JPH0196341A - Production of hypereutectic al-si alloy composite material - Google Patents

Abstract

PURPOSE:To produce the title homogeneous hypereutectic Al-Si alloy composite material by adding a reinforcement into the hypereutectic Al-Si alloy melt in a vacuum cooling chamber, and driving a rotor at low speed and then at high speed to crush a primary Si crystal. CONSTITUTION:The hypereutectic Al-Si alloy contained in a graphite crucible 12 is heated by the resistance heating furnace 5 in a heating chamber 4 in a vacuum vessel 1 to obtain a solid-liq. coexistent state. A shutter 2 is opened by operating an air cylinder 3, the crucible 12 is raised into the cooling chamber 6 through a supporting rod 11, and the rotor 9 is inserted into the crucible 12. In this case, the nonmetallic particles of graphite, etc., and the reinforcement consisting of staples are wrapped in aluminum foil, fixed to the rotor 9, and added into the melt. The rotor 9 is driven by a torque motor 10 in the melt at low speed to disperse the reinforcement in the melt. The melt is then cooled by the cooling outer cylinder 7 provided with a cooling coil 8 and begins to solidify, the rotor 9 is driven at high speed at this time, and the reinforcement is uniformly dispersed in the gaps between primary Si crystals.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a hypereutectic A Q-9i alloy composite material strengthened by dispersion of nonmetallic particles and short taM1.

[Conventional technology] A casting method that creates a homogeneous composite material by adding reinforcing materials such as nonmetallic particles and short fibers to an alloy material in a solid-liquid coexistence state while applying mechanical rotational agitation using a rotary blade. This is known as the composite casting method. There is also a powder metallurgy method in which fine crystal powder produced by a rapid solidification method or the like and nonmetal powder are homogeneously mixed and sintered.

However, in the above-mentioned composite casting method, since the rotational speed of the rotor is suppressed to 1100 Orp or less, homogeneous refinement of crystal grains and uniform dispersion of particles are not sufficiently achieved, resulting in a problem that casting defects are likely to occur. Furthermore, since the rotor is rotated in a reducing atmosphere or the atmosphere, inert gas or air is likely to be drawn in, and the resulting mechanical properties are not significantly improved.

On the other hand, with the powder metallurgy method described above, it is possible to obtain a dense microstructure with homogeneous and fine crystal grains, but because it requires a complicated material manufacturing process and large-scale equipment, it inevitably increases material manufacturing costs. However, this has no choice but to result in high costs.

[Problems to be Solved by the Invention] An object of the present invention is to solve the problem of primary Si crystallized by a simple method in order to eliminate casting defects and improve material properties in a hypereutectic Al-5r alloy composite material. In addition to making the particles finer, even if there is a large difference in specific gravity between the matrix alloy and the reinforcing material made of nonmetallic particles or short fibers, the whole can be mixed homogeneously. The object of the present invention is to enable the production of a hypereutectic A12-Si alloy composite material with excellent wear resistance and microstructure and mechanical properties at low cost.

[Means and effects for solving the problem] The method for producing an alloy composite material of the present invention to achieve the above object is to produce hypereutectic AΩ in a solid-liquid coexistence state in a cooling chamber whose interior is kept in vacuum.
- A reinforcing material made of non-metallic particles such as graphite or short fibers is added to the Si alloy by wrapping it in aluminum foil, and by rotating a rotor inserted into the molten metal at low speed, the reinforcing material is dispersed and solidified. At the same time as the start, the rotor is rotated at high speed to uniformly disperse the reinforcing material in the gaps between the crushed primary Si crystals.
This method is characterized by obtaining an alloy composite material which is homogeneously reinforced by particle dispersion or fiber reinforcement.

To explain the method of the present invention in more detail, first, the hypereutectic Ω-Si alloy as a matrix alloy is
This hypereutectic A is melted in a heating furnace in a vacuum container.
A reinforcing material consisting of nonmetallic particles such as graphite or short fibers is added to the l-Si alloy in a solid-liquid coexistence state. These reinforcing materials are preferably wrapped in aluminum foil and fixed to a rotor that rotates and stirs the hypereutectic AΩ-Si alloy in a solid-liquid coexistence state, and then inserted into the molten metal. By rotating the rotor at low speed immediately after inserting it into the molten metal, non-metallic particles and short fibers can be uniformly dispersed in the molten AΩ-9i alloy. can.

Examples of the reinforcing material include powders and short fibers of non-metallic materials suitable for obtaining particle dispersion-reinforced or fiber-reinforced alloy composite materials, for example, in addition to the graphite described above, carbides such as titanium carbide,
Any one of oxides such as alumina, nitrides such as silicon nitride, etc., or a mixture of multiple thereof can be used, and the mixing ratio of these to the matrix alloy is 3.
Approximately 8 wt% is suitable.

Generally, when adding other components to the molten metal, it is customary to inject the added components onto the surface of the molten metal.
When non-metallic particles such as graphite or short fibers are added into the molten Si alloy, their wettability is poor and they tend to separate from the molten metal.However, as mentioned above, non-metallic particles and short fibers When the fibers are wrapped in aluminum foil and pushed into the molten metal, there is less oxidation of the fibers, and even if they tend to separate from the molten metal, the rotor is immediately rotated, so particles and short fibers are removed extremely efficiently. Can be uniformly dispersed.

In the molten metal, the rotor is not rotated at a low speed and the molten metal continues to be cooled, so the molten metal starts to solidify within a short period of time.At the same time as this solidification starts, the rotor is rotated at a high speed and the non-metal is poured into the gaps between the formed crystals. Uniformly disperse particles and short ma. As a result, a homogeneous particle dispersion reinforced type or #a fiber reinforced type alloy composite material can be obtained.

The hypereutectic AΩ-S+ alloy as a matrix alloy has
If necessary, a small amount of a grain refining agent can be added in advance during the melting. As the grain refiner, for example, Ti and B having a weight ratio of about 5:1,
Alternatively, there are 1-choa, Nb, Zr, etc. These grain refiners refine the grain crystals of the matrix alloy, making it easier to uniformly disperse TiC particles.

Next, an example of an apparatus for manufacturing the hypereutectic Al-9i alloy composite material of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of an apparatus for manufacturing the above-mentioned alloy composite material. A chamber main body 1 with an opening/closing door on the front constitutes a vacuum container, and a heat-resistant shack inside the chamber is opened and closed by an air cylinder 3. The resistance heating furnace 5 is arranged in the lower heating chamber 4, and the upper cooling chamber 6 is divided into upper and lower parts by 2.
Inside, a water-cooled outer cylinder 7 having a cooling coil 8 and a rotor 9 having a cross-sectional shape as shown in FIG. It is designed to be rotationally driven.

In this device, the inside of the chamber body 1 is connected to a vacuum source (not shown), and after evacuation, the sample gold is heated and melted in a graphite crucible 12 in the furnace, and after the melting, the shutter 2 on the furnace is opened. Then, the support tP that penetrates the lower surface of the main body 1! 511 is used to raise and lower the graphite lug 12 into the water-cooled outer cylinder 7, the rotor 9 is inserted into the molten metal in the crucible 12, and the rotor 9 is rapidly moved into the cooling chamber 6. During the cooling process, the rotor 9
The semi-molten alloy is stirred by the rotation of the .

The torque motor 10 that rotates the rotor 9 is capable of rotating the rotor 9 at a high speed of about 10,000 rprrr, and is equipped with a torque detector and a rotation detector on its rotating shaft, and connects them to a digital display. ing.

When a rotor with an octagonal cross section is used in the graphite crucible with an inner diameter of 55 mm shown in the above device example, its low speed rotation is as follows.
It is necessary to rotate at about 500 to 11000 rpm,
Further, the subsequent high-speed rotation needs to be approximately 2000 to 6000 rpm.

[Example] Using an alloy composite material manufacturing apparatus having the configuration shown in FIGS. 1 and 2, a rotor was inserted into a vacuum-melted hypereutectic A (2-17!Si alloy in a water-cooled outer cylinder, At that time, 8% graphite particles wrapped in aluminum foil were pushed into the alloy by a rotor.
The rotor was rotated at a low speed of 1000 rpm, and then
The mixture was stirred at high speed at 3000 rpm from the start of solidification to just before the end of solidification to obtain an alloy composite material of Afl-17$5i-820.

Similarly, from the start of coagulation to just before the end of coagulation, 21
Continue stirring at 0 rpm, Al-17$5i-6
20 alloy composite materials were obtained.

Figures 3 and 4 show secondary electron images of the alloy composite material obtained as described above, and these show that an extremely homogeneous and fine hypereutectic Aρ-Si alloy can be obtained. I understand.

[Effects of the Invention] According to the method of the present invention, a hypereutectic AΩ-9i alloy composite material is made by homogeneous mixing of molten metal and high-speed rotational stirring casting, unlike the conventional powder metallurgy method. #I1 has a microstructure and mechanical properties comparable to those of the powder metallurgy method by homogeneously refining the primary Si particles that crystallize without powdering.
1. Abrasive materials can be manufactured at low cost.

In addition, since the rotation speed of the rotor is increased several times compared to the conventional composite casting method, homogeneous refinement and uniform dispersion of particles are possible, and since it is carried out in a vacuum, there is no entrainment of foreign matter. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an apparatus for producing a hypereutectic AΩ-Si alloy composite material based on the present invention, and FIG. 2 is a cross-sectional view of the main parts thereof.
Figures 3 and 4 show letter AU-17 obtained by the present invention.
$5i-820 and Al-17%'; 1-GZC (7)
It is a photograph substituted for a drawing showing the metallographic structure of an alloy composite material. l...Vacuum container, 6...Cooling chamber, 9...Rotor. Figure 3 Figure 4 Procedural amendment (voluntary) Yoshi, Commissioner of the Japan Patent Office 1) Mr. Tsuyoshi Moon ■, Indication of the case 1988 Patent Application No. 254344 2, Name of the invention Manufacture of hypereutectic An-5i alloy composite material Method 3: Relationship with the person making the amendment Patent applicant address: 1-3-1 Kasumigaseki, Chiyoda-ku, Tokyo (114)
) Name: Director of the Agency of Industrial Science and Technology Sachi Iizuka Address: 300 Takatsuka, Kamimura, Hamana-gun, Shizuoka Prefecture Name: Osamu Suzuki, President and CEO of Suzuki Motor Co., Ltd. Address: 1-2 Namiki, Tsukuba City, Ibaraki Prefecture (Due to administrative division change on November 30, 1982) (0030) person
Name: Nagaso, Mechanical Technology Research Institute, Agency of Industrial Science and Technology 1) Director: Part 5, Sub-Agent (Sub-Agent of the Director of the Agency of Industrial Science and Technology) Address: 9-12-6 Nishi-Shinjuku-chome, Shinjuku-ku, Tokyo, Agent (Suzuki Motor Corporation) Co., Ltd.'s agent) Address: Nishi-Shinjuku-chome 9-12-7, Shinjuku-ku, Tokyo 7. The date of the amendment order is voluntary 8. The detailed description of the invention in the specification to be amended. 9. Contents of the amendments Contents of the amendments (1) Change the "secondary electron image of the alloy composite material" stated on page 9, line 12 of the specification to "X-ray image of graphite particles in the alloy composite material" ” and correct it.

Claims (1)

[Claims] 1. A reinforcing material made of non-metallic particles such as graphite or short fibers is added to a hypereutectic Al-Si alloy in a solid-liquid coexistence state in a cooling chamber kept in a vacuum, wrapped in aluminum foil.
The reinforcing material is dispersed by rotating a rotor inserted into the molten metal at low speed, and at the same time as the solidification starts, the rotor is rotated at high speed to uniformly disperse the reinforcing material in the gaps between the crushed primary Si crystals. A hypereutectic Al-S characterized by obtaining an alloy composite material reinforced by particle dispersion or fiber reinforcement.
A method for producing an i-alloy composite material.