JPH06108180A - Composite material and its production - Google Patents

Abstract

PURPOSE:To produce a composite material excellent in flowability of molten material, easy of temp. control at the time of manufacture, and containing dispersed grains. CONSTITUTION:This composite material can be produced by using, as matrix, an Al alloy containing 8-26mass% Si, putting ceramic grains and short fibers into the molten Al alloy, dispersing them by stirring, allowing C liberated or decomposed from existing carbides to react with Si, with priority to Al, and forming SiC in the molten metal. Further, this material is a composite material where an Al alloy containing 8-16mass% Si is used as matrix and SiC grains are dispersed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material in which particles of ceramics or short fibers are dispersed using an Al alloy as a matrix and a method for producing the same.

[0002]

2. Description of the Related Art The following conventional techniques are known for composite materials in which ceramic particles and the like are dispersed. For example, there is a compocast method in which particles such as SiC and C are added to a molten metal which is completely melted or partially melted, and mechanical stirring is applied to the molten metal to form a composite material. Further, as a powder metallurgy method, there is a method of mixing particles such as SiC or C and powder such as an Al alloy and forming a composite material by a process such as isostatic pressing, sintering, hot extrusion or the like. Further, as a mechanical alloying method, particles such as SiC and C and powders such as Al alloy are mixed, and mechanical stirring is applied to the alloy powder in cold or hot to form particles such as SiC and C in the alloy powder. There is a method of kneading into a particle-dispersed composite material.

[0003]

According to the powder metallurgy method and the mechanical alloying method, it is possible to produce a composite material in which ceramic particles are uniformly dispersed, but alloy powder is expensive and a composite material is obtained. There are many steps up to, and the cost of the finished product is high. Furthermore, since the final process of manufacturing the material is extrusion, the shape of the finished product is limited to a simple shape. Further, in the compocast method, the added SiC particles and whiskers are partially decomposed in the molten metal having the Al alloy as a matrix to deteriorate the flow of the molten metal, and the toughness of the obtained composite material is also reduced. There is a problem. That is, when the additives of carbides and particles of C and short fibers (including whiskers) are dispersed and compounded by a molten metal (including semi-molten) stirring method using aluminum alloy as a matrix, 973K
Since the above high-temperature state continues to some extent, C released from the carbide or decomposed (if the additive is C, that C) and A
l reacts to form aluminum carbide, for example, Al ₄ C _{3 according} to the following equation. SiC → Si + C ……… Decomposition 4Al + 3C → Al ₄ C ₃ ……… Combination (formation) When this aluminum carbide is produced, the molten metal flows poorly and the castability deteriorates. The disadvantage is that the toughness of the Since the formation of aluminum carbide can occur not only during the production of the composite material but also during the subsequent reheating, strict temperature control is always required.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a composite material of an Al alloy which solves the above problems and a method for producing the same.

[0005]

According to the present invention, in accordance with the above object, an Al alloy containing 8 to 16 mass% of Si is used as a matrix, and ceramic particles or short fibers are added to this molten metal and stirred to be dispersed. By the method for producing a composite material in which C liberated or decomposed from carbide is reacted preferentially with Si over Al to form SiC in the molten metal, the present invention also provides Si in a matrix of 8 to 16 ma.
The above problem is solved by a composite material in which SiC particles are dispersed using an Al alloy containing ss%.

The present invention relates to an Al alloy used as a matrix of a composite material in which ceramic particles and the like are dispersed.
It is remarkable that the formation of aluminum carbide is remarkably suppressed when Si contains 8 mass% or more. That is, when the Al alloy serving as a matrix contains Si in an amount of 8 mass% or more, it is utilized that C liberated or decomposed from carbide in the molten metal reacts with Si preferentially with respect to Al to form SiC. is there. Si + C → SiC ... Chemical compound (generation) Many of the formed SiC have a grain shape. Therefore, by using the Al alloy containing Si of 8 mass% or more as a matrix, it is not necessary to perform severe temperature control as in the conventional case. Since the molten metal absorbs atmospheric gas, it is not preferable to heat it to a temperature higher than about 1100K. When SiC particles or short fibers (including whiskers) are compounded as described above, there is no problem because C liberated or decomposed from carbide combines with the Si component in the matrix to form SiC. Z
Even when combining particles such as rC, WC, B ₄ C, C or short fibers, even if SiC is produced, it is superior to Al ₄ C _{3 in} hardness, strength, wear resistance, heat resistance, etc. Also, since it has a grain shape, it is not a big disadvantage. on the other hand,
When the Si component in the Al alloy exceeds 16 mass%, a large amount of coarse Si crystals start to crystallize, and the toughness of the matrix alloy itself deteriorates, so that the formation of aluminum carbide becomes more difficult to occur. However, it is not preferable.

[0007]

EXAMPLE As shown in FIG. 3, in an crucible 2 heated by a heater 1, an Al alloy corresponding to JIS AC8A (Table 1
Reference material, containing Si of 11.0 to 13.0 mass%) was housed therein, and this was heated and melted at a temperature of 1073K. Then, in the obtained molten metal 3, SiC particles 5 having an average particle diameter of 5 μm
10 mass% was added from the material addition device 4. Next, the molten metal 3 was continuously stirred at 500 rpm by a stirring rod 6 for 7.2 Ks to uniformly disperse the SiC particles 5 in the molten metal 3 to obtain a composite material. The microscopic metallographic structure of this composite material is shown in FIG. Almost no formation of aluminum carbide (Al ₄ C ₃ ) was observed in this structure. on the other hand,
For comparison, an Al alloy corresponding to JIS AC4C (see Table 1, containing 6.5 to 7.5 mass% of Si) was heated and melted to 1073K in the same manner, and Si having an average particle diameter of 10 μm was used.
C particles were added in an amount of 10 mass%, and similarly stirred to obtain a composite material. The metallographic structure of this composite material is shown in FIG.
Black grain-shaped aluminum carbide is generated in this structure.

[0008]

[Table 1]

[0009]

As described above, according to the present invention, the generation of aluminum carbide which deteriorates the flowability of molten metal is suppressed, and the temperature control of the molten metal (similarly during reheating) is facilitated.
It can also prevent deterioration of toughness. In addition, SiC generated secondarily
There are few disadvantages.

[Brief description of drawings]

FIG. 1 is a diagram showing a metallographic structure of a composite material according to the present invention.

FIG. 2 is a diagram showing a metallographic structure of a conventional composite material corresponding to FIG.

FIG. 3 is a diagram illustrating a procedure of a compocast method used in the present invention.

[Explanation of symbols]

 2 Crucible 3 Molten metal 5 SiC particles 6 Stir bar

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[Procedure amendment]

[Submission date] September 10, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a photograph replacing a drawing showing a metallographic structure of a composite material according to the present invention.

2 is a photograph replacing a drawing showing a metallographic structure of a conventional composite material corresponding to FIG. 1. FIG.

FIG. 3 is a diagram illustrating a procedure of a compocast method used in the present invention.

[Explanation of symbols] 2 Crucible 3 Molten metal 5 SiC particles 6 Stir bar

Claims (2)

[Claims] 1. Al containing 8 to 16 mass% of Si
Using an alloy as a matrix, ceramic particles and short fibers are added to this melt and stirred to disperse, and C released or decomposed from intervening carbide is preferentially reacted with Si over Al to form SiC in the melt. A method for producing a composite material, characterized by comprising: 2. Si in a matrix of 8 to 16 mass
%, A composite material in which SiC particles are dispersed using an Al alloy containing 100%.