JPH05247561A - Manufacture of ti-al intermetallic compound - Google Patents

Abstract

PURPOSE:To manufacture a Ti-Al intermetallic compound excellent in oxidation resistance at a high temp. and ductility at ordinary temp. by executing prescribed homogenizing treatment. CONSTITUTION:This Ti-Al intermetallic compound consisting of 40 to 50at% Al, and the balance substantial Ti is manufactured by mixing, deaerating and vacuum-sealing a Ti-based material and an Al-based material thereafter subjecting the sealed mixture of powder to plastic deformation at the reacting and synthesizing temp. or below and heating the mixture subjected to the plastic deformation to the reacting and synthesizing temp. or above to subject the mixture to reaction sintering. As the Ti-based material, Ti powder or Ti alloy powder having <50mum grain size is used.

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 Ti-Al intermetallic compound used in fields such as automobile fields, aerospace fields, industrial machinery fields, etc., where light weight heat resistance or high specific rigidity is required. ..

[0002]

2. Description of the Related Art In recent years, for example, in the field of automobiles, there has been a demand for weight reduction and higher performance.
The parts are also required to be lighter. For example, in engine valves, steel or Ni alloy has been conventionally used, but these have a large density of about 8 g / cm ³ . Therefore, if the weight of this valve is reduced, the inertial mass of the valve can be reduced, so that the engine can be rotated at a high speed and the performance of the vehicle is expected to be improved.

Therefore, as a material which is lightweight and has heat resistance, a Ti--Al based intermetallic compound has been attracting attention.
For example, T at 800 ° C near the operating temperature of the exhaust valve
The high temperature strength of the i-Al intermetallic compound is almost the same as that of SUH35, which is a typical valve steel, and the density is about 1/2. Therefore, the Ti-Al-based intermetallic compound is considered to be a powerful lightweight heat resistant material.

[0004]

However, Ti-
Practical use of Al-based intermetallic compounds is hindered mainly due to the following reasons. Since it is a difficult-to-process material, it is difficult to give shape to parts.

The oxidation resistance is not always sufficient. Poor room temperature ductility. Therefore, in order to overcome these problems, various researches and developments have been conducted in recent years. For example, reduction of difficulty in imparting a shape of Ti-Al intermetallic compound (Japanese Patent Publication No. 1-308
98) and improvement of oxidation resistance (Japanese Patent Application No. 3-18).
453)). The contents of this research are specifically Ti powder or Ti alloy powder and Al powder or A powder.
1 alloy powder, mixed, deaerated, and further vacuum sealed,
The present invention relates to a technique for producing a Ti—Al-based intermetallic compound by plastically deforming a vacuum-filled mixed powder at a reaction synthesis temperature or lower, and heating the plastically deformed mixture at a reaction temperature or higher to perform reaction sintering.

However, even by the above-mentioned reaction sintering technique, the room temperature ductility is not sufficiently improved, and the oxidation resistance of the above is locally oxidized at a high temperature exceeding 950 ° C. There is not always enough. The present invention has been obtained as a result of conducting multifaceted research on the improvement of the properties of Ti-Al-based intermetallic compounds, and its object is to achieve excellent room temperature ductility by performing a predetermined homogenization treatment. Moreover, it is to provide a method for producing a Ti-Al-based intermetallic compound having excellent oxidation resistance at high temperatures.

[0007]

In order to achieve this object, the invention of claim 1 is to mix the Ti-based material and the Al-based material, perform deaeration and vacuum encapsulation, and then, enclose the mixed powder. Is plastically deformed below the reaction synthesis temperature, and the plastically deformed mixture is heated to the reaction synthesis temperature or higher to perform reaction sintering, and Al: 40-50 at% balance Ti-Al-based intermetallic A method for producing a Ti-Al intermetallic compound for producing a compound, comprising using Ti powder or Ti alloy powder having a particle size of less than 50 μm as the Ti-based material. The manufacturing method is the main point.

According to the second aspect of the invention, the additional element X is M
0.5 to 3 at% of the final composition after reaction synthesis of at least one or more of n, Cr and V, and / or after reaction synthesis of at least one or more of Nb, Mo, W, Ta and Si as an additional element Y. The final composition of T contains 0.5 to 3 at%
The gist of the method for producing a Ti-Al intermetallic compound according to claim 1 is to produce an i-Al intermetallic compound.

According to the invention of claim 3, Ti-X alloy powder, Al
-X alloy powder, Ti-Y alloy powder, Al-Y alloy powder,
The Ti-Al-based intermetallic compound is produced by using at least one or more of a Ti-XY alloy powder and an Al-XY alloy powder.
A gist is a method of manufacturing an Al-based intermetallic compound.

Now, the reason for defining the numerical values of each claim will be described. 1) Grain size of Ti: less than 50 μm If it exceeds 50 μm, heterogeneous coarse particles of 50 μm or more may be present after the reaction synthesis, and this may be a starting point of fracture to lower the room temperature ductility. It may also be locally oxidized significantly at high temperatures.

2) Al: 40 to 50 at% Except for the upper and lower limits, the ductility decreases in all cases. 3) X: 0.5 to 3 at% Addition amounts within this range are effective in improving room-temperature ductility, but below the lower limit, the effect is not observed, while above the upper limit, the effect saturates. , There is a bad effect of increasing the density. Of these, Mn has the effect of preventing the generation of pores within this range.

4) Y: 0.5 to 3 at% Addition amounts within this range are effective in improving high temperature oxidation resistance, but below the lower limit, no effect is observed, while above the upper limit, The effect is saturated, and there is an adverse effect of excluding Si and increasing the density.

That is, the room temperature ductility is further improved by the addition of the X component, and the high temperature oxidation resistance is remarkably improved when the Y component is added. When these are combined, particularly excellent room temperature ductility is obtained. And high temperature oxidation resistance is achieved. When adding each X, Y component, X, Y
When added in the form of alloy powder of the components and Ti, Al,
It is suitable because the intermetallic compound is likely to be homogeneous.

[0014]

The present invention was obtained as a result of multifaceted research on improvement of ductility and oxidation resistance of Ti-Al intermetallic compounds obtained by the reaction sintering method. In addition, by adjusting the particle size of the Ti-based material used as the raw material, it is possible to produce a Ti-Al-based intermetallic compound having a uniform composition and excellent in room temperature ductility and high temperature oxidation resistance.

Of the Ti--Al materials produced by the reaction sintering method, those having poor room temperature ductility and poor high temperature oxidation resistance were investigated and examined in detail.
Α-Ti phase surrounded by ₂ (Ti ₃ Al) phase, or Ti
-There are coarse inhomogeneous particles of 50 μm or more (hereinafter abbreviated as coarse particles) consisting of rich α ₂ phase, and these coarse particles serve as the starting point of fracture and reduce the ductility of this material. It was revealed that the oxidation was easy to proceed in the area.

The coarse particles are not
The powder and the Al powder are mixed, degassed, and vacuum sealed, and then the sealed mixed powder is plastically deformed at a temperature lower than the reaction synthesis temperature, which corresponds to Ti particles of 50 μm or more in the plastically deformed mixture. That is, it became clear that in order to improve the ductility and oxidation resistance of this material, it is sufficient to eliminate the coarse particles.

Therefore, in the present invention, by setting the maximum particle size of Ti powder or Ti alloy powder, which is a Ti-based material, to be less than 50 μm, coarse particles are eliminated and room temperature ductility and high temperature oxidation resistance are improved. To do.

[0018]

EXAMPLES Examples embodying the present invention will be described below together with comparative examples. (Example 1) After sieving titanium powder to 44 μm or less or 20 μm or less, Al powder produced by an argon gas atomizing method is sieved to 297, 149, 105 or 44 μm or less so that the final composition is Ti-48 at% Al. Titanium and aluminum were mixed. This mixture was inserted into an aluminum container, and the interior of the container was heated and evacuated to perform deaeration. After that, hot extrusion was performed together with the container, and the extrusion temperature was 440 ° C. and the extrusion ratio was 400. The aluminum container was removed from the obtained extruded material to obtain a raw material for reaction synthesis.

This extruded material (Sample Nos. 1 to 5 in Table 1 below)
About, the reaction synthesis (560 ℃) was performed by HIP, and
After forming the i-Al-based intermetallic compound, it was subsequently homogenized in HIP (temperature: 1150 ° C., time: 24 hours, pressure 150 MPa).

Tensile test pieces were prepared for the Ti--Al based intermetallic compound obtained by the above manufacturing method (diameter of parallel part: φ5 mm, gauge length: 15 mm), and tensile test was carried out at room temperature ( Strain rate: 10 ⁻³ / sec) was carried out.
Further, a high temperature oxidation test (950 ° C. × 50 hours) was carried out in the atmosphere. The results of this test are shown in Table 1 below together with the above production conditions.

As is clear from Table 1, sample N of this example
Those of o.1 to 5 all have room temperature tensile strength of 450 MPa or more and room temperature elongation of 0.58% or more, and are excellent in strength and ductility and are suitable. Further, the increase in oxidation is as small as 13 g / m ² or less, and the oxidation resistance is excellent.

Example 2 PREP (Plasma Arc Rotat)
Ti powder (2)
50 μm or less) is pulverized to 44 μm or less, and the pulverized T
i powder and Al produced by the helium gas atomization method
Powder (149 μm or less) with the final composition of Ti-48a
It was mixed so as to be t% Al. This mixture was inserted into an aluminum container, which was evacuated while heating the inside of the container to perform deaeration. After that, hot extrusion was performed together with the container, and the extrusion temperature was 400 ° C. and the extrusion ratio was 450. The aluminum container was removed from the obtained extruded material to obtain a raw material for reaction synthesis.

This extruded material (Sample No. 6 in Table 1) was subjected to reaction synthesis by HIP and homogenization treatment in the same manner as in the first embodiment. A tensile test was performed on the obtained Ti-Al-based intermetallic compound at room temperature in the same manner as in Example 1. The results of this test are shown in Table 1 together with the above production conditions.

As is apparent from Table 1, the sample No. 6 has a room temperature tensile strength of 480 MPa and a room temperature elongation of 0.
55%, which is excellent in strength and ductility, which is preferable. (Example 3) A produced by the helium gas atomizing method
l powder or Al-XY alloy powder (297 μm or less)
And a titanium sponge powder (44 μm
The following was mixed so that the final composition would be sample Nos. 7 to 18 in Table 1 (however, in sample No. 12, Ti manufactured by PREP was used.
-V alloy powder was pulverized to 44 μm or less). This mixture was inserted into an aluminum container, which was evacuated while heating the inside of the container to perform deaeration. After that, hot extrusion was performed together with the container, but the extrusion temperature was 450.
C. and the extrusion ratio was 350. The aluminum container was removed from the obtained extruded material to obtain a raw material for reaction synthesis.

This extruded material (Sample Nos. 7 to 18 in Table 1) was subjected to reaction synthesis with HIP and homogenization treatment in the same manner as in the first embodiment. The Ti—Al-based intermetallic compound thus obtained was subjected to a tensile test at room temperature in the same manner as in Example 1, and a high temperature oxidation resistance test was performed for some of the compounds. The results of this test are shown in Table 1 together with the above production conditions.

As is clear from Table 1, sample Nos. 7-18
All of them have room temperature tensile strength of 448 MPa or more and room temperature elongation of 0.51% or more, and are excellent in strength and ductility, and are suitable. Further, the increase in oxidation is as small as 15 g / m ² or less, and the oxidation resistance is excellent. In particular, Mn and C indicated by X in the table
In the case where the specified amounts of r and V (0.5 to 3 at%) were added (Sample Nos. 9 to 12 and No. 18), the room temperature tensile strength was all 4
It has a tensile strength of not less than 78 MPa and an elongation at room temperature of not less than 1.15%, which is excellent in strength and ductility, which is preferable.

Further, Nb, Mo, W, T indicated by Y in the table
With a and Si added (Sample Nos. 13 to 17),
Room temperature tensile strength is all 470 MPa or more, room temperature elongation is 0.62% or more, and it is excellent in strength and ductility and suitable, and the oxidation weight increase is 4 g / m ² or less and the oxidation resistance is also very excellent. ..

[0028]

[Table 1]

(Embodiment 4) Al powder or Al-XY alloy powder (149 μm) manufactured by the helium gas atomizing method.
m) and titanium powder (44 μm or less) are mixed so that the final composition is Sample Nos. 19 to 22 in Table 2 below, and then extrusion and HIP reaction are performed under the same conditions as in Example 3 above. A synthesis and homogenization treatment was performed.

Then, the Ti--Al based intermetallic compound thus obtained was subjected to a tensile test at room temperature and a high temperature oxidation test in the same manner as in Example 1. The results of this test are shown in Table 2 together with the above manufacturing conditions. As is clear from Table 2, the samples Nos. 19 to 22 all have room temperature tensile strength of 455 MPa or more and room temperature elongation of 0.52%.
With the above, it is preferable that the amount of increase in oxidation is 10 g / m ² or less, but the addition amount of X component and Y component is small.
In the case of 1, no remarkable improvement in ductility and oxidation resistance performance was observed. Samples No. 20 and 2 with a large addition amount
In the case of 2, the effect was saturated.

[0031]

[Table 2]

Comparative Example 1 Titanium powder (105 μm or less) and aluminum powder (149 μm or less) were mixed (Sample No. 23), or titanium powder (297 μm or less) and aluminum powder (44 μm) were mixed. (Sample No. 2
4), so that the final composition was Ti-48 at% Al. Then, under the same conditions as in Example 1, extrusion, H
Reaction synthesis and homogenization treatment with IP was performed.

Then, the obtained Ti--Al-based intermetallic compound
In the same manner as in Example 1, the tensile test at room temperature
And a high temperature oxidation test. The conclusion of this test
The fruits are shown in Table 3 together with the above production conditions. Clear from this table 3
As you can see, sample Nos. 23 and 24 are
Warm tensile strength is relatively small at 442,435MPa, at room temperature
Elongation is as small as 0.24 and 0.14%, and ductility is poor
Not good. In addition, the amount of oxidation increase is 18 and 20 g / m, respectively.
²It is not preferable because it is large and inferior in oxidation resistance.

(Comparative Example 2) Al powder (149 μm or less) and titanium powder (44 μm or less) produced by the helium gas atomization method were used as sample No. 2 in Table 2 below in the final composition.
After mixing so as to be 5, 26, extrusion, reaction synthesis by HIP and homogenization treatment were performed under the same conditions as in Example 3.

Then, the Ti--Al based intermetallic compound thus obtained was subjected to a tensile test at room temperature and a high temperature oxidation test in the same manner as in Example 1. The results of this test are shown in Table 3 together with the above production conditions. As is clear from Table 3, the sample Nos. 25 and 26 having Al contents outside the predetermined range (40 to 50 at%) have room temperature tensile strengths of 438 and 427 MPa, respectively, and are relatively small. Elongation is as small as 0.27, 0.18% and ductility is inferior, which is not preferable. Further, the sample No. 25 has a large increase in oxidation of 17 g / m ² and is inferior in oxidation resistance, which is not preferable.

[0036]

[Table 3]

That is, according to the method for producing the Ti-Al intermetallic compound of this embodiment, Ti powder or T having the above-mentioned particle diameter is used.
Since the i alloy powder is used, it is possible to produce a Ti—Al-based intermetallic compound which has excellent properties of normal-temperature tensile strength and elongation and excellent high-temperature oxidation resistance. On the other hand,
The comparative examples do not use materials having such a particle size, so they are inferior in the properties of normal-temperature tensile strength and elongation, do not have high room-temperature ductility, and have high high-temperature oxidation resistance. Not preferable.

The present invention is not limited to the above-described embodiments, and it goes without saying that the present invention can be implemented in various modes within the scope of the present invention.

[0039]

As is clear from the above description, in the method for producing a Ti--Al based intermetallic compound according to claim 1, T
As an i-based material, Ti powder or Ti with a particle size of less than 50 μm
Since the alloy powder is used, a lightweight and heat resistant material having excellent room temperature ductility and high temperature oxidation resistance can be obtained.

Further, in the invention of claim 2, since the X component is added, there is an advantage that the room temperature ductility is further improved, and since the Y component is added, there is an advantage that the high temperature oxidation resistance is further improved. .. Moreover, in the invention of claim 3, since various alloy powders containing the X and Y components are used as materials, the obtained intermetallic compound is homogenized and easily compounded with excellent room temperature ductility and high temperature oxidation resistance. Is obtained.

Claims (3)

[Claims] 1. A Ti-based material and an Al-based material are mixed, deaerated, and vacuum sealed, and then the sealed mixed powder is plastically deformed at a temperature lower than the reaction synthesis temperature. Al: 40 to 50 at% balance Ti substantially consisting of Ti by reaction sintering by heating above the reaction synthesis temperature.
A method for producing a Ti-Al intermetallic compound for producing a -Al intermetallic compound, wherein Ti powder or Ti alloy powder having a particle size of less than 50 μm is used as the Ti-based material. A method for producing an intermetallic compound. 2. The final composition after reaction synthesis of at least one of Mn, Cr, and V as the additional element X is 0.5 to 0.5.
3 at% and / or Nb, Mo, or Y as an additional element Y
The Ti-Al-based intermetallic compound according to claim 1, wherein a Ti-Al-based intermetallic compound containing 0.5 to 3 at% of the final composition after reaction synthesis of at least one of W, Ta and Si is produced. Method for producing intermetallic compound. 3. A Ti—X alloy powder, an Al—X alloy powder,
A Ti-Al-based intermetallic compound is manufactured by using at least one or more of Ti-Y alloy powder, Al-Y alloy powder, Ti-XY alloy powder, and Al-XY alloy powder. The method for producing a Ti-Al-based intermetallic compound according to claim 2.