JPH06279886A - Al3ti base intermetallc compound and production thereof - Google Patents

Abstract

PURPOSE:To remarkably improve the strength of an intermetallic compound without impairing its lightness by subjecting fine Al3Ti base alloy powder in which a part of Al is substituted by Mo to hot molding. CONSTITUTION:Al3Ti series powder is mixed with, by atom, 0.13 to 3.0 Mo powder, and after that, this mixed powder is uniformly dispersed and refined into alloy powder. This alloy powder is subjected to hot molding and is thereafter subjected to diffusion heat treatment of Mo, at need. By this method, the strength of the lightweight Al3Ti base intermetallic compound can remarkably be improved. Concerning the amt. of Mo to be added, in the case above the upper limit, the embrittlement of the stock is made severe, and in the case of the lower limit or below, the effect to be required can not be expected. Furthermore, uniform alloy powder produced by a rapid solidifying method, a mechanical alloying method or the like is preferably used as a raw material, and, in the case Mo is added by a mechanical alloying method, treatment can be executed without using lube oil owing to the excellent lubricating effect of Mo.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention method for manufacturing a lightweight the Al ₃ Ti intermetallic compound having excellent heat resistance, Al ₃ Ti intermetallic compound to dramatically improve the strength without impairing the lightweight And an Al ₃ Ti-based intermetallic compound produced by the method.

[0002]

2. Description of the Related Art Several methods have been provided for improving the toughness of Ti-Al intermetallic compounds. However, there is no known example of the method for improving the strength of the Ti-Al intermetallic compound. Further, a mechanical alloying method is used for the powder treatment, but in this method, an organic zinc stearate or aluminum stearate or a wax type lubricant is usually used.

[0003]

In order to improve the strength of the Ti-Al intermetallic compound, the strength can be improved by adding Cr, Mn, V or the like. However, it is necessary to add 8 wt% or more of these elements in a weight ratio so that the effect of improving the strength remarkably appears. Therefore, the specific gravity of the Ti-Al-based intermetallic compound is 3.4.
However, there is a problem that, for example, the number of positions increases to 3.8, and the merit that the cutting angle is light is lost. Further, when Hf is used as an additional element, it is light and has the effect of improving strength, but the price of Hf is very high and not practical. Therefore, there has been a demand for the development of a less costly method capable of obtaining the effect of improving the strength substantially the same as when Hf is added, without increasing the specific gravity.

On the other hand, in the mechanical alloying method, when the organic lubricant is used as described above, the duration of the lubricating effect is short. It takes time such as heating and degassing to evaporate this by sublimation. When the powder is sintered, the residual lubricant reacts to form carbides and hinder the improvement of the ductility of the material. With such conventional lubricants, the treated powder adheres to balls and containers, and it takes time to discharge the treated powder. There were many problems such as the wear of the balls used was large and the Fe content was easily mixed in the treated powder. The present invention has been made in view of the above circumstances, and Al which has solved the above problems and improved strength is provided.
_An object of the present invention is to provide a method for producing a ₃ Ti-based intermetallic compound and an Al ₃ Ti-based intermetallic compound produced by the method.

[0005]

According to the present invention, in accordance with the above object, a fine Al ₃ Ti-based alloy powder in which Mo in an atomic ratio of 0.1 to 3.0 is replaced with a part of Al is prepared, By hot-pressing this, the present invention also produces Al ₃ T
After mixing an i powder with a Mo powder having an atomic ratio of 0.1 to 3.0, the powder was uniformly dispersed and refined to make an alloy powder, which was further hot pressed and then The present invention solves the above problems by providing a diffusion heat treatment of Mo, and further by providing an Al ₃ Ti-based intermetallic compound manufactured by this manufacturing method. According to the present invention, the strength improvement of the Al ₃ Ti based intermetallic compound can be achieved without using expensive Hf, with almost no increase in specific gravity, and without using a lubricant in the mechanical alloying treatment. It was

[0006]

EXAMPLE In the present invention, in an Al ₃ Ti-based intermetallic compound having one crystal structure with an atomic ratio of Al: Ti = 3: 1, a part of the existing position (site) of Al is replaced with Mo. To do. Therefore, in the present invention, Al, T
A specific amount of Mo powder is added to the raw material powder containing two elements of i as a main component for processing. The method of the present invention is shown in FIG.
Implement according to the procedure shown in. Hereinafter, they will be sequentially described. First, Ti powder, Al powder and Mo powder having the following specifications are used as raw materials. Ti: O ₂ content 0.5 wt% or less, particle size 200 mes
A particle size smaller than h is used. Al: O ₂ content 0.5 wt% or less, particle size 32 to 250
The thing of mesh is used. Mo: A particle having a particle size smaller than 100 mesh is used. Since Mo has a high melting point, it is difficult to produce an Al-Mo alloy powder. Therefore, it is preferable to use the mechanical alloying method described later without using the Al-Mo alloy powder. These Al, Mo, and Ti powder raw materials have an atomic ratio (at
%)so Blend so that That is, in terms of atomic ratio,
Ti ≦ 25%, 0.1 ≦ Mo ≦ 3%, and the composition is the balance Al. Mo is set to 3% because if the addition of Mo exceeds 3%, the material becomes brittle,
This is because the desired effect cannot be obtained with 0.1 or less.

Next, the raw material powders in the above proportions are processed by a mechanical alloying method using, for example, an apparatus (attritor) conceptually shown in FIG. 2 to obtain uniformly mixed and refined alloy powder. In the figure, 10 is a closed container, which is provided with a water cooling jacket inside the wall, and is provided with a water inlet 14 for feeding cooling water and a water outlet 15 for discharge to prevent the temperature inside the closed container 10 from rising. There is. Reference numeral 12 is a rotary blade provided with a large number of stirring arms, 13 is an inlet for introducing an inert gas such as He or Ar into the closed container 10, 16 is an inlet for raw material powder, and 17 is an outlet for treated powder. Is.
Reference numeral 11 denotes a large number of steel balls housed in the closed container 10. The raw material powder is housed together with the balls 11 in the closed container 10 in an inert gas atmosphere, and the rotary blades 12 are rotated, The raw material powder is processed while being milled by a large number of balls 11 to prepare a fine and uniform mixed powder (alloy powder).

That is, processing is performed under the following processing conditions. First, for the ball 11, for example, a steel ball having a diameter of 3/8 inch is used, and the ratio of the raw material powder weight to the ball weight is No lubricant is used. Furthermore, the atmosphere in the closed container 10 is an Ar gas atmosphere, and the rotation speed of the rotary blades 12 is preferably 250 rpm. Then, the treatment time is set to a state in which the added Mo powder is uniformly taken into the Al matrix, and is substantially 2 to 30 hours.
If this processing time is long, not only will productivity decrease, but
Since impurities may be mixed due to wear of the balls, the most preferable time is set. Instead of the above treatment, an alloy powder having the same composition can be prepared by a conventional rapid solidification method in which a molten metal containing the same components is prepared and dispersed and rapidly cooled. Also, by other methods,
The alloy powder may be prepared.

Next, the raw material powder obtained as described above is
It is solidified by the following treatment. The raw material powder is filled in a capsule made of mild steel, depressurized by vacuuming at a temperature of 350 to 450 ° C., and then sealed. The thus-formed capsules are processed under the following conditions by a hot isostatic pressure (HIP) device. Processing temperature 1300 ° C. maximum Processing pressure 1000 kg / cm ² or more Processing time 1 H _r or more This gives a solidified material. The raw material powder obtained by the mechanical alloying method or the rapid solidification method is not press-filled into the capsule as shown in FIG. Alternatively, hot extrusion or hot pressing (HIP, HP, etc.) may be performed for molding. Next, the solidified material is subjected to diffusion heat treatment in a vacuum or in an inert gas atmosphere to improve the quality. The heat treatment temperature is preferably 1300 ° C. or lower and 4 hours or longer.

Next, a compression test was carried out to confirm whether or not the strength, which was obtained by the above treatment, was improved. Predetermined test piece 5 (w) x 5 from the obtained material
After making (d) × 10 (h) mm and polishing it sufficiently,
The significance of Mo added was investigated by examining the relationship between the displacement amount of the crosshead and the breaking strength by a compression test at a speed of 0.5 mm / min (movement speed of the crosshead).
Table 1 shows sample No. with Mo added. 1, No. 2 and sample No. 3 (Al ₃ Ti) was compared and evaluated by a compression test for compression strength, breaking strain, and hardness measurement.

[0011]

[Table 1]

Sample No. 1 shown in Table 1 As is clear from Sample No. 1, the addition of 1 atom% of Mo resulted in the sample No. The compressive strength σ _c is about 30%, and the breaking strain ε is
Also increased by about 10% and the specific strength increased by about 32%, which shows that the addition of Mo is effective. Moreover, there is almost no difference in specific gravity.

FIG. 3 shows the relationship between the compressive strength and the specific gravity of a sample obtained by adding various elements to an Al ₃ Ti-based material. The sample Mo ₁ containing 1% Mo by atomic ratio has a low specific gravity. It shows high strength. This is almost equivalent to the value of Hf ₁ (51.1) when compared in terms of specific strength, and in practice, M
It can be seen that the addition of o has a considerable advantage. In the sample code shown here, Mo ₁ is Ti: 25%, M
o: 1%, Al: 74%, and Ti ₂₅ Mo ₁ Al _74.
Indicates. Further, Hf ₁ represents Ti: 25%, Hf: 1%, and the balance Al. That is, in all the samples, the content and the amount of the additive element were changed to 25% Ti. Sample No. When Mo is added in an amount of 3% or more as in No. 2, embrittlement became severe, and the sample became brittle enough to crack even during cutting. Therefore, the upper limit of the amount of added Mo is substantially 3%.

As a side effect of the addition of Mo, when the treatment by the mechanical alloying method is performed, the adhesion of the alloy powder to the balls and the inner wall of the container is small, the treated powder can be discharged in a short time, and the man-hours are increased. I was able to reduce. Therefore, it is not necessary to use a stearic acid type lubricant which has been used conventionally. That is, since such a conventional lubricant is an organic substance, it is easily incorporated inside the powder during the mechanical alloying process and easily forms a carbide in the sintering step. When this carbide is formed, hardness is improved but toughness is decreased. On the other hand, Mo does not have such a problem, and its effect as a lubricant is far longer than that of the organic lubricant. For these reasons, the raw material powder produced by the mechanical alloying method with Mo added was extremely fine and uniform. As described above, the effect of adding Mo is that Al ₃
It was found that not only the effect of improving the strength of the Ti-based material, but also effective as a lubricant in the mechanical alloying treatment. Especially when using a powder having a strong ductility such as Al, Ti or Ni, the effect is extremely large. Further, since Fe content is extremely small due to wear of the balls, it is possible to further improve the toughness by using it together with an element for improving the toughness. Here, it is also possible to use an Al ₃ Ti-based metal compound whose strength has been improved by the method of the present invention and disperse this in Al serving as a matrix to obtain a reinforced aluminum alloy.

[0015]

According to the present invention, the following effects can be obtained. The addition of Mo significantly improves the strength of the Al ₃ Ti based intermetallic compound. Since the amount of Mo added is small, the material specific gravity does not increase. The specific strength is the same level as the Hf-added product, and the Mo price is less than 1/10 of the Hf price.
It can be lower than in the case of addition. When a small amount of Mo powder is added in the mechanical alloying method, since Mo itself has an excellent lubricating effect, it is possible to abolish the use of conventional lubricants and to obtain a uniform raw material powder (alloy powder) in a short time. can get. In addition, the powder can be discharged smoothly from the device after processing,
Man-hours can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a treatment process of a manufacturing method of the present invention.

FIG. 2 is a diagram illustrating an outline of an apparatus used for a mechanical alloying method in the manufacturing method of the present invention.

FIG. 3 is a diagram showing a relationship between compressive strength and specific gravity due to addition of a third element to an Al ₃ Ti-based intermetallic compound.

[Explanation of symbols]

 10 Sealed container 11 Ball 12 Rotor blade

Claims (6)

[Claims] 1. An atomic ratio of Mo of 0.1 to 3.0
Make a fine Al ₃ Ti-based alloy powder by replacing a part of
Al ₃ Ti, characterized by being hot-pressed
A method for producing an intermetallic compound. 2. An Al ₃ Ti-based powder is mixed with a Mo powder having an atomic ratio of 0.1 to 3.0, and the powder is uniformly dispersed and refined to make an alloy powder. A method for producing an Al ₃ Ti-based intermetallic compound, which comprises subjecting the material to pressure molding in step 1 above, and then performing a diffusion heat treatment of Mo. 3. The atomic ratio of Al, Mo and Ti is The method for producing an Al ₃ Ti-based intermetallic compound according to claim 1 or 2, characterized in that 4. The method for producing an Al ₃ Ti-based intermetallic compound according to claim 1, wherein the Al ₃ Ti-based alloy powder is produced by a rapid solidification method using a molten metal containing this component. . 5. The method for producing an Al ₃ Ti-based intermetallic compound according to claim 2, wherein the alloy powder uniformly dispersed and refined is produced by a mechanical alloying method. 6. The Al ₃ Ti-based intermetallic compound according to claim 1, which is produced by the method.