JPH1150179A - Aluminum matrix composite and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dispersion strengthened Al matrix composite improved in strength to a greater extent than a TiC grain dispersion strengthened Al matrix composite. SOLUTION: In the Al matrix composite, TiC grains and Ti-Al-Si ternary compound grains are dispersed as reinforcement in an Al or Al-alloy matrix. A compact, which is composed of Ti powder, C powder, and Al or Al-alloy powder and in which the value of (Ti powder)/(C powder) by weight is regulated to 4.5-7.0, is impregnated with a molten Si-containing Al alloy and then heated, by which TiC grains and Ti-Al-Si ternary compound grains are formed. A compact, which is composed of Ti powder, C powder, and Al or Al-alloy powder and in which the value of (Ti powder)/(C powder) by weight is regulated to 4.5-7.0, is impregnated with a primary molten metal of Al or Al alloy and TiC grains and Ti-Al binary compound grains are formed while forming a secondary molten metal of Al alloy by heating, and then, a tertiary molten metal of Si- containing Al alloy is poured into the secondary molten metal or the solidified substance of the secondary molten metal, by which TiC grains and Ti-Al-Si ternary compound grains are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dispersion-strengthened Al-based composite material in which the reinforcing effect of a reinforcing material is improved, and a method for producing the same.

[0002]

2. Description of the Related Art Until now, it has been very difficult to achieve the strength estimated from the volume ratio of a reinforcing material by the mixing rule (composite rule) in a dispersion strengthened Al-based composite material. On the other hand, the strength actually obtained was generally quite low. For example, even if 10 vol% of Si ₃ N ₄ particles are dispersed in an Al—Si—Cu alloy matrix, the strength of the Al-based composite material is improved by only about 5% with respect to the matrix strength. In this case, from the mixing rule, an improvement in strength of at least about 10 to 15% with respect to the matrix strength is expected, but in an actual composite material, only a strength that increases the estimated strength can be realized. Although the cause is not clear, it is considered that the interfacial adhesion between the reinforcing material and the matrix is low and the characteristics of the reinforcing material cannot be sufficiently exhibited, or the size of the reinforcing material particles is relatively large at a maximum of 44 μm. Can be

[0003] JP-A-6-17165 discloses a TiC particle dispersion strengthened Al-based composite material and a method for producing the same. This composite material is prepared by forming a green compact including Ti powder, graphite powder, and Al or Al alloy powder, impregnating the molten Al or Al alloy, and then heating to generate TiC particles. It is produced by dissolving a body in a molten Al or Al alloy.

[0004] Originally, a green compact similar to the above was prepared,
Japanese Patent Application Laid-Open No. 63-8 / 1988 discloses a method in which TiC particles are generated by heating this and then dissolved in a molten Al or Al alloy.
No. 3239 was known. However, since the molded body and the molten metal are poorly familiar due to various factors,
In practice, it is very difficult to dissolve
It was extremely difficult to obtain an Al-based composite material having a good structure in which the iC particles were uniformly dispersed, and it was not suitable for being adopted as an actual production method.

[0005] The technique disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-17165 is to produce a green compact similar to that described above, impregnate it with Al or an Al alloy melt, and then heat it to form a compact.
The iC particles are generated and then dissolved in Al or Al alloy melt. According to this method, since the voids of the green compact are filled with Al or an Al alloy by impregnation, the compatibility with the Al or Al alloy melt that finally dissolves the green compact becomes very good, and the melting is extremely high. It will be easy. Therefore, an Al-based composite material having a good structure in which fine TiC particles are uniformly dispersed can be manufactured. One of the points of this technique is that the impregnation is performed before the molded body is heated.
Since i exerts a getter function in the impregnation step and removes air (oxygen / nitrogen) in the voids of the molded body to create a vacuum and induces a suction action, the molten metal can easily enter the voids without being pressurized. And good impregnation is achieved.

As described above, according to the technique disclosed in Japanese Patent Application Laid-Open No. 6-17165, TiC particle dispersion strengthening A having good characteristics is used.
Although an l-based composite material can be obtained, it is still possible to realize a considerably lower strength than the estimated strength expected from the mixing rule, and further improvement in strength has been desired.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dispersion-strengthened Al-based composite material whose strength is further improved as compared with the conventional TiC particle dispersion-strengthened Al-based composite material, and a method for producing the same. I do.

[0008]

According to the present invention, there is provided according to the present invention, wherein TiC particles and Ti-Al-Si ternary compound particles are dispersed as a reinforcing material in a matrix of Al or an Al alloy. And an Al-based composite material. According to the first aspect, the method for producing an Al-based composite material of the present invention comprises Ti powder, graphite powder, and Al or Al alloy powder and has a Ti / C powder weight ratio of 4. A step of preparing a green compact of a mixed powder having a particle size of 5 to 7.0, a step of impregnating the molten body of the Si-containing Al alloy into the compact to form an integrated impregnated body, and heating the impregnated body. TiC particles and Ti-
The method includes a step of generating Al-Si ternary compound particles.

Further, according to a second aspect, the Al of the present invention
The method for producing the matrix composite material is a green compaction of a mixed powder comprising Ti powder, graphite powder, and Al or Al alloy powder and having a Ti / C weight ratio Ti / C of 4.5 to 7.0. Step of forming a body, Al or Al
A step of impregnating the first molten metal of the alloy to form an integral impregnated body;
By heating the impregnated body, TiC particles and Ti-Al are contained in the second alloy while forming a second molten metal of the Al alloy.
A step of generating binary compound particles, and pouring a third molten metal of an Si-containing Al alloy into the second molten metal or the solidified product of the second molten metal, thereby obtaining TiC particles and Ti-Al
Generating a Si ternary compound particle.

The inventor of the present invention has proposed that, as a reinforcing material for an Al-based composite material, in addition to TiC particles conventionally used, Ti
The present inventors have found a completely new fact that the coexistence of -Al-Si ternary compound particles can provide a much larger strengthening effect than estimated from the mixing rule based on the total volume ratio of both particles, and found this new finding. Based on this, the present invention has been completed.

The coexistence of TiC particles and Ti-Al-Si ternary compound particles as a reinforcing material in an Al or Al alloy matrix can be achieved by any one of the first and second aspects. That is, in the method according to the first aspect, a compact formed from Ti powder, graphite powder, and Al or Al alloy powder is impregnated with a molten metal of a Si-containing Al alloy, and then heated to heat the TiC particles and Ti-
Al-Si ternary compound particles are generated.

Since the Al-based composite material produced by the method of the first aspect contains a high concentration of reinforcing particles, it is mainly used as another Al or Al alloy (Si
(It may or may not be contained.) It is assumed that the reinforcing material is introduced into the molten metal to dilute the reinforcing material concentration to produce another Al-based composite material. Of course, depending on the use, there is no limitation on using the same as a structural member or the like.

According to the method of the second aspect, a green compact comprising Ti powder, graphite powder, and Al or Al alloy powder is first impregnated with a first molten metal of Al or Al alloy to be integrally impregnated. A TiC particle and a Ti-Al binary compound particle are generated in the second molten metal while forming the second molten metal of the Al alloy by heating the impregnated body, and then the second molten metal or the second molten metal is formed. Si to the solidified material of the molten metal
By pouring a third molten metal of the contained Al alloy, TiC particles and Ti-Al-Si ternary compound particles are generated.

The Al-based composite material manufactured by the method of the second aspect is already diluted with the third molten metal as compared with the Al-based composite material manufactured by the method of the first aspect. It is appropriate to use it as a structural member or the like. Further, when dissolved in another molten metal, it is excessively diluted, the concentration of the reinforcing material becomes low, and the effect of improving the strength cannot be expected.

Both methods are disclosed in Japanese Patent Laid-Open No. Hei 6-171.
As in JP-A-65, the molded body is impregnated with the molten metal by using the getter effect of Ti in the green compact to form the impregnated body, so that the molded body has good familiarity with the molten metal and is easily dissolved in the molten metal. I can do it. In any of the first and second aspects, the weight ratio Ti / C between the Ti powder and the graphite powder, which are the constituent components of the green compact, is in the range of 4.5 to 7.0, so that T
By the coexistence of the iC particles and the Ti-Al-Si ternary compound particles, a much higher strength improving effect can be obtained than the mixing rule based on the total volume ratio of both particles. When the weight ratio Ti / C is smaller than 4.5, the amount of the generated particles is reduced, and when the weight ratio is larger than 7.0, the size of the generated particles is increased. In any case, the strengthening action is reduced, and the mixing rule is exceeded. No strength improvement effect can be obtained.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The effect of the present invention can be obtained from a Si-containing Al alloy used in the method for producing an Al-based composite material of the present invention, if the Al-based alloy basically contains Si.
Preferably, the i content is 0.3 to 18% by weight,
More preferably, the content is 1.0 to 18% by weight.

When Si is present in an amount of 0.3% by weight or more, the effect of coexistence of Ti-Al-Si ternary compound particles in addition to TiC particles becomes clear, and compared with the case where only TiC particles are dispersed, the effect of Ti-Al-Si ternary compound particles is 2%. A greater strength improvement effect is obtained than the mixing rule based on the total volume fraction of the types of reinforcing material particles.
This effect becomes more remarkable when the Si content is 1.0 wt% or more, and the effect becomes larger as the Si content increases.
However, when Si exceeds 18 wt%, the Al-based composite material tends to be embrittled, which is not practical from the viewpoint of productivity.

[0018]

【Example】

[Example 1] A dispersion-strengthened Al-based composite material using TiC particles and Ti-Al-Si ternary compound particles as a reinforcing material was produced by the following procedure. [Preparation of green compact] 0.9 to 1.5 g (0.1 g steps, 7 levels) of Ti powder (Sumitomo Citix, -325)
0.2 g of graphite powder (manufactured by AESAR, -3)
25 mesh) and 0.5 g of pure Al powder (-100 mesh made by Toyo Aluminum) were weighed and mixed. The obtained mixed powder was pressed at a surface pressure of 4 tons by a metal mold compression method into φ11.
It was formed into a 3 mm × 5 mm cylindrical shape. Thereby, Ti
Seven types of green compacts having different contents at seven levels were obtained.

[Impregnation of Molten Metal into Compacts (Preparation of Impregnated Body)] These compacts are melted in pure Al (temperature: 780).
C.) for 30 seconds, then taken out and solidified so as not to glow red to obtain an impregnated body. [Heating of impregnated body (preliminary generation process of reinforcing particles)] The impregnated body was heated in an Ar gas atmosphere at a heating rate of 5 ° C / min.
After heating to ° C., the heating was stopped and the mixture was naturally cooled to room temperature in the same atmosphere to obtain pellets.

After cooling, the structure of each pellet was observed. As a result, it was found that pellets having a structure in which submicron-sized TiC particles and TiAl ₃ particles were finely dispersed were obtained in all samples regardless of the Ti content. confirmed. [Dissolution in molten Si-containing Al alloy (final formation of reinforcing particles)] The above seven kinds of the above-mentioned seven types were so adjusted that the volume ratio of TiC particles in the Al-based composite material was finally 0.5 vol%. An appropriate amount of the pellet is weighed, and the JIS-A4032 alloy (Al-
12wt% Si-1wt% Cu-1wt% Mg-1wt% Ni)
In 100 g of molten metal (temperature: 750 ° C.). When the structure was observed after solidification, it was confirmed that fine TiC particles and Ti-Al-Si ternary compound particles were uniformly dispersed in the Al alloy matrix, and an Al-based composite material having a good structure was obtained. Was done.

After subjecting the above seven types of Al-based composite materials to T6 treatment, test pieces were prepared by machining and subjected to a tensile test at room temperature. The results obtained are shown in FIG. As shown in FIG. 1, the compounding amount of Ti powder in the green compact was 0.9 to 1.
In the case of 4 g, the strength of the matrix alloy JIS-A4032 was much higher than the strength estimated by the mixing rule.

That is, the conventional TiC particles have 0.5 vol%
While the presence of the matrix alone could only improve the matrix strength by at most a few percent, the present invention provides T
By coexisting the iC particles and the Ti-Al-Si ternary compound particles, a strength improvement of nearly 20% with respect to the matrix strength was obtained. The above-mentioned Ti powder compounding amount 0.9-1.
When the range of 4 g is converted into the ratio of the constituent components of the molded body, T
Since i: Al: C = 9 to 14: 5: 2, the weight ratio of Ti / C is 4.5 to 4.5 in terms of the mixing ratio of Ti powder and graphite powder.
It becomes 7. By mixing the Ti powder and the graphite powder at a weight ratio in this range to form a green compact, the final Al
In the basic composite material, a strength improvement far exceeding that estimated from the mixing rule can be obtained.

Example 2 Heating of the impregnated body was performed at a heating rate of 3 ° C.
Seven kinds of TiC particles / Ti-Al-Si ternary compound particle dispersion strengthened Al-based composite materials were produced in the same procedure and under the same conditions as in Example 1 except that the reaction was carried out at a lower speed. After performing the same T6 treatment as in Example 1, a tensile test was performed.
In the range of C = 4.5-7, almost the same strength improving effect as in Example 1 was obtained. The heating rate during heating affects the size of the produced strengthening particles, but a difference in heating rate between 3 ° C./min and 5 ° C./min causes a difference in particle size such that the strength characteristics fluctuate substantially. It turns out there is no.

Example 3 The composition of a Si-containing Al alloy that dissolves the impregnated body after the heat treatment was determined according to JIS-A4032 (A
1-12wt% Si-1wt% Cu-1wt% Mg-1wt% N
Seven kinds of TiC particles / Ti-Al-Si ternary compound particle dispersion strengthened Al-based composite material were produced by the same procedure and conditions as in Example 1, except that Al-12 wt% Si-4 wt% Cu was used instead of i). did.

After performing the same T6 treatment as in Example 1, a tensile test was carried out. As a result, almost the same strength improving effect as in Example 1 was obtained in the range of Ti / C = 4.5-7. Compared to Example 1, the composition of the alloy that dissolves the impregnated body is free of Mg and Ni and has a large amount of Cu, but Si is the same at 12% by weight, so it is considered that a similar strength improving effect was obtained. Can be

In the first to third embodiments, the second
An example in which an Al-based composite material used directly as a structural member or the like is manufactured by the manufacturing method according to the first aspect has been described. However, when an Al-based composite material containing reinforcing material particles at a high concentration is manufactured by the manufacturing method according to the first aspect, As in the above, an effect of improving strength exceeding the mixing rule was obtained.

[0027]

As described above, according to the present invention,
Disclosed is a dispersion-strengthened Al-based composite material in which TiC particles and Ti-Al-Si ternary compound particles coexist, and a method for producing the same, in which the strength is further improved compared to the conventional TiC particle dispersion-strengthened Al-based composite material.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a graph showing Ti powder content and Al content in a green compact.
5 is a graph showing the relationship between the tensile strength of the base composite material and the Al alloy matrix strength.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuaki Sato 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Toru Dezaki 3-65 Midorigaoka, Toyota City, Aichi Prefecture Daitoyo Kogyo Co., Ltd. (72) Inventor Shoji Kamiya 3-65 Midorigaoka, Toyota-shi, Aichi Prefecture Inside Daitoyo Kogyo Co., Ltd.

Claims (3)

[Claims] 1. The method according to claim 1, wherein T or T
An Al-based composite material comprising iC particles and Ti-Al-Si ternary compound particles dispersed as a reinforcing material. 2. A weight ratio of Ti powder to graphite powder, which is composed of Ti powder, graphite powder, and Al or Al alloy powder.
A step of preparing a green compact of a mixed powder having a / C of 4.5 to 7.0; a step of impregnating the molten body of the Si-containing Al alloy into the compact to form an integral impregnated body; and the impregnated body. A step of generating TiC particles and Ti-Al-Si ternary compound particles by heating the Al-based composite material. 3. A weight ratio of Ti powder to graphite powder, comprising Ti powder, graphite powder, and Al or Al alloy powder.
A step of preparing a green compact of a mixed powder having a / C of 4.5 to 7.0; a step of impregnating the compact with a first molten metal of Al or an Al alloy to form an integral impregnated body; By heating the body, TiC particles and Ti-Al are contained in the second molten metal while forming a second molten metal of the Al alloy.
A step of generating binary compound particles, and pouring a third molten metal of an Si-containing Al alloy into the second molten metal or the solidified product of the second molten metal, thereby obtaining TiC particles and Ti-Al
A method for producing Al ternary compound particles, the method comprising: producing Si ternary compound particles.