JPH06248371A - Production of al3ti intermetallic compound, production of alloy powder worked in this production process, alloy powder and al3ti intermetallic compound - Google Patents

Abstract

PURPOSE:To provide the process for production of the Al3Ti intermetallic compd. having excellent toughness at ordinary temp. and excellent strength at a high temp. oxidation resistance (corrosion resistance), the process for produc tion of the alloy powder worked in this process for production, the alloy powder and the Al3Ti intermetallic compd. CONSTITUTION:Al powder and Mn powder or Al-Mn alloy powder and Ti powder are so compounded that the product consists of <=25atm.% Ti, 5atm.% <=Mn<=12atm.% and the balance Al and that the atomic ratio (Al+Mn)/Ti in the product attains nearly 3. The alloy powder formed by taking the Ti and the Mn into an Al matrix is thereafter produced by a mechanical ironing method. This alloy powder is then subjected to hot extruding or hot pressing. The ingots of Al, Mn and Ti or their alloy ingots are otherwise so melted as to attain these ratios and the rapidly solidified alloy powder is produced; thereafter, this alloy powder is subjected to hot extruding or hot pressing.

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 an Al ₃ Ti-based intermetallic compound, a method for producing an alloy powder processed by the method, an alloy powder and an Al ₃ Ti-based intermetallic compound.

[0002]

2. Description of the Related Art Conventionally, Ti-A based on TiAl
A technique for adding Mn in order to improve the characteristics of the 1-system intermetallic compound is described in JP-A-63-140049.

[0003]

However, in the conventional melting and casting process as a method for producing alloy powder, the crystal grains become large, and the segregation of the elements is large, so that a uniform product cannot be obtained, and the material strength is increased. Could not be secured. Furthermore, in such a conventional manufacturing method, there is a limit in improving the toughness. In addition, by simply mixing the elementary powders, the diffusion of Al becomes large at the time of sintering, many voids (voids) are generated, and Mn powder remains scattered in the structure as a simple substance. It happened.

Therefore, an object of the present invention is to provide a method for producing an Al ₃ Ti-based intermetallic compound which has excellent toughness at room temperature, strength at high temperature and excellent acid resistance (corrosion resistance), and an alloy powder processed by the method. It is to provide a manufacturing method, an alloy powder, and an Al ₃ Ti-based intermetallic compound.

[0005]

In order to achieve the above object, in the method for producing an Al ₃ Ti-based intermetallic compound according to claim 1, the product is Ti ≦ 25 atomic%, 5 atomic% ≦ Mn ≦ 12 atomic%, and Al, Ti, M in the product consisting of the balance Al
The Al powder and the Mn powder or the Al-Mn alloy powder and the Ti powder were blended so that the atomic ratio of n (Al + Mn) / Ti was approximately 3, and then the mechanical powder
It is characterized by including producing alloy powder in which Ti and Mn are incorporated in an Al matrix by an alloying method, and then subjecting the alloy powder to hot extrusion or hot pressing.

In order to achieve the above object, the Al ₃ T according to claim 2 is used.
The production method of the i-based intermetallic compound is such that the product is composed of Ti ≦ 25 atomic%, 5 atomic% ≦ Mn ≦ 12 atomic% and the balance Al, and the atomic ratio of Al, Ti, Mn in the product (A
Al, Mn, and Ti ingots or their alloy ingots are melted to produce rapidly solidified alloy powder so that 1 + Mn) / Ti becomes approximately 3, and then hot extrusion or hot pressing is performed on the alloy powder. It is characterized by including performing.

[0007] To achieve the above object, A according to claim 3
The l ₃ Ti-based intermetallic compound is manufactured by the manufacturing method according to claim 1 or 2.

In order to achieve the above object, the method for producing the alloy powder according to claim 4 is such that the product consists of Ti ≦ 25 atomic%, 5 atomic% ≦ Mn ≦ 12 atomic% and the balance Al, and Atomic ratio of Al, Ti, Mn (Al + Mn) /
By mixing Al powder and Mn powder or Al-Mn alloy powder with Ti powder so that Ti becomes approximately 3, and then incorporating Ti and Mn into the Al matrix by the mechanical alloying method. It is characterized by

To achieve the above object, in the method for producing an alloy powder according to claim 5, the product is composed of Ti ≦ 25 atomic%, 5 atomic% ≦ Mn ≦ 12 atomic% and the balance Al, and Atomic ratio of Al, Ti, Mn (Al + Mn) /
It is characterized in that a lump of Al, Mn and Ti, or an alloy lump thereof is melted to produce a rapidly solidified alloy powder so that Ti becomes approximately 3.

In order to achieve the above object, the alloy powder according to claim 6 is manufactured by the manufacturing method according to claim 4 or 5.

The present invention substitutes a part of Al sites in the crystal structure of an Al ₃ Ti intermetallic compound with Mn atoms. Therefore, in the present invention, Al in the product,
It is necessary that the atomic ratio of Ti and Mn (Al + Mn) / Ti is approximately 3, and the product is substantially composed of Ti ≦ 25 atomic%, 5 atomic% ≦ Mn ≦ 12 atomic% and the balance Al. is necessary. The amount of Mn added is limited up to 12 atomic% in order to reduce the weight, and if the amount of Mn exceeds this limit, Mn cannot be fully diffused and conversely tends to become brittle. Further, if it is 5 atomic% or less, it is not made into a single phase because of the structure,
Since a large amount of Al ₃ Ti is present, it is impossible to fundamentally improve the toughness.

The raw material used in the present invention is powder. Here, it is preferable that Ti has an O ₂ content of 0.5% by weight or less and the particle size is smaller than 200 mesh. Also, Al has an O ₂ content of 0.5% by weight or less and a particle size of 3
2 to 250 mesh, which has a larger diameter than Ti powder is preferable. Further, Mn having a particle size smaller than 32 mesh is suitable. If the powder having the above composition obtained by rapid solidification is used, it is finer than 100 mesh.

Instead of individually preparing the Al powder and the Mn powder, Al-Mn alloy powder may be used. When the Al-Mn alloy powder is used as described above, a particle size of 100 to 250 mesh can be applied.

In the present invention, the above raw materials are mixed (blended) in advance, and thereafter, an alloy powder in which Ti and Mn are incorporated in an Al matrix is manufactured by a mechanical alloying method, and then the alloy powder is prepared. Hot extrusion or hot pressing is performed. The flow of this manufacturing process is shown in FIG. As shown in this figure, in addition to mechanical alloying, the powder can be produced by a rapid solidification method.

In the rapid solidification method, first, a lump (ingot) of Al, Mn and Ti, or an alloy lump thereof is weighed and melted so that the product has a predetermined composition. Next, the obtained molten metal is dropped on a low-temperature rotating disk, or an inert gas is injected into the flowing molten metal. Thus, in the rapid solidification method, the alloy powder is obtained by direct rapid solidification from the molten metal. When an element that dislikes oxidation is included, the process is performed in an inert gas atmosphere. When this rapid solidification method is applied to, for example, those alloy compositions having different solubilities at high and low temperatures, when the additive element is taken into supersaturation in the powder to promote precipitation strengthening, or when casting is performed. There is no coarse crystallization that occurs in. This improves uniformity and reliability. The fact that the additive element is uniformly and finely incorporated in one powder particle regardless of the composition ratio makes the rapidly solidified alloy powder very similar to the properties of the alloy powder by mechanical alloying.

The case of performing mechanical alloying will be described in more detail along the flow of the thick line in FIG.

By this mechanical alloying, Al
A mixed powder in which Ti and Mn are uniformly and finely incorporated in a matrix is produced in a short time.

A ball mill, preferably an attritor, is used as the mixer. An attritor is a high energy ball mill, an example of which is shown in FIG.

In the attritor 1 of FIG. 2, the rotation of the shaft 2 causes the agitator 3 to rotate, which causes the ball 4 to move. The raw materials are mixed by the movement of the balls 4. During the mixing operation, gas is introduced from the gas inlet 5 to keep the mixed atmosphere constant. Further, cooling water is introduced from the water inlet 6 to keep the temperature constant. In FIG. 1, 7 is a gas outlet and 8 is a water outlet.

The ball 4 has a maximum size of 1 inch, preferably 3
/ 8 inch steel balls are preferred. The ratio of the total weight of the balls to the total weight of the powder is 150: 1 to 20: 1, which is the total weight of the balls to the total weight of the powder. As the lubricant, wax-based ones are preferable. The lubricant is
It is preferred to add 0.5% by weight of the total weight of the powder. The rotation speed of the shaft 2 is preferably 250 rpm. Ar or He or the like can be used as the mixed atmosphere. The treatment time is 2 hours to a maximum of 30 hours until the additive powder is uniformly incorporated in the Al matrix.

The peripheral speed at the tip of the agitator 3 is 3.5 m.
/ Sec and max. 1 inch ball 1
It is necessary to process within 0 hours.

As the balls 4, various kinds of balls such as WC type super hard balls, ceramics such as ZrO ₂ type or SiN ₄ type can be used in addition to steel balls.

It is necessary to strictly observe the above-mentioned mixing conditions. If this mixing condition is not observed, not only the productivity will deteriorate, but also Fe will be significantly mixed due to the abrasion of the balls and the container wall of the mixer. Furthermore, since the treated powder becomes too fine, the surface area becomes large and the amount of oxidation per unit weight increases significantly (this is mainly due to powder discharge
It occurs at the time of collection). Due to such an increase in contamination, the toughness is lowered, and in a heat treatment process described later, Fe preferentially reacts with Al to be melted, which causes a disadvantage. Further, if the mixing conditions are not so good, Ti or Mn will not be uniformly incorporated into the Al matrix, and the desired material strength cannot be ensured even if sintering is performed.

In the present invention, after the mixing operation, the mixed powder is sintered (solidified) by hot isostatic pressing (hereinafter, also referred to as HIP) or the like.

In this step, first, the homogeneous mixed powder is packed in a metal capsule such as mild steel having a melting point of 1,400 ° C. or higher, and sealed while vacuuming at 350 to 450 ° C. The thus obtained capsules are hot isostatically pressed at 1,100 ° C. or lower and 660 ° C. (melting point of Al) or higher, usually at 1,100 ° C. for 1 hour or longer, and applied pressure 1,
Sintering is performed at 000 kgf / cm ² or more.

In addition to this, in order to sinter the mixed powder, there is hot extrusion as shown in FIG. In this case, it is necessary to sinter the material (solidified product) after solidifying the mixed powder.

In the present invention, the steel skin formed by the capsule is peeled off after the hot isostatic pressing and the like. This is to prevent melting due to the reaction between Fe and Al in the subsequent heat treatment step.

After peeling the steel skin, the material (sintered product)
Is placed in an atmosphere heat treatment furnace and subjected to uniform diffusion heat treatment.
In a vacuum or in an inert atmosphere such as Ar or He, the furnace pressure is atmospheric pressure or higher. Do not perform in vacuum. This is because the evaporation of the constituent elements, especially Al becomes remarkable.
The temperature is not lower than the melting point of aluminum and not higher than 1,100 ° C. The processing time is 4 hours or more. Since Mn has a large self-diffusion coefficient as shown below, uniform diffusion heat treatment may be carried out if necessary, and this treatment is not essential. Sn>Zn>Pb>Mg>Al>Mn>Ti>Zr> F
e>Hf>Y>Ni>Co>Cr>V>Si>Nb> M
o

After the above heat treatment, the material (Al ₃ T
The i-based intermetallic compound) is sent to the processing step as shown in FIG. In the processing process, it is processed into parts that require toughness, high temperature strength, and oxidation resistance, such as engine valves for motorcycles and automobiles, pistons, and turbocharger rotors.

[0030]

【Example】

Example 1-7 and Comparative Example 1 Al, Ti, Mn powders were blended, and Al _{3 according} to the present invention was mixed.
A Ti-based intermetallic compound was produced by mechanical alloying.

Confirmation test of improvement of toughness 5 (w) × 5 (d) from the material obtained in this example
A × 10 (h) mm prismatic test piece was cut out, sufficiently polished, and then subjected to a compression test at a speed of 0.5 mm / minute (crosshead moving speed). Table 1 shows this result in comparison with the data of Al ₃ Ti (2 elements) obtained by the same method. Here, the breaking strain is the ratio of the absolute value of the amount of displacement of the height of the sample just before breaking to the height of the sample before the start of the test, and this is substantially a barometer for toughness evaluation. In the table, Examples 1 to 7 are examples in which Mn is added, and Comparative Example 1 is an example in which Mn is not added.

[0032]

[Table 1]

Here, for example, the symbol Mn5 means Ti ₂₅ Mn ₅ Al ₇₀ , and Ti; 25.
Atomic%, Mn; 5 atomic%, Al means the balance. Further, Mn8 means Ti ₂₅ Mn ₈ Al ₆₇
And Ti; 25 atomic%, Mn; 8 atomic%, A
It means that l is the rest. Table 2 shows the relationship with the component weight ratio.

[0034]

[Table 2]

Table 2 also shows the mechanical alloying conditions, the powder particle size used, and the HIP conditions in Examples 1-7 and Comparative Example 1. In each of Examples 1-7 and Comparative Example 1, ball weight: charging powder weight = 140:
1, and the rotation speed of the shaft 2 was kept constant at 250 rpm. The raw material powder used in mechanical alloying is Mn; purity 99%, 80 mesh or less, A
1; purity 99.8%, particle size 100 mesh or less, Ti;
The purity was 99.7% and the average particle size was 20.9 μm.

From Table 1, for example, comparing Example 4 and Comparative Example 1 manufactured under favorable conditions, the compressive strength σ _c is about 16.
7% and breaking strain ε increased by 289%.

FIG. 3 shows the relationship between the breaking strain ε and the specific gravity ρ, which serves as a guide for toughness evaluation. It can be seen that the breaking strain ε of the Mn-added product is remarkably large near the specific gravity of 3.8.

FIG. 4 shows the relationship between the amount of added Mn and each physical property value as seen by the mechanical alloying time (MA in FIG. 4). The breaking strain ε tends to increase with an increase in the amount of added Mn in both mechanical and alloying times of 2 hours and 5 hours, and tends to decrease when the amount exceeds a certain amount. The method of increasing the breaking strain ε is abrupt when the mechanical alloying time is short. However, when the mechanical alloying time is longer, the maximum value of the breaking strain ε shifts to the lower Mn side.

As described above, if productivity is taken into consideration (mechanical alloying time is desired to be shortened), Mn is added in a large amount (8 atom% to 12 atom%). It is preferable that the mechanical alloying time is set to a relatively long value by using about 10 atomic% to 10 atomic%.

FIG. 5 shows the relationship between the hardness of the product, the compressive strength σ _c and the breaking strain ε. As understood from FIG. 5, the breaking strain ε is sufficiently secured even at about Hv350. Thus, the intermetallic compound according to the present invention,
Although it is based on Al, it is at the level of hardness of steel after tempering. Therefore, the wear resistance is superior to that of the Al alloy and the rigidity is increased.

FIG. 6 shows Al ₃ Ti and Ti ₂₅ Mn ₁₀ Al _65.
The change amount of the cross head and the change in the load during the compression test are recorded. The Mn-added product has a higher breaking load,
It can be seen that the amount of crosshead displacement is extremely large.

[0042]

As is apparent from the above, according to the present invention, there is provided a method for producing an Al ₃ Ti-based intermetallic compound which has excellent toughness at room temperature and strength and acid resistance (corrosion resistance) at high temperature. It is possible to provide a method for producing an alloy powder processed in the production method, an alloy powder and an Al ₃ Ti-based intermetallic compound.

The Al ₃ Ti-based intermetallic compound provided by the present invention is excellent in strength at high temperatures, and therefore is exposed to high temperatures of engine valves of automobiles and motorcycles such as engine valves and turbocharger rotors. It is expected to be applied to turbine blades of parts and engines such as aircraft.

In addition, since it is also excellent in oxidation resistance (corrosion resistance), it can be applied to various flanges or valves used in chemical plants.

Further, in the present invention, since the uniform composite powder obtained by mechanical alloying or rapid solidification is used as the raw material, the uniformity is high and the reliability of the raw material itself is high. In addition, Mn, as an additional element, has a relatively small effect on the human body and can improve the working environment.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a flow of operations according to the present invention.

FIG. 2 is a conceptual diagram illustrating an attritor used in an embodiment of the present invention.

FIG. 3 is a graph showing the relationship between specific gravity and breaking strain for an Al ₃ Ti-based intermetallic compound according to the present invention.

FIG. 4 is a graph showing the relationship between the amount of added Mn and the respective physical properties of the Al ₃ Ti-based intermetallic compound according to the present invention as seen by mechanical alloying time.

FIG. 5 is a graph showing the relationship among hardness, compressive strength σ _c , and breaking strain ε of a product.

FIG. 6 is a graph showing changes in displacement and load of a crosshead during a compression test of Al ₃ Ti and Ti ₂₅ Mn ₁₀ Al ₆₅ .

[Explanation of symbols]

 1 Attritor body 2 Shaft 3 Agitator 4 Ball 5 Gas inlet 6 Water inlet 7 Gas outlet 8 Water outlet

Claims (6)

[Claims] 1. The product is Ti ≦ 25 atomic%, 5 atomic% ≦
Mn ≦ 12 atomic% and the balance Al and the product
Atomic ratio of Al, Ti, Mn (Al + Mn) / Ti
Al powder and Mn powder so that
Is a mixture of Al-Mn alloy powder and Ti powder.
Later, by the mechanical alloying method, Al matrix
To produce alloy powder that incorporates Ti and Mn in
After that, the alloy powder may be hot extruded or hot pressed.
And Al containing ₃Ti-based intermetallic compound
Production method. 2. The product is Ti ≦ 25 atomic%, 5 atomic% ≦
Atomic ratio (Al + Mn) / Ti of Mn ≦ 12 atomic% and the balance Al and Al, Ti, Mn in the product
Of Al, Mn, and Ti, or an alloy of these alloys is melted to produce a rapidly solidified alloy powder, and then the alloy powder is subjected to hot extrusion or hot pressing. A method for producing an Al ₃ Ti-based intermetallic compound, which comprises: _3. An Al ₃ Ti-based intermetallic compound manufactured by the manufacturing method according to claim 1. 4. The product is Ti ≦ 25 atomic%, 5 atomic% ≦
Atomic ratio (Al + Mn) / Ti of Mn ≦ 12 atomic% and the balance Al and Al, Ti, Mn in the product
Al powder and Mn powder or Al-Mn alloy powder and Ti powder are mixed so that the ratio becomes about 3, and then Ti and Mn are incorporated into the Al matrix by the mechanical alloying method. A method for producing an alloy powder characterized by the above. 5. The product is Ti ≦ 25 atomic%, 5 atomic% ≦
Atomic ratio (Al + Mn) / Ti of Mn ≦ 12 atomic% and the balance Al and Al, Ti, Mn in the product
Of Al, Mn, and Ti, or an alloy lump of these alloys is melted to produce a rapidly solidified alloy powder so that the alloy powder becomes approximately 3. 6. An alloy powder produced by the method according to claim 4 or 5.