Ti al alloy mixed powder, ti al alloy article and method for producing the same

Abstract

The application provides a TiAl alloy mixed powder, a TiAl alloy part and a preparation method of the TiAl alloy mixed powder, and the preparation method of the TiAl alloy mixed powder comprises the following steps: mixing Ti powder, TiAl3 powder, FeCl3 powder and alloy powder to obtain a mixed powder; the alloy powder comprises one or more combinations of AlV, AlCr and AlNb alloy powders; and the mixed powder is subjected to a modification reaction at a reaction temperature under a hydrogen atmosphere to obtain the TiAl alloy mixed powder. The TiAl alloy mixed powder prepared by the preparation method has low cost, high sintering property and high bulk density, the powder preparation process is clear and definite, the requirement for powder preparation equipment is low, large-scale production is suitable, and the application provides an important way for realizing the preparation of the TiAl alloy mixed powder with low cost, high sintering property and high bulk density.

Description

Technical Field

[0001] This invention relates to the field of titanium-aluminum alloy powder metallurgy technology, specifically to a TiAl alloy mixed powder, TiAl alloy parts, and their preparation methods. Background Technology

[0002] Titanium-aluminum alloys are intermetallic compounds. Due to the long-range ordered arrangement of their atoms and the coexistence of metallic and covalent bonds between atoms, they possess both the ductility of metals and the high-temperature strength of ceramics. Titanium-aluminum alloys have high specific strength, high specific stiffness, low density, good flame retardancy, and excellent high-temperature oxidation and creep resistance. Moreover, their creep resistance is similar to that of nickel-based superalloys, but their density is less than half that of nickel-based superalloys. They are a very promising lightweight high-temperature structural material with broad application prospects in aerospace, automotive manufacturing, and other industrial fields.

[0003] Currently, the main preparation process for TiAl alloys is ingot metallurgy, which suffers from compositional segregation and uneven microstructure. Powder metallurgy, on the other hand, can produce parts with uniform and fine microstructures and achieve near-net-shape forming, effectively solving the problem of difficult processing and forming of TiAl intermetallic compound alloys. Metal powder injection molding, as a novel near-net-shape forming technology in powder metallurgy, has significant advantages in preparing products with complex geometries. It has experienced rapid development in recent years, with the output and variety of powder raw materials continuously increasing. However, currently, its application is mainly concentrated on the large-scale use of stainless steel powder and carbonyl powder. To expand the application fields of injection molding, continuous improvements in product quality and cost are needed, and the variety and characteristics of the raw material powders also play a significant role.

[0004] In current titanium-aluminum alloy powder injection molding (TIA) technology, the selection of powder raw materials is a crucial step in the process. The particle size distribution and morphology of the powder directly affect the flowability and formability of the injection material, the shape retention of the preform during debinding, and the shrinkage rate during sintering. However, pre-alloyed powders are expensive, contradicting the cost-reduction goal of near-net-shape powder injection molding. Furthermore, spherical powders have poor sintering properties, requiring the addition of more binders to promote sintering, but this introduces new impurities and reduces the performance of the molded part. Therefore, reducing powder costs while improving powder sintering properties and packing density has become a major challenge in TiAl alloy powder injection molding technology.

[0005] Therefore, this invention is proposed. Summary of the Invention

[0006] The main objective of this invention is to propose a TiAl alloy mixed powder, TiAl alloy parts, and their preparation method. The TiAl alloy mixed powder prepared by the method of this invention has low cost, high sinterability, and high bulk density. Furthermore, the powder preparation process is clear and straightforward, with low requirements for powder preparation equipment, making it suitable for large-scale production. This provides an important pathway to achieve the preparation of low-cost, high-sinterability, and high-bulk-density TiAl alloy mixed powder, ultimately overcoming problems such as high raw material powder cost and poor shape retention of sinterable samples.

[0007] To achieve the above objectives, the present invention provides the following technical solutions.

[0008] A first aspect of the present invention provides a method for preparing TiAl alloy mixed powder, comprising the following steps:

[0009] Ti powder, TiAl3 powder, FeCl3 powder, and alloy powder are mixed to obtain a mixed powder; wherein the Ti powder, TiAl3 powder, and alloy powder are mixed according to the target TiAl alloy powder composition; the alloy powder includes one or more combinations of AlV, AlCr, and AlNb alloy powders.

[0010] Under hydrogen atmosphere, the mixed powder is modified at a reaction temperature so that the Fe element generated by the decomposition of FeCl3 powder is uniformly coated on the surface of the target TiAl alloy powder, thus obtaining the TiAl alloy mixed powder.

[0011] Furthermore, the Ti powder has a particle size of 10–30 μm, the TiAl3 powder has a particle size of ≤20 μm and is not zero, the alloy powder has a particle size of ≤20 μm and is not zero, and the FeCl3 powder has a particle size of ≤20 μm and is not zero.

[0012] Preferably, the Ti powder is spherical.

[0013] Preferably, the TiAl3 powder is irregular in shape.

[0014] Preferably, the alloy powder is irregular in shape.

[0015] Preferably, the FeCl3 powder is nearly spherical.

[0016] Furthermore, the mass percentage of FeCl3 powder in the mixed powder is 0.5 to 1 wt%.

[0017] Furthermore, the powder mixing is carried out under a protective atmosphere, and the ball-to-powder ratio during the powder mixing process is 1 to 2:1, the rotation speed is 100 to 150 rpm, and the powder mixing time is 8 to 10 hours.

[0018] Preferably, the protective atmosphere includes an argon atmosphere.

[0019] Furthermore, the reaction temperature of the modification reaction is 600–700°C, the reaction time is 6–8 h, and the rotation speed is 10–50 rpm.

[0020] Preferably, the modification reaction process includes: first, argon gas is introduced into the rotary furnace; when the temperature reaches 400°C, the argon gas is stopped and hydrogen gas is introduced; when the temperature continues to rise to 600-700°C, FeCl3 powder undergoes a decomposition reaction, and at the same time, hydrogen gas reacts with Ti powder to generate TiH2 powder, so that the Fe element generated by the decomposition of FeCl3 powder is uniformly coated on the surface of the target TiAl alloy powder formed by TiH2, TiAl3 and alloy powder; after the reaction is completed, the temperature is lowered to 400°C, the hydrogen gas is stopped and argon gas is introduced; after cooling, the TiAl alloy mixed powder is obtained.

[0021] A second aspect of the present invention provides a TiAl alloy mixed powder prepared by the preparation method described in the first aspect of the present invention.

[0022] A third aspect of the present invention provides a method for preparing a TiAl alloy part, comprising the following steps:

[0023] TiAl alloy mixed powder prepared by the preparation method described in the first aspect of the present invention or TiAl alloy mixed powder prepared by the second aspect of the present invention;

[0024] The TiAl alloy mixed powder was subjected to cold isostatic pressing and vacuum pressureless sintering in sequence to obtain the TiAl alloy part.

[0025] Furthermore, the process parameters for the cold isostatic pressing treatment include: a pressure of 250–300 MPa and a time of 5–10 min.

[0026] Furthermore, the vacuum pressureless sintering process includes:

[0027] Under the first vacuum condition, the temperature is increased to 600-800℃ at a rate of 10-20℃ / min and held for 2-4 hours;

[0028] Then, under a second vacuum condition, the temperature is increased to 1250–1400℃ at a rate of 3–5℃ / min and held for 3–5 hours.

[0029] Preferably, the vacuum level under the first vacuum state is greater than the vacuum level under the second vacuum state.

[0030] Preferably, the vacuum degree of the first vacuum state is 0.1 to 200 Pa.

[0031] Preferably, the vacuum degree of the second vacuum state is 10.-3 ~10 -2 Pa.

[0032] A fourth aspect of the present invention provides a TiAl alloy part prepared by the preparation method described in the third aspect of the present invention.

[0033] Compared with the prior art, the present invention achieves the following technical effects:

[0034] 1. This invention provides a low-cost, high-sinterability, and high-bulking-density TiAl alloy mixed powder and its preparation method, overcoming problems such as high raw material powder cost and poor shape retention of sinterable samples.

[0035] 2. Based on the inherent sintering properties of irregular TiAl alloy powder, this invention mixes pure Ti powder with TiAl3 powder and alloy powders such as AlV, AlCr, and AlNb. This results in a TiAl alloy mixed powder system that possesses a certain degree of powder flowability. Simultaneously, fine, irregular TiAl3 and alloy powders are incorporated into the gaps between the pure Ti powder, thereby improving the sintering properties and packing density of the mixed powder system to a certain extent. The density of the sintered sample can reach over 97%, and the packing density can reach over 50%. The sintered sample exhibits high shape retention.

[0036] 3. In this invention, argon gas is first introduced into a high-temperature rotary furnace at a low temperature to purge the air. Then, the temperature is raised to 400°C and hydrogen gas is introduced. During the period of 600-700°C, the hydrogen gas reacts with pure Ti powder to generate TiH2 powder. By adding FeCl3 powder, a decomposition reaction occurs at 600-700°C. The newly generated Fe element uniformly coats the surface of the target TiAl alloy powder formed by TiH2, TiAl3 and alloy powder. The newly generated chlorine gas reacts with hydrogen gas to generate HCl and is then discharged.

[0037] 4. Compared to the pre-alloyed powders used in traditional TiAl alloy injection molding processes, the TiAl alloy mixed powder system of this invention avoids the difficulties of sintering traditional pre-alloyed powders, which require the addition of large amounts of binders to aid sintering and result in high impurity content due to the difficulty in removing the binders. Simultaneously, the fine, irregular TiAl3 and alloy powders are mixed into the gaps between the spherical pure Ti powders, increasing the packing density of the mixed powder system. Pure Ti powder reacts in a hydrogen atmosphere to generate TiH2 powder, while FeCl3 powder undergoes a decomposition reaction. The newly generated Fe element uniformly coats the surface of the target TiAl alloy powder formed by TiH2, TiAl3, and alloy powders. The TiH2 powder and Fe element promote the sintering density of the TiAl alloy mixed powder. Finally, after cooling in a high-temperature rotary furnace, a TiAl alloy mixed powder with a uniform Fe element coating on the surface of the TiAl alloy powder is obtained.

[0038] 5. The TiAl alloy mixed powder in this invention has low cost, high sinterability, and high bulk density. Moreover, the powder preparation process is clear and well-defined, with low requirements for powder preparation equipment, making it suitable for large-scale production. It is an important way to prepare a low-cost, high-sinterability, and high-bulk-density TiAl alloy mixed powder system.

[0039] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0040] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. In the drawings:

[0041] Figure 1 The image shows a SEM image of the Ti-43Al-9V alloy part prepared in Example 1. Detailed Implementation

[0042] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and not intended to limit the scope of the invention. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concept of the invention.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0044] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0045] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0046] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0047] In the description of the embodiments of the present invention, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0048] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0049] In order to overcome the problems of high raw material powder cost and poor shape retention of sintered samples in the existing TiAl alloy injection molding process, the first aspect of the present invention provides a method for preparing TiAl alloy mixed powder.

[0050] The method for preparing TiAl alloy mixed powder in this invention is carried out according to the following steps.

[0051] (1) Powder selection.

[0052] In the embodiments of the present invention, pure Ti powder with a particle size of 10 to 30 μm, TiAl3 powder with a particle size ≤ 20 μm and not equal to 0, alloy powders such as AlV, AlCr, and AlNb with a particle size ≤ 20 μm and not equal to 0, and FeCl3 powder with a particle size ≤ 20 μm and not equal to 0 are selected as raw material powders.

[0053] In an embodiment of the present invention, the Ti powder is spherical.

[0054] In the embodiments of the present invention, the TiAl3 powder is irregular in shape.

[0055] In embodiments of the present invention, the alloy powder is irregularly shaped.

[0056] In the embodiments of the present invention, the FeCl3 powder is nearly spherical.

[0057] (2) Mixing powder.

[0058] In an embodiment of the present invention, Ti powder, TiAl3 powder, FeCl3 powder, and alloy powder are mixed to obtain a mixed powder.

[0059] Among them, Ti powder, TiAl3 powder, and alloy powder are mixed in proportion according to the target TiAl alloy powder composition.

[0060] In an embodiment of the present invention, the powder mixing is carried out under a protective atmosphere, the ball-to-powder ratio is 1 to 2:1, the rotation speed is 100 to 150 rpm, and the mixing time is 8 to 10 hours.

[0061] In embodiments of the present invention, the protective atmosphere may be an argon atmosphere.

[0062] For example, the ball-to-material ratio can be one of 1:1, 1.2:1, 1.5:1, 2:1 or any value that satisfies the above range.

[0063] For example, the rotation speed during the powder mixing process can be one of 100 rpm, 110 rpm, 120 rpm, 130 rpm, 140 rpm, 150 rpm, or any value that meets the above range.

[0064] For example, the mixing time can be one of 8h, 9h, 10h or any value that meets the above range.

[0065] In an embodiment of the present invention, the mass percentage of FeCl3 powder in the mixed powder is 0.5 to 1 wt%.

[0066] For example, the mass percentage of FeCl3 powder can be one of 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1.0wt%, or any value within the above range.

[0067] In embodiments of the present invention, the alloy powder includes one or more combinations of AlV, AlCr, and AlNb alloy powders.

[0068] It is worth mentioning that, in order to isolate oxygen, spherical pure Ti powder, irregular TiAl3 powder, irregular AlV, AlCr, AlNb alloy powders, FeCl3 powder and zirconia balls can be loaded into a mixing bottle in the glove box according to the required ratio, and then mixed with a mixer at 100-150 rpm for 8-10 hours to obtain a uniformly mixed powder.

[0069] (3) Powder modification.

[0070] In an embodiment of the present invention, the mixed powder is modified under a hydrogen atmosphere at a reaction temperature, so that the Fe element generated by the decomposition of FeCl3 powder is uniformly coated on the surface of the target TiAl alloy powder, thereby obtaining TiAl alloy mixed powder.

[0071] The reaction temperature for powder modification is 600–700℃, the reaction time is 6–8h, and the rotation speed is 10–50rpm.

[0072] In an embodiment of the present invention, hydrogen reacts with pure Ti powder at a reaction temperature of 600–700°C to generate TiH2 powder; and by adding FeCl3 powder, a decomposition reaction occurs at 600–700°C, and the newly generated Fe element uniformly coats the surface of the target TiAl alloy powder formed by TiH2, TiAl3 and alloy powder. The newly generated chlorine reacts with hydrogen to generate HCl and is then discharged.

[0073] For example, the reaction temperature can be one of 600°C, 650°C, 700°C, or any value that meets the above range.

[0074] For example, the reaction time can be one of 6h, 7h, 8h or any value that meets the above range.

[0075] In an embodiment of the present invention, the mixed powder and zirconia balls are loaded into a rotary furnace. Argon gas is first introduced into the rotary furnace at room temperature (20-30°C) to purge the air. When the temperature is raised from room temperature to 400°C, the argon gas is stopped and hydrogen gas is introduced. When the temperature is raised to 600-700°C, the reaction begins, and the FeCl3 powder decomposes. At the same time, hydrogen gas reacts with pure titanium powder to generate TiH2. The Fe element generated by the reaction is uniformly coated on the surface of the target TiAl alloy powder formed by TiH2, TiAl3 and alloy powder. The reaction is carried out for 6-8 hours, and hydrogen gas is continuously introduced during this period. After the reaction is completed, the temperature is lowered to 400°C, the hydrogen gas is stopped and argon gas is introduced. Finally, the mixture is cooled to obtain a TiAl alloy mixed powder with a high packing density of Fe element uniformly coated on the surface of the target TiAl alloy powder.

[0076] It is worth mentioning that the rotary furnace rotates at a speed of 10 to 50 rpm throughout the entire process.

[0077] For example, the rotational speed can be one of 10 rpm, 20 rpm, 30 rpm, 40 rpm, 50 rpm, or any value that satisfies the above range.

[0078] The second aspect of the present invention provides a TiAl alloy mixed powder prepared by the method for preparing TiAl alloy mixed powder described in the first aspect of the present invention.

[0079] In embodiments of the present invention, the TiAl alloy mixed powder is composed of TiAl alloy powder and Fe elements coated on its surface; wherein,

[0080] TiAl alloy powder includes one of Ti-48Al-2Cr-2Nb, Ti-43Al-9V, and Ti-45Al-8.5Nb alloy powder.

[0081] In embodiments of the present invention, the TiAl alloy powder may be alloy powders such as Ti-48Al-2Cr-2Nb, Ti-43Al-9V, and Ti-45Al-8.5Nb.

[0082] The TiAl alloy mixed powder prepared in this invention has advantages such as low cost, high sinterability, and high packing density.

[0083] The third aspect of this invention provides a method for preparing TiAl alloy parts.

[0084] The method for preparing TiAl alloy parts in this invention is carried out according to the following steps.

[0085] The TiAl alloy mixed powder prepared by steps (1) to (3) of the preparation method provided in the first aspect of this invention is used as the raw material powder. Or

[0086] The TiAl alloy mixed powder provided in the second aspect of this invention is directly used as the raw material powder.

[0087] (4) Cold isostatic pressing treatment.

[0088] In an embodiment of the present invention, TiAl alloy mixed powder is subjected to cold isostatic pressing to obtain a green billet.

[0089] The process parameters for cold isostatic pressing include: pressure of 250-300 MPa and time of 5-10 min.

[0090] For example, the cold isostatic pressure can be one of 250MPa, 260MPa, 270MPa, 280MPa, 290MPa, 300MPa or any value that meets the above range.

[0091] For example, the cold isostatic pressing time can be one of 5 min, 6 min, 7 min, 8 min, 9 min, 10 min or any value that meets the above range.

[0092] (5) Powder sintering.

[0093] In an embodiment of the present invention, the cold-pressed green blank is subjected to vacuum pressureless sintering to obtain TiAl alloy parts.

[0094] In an embodiment of the present invention, the vacuum pressureless sintering process includes:

[0095] Under the first vacuum condition, such as a low vacuum condition, the temperature is increased to 600-800℃ at a rate of 10-20℃ / min and held for 2-4 hours.

[0096] Then, under a second vacuum condition, such as a high vacuum condition, the temperature is increased to 1250-1400℃ at a rate of 3-5℃ / min, held for 3-5 hours, and finally cooled to room temperature in the furnace to obtain a highly dense TiAl alloy part.

[0097] For example, the heating rate under the first vacuum state can be one of 10℃ / min, 11℃ / min, 12℃ / min, 13℃ / min, 14℃ / min, 15℃ / min, 16℃ / min, 17℃ / min, 18℃ / min, 19℃ / min, 20℃ / min or any value satisfying the above range.

[0098] For example, the sintering temperature under the first vacuum condition can be one of 600°C, 650°C, 700°C, 750°C, 800°C or any value that satisfies the above range.

[0099] For example, the sintering time under the first vacuum condition can be one of 2h, 3h, 4h or any value that satisfies the above range.

[0100] For example, the heating rate under the second vacuum state can be one of 3℃ / min, 4℃ / min, 5℃ / min or any value that satisfies the above range.

[0101] For example, the sintering temperature under the second vacuum condition can be one of 1250°C, 1300°C, 1350°C, 1400°C or any value that satisfies the above range.

[0102] For example, the sintering time under the second vacuum state can be one of 3h, 4h, 5h or any value that satisfies the above range.

[0103] In an embodiment of the present invention, the vacuum degree of the first vacuum state is 0.1 to 200 Pa.

[0104] For example, the vacuum degree of the first vacuum state can be one of 0.1Pa, 0.5Pa, 0.8Pa, 1Pa, 1.5Pa, 2Pa, 3Pa, 5Pa, 8Pa, 10Pa, 30Pa, 50Pa, 80Pa, 100Pa, 120Pa, 150Pa, 180Pa, 200Pa or any value that satisfies the above range.

[0105] In an embodiment of the present invention, the vacuum degree of the second vacuum state is 10. -3 ~10 -2 Pa.

[0106] A fourth aspect of the present invention provides a TiAl alloy part prepared by the preparation method described in the third aspect of the present invention.

[0107] The following detailed description of the TiAl alloy mixed powder, TiAl alloy parts and their preparation methods in this invention will be provided through specific embodiments.

[0108] Example 1

[0109] S1. Powder selection: spherical pure Ti powder with a particle size of 30μm, irregular TiAl3 powder with a particle size of 15μm, irregular AlV alloy powder with a particle size of 15μm (the mass ratio of Al to V in the AlV alloy powder is 4:6), and near-spherical FeCl3 powder with a particle size of 15μm.

[0110] S2. Powder Mixing: In a glove box, spherical pure Ti powder, irregular TiAl3 powder, and irregular AlV alloy powder are mixed according to the Ti-43Al-9V grade and added to a mixing bottle. The mass ratio of the three powders in every 100g of Ti-43Al-9V mixed powder is pure Ti powder: TiAl3 powder: AlV alloy powder = 46.25:33.56:20.19. Then, 0.5wt.% FeCl3 powder and zirconia spheres with a 1:1 spherical-to-powder ratio are added. Finally, the mixing bottle is heated to 100rpm for 10h under an argon protective atmosphere to obtain a uniformly mixed powder.

[0111] S3. Powder modification: The uniformly mixed powder and zirconia balls are loaded into a rotary furnace with a ball-to-powder ratio of 1:1. The rotation speed of the rotary furnace is 50 rpm, and the reaction is carried out at a reaction temperature of 600℃ for 6 hours to obtain Ti-43Al-9V alloy mixed powder.

[0112] Specifically, argon gas is first introduced into a rotary furnace at room temperature to purge the air. Then, the temperature is raised to 400°C, at which point the argon gas supply is stopped and replaced with hydrogen gas. When the temperature is further raised to 600°C, the reaction begins, and the FeCl3 powder decomposes. Simultaneously, hydrogen gas reacts with pure titanium powder to generate TiH2. The reaction continues for 6 hours, resulting in the Fe element generated from the decomposition of FeCl3 powder uniformly coating the surface of the Ti-43Al-9V alloy powder formed from TiH2, TiAl3, and AlV alloy powders. After the reaction is complete, the temperature is lowered to 400°C, the hydrogen gas supply is stopped, and argon gas is replaced. Finally, after cooling, a Ti-43Al-9V alloy mixed powder with a uniform Fe element coating on the surface of the TiH2, TiAl3, and AlV alloy powder is obtained, with a bulk density exceeding 51%.

[0113] S4, Powder Sintering:

[0114] Ti-43Al-9V alloy mixed powder was cold isostatically pressed at 300 MPa for 6 min, and then the cold isostatically pressed green blank was vacuum pressureless sintered. Specifically, the temperature was increased to 600℃ at a rate of 10℃ / min under low vacuum (0.1 Pa) and held for 4 h; then, under high vacuum (10... -3 The temperature was increased to 1250℃ at 3℃ / min under the Pa condition and held for 3h; finally, it was furnace cooled to room temperature to obtain Ti-43Al-9V alloy parts with a density of 98.3%.

[0115] The SEM image of the Ti-43Al-9V alloy part prepared in Example 1 is shown below. Figure 1 As shown.

[0116] Example 2

[0117] S1. Powder selection: spherical pure Ti powder with a particle size of 30μm, irregular TiAl3 powder with a particle size of 15μm, irregular AlCr and AlNb alloy powder with a particle size of 15μm (the mass ratio of Al to Cr in AlCr alloy powder is 3:1, and the mass ratio of Al to Nb in AlNb alloy powder is 1:1), and near-spherical FeCl3 powder with a particle size of 15μm.

[0118] S2. Powder Mixing: In a glove box, spherical pure Ti powder, irregular TiAl3 powder, and irregular AlCr / AlNb alloy powder are mixed according to the Ti-48Al-2Cr-2Nb grade and added to a mixing bottle. The mass ratio of the four powders in 100g of Ti-48Al-2Cr-2Nb mixed powder is pure Ti powder: TiAl3 powder: AlCr alloy powder: AlNb alloy powder = 47.11:32.59:10.72:9.58. Then, 0.8wt.% FeCl3 powder and zirconia balls with a ball-to-powder ratio of 1.2:1 are added. Finally, the mixing bottle is heated under an argon protective atmosphere at a speed of 125rpm for 9 hours to obtain a uniformly mixed powder.

[0119] S3. Powder modification: The uniformly mixed powder and zirconia balls are loaded into a rotary furnace with a ball-to-powder ratio of 1.2:1. The rotation speed of the rotary furnace is 30 rpm, and the reaction is carried out at a reaction temperature of 600℃ for 7 hours to obtain Ti-48Al-2Cr-2Nb alloy mixed powder.

[0120] Specifically, argon gas is first introduced into a rotary furnace at room temperature to purge the air. Then, the temperature is raised to 400°C, at which point the argon gas supply is stopped and replaced with hydrogen gas. When the temperature is further raised to 600°C, the reaction begins, and the FeCl3 powder decomposes. Simultaneously, hydrogen gas reacts with pure titanium powder to generate TiH2. The reaction continues for 7 hours, resulting in a uniform coating of Fe elements generated from the decomposition of FeCl3 powder onto the surface of Ti-48Al-2Cr-2Nb alloy powder, which is composed of TiH2, TiAl3, AlCr, and AlNb alloy powders. After the reaction is complete, the temperature is lowered to 400°C, the hydrogen gas supply is stopped, and argon gas is replaced. Finally, after cooling, a Ti-48Al-2Cr-2Nb alloy mixed powder with a uniform Fe element coating on its surface is obtained, with a bulk density exceeding 53%.

[0121] S4, Powder Sintering:

[0122] Ti-48Al-2Cr-2Nb alloy mixed powder was cold isostatically pressed at 270 MPa for 8 min, and then the cold isostatically pressed green blank was vacuum pressureless sintered. Specifically, the temperature was increased to 700℃ at a rate of 15℃ / min under low vacuum (10 Pa) and held for 3 h; then, under high vacuum (10... -2 The temperature was increased to 1300℃ at 4℃ / min under the Pa condition and held for 4h; finally, it was furnace cooled to room temperature to obtain Ti-48Al-2Cr-2Nb alloy parts with a density of 97.8%.

[0123] Example 3

[0124] S1. Powder selection: spherical pure Ti powder with a particle size of 30μm, irregular TiAl3 powder with a particle size of 15μm, irregular AlNb alloy powder with a particle size of 15μm (the mass ratio of Al to Nb elements in the AlNb alloy powder is 1:1), and near-spherical FeCl3 powder with a particle size of 15μm.

[0125] S2. Powder Mixing: In a glove box, spherical pure Ti powder, irregular TiAl3 powder, and irregular AlNb alloy powder are mixed according to the Ti-45Al-8.5Nb grade and added to a mixing bottle. The mass ratio of the three powders in every 100g of Ti-45Al-8.5Nb mixed powder is pure Ti powder: TiAl3 powder: AlNb alloy powder = 46.72:15.94:37.34. Then, 1 wt.% FeCl3 powder and zirconia balls with a ball-to-powder ratio of 1.5:1 are added to the mixed powder. Finally, the mixing bottle is heated to 150 rpm for 8 hours under an argon protective atmosphere to obtain a uniformly mixed powder.

[0126] S3. Powder modification: The uniformly mixed powder and zirconia balls are loaded into a rotary furnace with a ball-to-powder ratio of 1.5:1. The rotation speed of the rotary furnace is 20 rpm, and the reaction is carried out at a reaction temperature of 600℃ for 8 hours to obtain Ti-45Al-8.5Nb alloy mixed powder.

[0127] Specifically, argon gas is first introduced into a rotary furnace at room temperature to purge the air. Then, the temperature is raised to 400°C, the argon gas supply is stopped, and hydrogen gas is introduced instead. When the temperature is further raised to 600°C, the reaction begins, and FeCl3 powder decomposes. Simultaneously, hydrogen gas reacts with pure titanium powder to generate TiH2. The reaction lasts for 8 hours, resulting in the Fe element generated from the decomposition of FeCl3 powder uniformly coating the surface of Ti-45Al-8.5Nb alloy powder, which is composed of TiH2, TiAl3, and AlNb alloy powders. After the reaction is complete, the temperature is lowered to 400°C, the hydrogen gas supply is stopped, and argon gas is introduced instead. Finally, after cooling, a Ti-45Al-8.5Nb alloy mixed powder with Fe element uniformly coated on the surface of the Ti-45Al-8.5Nb alloy powder composed of TiH2, TiAl3, and AlNb alloy powders is obtained, with a bulk density of over 52%.

[0128] S4, Powder Sintering:

[0129] Ti-45Al-8.5Nb alloy mixed powder was cold isostatically pressed at 250 MPa for 10 min, and then the cold isostatically pressed green blank was vacuum pressureless sintered. Specifically, the temperature was increased to 800℃ at a rate of 20℃ / min under low vacuum (10 Pa) and held for 2 h; then, under high vacuum (10... -2The temperature was increased to 1400℃ at 5℃ / min under the Pa condition and held for 5h; finally, it was furnace cooled to room temperature to obtain Ti-45Al-8.5Nb alloy parts with a density of 97.5%.

[0130] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A method for preparing TiAl alloy mixed powder, characterized in that, Includes the following steps: Ti powder, TiAl3 powder, FeCl3 powder, and alloy powder are mixed to obtain a mixed powder; wherein the Ti powder, TiAl3 powder, and alloy powder are mixed according to the target TiAl alloy powder composition; the alloy powder includes one or more combinations of AlV, AlCr, and AlNb alloy powders. Under a hydrogen atmosphere, the mixed powder is subjected to a modification reaction at a reaction temperature. First, argon gas is introduced into a rotary furnace, which rotates at a speed of 10-50 rpm throughout the process. When the temperature reaches 400°C, the argon gas is stopped and hydrogen gas is introduced. The temperature is then raised to 600-700°C, at which point the FeCl3 powder undergoes a decomposition reaction. Simultaneously, hydrogen gas reacts with Ti powder to generate TiH2 powder, so that the Fe element generated by the decomposition of the FeCl3 powder is uniformly coated on the surface of the target TiAl alloy powder formed by TiH2, TiAl3, and alloy powder. The reaction time is 6-8 hours. After the reaction is completed, the temperature is lowered to 400°C, the hydrogen gas is stopped, and argon gas is introduced. After cooling, the TiAl alloy mixed powder is obtained.

2. The method for preparing TiAl alloy mixed powder as described in claim 1, characterized in that, The Ti powder has a particle size of 10~30μm, the TiAl3 powder has a particle size ≤20μm and not 0, the alloy powder has a particle size ≤20μm and not 0, and the FeCl3 powder has a particle size ≤20μm and not 0.

3. The method for preparing TiAl alloy mixed powder as described in claim 1, characterized in that, The Ti powder is spherical.

4. The method for preparing TiAl alloy mixed powder as described in claim 1, characterized in that, The TiAl3 powder is irregular in shape.

5. The method for preparing TiAl alloy mixed powder as described in claim 1, characterized in that, The alloy powder is irregular in shape.

6. The method for preparing TiAl alloy mixed powder as described in claim 1, characterized in that, The FeCl3 powder is nearly spherical.

7. The method for preparing TiAl alloy mixed powder as described in claim 1, characterized in that, The FeCl3 powder in the mixed powder is 0.5~1wt% by mass.

8. The method for preparing TiAl alloy mixed powder as described in claim 1, characterized in that, The powder mixing is carried out under a protective atmosphere. During the powder mixing process, the ball-to-powder ratio is 1~2:1, the rotation speed is 100~150 rpm, and the mixing time is 8~10 hours.

9. The method for preparing TiAl alloy mixed powder as described in claim 8, characterized in that, The protective atmosphere includes an argon atmosphere.

10. A TiAl alloy mixed powder prepared by the preparation method according to any one of claims 1-9.

11. A method for preparing TiAl alloy parts, characterized in that, Includes the following steps: The TiAl alloy mixed powder prepared by the preparation method according to any one of claims 1-9 or the TiAl alloy mixed powder according to claim 10; The TiAl alloy mixed powder was subjected to cold isostatic pressing and vacuum pressureless sintering in sequence to obtain the TiAl alloy part.

12. The method for preparing TiAl alloy parts as described in claim 11, characterized in that, The process parameters for the cold isostatic pressing treatment include: pressure of 250~300MPa and time of 5~10min.

13. The method for preparing TiAl alloy parts as described in claim 11, characterized in that, The vacuum pressureless sintering process includes: Under the first vacuum condition, the temperature is increased to 600-800℃ at a rate of 10-20℃ / min and held for 2-4 hours; Then, under a second vacuum condition, the temperature is increased to 1250-1400℃ at a rate of 3-5℃ / min and held for 3-5 hours.

14. The method for preparing TiAl alloy parts as described in claim 13, characterized in that, The vacuum level under the first vacuum state is greater than the vacuum level under the second vacuum state.

15. The method for preparing TiAl alloy parts as described in claim 13, characterized in that, The vacuum level of the first vacuum state is 0.1~200 Pa.

16. The method for preparing TiAl alloy parts as described in claim 13, characterized in that, The vacuum level in the second vacuum state is 10. -3 ~10 -2 Pa.

17. A TiAl alloy part prepared by the preparation method according to any one of claims 11-16.

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