JPH08176704A - Production of in situ al and mg composite material - Google Patents

Abstract

PURPOSE: To obtain a simple process for production which forms and disperses fine carbide or oxide in situ as a process for producing an aluminum or magnesium composite material. CONSTITUTION: Solid oxide or carbide relatively low in thermodynamical stability is added into molten aluminum or magnesium and further their alloy and the oxide or carbide of the different kind having high stability is formed and dispersed therein in situ. The fine oxide or carbide particles are uniformly dispersed into the aluminum or magnesium matrix by the simple in situ method.

Description

Detailed Description of the Invention (Social Contribution) Establishment of a method for manufacturing a lightweight, tough, and fine particle dispersion-reinforced magnesium composite material at low manufacturing cost according to the present invention. (Conventional method for producing particle-dispersion-strengthened metal-based composite material and problems therefor) As a conventional method for producing particle-dispersion-strengthened metal-based composite material, a powder metallurgy method of mixing, molding, and sintering metal and ceramic powders has been used. , Or compo-casting method in which particles are mixed in a highly viscous semi-molten metal, both of them have poor wettability, for example, between aluminum and ceramics, so that the particles are forced into the matrix. It is a method of dispersion, but it has a problem that high costs cannot be avoided. The method called the Fortex method or the molten metal stirring method mixes and disperses the particles in the molten metal only by stirring, and in this method, it is essential to add a component that improves the wettability between the ceramic and the metal. Yes, without this, it becomes difficult to mix the particles. Moreover, even if the wettability is improved, it is quite difficult to disperse fine particles having a particle diameter of 1 μm or less in the molten metal. (Means for Solving the Problems According to the Present Invention) The molten metal stirring method is adopted while avoiding the powder metallurgy method or the component casting method, which leads to high cost due to the complicated process. However,
Since there is a limit to the difficulty of fine particle dispersion in the particle dispersion by this method, a so-called In SiTu composite material manufacturing method is adopted. That is, the theoretical background on which the present invention is based is that oxides, carbides, and nitrides having a lower chemical stability than the oxides, carbides, and nitrides of the matrix metal, that is, the standard free energy of formation is relatively large. This is the addition of compound particles, and the particle size is such that mixing into the molten metal is easy. At this time, since the added particles are relatively inferior in chemical stability, they decompose in the molten metal to generate oxygen, carbon or nitrogen, and react with a matrix metal having a small standard free energy of formation to form an oxide. Form carbide or nitride. The amount of this decomposition can be adjusted by controlling the feed rate or temperature of the added particles to adjust the particle size and the amount of the compound produced in the melt. According to this method, since the compound is formed in the molten metal, not by mixing and dispersing the particles from the surface of the molten metal, extremely fine particles can be dispersed. Therefore, it is generally known that the strength of the particle dispersion-reinforced composite material is improved as the particle diameter is finer, and it is expected that high strength is achieved by dispersing the fine particles generated by the In Situ method. Further, among the decomposition components of the additive compound, components other than oxygen, carbon and nitrogen also have the advantage of being effectively utilized as alloy components of the matrix. In the present invention, from the viewpoint of the low cost composite process, first, the molten metal stirring method is adopted, and a compound having a chemical stability lower than that of the matrix is added, and the fine particles are dispersed by causing decomposition and reaction in the molten metal. Therefore, it has the feature of providing a high-strength particle dispersion-reinforced composite material. (Setting of manufacturing conditions) (1) Temperature: Since magnesium easily evaporates and is active, it is preferable to operate at a low temperature, and the temperature is 700 to 800 ° C. However, when aluminum is used as a matrix, the reaction is performed more quickly. High temperature is good. However, CuO
Has a thermal decomposition temperature of 1086 ° C, so care must be taken when exploding when adding. (2) Size of added compound: Since the stirring time required for mixing and dispersing particles by the molten metal stirring method becomes longer as the particle diameter decreases, 10 μm or more is preferable. (3) Stirring speed: 60r is not required to be particularly high.
pm is sufficient. (4) Atmosphere: The operation should be performed in an inert atmosphere. (5) Particle addition method: Either continuous addition or semi-continuous addition is possible. (Example) 60 in an MgO crucible under an argon atmosphere
Gram of Al-3% Mg alloy was melted, and when the temperature reached 1000 ° C., stirring of the molten metal by a motor was started, and CuO particles were gradually added while stirring was continued. At this time, CuO is decomposed in the molten metal, oxygen reacts with aluminum to form fine Al ₂ O ₃ , and is dispersed, while Cu is an alloy component. After completion of stirring, the composite material was cast in a mold, and this sample was hot extruded to prepare a sample for measuring the strength. As a result of measuring the tensile strength of this composite material, as shown in FIG. 1, it was 40.0 kgf / mm ^2.
The matrix composition Al-3% Mg-7., Assuming that all of the added CuO was decomposed and alloyed.
Higher strength than the tensile strength of 34.1 kgf / mm ^{2 of} 8% Cu is obtained. (Effect of the invention) The most promising process for reducing the manufacturing cost of metal-based composite materials is the melt stirring method, but in this method, good wettability is essential and there is a limit to the dispersion of small particles. There is. On the other hand, dispersion of small particles is essential for improving the strength of particle dispersion-reinforced composite materials, and the development of a new process for that purpose has been awaited. In this respect, the present invention is characterized by forming fine oxides, carbides or nitrides in the molten metal, and the process is simple and low cost. Thus, the present invention provides a high-strength metal matrix composite material that is low in cost and lightweight.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1: Tensile strength of Al ₂ O ₃ In Situ generated particle dispersion strengthened aluminum composite material

Claims (1)

(Claims) (1) Various compounds are added to molten aluminum, aluminum alloy, magnesium, magnesium alloy,
A method for producing a composite material by dispersing an In Situ-produced compound accompanying the decomposition of the compound. (2) The composite according to claim 1, wherein the various compounds are one kind or two kinds or more of a carbide, an oxide and a nitride. (3) The carbides are Al ₄ C ₃ , CaC ₂ , Cr
₇ C ₃ , Cr ₃ C ₂ , Cr ₂₃ C ₆ , Ni ₃ C, Mo ₂
C, WC, SiC, Fe ₃ C is any one kind or two kinds or more, The composite body according to any one of claims 1 and 2. (4) the oxide _{CuO, Cu 2 O, Fe 2} O 3, F
eO, NiO, CoO, SnO ₂ , ZnO, Cr
₂ O ₃ , MnO, SiO ₂ , V ₂ O ₃ , TiO ₂ , Al
The composite according to any one of claims 1 to 3, wherein the composite is any one or more of ₂ O ₃ . (5) The nitrides are CrN, VN, Si ₃ N ₄ , Mg
Any one of ₃ N ₂ and TaN or two or more thereof. The composite according to any one of claims 1 to 4, wherein the complex is any one of ₃ N ₂ and TaN.