JP3380892B2 - Ti-Al alloy, method for producing the same, and method for joining the same - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a high-temperature corrosion resistance and a high-temperature specific strength, which have a fine structure without pores by a pulse current pressurization-combustion synthesis method using Ti powder and Al powder. The present invention relates to a Ti—Al alloy useful for an automobile engine intake / exhaust valve (hereinafter “intake / exhaust” is omitted), a method for producing the alloy, and a method for joining the Ti—Al alloy.

[0002]

2. Description of the Related Art A combustion synthesis method is known as a method for producing an intermetallic compound such as a Ti--Al alloy or a high melting point inorganic compound. It utilizes the heat of reaction of the elements that make up the intermetallic compounds and high-melting-point inorganic compounds as described above, and is considered to be an effective method because it requires relatively little equipment and requires less manufacturing energy. . Further, it is considered that the gas and impurities adsorbed on the surface of the powder particles are volatilized by the rapid release of the reaction heat during the reaction, so that a high-purity material can be produced if the conditions on the apparatus are adjusted.

However, even if this combustion synthesis method is used as it is, there is a drawback in that a rapid reaction is apt to cause a porous body and a material having high strength cannot be obtained. For this reason,
As a method for densifying the combustion composition, a hot press method, a hydrostatic pressure method, a gas pressure method, in which a pressure is applied simultaneously with the combustion synthesis, and a HIP in which a pressure is applied again after the synthesis.
The method (hot isostatic pressing) was proposed. However, since pressure is applied in a sealed state in any of these methods, it was originally thought that the gas and impurities adsorbed on the powder particle surface could be volatilized and removed during the synthesis reaction. It has the drawback that it remains, resulting in a high impurity level and inability to densify. Further, since there is a step of encapsulation in such a manufacturing method, there have been many problems economically.

Under these circumstances, a pulse energization pressurization-combustion synthesis method has been proposed in which heat generated by pulse energization is used as a heat source for a combustion synthesis reaction, and pressure can be applied simultaneously with the reaction. It is considered that this method is capable of densifying the material and sintering at a low temperature for a short time, so that it is possible to obtain a material which is remarkably superior to the hot pressing method, the hydrostatic pressure method, and the gas pressure method as described above. However, in reality, the crystal grains become coarse, and in particular, in the case of a long and slender material (for example, a material such as an automobile engine valve shaft), pores are generated in the middle of the material, which results in a dense structure throughout. Was difficult to obtain.

[0005]

DISCLOSURE OF THE INVENTION The present invention adjusts the Ti powder and Al powder as raw materials and controls the temperature rising rate, synthesis temperature, pressure, etc. in the pulse current pressurization-combustion synthesis method to control the internal Provided are a Ti-Al alloy having no defects, excellent high-temperature specific strength and high-temperature corrosion resistance, and a uniform and dense metal structure, a method for producing the same, and a method for joining the alloys.

[0006]

The present invention includes: It has a relative density of 99% or more and a TiAl phase of 80-
88% (volume ratio) and _Ti 3 Al phase 12 to 20% (vol
1. A Ti-Al alloy characterized by having a dense structure in which a mixed crystal having a layered structure and having a layered structure is uniformly dispersed . The TiAl phase having an average particle diameter of 10 m to 20 m TiAl and _Ti 3, characterized in that the Al mixed crystal is provided with a uniformly dispersed dense structure of claim 1, wherein the Ti-A
1 alloy 3. The Ti according to 1 or 2 above, which is formed by a pulse current pressurization-combustion synthesis method.
-Al alloy 4. 4. Ti-Al alloy according to each of 1 to 3, which is an alloy for engine valves. A Ti powder having an average particle size of 20 μm or less and an Al powder having an average particle size of 50 μm or less were used, and after mixing these, a temperature rising rate was 10 to 100 K / min and a synthesis temperature was 1273 in a vacuum atmosphere.
5. A method for producing a Ti-Al alloy by pulse energization pressurization-combustion synthesis method, characterized by performing pulse energization pressurization sintering under conditions of ˜1323 K and pressure of 45-70 MPa. Between a plurality of Ti-Al alloys previously formed by the pulse current pressurization-combustion synthesis method, or one of them is the Ti
-Al alloy and the other of the heat-resistant steel or other Ti alloy, the raw material powder of the Ti-Al alloy, a mixed powder containing the raw material powder as a main component, or Ni powder is filled, and pulse current pressurization-combustion is performed. Depending on the synthesis method, the Ti-Al alloys may be exchanged with each other or the Ti-Al alloys with heat-resistant steel or other Ti.
6. Joining method for Ti-Al alloy characterized by joining with alloy Temperature increase rate of 10 to 100 K / mi under vacuum atmosphere
n, synthesis temperature 1273-1323K, pressure 45-70M
7. The method for joining a Ti-Al alloy as described in 6 above, which is characterized in that pulse current energization pressure sintering is performed under the condition of Pa to perform the joining. TiA having a mean particle size of 10 μm to 20 μm in the TiAl phase previously formed by the pulse current pressurization-combustion synthesis method
l- and Ti ₃ Al mixed crystals uniformly dispersed in a plurality of Ti-
A method for joining Ti-Al alloys, characterized in that Al alloys are joined to each other or one of them is a Ti-Al alloy and the other is a heat-resistant steel or another Ti alloy by friction welding.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The raw material powder has an average particle size of 20 μm.
Ti powder of m or less (for example, purity of 99.9% or more) and 2
Al powder of 0 μm or less (for example, purity of 99.9% or more)
By using, for example, Ti: Al = 1: 1 (molar ratio)
Was mixed in hexane for about 3 hours in a ball mill and dried to obtain a mixed powder. Next, pulse energization pressurization-combustion synthesis is performed using this mixed powder. FIG. 1 shows a conceptual diagram of a pulse current pressurization-combustion synthesis apparatus. Graphite mold 1
Powder 2 is filled into the space between the upper and lower electrodes (upper rod 3,
While being compressed by the lower punch 4), direct current pulses are applied to carry out combustion synthesis to sinter and densify. Since the Ti-Al intermetallic compound forms a melt during combustion synthesis, it is possible to achieve a densification of approximately 99% or more even with a small amount of pressure. As shown in FIG. 1, the temperature during heating is measured by making a hole in the mold 1 up to a distance of 5 mm from the mixed powder and using a K type sheath thermocouple 5 therein. When the temperature becomes high, the temperature of the mold surface may be measured using an infrared radiation thermometer. In FIG. 1, the outer layer 6 of the mold 1 is a graphite felt.

The atmosphere is vacuum (for example, a vacuum degree of 10 ^-3 Pa)
And the temperature rising rate is 10 to 100 K / min, preferably 1
0-40K / min, synthesis temperature 1273-1323K,
Pulse current energization pressure sintering is performed under the condition of pressure of 45 to 70 MPa. In particular, in order to obtain a long member such as a shaft portion of an automobile engine valve, it is necessary to relatively slow the temperature rising rate and to perform combustion synthesis for a long time. If the rate of temperature rise is too high, only the punched portion becomes much higher than the synthesis temperature, and the forming phase of the produced material becomes non-uniform, which is not preferable. Further, if the temperature rising rate is too slow, the peculiarity (economic effect) of this method that rapid production is possible is lost, which is not a good idea. From the above, the above temperature increase rate range is set. By performing pulse current pressurization-combustion synthesis under such conditions, the TiA having a relative density of 99% or higher
80% to 88% (volume ratio) of 1 phase and 1% of Ti ₃ Al phase
2 to 20%, and the average grain size in the TiAl phase is 10μ
TiAl alloys mixed crystal of a M～20myuemu TiAl and Ti ₃ Al are provided with uniformly dispersed dense structure is obtained.

The maximum length that can be produced at one time is limited due to the relationship of the optimum forming phase that maintains compactness and strength.
Therefore, in order to obtain a longer member, these are joined together, that is, the Ti-A alloy is formed between a plurality of Ti-Al alloys previously formed by the pulse current pressurization-combustion synthesis method.
l Mixed powder or Ni powder which is a raw material of the alloy,
Similarly, a long Ti-Al alloy material can be obtained by joining the fillers by pulse current pressurization-combustion synthesis method. In this case, there is no limitation on the length that can be joined, and two or more preformed Ti-Al alloy materials can be joined one after another. Further, it is desirable to use a mixed powder having the same composition as the already formed Ti-Al alloy material as the mixed powder to be filled for joining, but the powder having the composition of the Ti-Al alloy as the main component and other powders It is possible to use a powder or a Ni powder mixed as a filler to form a filling material, and join by a pulse current pressurization-combustion synthesis method. In this case, the metal structure hardly changes and the bonding strength does not become a particular problem.

Generally, automotive engine valves are JIS
SUH11 (0.5C-1.8Si-8Cr-remaining Fe)
Or JISSUH35 (0.55C-21Cr-1
Heat resistant steels such as 0Mn-4Ni-0.4N-remaining Fe) have been used, but in recent years, the engine valve for automobiles has responded to the demand for high temperature complete combustion of automobile engines.
A material having higher high temperature specific strength is required. The Ti-Al alloy of the present invention is a material that meets such requirements. In the present invention, the bulk portion and the coaxial portion of the automobile engine valve can be manufactured integrally from the beginning, but separately from this, by using the joining method of the present invention, the bulk portion and the coaxial portion of the automobile engine valve can be made coaxial. Section and a pulse section are separately prepared in advance by a pulse current pressurization-combustion synthesis method, and then the Ti section is formed between these Ti-Al alloy and the Ti section.
-A mixed powder that is a raw material of an Al alloy is filled, and similarly, by a pulse current pressurization-combustion synthesis method of the filler, the bulk portion, the shaft portion, and all of these joints are made into a TiAl phase in a T
It can be mixed crystals of iAl and Ti ₃ Al are prepared automotive engine valve made of Ti-Al alloy having a uniformly dispersed dense tissue. The engine valve for an automobile thus obtained has extremely high heat resistance specific strength and corrosion resistance.

One of the drawbacks of the above-mentioned automobile engine valve made of Ti-Al alloy is that it is rather expensive. As a solution to this point, a Ti-Al alloy can be used for the bulk portion of an automobile engine valve, and a relatively inexpensive heat-resistant steel or Ti alloy can be used for the shaft portion that is not strongly affected by high temperature corrosion. In this case, the above-mentioned gap is formed between the bulkhead of the automotive engine valve made of Ti-Al alloy and the shaft made of heat-resistant steel (forged product, etc.), which is produced in advance by the pulse current pressurization-combustion synthesis method of the present invention. A mixed powder or a Ni powder, which is a raw material of a Ti-Al alloy, is filled, and similarly, a pulse current pressurization-combustion synthesis method of the filler of the present invention is carried out, and an automobile engine made of the Ti-Al alloy of the present invention. It is possible to manufacture an automobile engine valve in which the bulb portion of the valve and the shaft portion made of heat-resistant steel are joined together. The engine valve for an automobile thus obtained has a strong bond strength, a high production speed, is relatively inexpensive, and has excellent heat resistance specific strength and high temperature corrosion resistance. As the material used for the shaft portion, in addition to JIS standard materials such as JIS SUH11 and JIS SUH35, other low alloy steels, martensitic heat resistant steels such as high chromium steels, austenitic heat resistant steels such as Cr-Ni steels or 6Al4V Other relatively inexpensive Ti alloys such as

The joining powder to be filled between the bulk portion of the automobile engine valve and the shaft portion made of heat-resistant steel is the above-mentioned T powder.
Not only the mixed powder which is a raw material of the i-Al alloy, but also other powders having the mixed powder as a main component are mixed, or the Ti-Al alloy side of the present invention is mixed with the Ti-
A mixed powder or a Ni powder, which is a raw material of an Al alloy, may be used by gradually mixing a powder having a composition of the heat-resistant steel or other Ti alloy used at that time or a thermal expansion similar to that of the Ni powder on the shaft side. . As a result, the difference in thermal expansion between the bulky portion and the shaft portion at the time of joining can be reduced, the thermal effect (thermal stress) on the material can be suppressed, and the joining strength can be increased. Furthermore, TiAl and Ti in the TiAl phase of the present invention
₃ Ti with a dense structure in which a mixed crystal of Al is uniformly dispersed
-Al alloy is used and the heat resistant steel or other T
The i alloy can be used to manufacture an automobile engine valve in which the friction welded helix and the shaft portion made of heat-resistant steel are joined together. This makes it possible to obtain a cheaper engine valve for automobiles by making the most of the characteristics of both materials.

The combustion synthesis reaction of Ti-Al alloy begins with the dissolution of Al. The starting temperature of the combustion synthesis reaction varies depending on the size of the Ti powder, and the smaller the powder size, the lower the starting temperature tends to be. It is considered that this cause is based on the difference in the thermal conductivity of the mixed powder due to the particle size and the difference in the contact area between the Ti particles and the Al particles. In order to obtain a denser Ti-Al alloy member, the particle size range of the powder of the present invention is the best.

FIG. 2 schematically shows the process of the pulse current pressurization-combustion synthesis reaction according to the present invention. Al and T
In the mixed powder of i, Al was first melted,
To exist in. Further, Al is diffused by the combustion reaction, and an intermetallic compound of Al and Ti is formed. FIG. 2 shows the process. The outer layer is an Al-rich TiAl ₃ phase.
Phase, the Ti ₃ Al phase is formed. In the case of the present invention TiAl alloy is formed consisting of two phases of final TiAl phase and Ti ₃ Al phase. The upper part of FIG. 2 is 100 μm
In the case of using Ti powder of No. 3, the lower part is the case of using Ti powder of 10 μm. It is shown that the finer the Ti powder, that is, the more easily Al diffuses when the Ti powder of 10 μm is used.

When the Ti powder having an average particle size of 20 μm or less and the Al powder having an average particle size of 50 μm or less according to the present invention are used, 80 to 8
It is composed of 8% TiAl phase and 12-20% Ti ₃ Al phase, and there is no layered structure in which a mixed crystal of TiAl and Ti ₃ Al having an average particle size of 10 μm to 20 μm is uniformly dispersed in the TiAl phase, and the entire layer is formed. Ti with high strength and dense structure
-Al alloy member is obtained. As described later, the Al powder has an average particle size of 50 μm or less in order to increase strength.
1 powder is preferably used. On the other hand, the Ti powder should also be as fine as possible. This is because solid phase diffusion occurs when forming the TiAl phase and the Ti ₃ Al phase. The smaller the particle size of the powder, the faster the diffusion. Therefore, the Ti powder should preferably have an average particle size of 20 μm or less. Even if the Ti-Al alloy member obtained by the melting method is subjected to thermal diffusion treatment, a Ti-Al alloy having the same composition may be obtained, but in this case, a layered structure is formed, which reduces strength and is uniform and dense. Can't get a good organization.

Set of Ti-Al alloy materials obtained according to the invention
The weave is shown in FIG. The microstructure chart (copy
True), the black part is the TiAl phase, the white part is TiAl
And Ti ₃ The mixed crystal of Al is shown. The average grain size of this mixed crystal is 10
μm to 20 μm. Dense without such layered structure
This structure is suitable for automobile engine valves. to this
On the other hand, when a larger Ti powder is used, for example, 100
When using Ti powder of μm, Ti phase and TiAl
₃ Phase is formed, and if it is left as it is,
No phase formation is obtained. In the case of conventional combustion synthesis reaction
Has a very short reaction time (it takes only a few tens of seconds)
Formed by heat treatment when the synthesis reaction is completed.
Almost no control of phase. However, pulse current pressurization-fuel
In the calcination synthesis method, the temperature is set even after the combustion synthesis reaction is completed.
Since it can be controlled, as described above, T of 100 μm
Even when i powder is used, it is possible to use T by utilizing the heat diffusion of Al.
i phase and TiAl₃ Phase to TiAl phase and Ti₃ To the Al phase
It can be changed.

However, controlling the reaction phase after the fact increases the heat treatment time accordingly,
It also leaves instability as to whether the desired reaction phase can be formed. Therefore, it is necessary to avoid such an uncertain method, and it is desirable to use Ti powder having an average particle size of 20 μm or less and Al powder having an average particle size of 50 μm or less from the mixed powder stage. Further, the strength varies depending on the particle size of the raw material powder, and the strength is most improved in the range of the average particle size of the powder. 10 μm Ti powder above and 100
When using μmAl powder, and when using 10μmTi powder and 20μ
A four-point bending strength test was conducted to compare the case of using the mAl powder. The results are shown in Table 1. As is clear from Table 1, the strength is remarkably lowered when the particle size of the powder used is large.

[0018]

[Table 1]

In the present invention, a Ti--Al alloy is used as a basic component, and a metallographic structure has a TiAl phase and a Ti ₃ Al phase as a central phase. As long as the characteristics such as properties are not significantly changed, there is no problem that other alloying elements or impurity elements of 0 or 5% or less are contained, and the present invention includes these.

[0020]

Examples and Comparative Examples [Example 1] As raw material powders, Ti powder having an average particle diameter of 10 µm and Al powder having an average particle diameter of 20 µm were used. These raw material powders have an atomic weight ratio of Ti and Al of 1:
The ingredients were blended so as to be 1 and mixed using a three-dimensional mixer for 24 hours. This mixer is a dry type, and the capacity of the mixing container is 2 liters, and the total amount of powder packed at one time is 200 g. The obtained mixed powder was subjected to a vacuum atmosphere (1) using a pulse current pressure sintering machine equipped with a graphite mold and a punch.
0 ^-3 Pa), synthesis temperature 1273K, heating rate 40K / m
Synthesis was carried out under the conditions of in, holding for 5 minutes and pressure of 70 MPa. The size of the prepared sample is 8mm in diameter and 40, 5 in length.
0 and 60 mm, and 10 samples (rods) were prepared for each of them. The density of the prepared sample was 3.8 g / cm ³ on the whole average, which showed a relative density of about 99% or more, and a dense sample was obtained. The 50 mm rod thus prepared was cut at 10 mm intervals, and the density of each part and the forming phase were observed. As a result, the density of only one central part of the sample was 3.67 g / cm ^3. However, other than that, it was sufficiently densified.
Further, according to the formation phase observation, the TiAl phase and the T
The i ₃ Al phase was observed, and a uniform Ti—Al alloy rod was obtained. This microstructure photograph is FIG. 3 described above. As already described, in the microscopic structure diagram (photograph) in FIG. 3, the black portion shows the TiAl phase, and the white portion shows the mixed crystal of TiAl and Ti ₃ Al. The average grain size of this mixed crystal is 10 μm to 20 μm. Thus, a dense structure without a layered structure can be obtained. However, in the case of producing a slender product, the maximum length that can be produced at one time with the above-mentioned diameter of 8 mm is 70 mm at the most, considering the compactness and the forming phase, unless special temperature control is performed. It is considered to be the degree. Therefore, when manufacturing a longer product, it is necessary to join them.

[Embodiment 2] Next, a diameter of 8 m prepared in advance.
Two rods of m and 40 mm in length were prepared. Between the rods, Ti powder having an average particle diameter of 10 μm and Al powder having an average particle diameter of 10 μm were used. About 0.25 g of the raw material mixed powder of
A vacuum atmosphere (10
^-3 Pa), synthesis temperature 1273K, heating rate 40K / mi
Bonding was performed by a synthetic reaction under the conditions of n, holding for 5 minutes and pressure of 70 MPa. As a result, the diameter is 8 mm and the length is about 80 m.
m rods were obtained. As a result of microscopic observation of the joint interface of the rods thus obtained, there were no defects at all, and rods with sufficient strength were obtained. This microstructure photograph is shown in FIG. In FIG. 5, the central part is the powder part put in for joining, and the left and right parts are the already prepared T
It is an i-Al alloy rod part. Thus, although it is not so clear in FIG. 5, it is composed of three parts, that is, the central part where the powder for bonding is newly added and the left and right rod parts to be bonded. As shown in FIG. 5, there are thin streaks in the vertical direction between the powder part put in for bonding and the Ti-Al alloy rod already manufactured, and it can be seen that there are some pores remaining and this is the interface. . However, the formation layer of such a joint portion is almost the same as the structure of other portions, and also in terms of strength, it is the same as the Ti—Al alloy rod produced before the joining, and extremely strong joining is obtained. I understand. According to the bonding method of the present invention as described above, a plurality of Ti--Al
The alloy rods can be joined one after another to produce a longer Ti-Al alloy rod.

Comparative Example Similar to Example 1, Ti powder having an average particle size of 40 μm and Al powder having an average particle size of 40 μm were used as raw material powders. These raw material powders were blended so that Ti and Al were in an atomic ratio of 1: 1, mixed in hexane for 3 hours with a ball mill, and then dried. A Ti-Al alloy was obtained from the mixed powder obtained by a combustion synthesis method in a refractory furnace. A sample was taken from the alloy thus produced and the structure was observed. A cross-sectional microscopic structure photograph of the sample is shown in FIG. In FIG. 4, the white portion shows a compound phase of Ti and Al, and the black portion shows pores. In this way, Ti-Al is produced by the combustion synthesis method.
When an alloy is manufactured, pores occupy many parts, and a normal Ti-Al alloy having a uniform fine structure cannot be obtained. The result was that the material powder was always porous regardless of the particle size of the raw material powder.

[0023]

EFFECTS OF THE INVENTION According to the present invention, Ti powder and A as raw materials are used.
l powder is adjusted, and the temperature rising rate in the pulse current pressurization-combustion synthesis method, synthesis temperature, pressure, etc. are controlled,
It is possible to obtain a Ti-Al alloy having a uniform and dense metal structure with no internal defects and excellent in high temperature specific strength and high temperature corrosion resistance, and particularly useful for automobile engine valves.
An i-Al alloy, a method for producing the same, and a method for joining the same are provided.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a pulse current pressurization-combustion synthesizer.

FIG. 2 is a schematic diagram showing a reaction process of pulse current pressurization-combustion synthesis.

FIG. 3 is a view showing a structure of a Ti—Al alloy of the present invention (micrograph).

FIG. 4 is a diagram (micrograph) showing the structure of a Ti—Al alloy obtained by a conventional combustion synthesis method.

FIG. 5 is a graph showing T obtained by the pulse current pressurization-combustion synthesis method of the present invention.
The figure which shows the joint interface structure which joined the i-Al alloy (micrograph).

[Explanation of symbols]

1 Mold made of graphite 2 powder 3 Upper rod 4 Lower punch 5 thermocouple

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI C22C 1/00 C22C 1/00 Q // B23K 35/30 310 B23K 35/30 310Z B23K 103: 14 103: 14 103: 24 103 : 24 (73) Patent holder 598002408 Hashimoto et al. 3-11-19 Koriyama, Taichiro-ku, Sendai City, Miyagi Prefecture (74) 3 agents above 100093296 Patent Attorney Isamu Kogoshi (72) Inventor Toshihiko Abe Higashitanaka, Tagajo City, Miyagi Prefecture 2-40-27-601 (72) Inventor Yasunaga Tetsu, 2-2-18, Mikamimine, Taishaku-ku, Sendai-shi, Miyagi A205 (72) Inventor Hashimoto, et al. 3-11-19, Koriyama, Taihaku-ku, Sendai-shi, Miyagi Prefecture (72) Inventor Yoshinobu Saito 23 Tohoku Special Steel Co., Ltd., Tohoku Special Steel Co., Ltd., Murata, Shibata-gun, Miyagi Prefecture 23 (72) Inventor Yoshitaka Nishizawa, Murata, Shibata-gun, Miyagi Prefecture, Nishigaoka 23, Tohoku Special Steel Co., Ltd. (56) References -145848 (JP, A) JP 8-199266 (JP, A) JP 8-85802 (JP, A) JP 3-93670 (JP, A) (58) Fields investigated (Int.Cl) . ⁷ , DB name) C22C 1/00-49/14 B22F 3/00 B23K 20/12 B23K 35/30

Claims (8)

(57) [Claims] 1. TiAl having a relative density of 99% or more,
Phase 80-88% (volume ratio) and _Ti 3 Al phase 12-2
A mixed crystal of 0% (volume ratio) with no layered structure is uniformly distributed.
Ti- characterized by having a dispersed and dense structure
Al alloy. 2. The TiAl phase has an average particle size of 10 μm to 20 μm.
m is a TiAl and _Ti 3 Al mixed crystal is TiAl alloy according to claim 1, characterized in that it comprises a uniformly dispersed dense tissue. 3. The Ti-Al alloy according to claim 1, which is formed by a pulse current pressurization-combustion synthesis method. 4. The Ti-Al alloy according to each of claims 1 to 3, which is an alloy for engine valves. 5. A Ti powder having an average particle size of 20 μm or less and 50
Using Al powder of μm or less, after mixing these, pulse current energization pressure sintering is performed under conditions of a temperature rising rate of 10 to 100 K / min, a synthesis temperature of 1273 to 1323 K, and a pressure of 45 to 70 MPa in a vacuum atmosphere. A method for producing a Ti-Al alloy by a pulse current pressurization-combustion synthesis method. 6. Between a plurality of Ti—Al alloys previously formed by a pulse current pressurization-combustion synthesis method, or one of the Ti—Al alloys and the other of heat resistant steel or another T
The Ti-Al alloy raw material powder, a mixed powder containing the raw material powder as a main component, or a Ni powder is filled between the i-alloy and the Ti-A alloy by a pulse current pressurization-combustion synthesis method.
1-Al alloys, or Ti-Al alloys and heat-resistant steels or other Ti alloys are joined together.
Method of joining alloys. 7. A heating rate of 10 to 100 K in a vacuum atmosphere.
/ Min, synthesis temperature 1273-1323K, pressure 45-
7. The Ti-Al alloy joining method according to claim 6, wherein the joining is performed by pulse current pressure sintering under a condition of 70 MPa. 8. A plurality of Ti—Al alloys in which a mixed crystal of TiAl and Ti ₃ Al having an average particle size of 10 μm to 20 μm are uniformly dispersed in a TiAl phase previously formed by a pulse current pressurization-combustion synthesis method. Alternatively, a Ti-Al alloy joining method is characterized in that one is joined with the Ti-Al alloy and the other is joined with heat-resistant steel or another Ti alloy by a friction welding method.