JPH03138325A - Manufacture of intermetallic compound sintered compact - Google Patents

Abstract

PURPOSE:To easily manufacture the intermetallic compound sintered compact of optional shape which is dense and free from the generation of internal defects by subjecting a mixture of Al and other elemental powder to precompacting, applying pressure thereto by a powdery pressure medium, executing heating and utilizing the heat of reaction. CONSTITUTION:Al powder and other elemental powder of Ti, Ni, Fe, etc., are mixed, to which 50kg/mm<2> pressure is applied, and precompacting is executed in the state where the new faces of each powder are brought into contact. Next, >=1kg/mm<2> pressure is applied thereto by using a powdery pressure medium such as sand and ceramic powder. While the pressure is held, the green compact is heated to >=400 deg.C to start an intermetallic compound forming reaction. By utilizing the heat of reaction generated by the reaction, the above forming reaction is progressed. In this way, the intermetallic compound sintered compact light in weight and provided with excellent heat resistance, high temp. strength, wear resistance and corrosion resistance can be obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is lightweight and has high heat resistance, and can be used as a material for engines and gas turbines in heating furnaces, automobiles, aircraft, etc., and also as airframe materials for rockets and spacecraft. Regarding the method for producing a useful intermetallic compound molded body, this molded body has excellent wear resistance and corrosion resistance, and is also useful as various mechanical parts.

[Prior art] Lightweight and excellent in heat resistance and high temperature strength, A
Intermetallic compounds containing Al such as l-Ti, Al-Ni, and Al-Fe are known. However, these intermetallic compounds have extremely poor malleability and are difficult to mold into a shape that meets the intended use, so their uses are extremely limited.

Therefore, a method of solidifying and molding the intermetallic compound powder at high temperature and high pressure and a method of molding it by precision casting have been developed.
Implementing these methods not only requires expensive molding equipment, but also poses problems such as molded products becoming porous and causing casting defects, and it is difficult to take full advantage of the characteristics of intermetallic compounds. has not yet been reached.

[Problems to be Solved by the Invention] The present invention has been made in view of the above circumstances, and its purpose is to easily obtain an intermetallic compound molded body of any shape that is dense and free of internal defects. [Means for solving the problem] The above! ! The configuration of the present invention that can solve the problem is A.
In producing a molded body made of an intermetallic compound containing I as a constituent element, At powder and other elemental powders forming the intermetallic compound are used as raw materials, and the mixture of these raw materials is subjected to a pressure of 50 to 8716012 or more. or ■ mechanically mix the above raw materials and repeat adhesion and separation of the individual powders to form an alloy. After producing the powder (which exists in The gist of this method is to start a production reaction and use the reaction heat generated by the production reaction to advance the production reaction and densify it.

[Function] As mentioned above, intermetallic compounds such as Al-Ti, Al-Ni, and Al-Fe are lightweight, have high heat resistance and high-temperature strength, and are also excellent in corrosion resistance. If this is possible, a wide range of applications can be expected. However, as mentioned above, these materials have extremely poor ductility and are difficult to mold, so the development of their uses has lagged significantly behind. Therefore, the present inventors conducted various studies to solve the problem of formability, and found that AI and other elements were mixed in powder form and then preformed, and then the two elements were reacted to form an intermetallic compound. It was found that an intermetallic compound molded body of any shape can be easily obtained by adopting a procedure for producing . However, AI is very easily oxidized, and if ordinary powder metallurgy methods were applied as is, the oxide film covering the surface of the AI powder would inhibit the generation of intermetallic compound-forming reactions with other elements, and the initially expected result would not be possible. It was not possible to obtain an intermetallic compound molded body with such performance. Therefore, we conducted further research in order to successfully progress the intermetallic compound generation reaction in the mixed powder state. As a result, we applied a pressure of 50 kg/mm or more to the raw powder mixture that makes up the intermetallic compound, so that the new surfaces of each powder came into contact with each other. Intermetallic compounds can be formed by preforming the raw material powder, or by mechanically alloying the raw material powder to transform it into a powder in which regions of each element are present, and then heating and pressurizing it under predetermined conditions. The production reaction progresses well,
We learned that it is possible to obtain intermetallic compound compacts that are dense and exhibit excellent physical properties. That is, when the raw material powder is preformed by applying a pressure of 50 kg/am" or more, the raw material powder is deformed by the pressure and the oxide film on the surface is torn, exposing the active new surface. In this case, the formation of intermetallic compounds In order to expose the minimum new surface required for the AI powder on the surface of the AI powder, the pressure during preforming must be set to 50 Kg/am” or higher; at a pressure lower than this, the metal will form at temperatures as low as 400°C. The intermediate compound formation reaction does not proceed sufficiently, and most of the product is simply compacted, making it impossible to obtain a molded product with physical properties that meet the purpose. There is no particular upper limit to the pressure during preforming, but the new surface exposure effect is 100 kg/
It is saturated at about mm2, and even if the pressure is increased further, no further effect can be obtained, so it is economically wasteful.

Another way to expose the new surface is to mechanically stir the raw material powder using a ball mill, attritor, etc.
There is a method of repeatedly adhering and separating each raw material powder to produce a powder in which each element coexists within the same powder. In this case, the new surface of each powder is exposed and each element is in close contact with each other. Therefore, a particularly large preforming pressure is not required at the preforming stage, and it is sufficient to apply a pressure of about 10 to 30 kg/mm2.

After preforming, a pressure of 37 mm 2 or more is applied to 1 using a powder pressure medium such as sand or ceramic powder, and while maintaining this pressure, it is heated to 400° C. or more. Then, an intermetallic compound production reaction occurs in the preform at the part where the newly formed surfaces come into contact with each other, and the intermetallic compound production reaction progresses due to the reaction heat generated by this reaction, and the entire preform becomes an intermetallic compound. If the pressure at this time is less than 1 g/is, the preform will not only be insufficiently compacted and void defects will easily form inside, but also the new surfaces will Contact is also insufficient, and the progress of the intermetallic compound formation reaction is also slowed down.

The pressurization at this time may be increased all at once to a predetermined pressure, or may be increased in steps, and the heating temperature may be 400
If the temperature is less than 0.degree. C., the intermetallic compound formation reaction rate will be extremely slow and little reaction heat will be generated, so the subsequent reaction progress rate will not increase and it will take an enormous amount of time to convert the entire reaction into an intermetallic compound. In addition, after preforming, it is necessary to first apply a predetermined pressure to consolidate, and then heat it to initiate the intermetallic compound generation reaction. If heated to 400°C or higher first, hard intermetallic compounds will be generated before consolidation. However, this forms a bridge shape, making subsequent consolidation impossible, and void defects remain inside. However, if the pressure is increased first to consolidate and then heated, this problem will not occur and a dense intermetallic compound molded body without void defects can be obtained. The reason why a granular compression medium is used in this pressurization/heating process is as follows.

In other words, the preformed body has been preliminarily press-formed and is not sufficiently compacted, and there are quite a few voids left inside. Therefore, in the pressurizing process, it is necessary to effectively release the residual gas in the voids to the outside of the molded body. However, if a granular compression medium is used, almost uniform pressure will be applied to the entire surface of the preformed body, and the gas will not be released to the outside of the molded body. Since the gas is extracted through the gaps in the granular compression medium, it is possible to obtain a very dense compact with no void defects. The type of powder used as the compression medium is not particularly limited, but ceramic powders such as alumina, boron nitride, and silica are preferred, as they are said to uniformly pressurize the entire surface of the preform and improve gas release. From the point of view, it is preferable to use a powder that does not contain coarse particles exceeding 1 mmφ and has an average particle size of about 50 to 200 μm.

The Al powder used in the present invention has the characteristics of being easily deformed, giving a dense compact of any shape by pressure molding, and easily forming a passive film made of oxide on the surface. Therefore, it is a component that can most effectively exhibit the features of the present invention. This A
Any type of other element may be used in combination with l as long as it can form a useful intermetallic compound with AI, but typical examples include Ti and Ni.

It is Fe. The blending ratio of these elements and AI can be changed appropriately depending on the application and target properties, but the characteristics of an AI-based gold intermetallic compound are most effectively exhibited by ■ (1
5-63%) AI-(85-37%) Ti, ■(13-
47%) AI-(87-53%) Ni, ■(33-60
%) Al-(67 to 40%) Fe, and these intermetallic compounds (■ to ■) contain 5 parts by weight when these are taken as 100 parts by weight while maintaining the above-mentioned preferred composition. The following third component (e.g. B.

It is also effective to add and modify materials (Si, Mg, Nb, Y, etc.).

[Examples] Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited by the following Examples.

Using the metal powders shown in Table 1, preforming and alloying were performed under the conditions shown in Table 1 to produce intermetallic compound compacts.

However, in press molding of No. 1 to 15.19 to 28,
After uniformly mixing each metal powder with a V mixer, it was filled into a mold whose inner surface was coated with zinc stearate, and preformed by applying a predetermined pressure. In addition, in the extrusion molding of Nos. 26 to 18, after uniformly mixing each metal powder, 7
A billet with a diameter of 0 mm is prepared, the heating temperature is set to 300°C, and the preforming pressure is adjusted by changing the extrusion ratio to obtain an extruded material with an L half cross section, which is then cut to a predetermined length and preformed. As a body.

Next, the preform was embedded in a hot press mold filled with sand with a particle size of 50 to 200 μm, and after applying a pressure of 0.5 g/ram with an upper punch, the temperature was raised to 300°C. After further increasing the pressure to the pressure shown in Table 1, the temperature was raised to the temperature shown in the same table and held for 30 minutes.

The structure of each of the obtained molded bodies was observed to confirm the presence or absence of cavities, the physical properties were confirmed by hardness measurement, and the presence of intermetallic compounds was confirmed by X-ray diffraction.

The results are summarized in Table 1.

From Table 1, it can be considered as follows.

Experiment Nos. 1 to 7 investigated the influence of preforming pressure, and in Experiments No. 1 to 4 (all comparative examples) where the preforming pressure was less than 50 Kg/mff12, I Kg/mff after preforming. ff1 m2 It was poor. On the other hand, experiment no. Examples 5 to 7 are examples in which the preforming pressure meets the specified requirements of the present invention, and there are no pore defects observed in the molded product, and most of the molded product has been converted to intermetallic compounds, so it has excellent hardness. It was something.

From Experiment Nos. 8.8 to 10.15, it is possible to confirm the effect of changing the pressure while fixing the temperature after preforming. That is, experiment No. 8.9 has a pressure of 1 to 37 mm.
In this comparative example, a large number of microvoids were confirmed inside the molded body.
In experiments Nc, 6 and 10, in which ra was set to 2 or higher, no such microvoids were observed.

Experiment No. 1 to 21 are Al-Ti system, experiment No.

22.23 is an example of Al-Fe system, experiment No. 24.25 is an example of AI-Ni system, and Nos. 26 to 28 are examples of adding other trace elements to these, and the preforming conditions and subsequent In the examples in which the pressurization and heating conditions meet the specified requirements of the present invention, no microvoid defects were observed in any of the molded products, intermetallic compounds were formed, and all of them had excellent hardness. ing.

In addition, Fig. 1 shows that, based on the above experimental data, the m-densification/intermetallic compound generation reaction conditions after pretreatment are set to 10 g/mm' x
This is a graph showing the effect on hardness when the pre-forming pressure is set at 500℃ and the pre-processing pressure is changed.The hardness of the molded product increases significantly by setting the pre-forming pressure to 50 Kg/Ill'' or higher. It can be confirmed that

In addition, Figure 2 shows the pretreatment conditions at 70 Kg/lam2x.
When the temperature was set at 500℃ and the temperature during the subsequent densification/intermetallic compound generation reaction was changed (the pressure was 1.5 Kg/m+
This is a graph showing the influence of temperature (set at n2) on hardness, and the hardness of the molded body is significantly improved by setting the temperature to 400°C or higher. In addition, Figure 3 is a graph showing the effect on the hardness of changing the pressure during the densification/intermetallic compound generation reaction (temperature set at 500°C), and shows that the hardness of the compact is It can be seen that in order to satisfactorily increase the pressure, the pressure should be set to 1 g/mva2 or higher.

Next, Experiment Nos. 30 to 33 shown in Table 2 below are examples in which the new surface exposure treatment before preforming was performed by mechanical stirring using a ball mill or an attritor (Experiment Nos. 1 to 28 are as follows: This is an example in which the raw material powder is deformed by pressure to destroy the oxide film and expose the new surface).
In this case as well, by appropriately setting the preforming conditions and the densification/intermetallic compound formation reaction conditions, a highly hard intermetallic compound molded body without pore defects was obtained.

[Effects of the Invention] The present invention is configured as described above, and instead of forming the intermetallic compound in the form of an intermetallic compound that is difficult to thermally deform, the intermetallic compound is formed after being formed in the form of a raw material powder that is easy to process. Because it is a method of changing to
A molded article with wear resistance and corrosion resistance can be obtained, and the range of applications can be greatly expanded.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the preforming pressure and the compact, and FIGS. 2 and 3 are graphs showing the relationship between the temperature or pressure during the densification/intermetallic compound production reaction and the hardness of the compact.

Claims (6)

[Claims] (1) In producing a molded body made of an intermetallic compound containing Al as a constituent element, 50 kg/
Apply a pressure of mm^2 or more to preform the new surfaces of each powder in contact with each other, then use powder-granular compression medium to form the powder into 1 kg.
/mm^2 or more, and while maintaining this pressure,
1. A method for producing an intermetallic compound molded article, which comprises heating to 00° C. or higher to start an intermetallic compound production reaction, and densifying the product while progressing the production reaction using the reaction heat generated by the production reaction. (2) When producing a compact made of an intermetallic compound containing Al as a constituent element, a new surface is generated on the surface of each powder by mechanically mixing Al powder and powder of other elements that form the intermetallic compound. After tightening and preforming this, a pressure of 1 kg/mm^2 or more is applied using a granular compression medium, and while maintaining this pressure, heating is performed to 400 ° C. or more to start an intermetallic compound production reaction. 1. A method for producing an intermetallic compound molded article, which comprises densifying the product while advancing the production reaction using reaction heat generated by the production reaction. (3) Al powder: 15~63% by weight and Ti powder: 85~
Claim (1) or (1) in which 37% by weight is used as raw material
2) The manufacturing method described. (4) Al powder: 13~47% by weight and Ni powder: 87~
Claim (1) or (1) in which 53% by weight is used as raw material
2) The manufacturing method described. (5) Al powder: 33~60% by weight and Fe powder: 67~
Claim (1) or (1) in which 40% by weight is used as raw material
2) The manufacturing method described. (6) When the total of the above raw material elements is 100 parts by weight,
According to any one of claims (3) to (5), the raw material contains at most 5 parts by weight of one or more of B, Si, Mg, Nb, and Y as other elements. Manufacturing method.