 100%) by volume Ar, based on the total volume of the atmosphere; typically not greater than 10%, 5%, 1%, or even 0% by volume O 2 , based on the total volume of the atmosphere) is provided such that providing the molten third metal into the mold is conducted under the atmosphere; and cooling the molten third metal to provide the metal matrix composite article.
• the first metal has an outer surface, and a second metal (e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof) on the outer surface of the first metal, wherein the second metal has a thickness of at least 5 micrometers (in some embodiments, preferably at least 10 micrometers, at least 15 micrometers or even at least 20 micrometers; more preferably, in the range from 5 to 20 micrometers).
• the method includes hot isostatic pressing (HIPing) after at least partially cooling the molten third metal to provide the metal matrix composite article.
• HIPing hot isostatic pressing
• peak bond strength value refers to the peak bond strength value as determined in at least one of Comparative Example A or Example 4, below;
• free of oxygen means no visibly discernable continuous oxide layer at the interface when viewed at 250X with optical microscope as described in the "Oxygen Layer Test” below;
• substantially continuous ceramic oxide fibers refers to ceramic oxide fibers having lengths of at least 5 cm.
• metal matrix composite articles according to the present invention include structural parts for aerospace applications, brake calipers, high speed rotating rings, and high speed mechanical arms for industrial machinery.
• FIGS. 1-3 and 5-7 are perspective views of exemplary (metal matrix composite) inserts for making embodiments of metal matrix composite articles according to the present invention.
• FIG. 4 is a perspective view of an exemplary metal matrix composite article made from the (metal matrix composite) insert shown in FIG. 3.
• FIGS. 8 A and 8B are schematic side and top views, respectively, of a sand casting mold assembly used in the working examples.
• FIGS. 9 A, 9B, 9C are schematic top, side, end views of a test coupon.
• FIG. 10 is an optical photomicrograph of a fracture surface of a Comparative Example A metal matrix composite article at about 4X.
• FIG. 11 is a scanning auger electron (SAM) photomicrograph of a Comparative
• FIG. 12 is a scanning auger electron (SAM) photomicrograph and electron microprobe copper line scan of a Comparative Example A metal matrix composite article cross-section.
• SAM scanning auger electron
• FIG. 13 is a scanning auger electron (SAM) photomicrograph of a Comparative Example C metal matrix composite article cross-section.
• FIG.14 is a scanning auger electron microprobe oxygen line scan of a Comparative Example C metal matrix composite article cross-section.
• FIG. 15 is a photomicrograph of an x-ray radiograph of a Comparative Example C metal matrix composite article.
• FIG. 16 is a photomicrograph of an x-ray radiograph of an Example 1 metal matrix composite article.
• FIG. 17 is an optical photomicrograph of an Example 1 metal matrix composite article cross-section at 20X.
• FIG. 18 is a scanning auger electron (SAM) photomicrograph and electron microprobe oxygen line scan of a Example 1 metal matrix composite article cross-section.
• SAM scanning auger electron
• FIG. 19 is an optical photomicrograph of a fracture surface of Example 4 metal matrix composite article at about 4X.
• FIG. 20 is a scanning auger electron (SAM) photomicrograph and electron microprobe oxygen line scan of a Example 4 metal matrix composite article cross-section.
• SAM scanning auger electron
• the present invention provides metal matrix composite articles comprising at least one metal and substantially continuous ceramic oxide fibers.
• metal matrix composite articles according to the present invention are designed for the particular application to achieve an optimal, or at least acceptable balance of, desired properties, low cost, and ease of manufacture.
• metal matrix composite articles according to the present invention are designed for a specific application and/or to have certain properties and/or features.
• an existing article made of one metal e.g., steel
• another metal e.g., aluminum
• material including substantially continuous ceramic oxide fibers such that the latter (i.e., the metal matrix composite version of the article) has certain desired properties (e.g., Young's modulus, yield strength, and ductility) at least equal to that required for the use of the original article made from the first metal.
• the article may be redesigned to have the same physical dimensions as the original article.
• a preferred method for generating possible constructions is the use of finite element analysis (FEA), including the use of FEA software run with the aid of a conventional computer system (including the use of a central processing unit (CPU) and input and output devices).
• FEA software is commercially available, including that marketed by Ansys, Inc., Canonsburg, PA under the trade designation "ANSYS”.
• FEA assists in modeling the article mathematically and identifying regions where placement of the continuous ceramic oxide fibers, metal(s), and possibly other materials would provide the desired property levels. It is typically necessary to run several iterations of FEA to obtain a more preferred design.
• an exemplary (metal matrix composite) insert 10 for making a metal matrix composite article according to the present invention comprises substantially continuous (as shown, longitudinally aligned) ceramic oxide fibers 12 and aluminum or alloy thereof 14.
• outer surface 15 of aluminum or alloy thereof 14 has first metal (e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof) 16 thereon.
• outer surface 17 of second optional metal 18 has second optional metal (e.g., Ni) 18 thereon.
• the second optional metal is typically used if the first optional metal is Cu and/or Ag.
• the use of the Ni tends to aid in the adhesion of metal such as Cu and/or Ag to the insert surface.
• another exemplary (metal matrix composite) insert 10 for making a metal matrix composite article according to the present invention comprises substantially continuous (as shown, longitudinally aligned) ceramic oxide fibers 22 and aluminum or alloy thereof 24.
• outer surface 25 of aluminum or alloy thereof 24 has first metal (e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof) 26 thereon.
• first metal e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof
• outer surface 27 of second optional metal 28 has second optional metal (e.g., Ni) 28 thereon.
• the continuous ceramic oxide fibers are substantially longitudinally aligned such that they are generally parallel to each other. While the ceramic oxide fibers may be incorporated into the insert as individual fibers, they are more typically incorporated into the insert as a group of fibers in the form of a bundle or tow. Fibers within the bundle or tow may be maintained in a longitudinally aligned (i.e., generally parallel) relationship with one another. When multiple bundles or tows are utilized, the fiber bundles or tows are also maintained in a longitudinally aligned (i.e., generally parallel) relationship with one another.
• the continuous ceramic oxide fibers are maintained in an essentially longitudinally aligned configuration where individual fiber alignment is maintained within ⁇ 10°, more preferably ⁇ 5°, most preferably ⁇ 3°, of their average longitudinal axis.
• the ceramic oxide fibers may be curved, as opposed to straight (i.e., do not extend in a planar manner).
• the ceramic oxide fibers may be planar throughout the fiber length, non-planar (i.e., curved) throughout the fiber length, or they may be planar at some portions and non-planar (i.e., curved) at other portions.
• the substantially continuous ceramic oxide fibers are maintained in a substantially non-intersecting, curvilinear arrangement (i.e., longitudinally aligned) throughout the curved portion of the metal matrix composite article. In some embodiments, the substantially continuous ceramic oxide fibers are maintained in a substantially equidistant relationship with each other throughout the curved portion of the metal matrix composite article.
• an exemplary insert 50 for making a metal matrix composite article according to the present invention comprises substantially continuous (as shown, longitudinally aligned) ceramic oxide fibers 52 and aluminum or alloy thereof 54, wherein substantially continuous ceramic oxide fibers 52 are curved throughout their lengths.
• outer surface 55 of aluminum or alloy thereof 54 has first metal (e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof) 56 thereon.
• outer surface 57 of second optional metal 58 has second optional metal (e.g., Ni) 58 thereon.
• An example of a metal matrix composite article which can be made from the latter type of insert is a metal matrix composite ring, such as shown in FIG. 4.
• Ring 60 comprises aluminum or alloy thereof 54 and ceramic oxide fibers 52 (see Fig. 3). Such rings are useful, for example, in high speed rotating machinery where they are subject to large centrifugal forces.
• a ply is at least one layer of substantially continuous ceramic oxide fibers (in some embodiments, preferably at least one layer of tows comprising the substantially continuous ceramic oxide fibers)).
• the plies may be oriented with respect to each other any of a variety of ways. Examples of the relationships of the plies to each other are shown in FIGS. 5 and 6.
• insert 70 comprises first and second plies of substantially continuous (as shown, longitudinally aligned) ceramic oxide fibers 71 and 72 and aluminum or alloy thereof 74.
• outer surface 75 of aluminum or alloy thereof 74 has first metal (e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof) 76 thereon.
• outer surface 77 of second optional metal 78 has second optional metal (e.g., Ni) 78 thereon.
• First ply of substantially continuous ceramic oxide fibers 71 is positioned 45° with respect to second ply of substantially continuous ceramic oxide fibers 72, although depending on the particular application, the difference in position of a ply with respect to another ply(s) may be anywhere between greater than zero degrees to 90°. Such arrangements of ply may be useful, for example if the metal matrix article is to encounter biaxial and trialaxial loads during use.
• metal matrix composite articles according to the present invention can have two or more plies.
• a grouping of fibers may also benefit from being wrapped with substantially continuous ceramic oxide fibers such as shown in FIG. 6, wherein insert 80 comprises substantially continuous (as shown, longitudinally aligned) ceramic oxide fibers 82 spirally wrapped around substantially continuous (as shown, longitudinally aligned) ceramic oxide fibers 81 and aluminum or alloy thereof 84.
• outer surface 75 of aluminum or alloy thereof 74 has first metal (e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof) 76 thereon.
• outer surface 77 of second optional metal 78 has second optional metal (e.g., Ni) 78 thereon.
• An example of a metal matrix composite article which may benefit from the properties offered by plies of substantially continuous ceramic oxide fibers include an article that under use is subjected to bending forces about two perpendicular axes.
• the substantially continuous ceramic oxide fibers have lengths of at least 10 cm (frequently at least 15 cm, 20 cm, 25 cm, or more).
• the substantially continuous ceramic oxide fibers are in the form of tows (i.e., the tows comprise the substantially continuous ceramic oxide fibers).
• the substantially continuous ceramic oxide fibers comprising the tow have lengths of at least
• the ceramic oxide fibers can include, or even consist essentially of, substantially continuous, longitudinally aligned, ceramic oxide fibers, wherein "longitudinally aligned” refers to the generally parallel alignment of the fibers relative to the length of the fibers.
• the substantially continuous reinforcing ceramic oxide fibers used to make a metal matrix composite article according to the present invention preferably have an average diameter of at least about 10 micrometers.
• the average fiber diameter is no greater than about 200 micrometers, more preferably, no greater than about 100 micrometers.
• the average fiber diameter is preferably, no greater than about 50 micrometers, more preferably, no greater than about 25 micrometers.
• the substantially continuous ceramic oxide fibers have an average tensile strength of at least about 1.4 GPa, more preferably, at least about 1.7 GPa, even more preferably, at least about 2.1 GPa, and most preferably, at least about 2.8 GPa, although fibers with lower average tensile strengths may also be useful, depending on the particular application.
• Continuous ceramic oxide fibers are available commercially as single filaments, or grouped together (e.g., as yarns or tows).
• Yams or tows may comprise, for example, at least 420 individual fibers per tow, at least 760 individual fibers per tow, at least 2600 individual fibers per tow, or more.
• Tows are well known in the fiber art and refer to a plurality of (individual) fibers (typically at least 100 fibers, more typically at least 400 fibers) collected in an aligned untwisted form, whereas yarns imply some degree of twist or rope-like construction.
• Ceramic oxide fibers, including tows of ceramic oxide fibers are available in a variety of lengths.
• the fibers may have a cross-sectional shape that is circular or elliptical.
• useful ceramic oxide fibers include alpha alumina fibers, aluminosilicate fibers, and aluminoborosilicate fibers. Other useful ceramic oxide fibers may be apparent to those skilled in the art after reviewing the present disclosure.
• alumina fibers are polycrystalline alpha alumina-based fibers and comprise, on a theoretical oxide basis, greater than about 99 percent by weight Al 2 O 3 and about 0.2-0.5 percent by weight SiO 2 , based on the total weight of the alumina fibers.
• preferable polycrystalline, alpha alumina-based fibers comprise alpha alumina having an average grain size of less than 1 micrometer (more preferably, less than 0.5 micrometer).
• preferable polycrystalline, alpha alumina-based fibers have an average tensile strength of at least 1.6 GPa (preferably, at least 2.1 GPa, more preferably, at least 2.8 GPa).
• Alpha alumina fibers are commercially available, for example, under the trade designation "NEXTEL 610" from the 3M Company of St. Paul, MN.
• Another alpha alumina fiber which comprises about 89 percent by weight Al 2 O 3 , amount 10 percent by weight ZrO 2 , and about 1 percent by weight Y 2 O 3 , based on the total weight of the fibers, is commercially available from the 3M Company under the trade designation "NEXTEL 650".
• aluminosilicate fibers comprise, on a theoretical oxide basis, in the range from about 67 to about 85 percent by weight Al 2 O 3 and in the range from about 33 to about 15 percent by weight SiO 2 , based on the total weight of the aluminosilicate fibers.
• preferable aluminosilicate fibers comprise, on a theoretical oxide basis, in the range from about 67 to about 77 percent by weight Al 2 O 3 and in the range from about 33 to about 23 percent by weight SiO 2 , based on the total weight of the aluminosilicate fibers. In some embodiments, preferable aluminosilicate fibers comprise, on a theoretical oxide basis, about 85 percent by weight Al 2 O 3 and about 15 percent by weight SiO 2 , based on the total weight of the aluminosilicate fibers.
• preferable aluminosilicate fibers comprise, on a theoretical oxide basis, about 73 percent by weight Al 2 O 3 and about 27 percent by weight SiO 2 , based on the total weight of the aluminosilicate fibers.
• Aluminosilicate fibers are commercially available, for example, under the trade designations "NEXTEL 440", “NEXTEL 720", and “NEXTEL 550" from the 3M Company.
• the aluminoborosilicate fibers comprise, on a theoretical oxide basis: about 35 percent by weight to about 75 percent by weight (or even, for example, about 55 percent by weight to about 75 percent by weight) Al 2 O 3 ; greater than 0 percent by weight (or even, for example, at least about 15 percent by weight) and less than about 50 percent by weight (or, for example, less than about 45 percent, or even less than about 44 percent) SiO 2 ; and greater than about 5 percent by weight (or, for example, less than about 25 percent by weight, less than about 1 percent by weight to about 5 percent by weight, or even less than, about 2 percent by weight to about 20 percent by weight) B 2 O 3 , based on the total weight of the aluminoborosilicate fibers.
• Aluminoborosilicate fibers are commercially available, for example, under the trade designation "NEXTEL 312" from the 3M Company.
• substantially continuous ceramic oxide fibers often include an organic sizing material added to the fiber during their manufacture to provide lubricity and to protect the fiber strands during handling. It is believed that the sizing tends to reduce the breakage of fibers, reduces static electricity, and reduces the amount of dust during, for example, conversion to a fabric. The sizing can be removed, for example, by dissolving or burning it away.
• Coatings may be used, for example, to enhance the wettability of the fibers, to reduce or prevent reaction between the fibers and molten metal matrix material.
• Such coatings and techniques for providing such coatings are known in the fiber and metal matrix composite art.
• the metal cast around an insert may be the same or different than the metal securing the continuous ceramic oxide fibers.
• the aluminum and aluminum alloys used to make, and which comprise, inserts and metal matrix composite articles according to the present invention may contain impurities, in some embodiments it may be preferable to use relatively pure metal (i.e., metal comprising less than 0.1 percent by weight, or even less than 0.05 percent by weight impurities (i.e., less than 0.25 percent 0.1 percent, or even less than 0.05 percent by weight of each of Fe, Si, and/or Mg)). Although higher purity metals tend to be preferred for making higher tensile strength materials, less pure forms of metals are also useful. Suitable aluminum and aluminum alloys are commercially available. For example, aluminum is available under the trade designation "SUPER PURE ALUMINUM; 99.99% Al" from Alcoa of Pittsburgh, PA.
• Aluminum alloys e.g., Al-2% by weight Cu (0.03% by weight impurities) can be obtained from Belmont Metals, New York, NY.
• examples of preferred aluminum alloys include alloys comprising at least 98 percent by weight Al, aluminum alloy comprises at least 1.5 percent by weight Cu
• Aluminum alloys comprising Cu in the range from 1.5 to 2.5, preferably, 1.8 to 2.2, percent by weight Cu, based on the total weight of the alloy.
• Useful series of aluminum alloys include 200 (e.g., 201 aluminum alloy, A201.1 aluminum alloy, 201.2 aluminum alloy, 203 aluminum alloy, 206 aluminum alloy, A206.0 aluminum alloy, 224 aluminum alloy, and 224.2 aluminum alloy), 300 (e.g., A319.1 aluminum alloy, 354.1 aluminum alloy, 355.2 aluminum alloy, A356 aluminum alloy, D356 aluminum alloy, A356.1 aluminum alloy, A357 aluminum alloy, and D357 aluminum alloy), 400 (e.g., 413 aluminum alloy, 443 aluminum alloy, 443.2 aluminum alloy, and 444.2 aluminum alloy), 700 (e.g., 713 aluminum alloy and 771 aluminum alloy), 2000 (e.g., 2036 aluminum alloy and 2618 aluminum alloy), 6000 (e.g., 6061 aluminum alloy, 6063 aluminum alloy, 6101 aluminum alloy, 6151 aluminum alloy, and 6201 aluminum alloy), and/
• examples of preferred aluminum alloys for the insert(s) include alloys comprising at least 98 percent by weight Al, aluminum alloy comprises at least 1.5 percent by weight Cu (e.g., aluminum alloys comprising Cu in the range from 1.5 to 2.5, preferably, 1.8 to 2.2, percent by weight Cu, based on the total weight of the alloy.
• preferred aluminum alloys for the insert(s) include 2000 (e.g., 2036 aluminum alloy and 2618 aluminum alloy), 6000 (e.g., 6061 aluminum alloy, 6063 aluminum alloy, 6101 aluminum alloy, 6151 aluminum alloy, and 6201 aluminum alloy), and/or 7000 (e.g., 7072 aluminum alloy) series aluminum alloys.
• preferred aluminum alloy cast around the insert(s) include
• 200 e.g., 201 aluminum alloy, 203 aluminum alloy, 206 aluminum alloy, and 224 aluminum alloy
• 300 e.g., A356 aluminum alloy, D356 aluminum alloy, A357 aluminum alloy, and D357 aluminum alloy
• 400 e.g., 413 aluminum alloy and 443 aluminum alloy
• 700 e.g., 771 aluminum alloy
• 6000 e.g., 6061 aluminum alloy series aluminum alloys.
• thicknesses of metals such as Cu, Au, Ni, Ag, Zn, and combinations thereof outside of specified values may also be useful, if the thickness is too low, the coatings tend to diffuse if the insert is preheated and consequently may not protect the interface from oxidation or otherwise aid in reducing oxidation at the interface, while excess thicknesses tend to interfere with the establishment of a desirable bond strength between the metal of the insert and the metal of the metal matrix composite article.
• Techniques for depositing metals such as Cu, Au, Ni, Ag, Zn, and combinations thereof are known in the art and include electroplating and vacuum deposition techniques.
• thicknesses of the optional Ni are greater than about 1 micrometer, more typically greater than 2 micrometers. In another aspect, typically thicknesses of such metal are less than about 10 micrometers, more typically less than about 5 micrometers. Although thicknesses outside of these values may also be useful, if the thickness is too low, the coatings tend not be as useful in aiding the adhesion of metals such as Cu, Au, Ag, Zn, and combinations thereof to the insert, while excess thicknesses tend to interfere with the establishment of a desirable bond strength between the metal of the insert and the metal of the metal matrix composite.
• the Ni is deposited via electroless deposition.
• Inserts can be made, for example, by winding a plurality of continuous ceramic oxide fibers (in some embodiments, preferably grouped together (e.g., as yams or tows)) onto a mandrel having the desired dimension and shape for the intended metal insert design.
• the fibers being wound are sized.
• Exemplary sizings include water (in some embodiments, preferably deionized water), wax (e.g., paraffin), and polyvinyl alcohol (PNA). If the sizing is water, the fiber is typically wound onto the mandrel. After winding is completed, the mandrel is removed from the winder and then placed in a refrigerated cooler until the wound fiber freezes.
• the frozen, wound fiber can be cut as needed. For example, if the fiber is wound around a mandrel made up of four contiguous plates, the rectangular plates can be removed to provide a frozen, fiber preform. The preform can be cut into pieces to provide small preforms.
• the sizing is removed before it is used to form an insert. The sizing can removed, for example, by placing the formed fiber into a die (in some embodiments, preferably graphite or sand), and then heating the die. The die is used to make an insert.
• a die is placed in a can, typically a stainless steel can, preferably open only at one end.
• the interior of the can in some embodiments is preferably coated with boron nitride or a similar material to protect, minimize reaction between the aluminum/aluminum alloy and the can during the subsequent casting, and/or facilitate release of the metal matrix composite article from the mold.
• the can with the die within is placed inside the pressure vessel of a pressure casting machine. Subsequently, aluminum and/or aluminum alloy (e.g. pieces of aluminum and/or an aluminum alloy cut from an ingot) is placed on top of the can.
• the pressure vessel is then evacuated of air and heated above the melting point of the aluminum/aluminum alloy (typically about 50°C to about 120°C above the liquidus temperature). Upon reaching the desired temperature, the heater is turned off and the pressure vessel is then pressurized with typically argon (or a similar inert gas) to a pressure of about 8.5 to about 9.5 MPa, forcing the molten aluminum aluminum alloy to infiltrate the preform. The pressure in the pressure vessel is allowed to decay slowly as the temperature falls. When the article solidifies (i.e., its temperature drops below about 500°C), chamber is vented the cast metal matrix composite article(s) (e.g., insert(s)) is removed from the die(s), and then allowed to further cool in air.
• typically argon or a similar inert gas
• Inserts can also be made, for example, other techniques known in the art, including squeeze casting.
• the formed ceramic oxide fiber can be placed in a die (e.g., a steel die), any sizing present burned away, molten aluminum aluminum alloy introduced into the die cavity, and pressure applied until solidification of the cast article is complete. After cooling, the resulting insert is removed from the die.
• the resulting insert can be further processed (e.g., sand blasted and/or surface ground (e.g., with a vertical spindle diamond grinder), for example to remove or reduce oxidation on the surface of the insert.
• the insert may also be cut as needed to provide a desired shape (including being cut with a water jet).
• the insert can be coated, if desired with a first metal such as Cu, Au, Ni, Ag, Zn, and combinations thereof.
• a second metal such as Ni is coated onto the insert prior to coating the first metal.
• Ni aids in the adhesion of metals such as Cu and Ag onto the insert.
• the particular substantially continuous ceramic oxide fibers, matrix material, and process steps for making inserts and/or metal matrix composite articles are selected to provide metal matrix composite articles with the desired properties.
• the substantially continuous ceramic oxide fibers and metal matrix materials are selected to be sufficiently compatible with each other and the article fabrication process in order to make the desired article.
• the metal comprising the region of an insert and/or metal matrix composite article according to the present invention in some embodiments is preferably selected such that the metal matrix does not significantly react chemically with the substantially continuous ceramic oxide fibers, (i.e., is relatively chemically inert with respect to the molten metal), for example, to eliminate the need to provide a protective coating on the fiber exterior.
• Metal matrix composite articles according to the present invention can be cast with inserts using, in general, techniques known in the art (e.g., gravity casting die casting, and squeeze casting).
• Finite Element Analysis (FEA) modeling can be used, for example, to identify optimal positions and quantities of the ceramic oxide fiber for meeting desired performance specifications. Such analysis can also be used, for example, to aid in selecting the dimension(s), number, and location, for example of the inserts used.
• the insert(s) and/or die may be preheated prior to casting. In some embodiments, preferably the insert(s) is preheated to about 500°C-600°C. In some embodiments, preferably the die is preheated to 200°C-500°C.
• FEA may also be used, for example, to aid in choosing a casting technique, casting conditions, and/or mold design for casting an insert and/or metal matrix composite article according to the present invention.
• Suitable FEA software is commercially available, including that marketed by UES, Annapolis, MD, under the trade designation "PROCAST".
• the inserts typically include the optional Cu, Au, Ni, Ag, Zn, or combinations thereof.
• the inserts typically include the optional Cu, Au, Ni, Ag, Zn, or combinations thereof.
• metal matrix composite articles according to the present mvention cast in an atmosphere comprising, for example, argon, it is generally more favorable to purge the casting atmosphere with the argon one or more times prior to casting.
• the article may be further processed using hot isostatic pressing (HIPing) to break and diffuse the oxide away from the interface and force more complete wetting and/or densification.
• HIPing hot isostatic pressing
• Techniques for HIPing are well known in the art. Examples of HIPing temperatures, pressures, and times that may be useful for embodiments of the present invention include 500°C to 600°C, 25MPa to 50 MPa, and 4 to 6 hours, respectively. Temperatures, pressures, and times outside of these ranges may also be useful. Lower temperatures tend, for example, to provide less densification and/or increase the HIPing time, whereas higher temperatures may deform the metal matrix composite article.
• the metal matrix composite articles are typically designed for a certain purpose, and as a result, it is desired to have certain properties, to have a certain configuration, be made of certain materials, etc.
• the mold is selected or made to provide the desired shape of the metal matrix composite articles to be cast so as to provide a net shape or near net shape.
• Net-shaped or near net- shaped articles can, for example, minimize or eliminate the need for and cost of subsequent machining or other post-casting processing of a cast metal matrix composite articles.
• the mold is made or adapted to hold the insert(s) in a desired location(s) such that the substantially continuous ceramic oxide fibers are properly positioned in the resulting metal matrix composite articles.
• Techniques and materials for making suitable cavities are known to those skilled in the art.
• the material(s) from which a particular mold e.g., graphite, steel, and sand
• Metal matrix composite articles according to the present invention may comprise more than one groupings (e.g., two groupings, three groupings, etc.) of substantially continuous ceramic oxide fibers, wherein a grouping of substantially continuous ceramic oxide fibers is spaced apart from another grouping(s) with the metal secures the substantially continuous ceramic oxide fibers in place there between.
• insert 90 comprises groupings 93A, 93B, and 93C of substantially continuous, (as shown, longitudinally aligned) ceramic oxide fibers 92 and aluminum or alloy thereof 94.
• outer surface 95 of aluminum or alloy thereof 94 has first metal (e.g., Cu, Au, Ni, Ag, Zn, and combinations thereof) 96 thereon.
• outer surface 97 of second optional metal 98 has second optional metal (e.g., Ni) 98 thereon.
• Metal matrix composite articles according to the present invention may be in any of a variety of shapes, including a rod (including a rod having a circular, rectangular, or square cross-section), an I-beam, L-shape, or a tube.
• Metal matrix composite articles according to the present invention may be elongated and have a substantially constant cross-sectional area.
• inserts and metal matrix composite articles according to the present invention comprise, in the region comprising the substantially continuous ceramic oxide fibers, in the range from about 30 to about 70 percent (in some embodiments, preferably about 35 to about 60 percent, or even about 35 to about 45 percent) by volume metal and in the range from about 70 to about 30 percent (in some embodiments, preferably about 65 to about 40 percent, or even about 65 to about 55 percent) by volume of the substantially continuous ceramic oxide fibers, based on the total volume of the region, hi some embodiments, preferably the inserts and metal matrix composite articles according to the present invention comprise, in the region comprising the substantially continuous ceramic oxide fibers, at least 50 by volume of the substantially continuous ceramic oxide fibers, based on the total volume of the region.
• inserts comprise the substantially continuous ceramic oxide fibers, in the range from about 30 to about 70 percent (in some embodiments, preferably about 35 to about 60 percent, or even about 35 to about 45 percent) by volume metal and in the range from about 70 to about 30 percent (in some embodiments, preferably about 65 to about 40 percent, or even about 65 to about 55 percent) by volume substantially continuous ceramic oxide fibers, based on the total volume of the insert, hi some embodiments, preferably the inserts comprise at least 50 by volume of the substantially continuous ceramic oxide fibers, based on the total volume of the insert.
• Oxygen Layer Test A portion of a metal matrix composite article is cut to obtain a cross-section of the insert or holder and the aluminum or aluminum alloy cast around the insert or holder. Then cross-section is polished with semi-automatic metallographic grinding/polishing equipment (obtained under the trade name "ABRAMLN” from Struers, Inc, Cleveland, OH). The polishing speed is 150 rpm. The polishing is done in the following successive 6 stages. The polishing force is 150 N, except in Stage 6 it is 250 N: -Stage 1
• the sample is polished for 45 seconds using 120 grit silicon carbide paper (obtained from Pace Technologies, Northbrook, IL) while continuously, automatically dripping water onto abrasive pad during polishing. After polishing, the sample is thoroughly rinsed with water. -Stage 2
• the sample is polished for 45 seconds using 220 grit silicon carbide paper (obtained from Pace Technologies) while continuously, automatically dripping water onto abrasive pad during polishing. After polishing, the sample is thoroughly rinsed with water. -Stage 3
• the sample is polished for 45 seconds using 600 grit silicon carbide paper (obtained from Pace Technologies) while continuously, automatically dripping water onto abrasive pad during polishing. After polishing, the sample is thoroughly rinsed with water.
• 600 grit silicon carbide paper obtained from Pace Technologies
• the sample is polished for 4.5 minutes using polishing pad (obtained under the trade designation "DP-MOL” from Struers, Inc.), wetted lightly with periodic droplets of lubricant (obtained under the trade designation “PURON, DP- LUBRICANT” from Struers) and sprayed for 1 second with 6 micrometer diamond grit (obtained under the trade designation "DP-SPRAY, P-6 ⁇ m” from Stmers). After polishing, the sample is thoroughly rinsed with water. -Stage 5
• the sample is polished for 4.5 minutes using polishing pad ("DP-MOL”), wetted lightly with periodic droplets of lubricant (obtained under the trade designation
• Example 3 (see FIG. 10) of copending application having U.S. Serial No. 60/404,672, filed August 20, 2002, when evaluated with this test did not have a visibly discemable continuous oxide layer at the interface
• Comparative Example H (see FIG. 11) from the same application did.
• the polished cross-section of Example 3 showed no abrupt boundary at interface 162 between insert matrix 166 and casting alloy 163.
• the polished cross-section of Comparative Example H showed an abrupt boundary, believed to be an oxide layer, at interface 182 between insert matrix 186 and casting alloy 183.
• metal matrix composite articles according to the present invention include brake calipers and aerospace applications (e.g., electrical access doors, reinforcing structural members (e.g., I beams, stiffners, and panels), and landing gears).
• aerospace applications e.g., electrical access doors, reinforcing structural members (e.g., I beams, stiffners, and panels), and landing gears).
• Two aluminum matrix composite articles were made as follows. Tows of continuous alpha alumina fibers (available under the trade designation "NEXTEL 610" from the 3M Company, St. Paul, MN; 3,000 denier; Young's modulus of about 370 GPa; average tensile strength of about 3 GPa; average diameter 11 micrometers) were wound using a deionized water sizing, wherein the tows of fiber were dipped fiber in a water bath immediately before being wound onto a four-faced 20.3 cm. (8-inch) square mandrel to produce a fiber preform having a 49.5% volume loading of fiber.
• Tows of continuous alpha alumina fibers available under the trade designation "NEXTEL 610" from the 3M Company, St. Paul, MN; 3,000 denier; Young's modulus of about 370 GPa; average tensile strength of about 3 GPa; average diameter 11 micrometers
• the fiber was wound under tension (about 75 grams, as measured by a tension meter (obtained under the trade designation "CERTEN” from Tensitron, Boulder CO) to form rectangular preform plates 8.25 cm (3.25 inches) by 20.3 cm (8 inches) by 0.254 cm (0.1 inch thick).
• the mandrel was then placed in a cooler to freeze the water and stabilize the resulting preform.
• the edges of the preform were trimmed and the plates were cut into 7.6 cm by 15.2 cm (3 inches by 6 inches) preforms.
• the resulting 7.6 cm by 15.2 cm by 0.254 cm fiber pre-forms were placed inside a graphite mold, which had been coated with boron nitride.
• the graphite mold containing the preforms was placed inside a stainless steel can that was open at one end.
• the can assembly was then placed inside the cylindrical vessel of a conventional gas pressure casting machine.
• Pieces of aluminum alloy 6061 aluminum alloy obtained from Alcoa of
• the can is placed within pressure vessel designated heating zones to ensure a uniform melt temperature.
• the pressure vessel is then evacuated of air and heated above the liquidus point of the aluminum alloy (715°C).
• the heater was turned off and the pressure vessel pressurized with argon to a pressure of about 9 MPa (1300 psi), forcing the molten aluminum alloy to infiltrate the preforms.
• the pressure in the pressure vessel was allowed to decay slowly as the temperature falls.
• the insert temperature was below about 500 C, the chamber was vented, the can removed from the pressure vessel, and the cast metal matrix composite articles (insert plates) removed from the can and let cool in air.
• insert plates were then sawn lengthwise and milled to form finished inserts having a dimension of 0.9525 cm (0.375 inch) by 15.2 cm (6 inches) by 0.254 cm (0.1 inch).
• the surface of the finished insert was sandblasted to clean the surface and remove any oxide layer thereon.
• the insert was then submerged in a conventional nickel sulfamate plating solution, and a current of 1.5 A applied for 4.5 minutes to deposit a 1 micrometer layer of Ni on the surface of the insert.
• the insert was then submerged in a conventional copper sulfate plating solution, and a current of 4.4 A applied for 3 minutes to deposit about 5 micrometers of Cu.
• Four of the copper coated inserts were placed in a sand mold. Referring FIGS. 8 A and 8B, mold 100 is shown in solid lines, and four inserts 101 will be located in the sand mold are shown in phantom lines.
• Plate 102 which will define the final metal matrix composite article was a right rectangular prism having dimensions of 15.2 cm by 20.3 cm by 2.54 cm. Mold 100 had sprue 104 with 12.5 mm by 19 mm choke 106 feeding tapered runner 108 having a width 63 mm wide. Runner 108 fed four 25.4 mm diameter risers
• the metal matrix composite article was cast in air by pouring molten aluminum alloy D357 at 746 °C (1375°F) into the mold at the sprue. Pouring time was 7 seconds. The inserts were not preheated. To accelerate cooling metal chills were buried into the sand mold. After solidification of the molten aluminum alloy, the resulting metal matrix composite article was removed from the sand mold, and mold waste was cut away from the article.
• One of the four resulting metal matrix composite articles was cross-sectioned, cut to about 10 cm size, mounted in epoxy, and polished as follows using semi-automatic metallographic grinding/polishing equipment (obtained under the trade name "ABRAMIN” from Stmers, Inc, Cleveland, OH).
• the polishing speed was 150 rpm.
• the polishing was done in the following successive 6 stages.
• the polishing force was 150 N, except in Stage 6 it was 250 N: -Stage 1
• the sample was polished for 45 seconds using 120 grit silicon carbide paper (obtained from Pace Technologies, Northbrook, IL) while continuously, automatically dripping water onto abrasive pad during polishing. After polishing, the sample was thoroughly rinsed with water. -Stage 2
• the sample was polished for 45 seconds using 220 grit silicon carbide paper (obtained from Pace Technologies) while continuously, automatically dripping water onto abrasive pad during polishing. After polishing, the sample was thoroughly rinsed with water. -Stage 3
• the sample was polished for 45 seconds using 600 grit silicon carbide paper (obtained from Pace Technologies) while continuously, automatically dripping water onto abrasive pad during polishing. After polishing, the sample was thoroughly rinsed with water. -Stage 4
• the sample was polished for 4.5 minutes using polishing pad (obtained under the trade designation "DP-MOL” from Stmers, Inc.), wetted lightly with periodic droplets of lubricant (obtained under the trade designation “PURON, DP- LUBRICANT” from Stmers) and sprayed for 1 second with 6 micrometer diamond grit (obtained under the trade designation "DP-SPRAY, P-6 ⁇ m” from Stmers). After polishing, the sample was thoroughly rinsed with water. -Stage 5
• the sample was polished for 4.5 minutes using polishing pad ("DP-MOL”), wetted lightly with periodic droplets of lubricant (obtained under the trade designation
• the polished cross-section was coated with few angstroms gold layer via sputtering gold thereon.
• the resulting sample was viewed in a scanning auger electron (SAM) microscope (obtained under the trade designation SAM 600" from Physical Electronics Company (previously know as Perkins Elmer), Eden Prairie, MN). Referring to FIG. 11, the SAM photomicrograph shows insert 111, interface 112, and cast aluminum alloy 113.
• FIG. 12 An electron microprobe copper line scan was conducted in a line across the insert, interface and cast aluminum alloy. The results are shown in FIG. 12, wherein 121 is the insert, 122 is the interface, 123 is the cast aluminum alloy, and the copper line scan is 124.
• One of the four resulting metal matrix composite articles was slit with a diamond saw into four portions, each having one insert therein to form test coupons. Each portion was then milled to a finished test coupon 130 as illustrated in FIGS.
• test coupon was clamped into the lower jaws of the testing machine. About 10 MPa (1.5 Ksi)) hydraulic pressure was applied (using a foot pedal connected servo) to move the jaw to clamp the test coupon. The upper cross-head was then lowered and the test coupon clamped by the upper jaw, again using about 10 MPa of pressure. Care was taken to ensure good alignment of the loading axis with the test coupon bond plane. The test coupon was pulled at a rate of 0.017 mm/sec, and both displacement and load ("Load”) were recorded up to the point of complete separation of the interface. The Peak Bond Strength was determined by dividing the maximum "Load" by the "Interface Area". The results for Examples la and lb are shown in Table 1, below.
• Comparative Examples Bl, B2, and B3 Three other metal matrix composite articles (i.e., Comparative Examples Bl, B2, and B3) were prepared as described in Example 1, except the copper plating was conducted for 8 minutes, and the resulting Cu coating was about 20 micrometers thick.
• Comparative Example C Four Comparative Example A (i.e., Comparative Examples CI, C2, C3, and C4) metal matrix composite articles was prepared as described in Comparative Example A, except the inserts were not sandblasted and no Ni or Cu coating was provided. The bond strength for each of Comparative Examples CI, C2, C3, and C4 are provided in the Table 1, above.
• One of the four resulting metal matrix composite articles was cross-section and polished and viewed in a SAM as described in Comparative Example A. Referring to FIG. 13, the SAM photomicrograph shows insert 131, interface 132, and cast aluminum alloy 133. Further, an electron microprobe oxygen line scan was conducted in a line across the insert 131, interface 132, and cast aluminum alloy 133 is shown in FIG. 14 wherein 145 is the oxygen line scan. A sharp oxide peak (believed to be aluminum oxide) about 3 micrometers wide was believed to have inhibited bonding between the insert and the cast aluminum alloy.
• One of the four resulting metal matrix composite articles was placed in a conventional x-ray radiography machine.
• the article was placed on a turntable inside the machine chamber and centered to be positioned in the path of the x- ray beam.
• Unexposed x-ray film (medium speed film obtained from Eastman Kodak Company, Rochester, NY), inside a protective frame, was placed behind the article.
• the x- ray source was turned on and the article exposed to 90 KV at 3.5 amps for about 3 to 5 minutes (ASTM Standard E- 94-88, was followed to provide a film density of about 3.
• the exposed film was processed using conventional technique.
• a print is shown in FIG. 15, wherein 151 is the insert and 153 is the cast aluminum alloy. Debonding between insert 151 and cast aluminum alloy 153 is clearly seen.
• Example 1 A print is shown in FIG. 15, wherein 151 is the insert and 153 is the cast aluminum alloy. Debonding between insert 151 and cast aluminum alloy 153 is clearly seen.
• Example 1 (i.e., Examples la, lb, lc, Id, le, If, lg, and lh) metal matrix composite articles was prepared as described in Comparative Example A, except no Ni or Cu coating was provided, and the mold was purged with argon gas (i.e., argon was flowed through the mold for about 15 minutes).
• argon gas i.e., argon was flowed through the mold for about 15 minutes.
• the bond strength for each of Examples la, lb, lc, Id, le, If, lg, and lh are provided in the Table 1, above.
• One of the four resulting metal matrix composite articles was cross-section and polished as described in Comparative Example A.
• the polished cross-section was coated with few angstroms of gold as described in Comparative Example A.
• the resulting sample was viewed in a scanning electron microscope (SEM) (obtained from Physical Electronics, Eden Prairie, MN; Model 600). Referring to FIG. 17, the optical photomicrograph shows insert 171 and cast aluminum alloy 173.
• One of the four resulting metal matrix composite articles was cross-section and polished and viewed in a SAM as described in Comparative Example A. Further, an electron microprobe oxygen line scan was conducted in a line across the insert, interface and cast aluminum alloy. Referring to FIG. 18, the SAM photomicrograph shows insert 181, interface 182, cast aluminum alloy 183, and oxygen line scan 185.
• Example 2a and 2b Two metal matrix composite articles (i.e., Examples 2a and 2b) were prepared as described in Comparative Example A, except the articles were further processed by hot isostatic pressing.
• the articles were hot isostatically pressed in argon at a temperature of about 1010 °F (543 °C) and a pressure of about 34.5 MPa (5.0 Ksi) for about 4 hours.
• the bond strength for each of Examples 2a and 2b are provided in the Table 1, above, along with the thickness of the Cu.
• Example 3a and 3b Two metal matrix composite articles (i.e., Examples 3a and 3b) were prepared as described in Example 2, except the articles were further processed by hot isostatic pressing as described in Example 3.
• the bond strength for each of Examples 3a and 3b are provided in the Table, above, along with the thickness of the Cu.
• Example 4 Eight metal matrix composite articles (i.e., Examples 4a, 4b, 4c, 4d, 4e, 4f, 4g, and
• Example 4h were prepared as described in Example 3 and tested as described in Comparative Example A, except that the test coupons machined from these articles had a thickness in the d4 dimension of 5 mm (0.2 inch).
• the Peak bond strength for each of Examples 4a, 4b, 4c, 4d, 4e, 4f, 4g, and 4h are provided in Table 2, below, along with the thickness of the Cu.
• One of the four resulting metal matrix composite articles was cross-section and polished and viewed in a SAM as described in Comparative Example A. Further, an electron microprobe oxygen line scan was conducted in a line across the insert, interface and cast aluminum alloy. Referring to FIG. 20, the SAM photomicrograph shows insert 201, interface 202, cast aluminum alloy 203, and oxygen line scan 205.

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