JPH07310131A - Production of mg-base composite material - Google Patents

Abstract

PURPOSE:To obtain an Mg-base composite material without the mechanical properties being deteriorated due to the entrainment of an atmospheric gas at the time of bringing molten matrix Mg into contact with reinforcement powder to infiltrate the melt into the powder by mixing an infiltration assistant in the reinforcement powder. CONSTITUTION:An infiltration assistant (SiO2, etc.) is mixed with reinforcement powder (of SiC, etc., having about 0.1-100mum grain diameter) so that the obtained mixed powder 2 contains 1-99vol.% assistant, and the mixed powder 2 is placed on the bottom of a steel crucible 1. A matrix alloy consisting of the ingot of Mg or Mg alloy is put on the mixed powder 2, and the crucible 1 is arranged in a high-frequency induction furnace 6, surrounded with a chamber 7 contg. an Ar atmosphere and placed in the atmosphere. The ingot is heated into a melt 3a, the melt 3a is infiltrated into the mixed powder 2 and allowed to react with the infiltration assistant to form magnesium oxide, and an Mg-base composite material wherein the reinforcing grains are dispersed is produced. Consequently, the entrainment of the atmospheric gas is prevented, and an Mg-base composite material without the mechanical properties being deteriorated is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a metal matrix composite material having Mg or a Mg alloy as a matrix.

[0002]

2. Description of the Related Art As a typical method for producing a composite material having a metal matrix, there are a molten metal stirring method, a powder metallurgy method, a squeeze casting method, and the like, and relatively new methods such as the Primex method and the Lanxide method. Company). The molten metal stirring method is a method of adding a reinforcing material while stirring molten metal with a stirring blade. The powder metallurgy method is a method in which a powder of a matrix metal and a powder of a reinforcing material are mixed in advance, which is molded and then subjected to processing such as hot extrusion to obtain a composite material. The squeeze casting method is a method in which a reinforcing material preform is prepared, placed in a mold, and then molten metal is poured and pressurized to impregnate it. Further, in the premex method, as shown in FIG. 3, a crucible a in a heating furnace contains a powder made of reinforcing particles b, and an Al-Mg alloy ingot c serving as a matrix is arranged on the upper portion of the powder. ₂ gas, or heated to the original mixed gas atmosphere of N ₂ gas and an inert gas, there is a method to suck pressure permeate the molten metal to melt the Al ingot c strengthening particles b.

[0003]

In the above-mentioned molten metal stirring method,
With the addition of reinforcements and the accompanying mechanical agitation,
There is a drawback in that the atmospheric gas is entrained in the molten metal to create bubbles and deteriorate the mechanical properties of the material. Further, when the particle size of the reinforcing material is small, there is a problem in that the particles easily aggregate, the aggregate is hard to break, and the dispersed state of the particles is poor.
Further, although the powder metallurgy method is suitable for manufacturing a mold material and the like, it has a drawback that it is difficult to manufacture a near net member. Further, the squeeze cast method has a drawback that the shape and volume ratio range of the reinforcing material are limited because a preform is used. Further, in the above-mentioned Primex method, only an example in which an Al-Mg alloy is used for the molten metal has been reported. Further, since the primex method is a relatively high temperature process, it is not suitable for high vapor pressure such as Mg or Mg alloy. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a metal-based composite material using Mg or a Mg alloy as a matrix, which solves the above problems.

[0004]

According to the above-mentioned object, the present invention provides a method for producing a composite material in which a reinforcing material powder and a matrix metal melt are brought into contact with each other and the molten metal penetrates into the reinforcing material powder. The above problem was solved by providing a method for producing a Mg-based composite material in which a permeation phenomenon is expressed by mixing the materials.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. Mg or a Mg alloy is used for the matrix of the metal-based composite material in the present invention. In actual practice, an Mg or Mg alloy ingot is used. Ceramics such as SiC, Al as a reinforcing material
Other commonly used particles such as ₂ O ₃ and TiC that do not react with Mg are used. The particle size used is 0.1 to 100 μm. When it is 100 μm or more, the strength of the composite material is lowered, and when it is 0.1 μm or less, the viscosity of the melt of the composite material becomes too high and it is not suitable for practical use. Next, a penetration aid is used. This penetration aid is mixed with the particles of the reinforcement. As this penetration aid, for example, SiO ₂ powder is used. Another penetration aid is ZnO. That is, as the penetration aid, an oxide is used which is brought into contact with the molten Mg and reacts with heat generation. The amount of the penetration aid added to the reinforcement is 1 to 99% in terms of volume ratio in the mixed powder of the reinforcement and the penetration aid. Here, if it is less than 1%, penetration into the reinforcing material does not occur. If it exceeds 99%,
When the composite material is used, even if the volume ratio of the reinforcing material in the composite material is very small, the concentration of the penetration aid (specifically, Si) becomes too high, the melting point of the alloy remarkably rises, and the Mg-based composite material Practicality as a material is impaired.

First, as shown in FIG. 1, a crucible (made of steel) 1 used for heating and melting contains a mixed powder 2 of a reinforcing material and a penetration aid mixed in a predetermined ratio, and then an upper portion of the mixed powder 2. An ingot 3 of an alloy serving as a matrix, that is, Mg or a Mg alloy is placed on. Reference numeral 4 is a gas vent hole provided in the bottom of the crucible 1. FIG. 2 shows a manufacturing procedure using the crucible 1. That is, 6 is a high-frequency induction furnace in which the crucible 1 is arranged. The high-frequency induction furnace 6 is surrounded by an atmosphere substitution chamber 7, and the chamber 7 is provided with an inlet 8 for feeding an atmosphere gas into the chamber 7 and an outlet 9 for discharging the substitution atmosphere to the outside. As the atmosphere gas, Ar gas, CO ₂ + SF
₆ Any gas, such as a mixed gas, which is usually used as a heating and melting atmosphere of Mg, may be used. The Mg ingot 3 is heated in the above atmosphere for a predetermined time (about 700 ° C.) to form a molten metal 3a, and this molten metal 3a permeates into the mixed powder 2 in the lower portion.
At this time, the penetration aid reacts with the molten Mg with heat generation to generate magnesium oxide. The gas in the powder is discharged from the holes 4 during permeation. After permeation is complete, upon cooling, a Mg-based composite with dispersed reinforcing particles is obtained. When it is necessary to uniformly disperse the reinforcing particles (SiC or the like) in the matrix, the particles may be uniformly dispersed by adding a light agitation that does not entrap air bubbles after permeation.

[0007]

EXAMPLE 15 g of SiC particles having an average particle diameter of 3 μm and SiO ₂ particles having a volume ratio of 10% were uniformly mixed to prepare mixed powder. Next, as shown in FIG. 1, this was put into a steel crucible, and about 70 g of a pure Mg ingot was placed on the crucible.
Was placed. This was heated at 700 ° C. in a high frequency induction furnace as shown in FIG. 2 and held for 20 minutes. The atmosphere was argon and the pressure was 1 atm. After cooling, this material was taken out and observed under a microscope to find that it was a complete composite material having a structure with few defects. For comparison, S
When the iC particles were treated in exactly the same manner without mixing the SiO ₂ particles, no penetration like the present example occurred in the powder layer of the SiC particles.

[0008]

According to the method of the present invention, it is possible to prevent the mechanical properties from being deteriorated due to the entrainment of the atmospheric gas, because strong stirring unlike the molten metal stirring method is not required. Further, since the SiO ₂ powder used as the penetration aid is inexpensive, the increase in cost is small. Since the method of the present invention utilizes the infiltration phenomenon, a composite material in a good dispersed state can be obtained even with reinforcing particles having a small particle size. In addition, fine MgO is generated in the molten metal, and this serves as a reinforcing material.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a part of steps of an embodiment of a method according to the present invention.

FIG. 2 is a diagram illustrating an example of a method according to the present invention.

FIG. 3 is a diagram illustrating a conventional method.

[Explanation of symbols]

 1 crucible 2 mixed powder 3 ingot 6 high frequency induction furnace 7 atmosphere replacement chamber

Claims (3)

[Claims] 1. In a method for producing a composite material in which a reinforcing material powder and a molten matrix metal are brought into contact with each other, and the molten metal is allowed to penetrate into the reinforcing material powder, an infiltration phenomenon is expressed by mixing an infiltration aid with the reinforcing material powder. A method for producing a Mg-based composite material, comprising: 2. The reinforcing particles, which do not react with Mg, are used as the reinforcing material, and the oxide, which reacts with the molten Mg or Mg alloy with heat generation, is used as the penetration aid. Method for producing Mg-based composite material. 3. The reinforcing material is SiC and the penetration aid is Si.
O ₂ is used, and the volume ratio of SiO _{2 in} these mixed powders is 1
~ 99%, Mg according to claim 1, characterized in that
Method of manufacturing base composite material.