High-structure-uniformity Ti2AlNb alloy and powder metallurgy preparation method and application thereof

Abstract

The invention discloses a high-structure-uniformity Ti2AlNb alloy and a powder metallurgy preparation method and application thereof, and belongs to the technical field of metal powder machining. The powder metallurgy preparation method comprises the following steps that spherical Ti2AlNb pre-alloy powder and lamellar-morphology reinforced phase powder are prepared, the spherical Ti2AlNb pre-alloy powder and the reinforced phase powder are mixed after being subjected to stress relief annealing treatment, and then wet-process high-energy ball milling treatment, drying, sieving, spark plasma sintering and double heat treatment are sequentially conducted; the high-structure-uniformity Ti2AlNb alloy is used for solving the problems that when an existing powder metallurgy and spark plasma sintering process is combined for preparing the Ti2AlNb alloy, due to the fact that the sintering temperature is high, the cooling speed is too high, and the element diffusion rate is inconsistent, Al is segregated at the grain boundary, Nb is enriched in the grain, the alloy structure is uneven, and the structure uniformity is poor. And a brittle alpha2 phase is easy to separate out in an Al-rich area in subsequent heat treatment, so that the toughness of the material is damaged.

Description

Technical Field

[0001] This invention belongs to the field of metal powder processing technology, specifically relating to a Ti2AlNb alloy with high microstructure uniformity, its powder metallurgy preparation method, and its application. Background Technology

[0002] As aerospace technology advances towards higher performance, more stringent requirements are being placed on high-temperature structural materials. Ti2AlNb alloy, with its excellent specific strength, low thermal conductivity, and superior corrosion resistance, is considered a potential alternative to traditional nickel-based high-temperature alloys, especially meeting the dual requirements of lightweight and high-temperature performance in aero-engines.

[0003] Currently, Ti2AlNb alloys are mainly prepared using vacuum melting. However, the large difference in melting points and inconsistent diffusion behaviors of Al and Nb elements in this alloy easily leads to macroscopic segregation and inhomogeneous microstructure during melting, thus affecting the stability of material properties. More importantly, the temperature of vacuum melting far exceeds the boiling point of Al, causing severe Al burn-off, resulting in uncontrolled composition, deterioration of microstructure, and low yield.

[0004] Powder metallurgy, with its advantages in compositional uniformity and microstructure control, is gradually becoming an important alternative to traditional smelting processes. Combining it with spark plasma sintering (SPS) technology can effectively suppress grain coarsening and achieve rapid densification of materials. Although introducing particulate reinforcing phases has become a common method to improve the performance of powder metallurgy titanium alloys in recent years, the high sintering temperature and rapid cooling rate during SPS often result in an alloy microstructure dominated by a single α2 phase. Furthermore, due to differences in element diffusion behavior, Al tends to segregate at grain boundaries, while Nb tends to accumulate within the grains, causing severe microstructure inhomogeneity. This, in turn, induces the precipitation of brittle α2 phase during subsequent heat treatment, impairing the material's toughness. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, the present invention aims to provide a Ti2AlNb alloy with high microstructure uniformity, its powder metallurgy preparation method, and its application. By introducing a novel lamellar reinforcing phase rich in β-stabilizing elements to suppress element segregation, and combining it with spark plasma sintering and dual heat treatment processes, the microstructure of the alloy can be precisely controlled, significantly improving the microstructure uniformity and comprehensive mechanical properties of the material. This solves the technical problem that when preparing Ti2AlNb alloys using existing powder metallurgy combined with SPS process, high sintering temperature, excessively fast cooling rate, and inconsistent element diffusion rate lead to Al segregation at grain boundaries and Nb enrichment within grains, resulting in uneven alloy microstructure. Furthermore, the Al-rich regions are prone to precipitate brittle α2 phases during subsequent heat treatment, which impairs the toughness of the material.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a powder metallurgy preparation method for Ti2AlNb alloy with high microstructure uniformity, comprising the following steps: Titanium powder, AlNb master alloy powder and AlMo master alloy powder are mixed and then subjected to a first high-energy ball milling process to obtain spherical Ti2AlNb pre-alloyed powder. TiMo master alloy powder and NbTi master alloy powder are mixed and then subjected to a second high-energy ball milling treatment to obtain a lamellar reinforcing phase powder; wherein, the TiMo master alloy powder accounts for 15% to 30% of the mass of the reinforcing phase powder; and the aspect ratio of the reinforcing phase powder is (3 to 5): 1. Spherical Ti2AlNb pre-alloyed powder and reinforcing phase powder were subjected to stress-relief annealing and then cooled to obtain annealed spherical Ti2AlNb pre-alloyed powder and annealed reinforcing phase powder. Annealed spherical Ti2AlNb pre-alloyed powder and annealed reinforcing phase powder were mixed, and then subjected to wet high-energy ball milling, drying and sieving to obtain Ti2AlNb-based composite powder; wherein the annealed reinforcing phase powder accounted for 5% to 10% of the mass of the Ti2AlNb-based composite powder; Ti2AlNb-based composite powder was subjected to spark plasma sintering and two heat treatments in sequence to obtain a Ti2AlNb alloy with high microstructure uniformity.

[0007] In one embodiment, the titanium powder has a particle diameter of 75 μm to 150 μm and a purity of 99.99%; the AlNb master alloy powder has an Al content of 20% to 30% by mass and a particle diameter of 80 μm to 120 μm; the AlMo master alloy powder has an Al content of 80% to 90% by mass and a particle diameter of 80 μm to 100 μm; and, by atomic percentage, the spherical Ti2AlNb pre-alloy powder comprises 22% Al, 24% Nb, and 0.45% to 0.55% Mo, with the balance being Ti and unavoidable impurity elements. The TiMo master alloy powder contains 25% to 30% Mo by mass and has a particle diameter of 100 μm to 120 μm; the NbTi master alloy powder contains 40% to 50% Nb by mass and has a particle diameter of 100 μm to 150 μm.

[0008] In one embodiment, the stress-relief annealing process is carried out in an argon atmosphere, at a temperature of 750°C to 800°C, for a time of 30 to 60 minutes.

[0009] In one embodiment, the cemented carbide balls used in the first high-energy ball milling treatment, the second high-energy ball milling treatment, and the wet high-energy ball milling treatment are made of ZrO2, with small balls having a diameter of 3 mm, medium balls having a diameter of 5 mm, and large balls having a diameter of 8 mm, and the grinding jars used are made of titanium-based alloy.

[0010] In one embodiment, during the first high-energy ball milling process, the ball-to-material ratio is (8~10):1, the rotation speed is 400r / min~450r / min, and the total ball milling time is 8h~10h. Intermittent operation is adopted: every 30min~45min of operation, a 5min~10min pause is performed, and this cycle is repeated until the total ball milling time is reached. By mass percentage, the proportions of small balls, medium balls, and large balls are 45%~50%, 25%~30%, and 20%~30%, respectively. In the second high-energy ball milling process, the ball-to-material ratio was (20~25):1, the rotation speed was 500r / min~800r / min, and the total ball milling time was 5h~8h. Intermittent operation was adopted: every 30min~45min of operation, there was a 5min~10min pause, and the cycle was repeated until the total ball milling time was reached. By mass percentage, the proportions of small balls, medium balls, and large balls were 5%~10%, 25%~30%, and 60%~70%, respectively. The second high-energy ball milling process involves adding a process control agent with a mass fraction of 3% to 5%, wherein the process control agent is stearyl alcohol.

[0011] In one embodiment, the medium for the wet high-energy ball milling treatment is anhydrous ethanol, and the mass ratio of the medium to the total mass of the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder is (8~10):1, the ball-to-material ratio is (3~5):1, the rotation speed is 300 r / min~400 r / min, and the ball milling time is 1 h~3 h; by mass percentage, the proportions of small balls, medium balls, and large balls are 60%~65%, 20%~25%, and 10%~20%, respectively. The drying temperature is 60℃~80℃.

[0012] In one embodiment, the process parameters for the spark plasma sintering are as follows: First, raise the temperature to 825℃~960℃ at a heating rate of 80℃ / min~100℃ / min, then raise it to the target sintering temperature of 1100℃~1200℃ at a heating rate of 10℃ / min~15℃ / min. At the target sintering temperature of 1100℃~1200℃, maintain a sintering pressure of 130MPa~150MPa and a pressure ≤1×10⁻⁶ MPa. -3 The vacuum degree is set at 50 MPa, and the temperature is maintained for 15 to 30 minutes. After the temperature maintenance is completed, the sintering pressure is reduced to 50 MPa to 70 MPa, and then the temperature is cooled by circulating water cooling.

[0013] In one embodiment, the two-stage heat treatment includes a first heat treatment and a second heat treatment performed sequentially; the temperature of the first heat treatment is 20°C to 30°C above the phase transition point of the three-phase region of B2, O, and α2, the holding time is 2h to 4h, the cooling method is oil cooling, and the time from taking the first heat treatment out of the furnace to transferring it into the cooling box is less than 30s; the temperature of the second heat treatment is 770°C to 810°C, the holding time is 12h to 24h, and the cooling method is air cooling.

[0014] The present invention also provides a Ti2AlNb alloy with high microstructure uniformity, which is prepared by the powder metallurgy preparation method of the aforementioned Ti2AlNb alloy with high microstructure uniformity; the microstructure of the Ti2AlNb alloy with high microstructure uniformity consists of a B2 matrix phase, an O phase and an α2 phase, wherein the O phase and the α2 phase are lath-shaped and uniformly distributed; the microstructure morphology of the edge region, the half-radius region and the central region of the cross-section of the Ti2AlNb alloy with high microstructure uniformity is similar.

[0015] The present invention also provides an application of a high-uniformity Ti2AlNb alloy in hot-end components of aerospace engines, wherein the high-uniformity Ti2AlNb alloy is prepared by the powder metallurgy preparation method of the above-mentioned high-uniformity Ti2AlNb alloy.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a powder metallurgy preparation method for a Ti2AlNb alloy with high microstructure uniformity. The core of this method lies in introducing a novel lamellar reinforcing phase, which is prepared by high-energy ball milling of TiMo master alloy powder and NbTi master alloy powder rich in β-stabilizing elements, exhibiting a specific lamellar morphology. Compared with traditional spherical reinforcing phases, the lamellar structure demonstrates superior efficiency in load transfer and crack suppression, and enhances the overall coordinated deformation capability of the alloy. Furthermore, the abundant β-stabilizing elements in this reinforcing phase effectively suppress the formation of brittle Al-rich phases at grain boundaries after spark plasma sintering, thereby further improving the uniformity of the microstructure and the plasticity of the alloy. In the design of the reinforcing phase, this invention precisely controls the content of the β-stabilizing elements Mo and Nb to prevent the formation of excessive plastic phases in the interface region, which would impair the material strength. Simultaneously, the aspect ratio of the lamellar reinforcing phase is optimized and limited to avoid the problems of excessively high aspect ratios leading to stress concentration at the lamellar tips and increased brittle fracture tendency, and excessively low aspect ratios failing to fully utilize the reinforcing effect of the lamellar structure. Finally, the content of the annealed reinforcing phase powder in the Ti2AlNb-based composite powder is strictly controlled within the range of 5% to 10% to avoid a decrease in microstructure uniformity caused by improper content, thereby ensuring the stability and improvement of the material's comprehensive mechanical properties. In the preparation of the Ti2AlNb-based composite powder, this invention selects wet high-energy ball milling to avoid cold welding and overheating caused by prolonged dry milling. Through SPS and subsequent dual heat treatment, O / α2 phases are generated at the interface, alleviating the formation of Al-rich brittle phases and obtaining a Ti2AlNb alloy with high microstructure uniformity. After SPS, this invention implements a dual heat treatment scheme on the alloy. The first stage is carried out in the lower temperature range of the three-phase region to induce the precipitation of micron-sized coarse lath O phase in the B2 matrix phase, which helps improve plasticity, while retaining a certain content of α2 phase. The second stage involves long-term heat treatment in the B2+O two-phase region to promote the precipitation of nanoscale O phase in the B2 matrix phase, which can improve material strength. Through the combination of the above two stages of heat treatment, the synergistic improvement of the alloy's strength and toughness is achieved.

[0017] Furthermore, in terms of the selection of raw materials for the matrix and reinforcing phase, the raw materials for the spherical Ti2AlNb pre-alloyed powder and the reinforcing phase powder used in this invention are prepared by using a variety of intermediate alloys. Compared with the traditional gas atomization method, the raw material preparation cost is reduced. Compared with the single-element ball milling method, the ball milling time is shortened and the solid solution degree of each element is improved, thus avoiding the core defects of uneven composition, time-consuming and energy-intensive, and serious pollution.

[0018] Furthermore, the present invention performs vacuum annealing of spherical Ti2AlNb pre-alloyed powder and reinforcing phase powder in a high-purity argon atmosphere, which eliminates defects and internal stresses generated during ball milling, makes the powder tend to stabilize from a metastable state, and helps to remove moisture and gas adsorbed on the powder surface. Attached Figure Description

[0019] Figure 1 In the middle (a), (b) and (c), respectively, the microstructure morphology of the edge region, half radius and center region of the Ti2AlNb alloy with high microstructure uniformity prepared in Example 1 of the present invention are shown. Figure 2 In the middle (a), (b) and (c), respectively, the microstructure morphology of the edge region, half radius and center region of the Ti2AlNb alloy with high microstructure uniformity prepared in Example 2 of the present invention are shown. Figure 3 In Figures (a), (b), and (c), the microstructure morphology of the high microstructure uniformity Ti2AlNb alloy obtained in Example 3 of the present invention is shown at the edge region, at half the radius, and at the center region of the cross section. Detailed Implementation

[0020] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions mentioned in the specification are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0021] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0022] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0023] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0024] This invention provides a Ti2AlNb alloy with high microstructure uniformity, its powder metallurgy preparation method, and its application. A novel lamellar reinforcing phase is prepared by using TiMo master alloy powder and NbTi master alloy powder. By introducing β-stabilizing elements Nb and Mo at the interface and combining them with a dual heat treatment process, a beneficial O / α2 phase is induced at the interface, which alleviates the formation of Al-rich brittle phases at the grain boundaries, thereby improving the microstructure uniformity and overall performance.

[0025] On one hand, this invention provides a powder metallurgy preparation method for a Ti2AlNb alloy with high microstructure uniformity. By adjusting a high-energy ball milling process to prepare a lamellar reinforcing phase with high β element content, combined with spark plasma sintering and subsequent heat treatment, a Ti2AlNb alloy with high microstructure uniformity is prepared, improving the material's comprehensive mechanical properties. The specific preparation method includes the following steps: (1) Titanium powder, AlNb master alloy powder, AlMo master alloy powder, TiMo master alloy powder and NbTi master alloy powder were sieved respectively. (2) The raw material titanium powder, AlNb master alloy powder and AlMo master alloy powder after sieving in step (1) are mixed and then subjected to a first high-energy ball milling process to obtain spherical Ti2AlNb pre-alloyed powder. (3) The raw material TiMo master alloy powder and NbTi master alloy powder after sieving in step (1) are mixed and then subjected to a second high-energy ball milling process to obtain the reinforcing phase powder with lamellar morphology. Among them, TiMo master alloy powder accounts for 15%~30% of the mass of the reinforcing phase powder; the aspect ratio of the reinforcing phase powder is (3~5):1; (4) The spherical Ti2AlNb pre-alloy powder and the reinforcing phase powder were subjected to stress-relief annealing treatment and then cooled to obtain annealed spherical Ti2AlNb pre-alloy powder and annealed reinforcing phase powder. (5) The annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder are mixed, and then subjected to wet high-energy ball milling, drying and sieving in sequence to obtain Ti2AlNb-based composite powder; wherein the annealed reinforcing phase powder accounts for 5% to 10% of the mass of Ti2AlNb-based composite powder; (6) Ti2AlNb-based composite powder was sintered and formed by spark plasma sintering to prepare Ti2AlNb alloy bulk material; (7) The Ti2AlNb alloy bulk is subjected to two heat treatments to obtain a Ti2AlNb alloy with high microstructure uniformity.

[0026] In step (1), sieving requires the use of a sieve with a specified mesh size to remove large particles and agglomerated powder.

[0027] In step (2), the titanium powder used to prepare the spherical Ti2AlNb pre-alloyed powder has a particle diameter of 75μm~150μm and a purity of 99.99%; the AlNb master alloy powder has an Al element mass ratio of 20%~30% and a particle diameter of 80μm~120μm; the AlMo master alloy powder has an Al element mass ratio of 80%~90% and a particle diameter of 80μm~100μm; by atomic percentage, the spherical Ti2AlNb pre-alloyed powder includes 22% Al, 24% Nb and 0.45%~0.55% Mo, with the balance being Ti and unavoidable impurity elements.

[0028] More preferably, the spherical Ti2AlNb pre-alloyed powder comprises, by atomic percentage, 22% Al, 24% Nb and 0.5% Mo, with the balance being Ti and unavoidable impurity elements.

[0029] In step (2), the TiMo master alloy powder used to prepare the reinforcing phase powder has a Mo element content of 25% to 30% by mass and a particle diameter of 100 μm to 120 μm; the NbTi master alloy powder has a Nb element content of 40% to 50% by mass and a particle diameter of 100 μm to 150 μm.

[0030] The cemented carbide balls used in the first high-energy ball milling treatment, the second high-energy ball milling treatment, and the wet high-energy ball milling treatment in steps (2), (3), and (5) are made of ZrO2. The diameter of the small ball is 3mm, the diameter of the medium ball is 5mm, and the diameter of the large ball is 8mm. The material of the ball milling jar used is titanium-based alloy.

[0031] The first high-energy ball milling process for preparing spherical Ti2AlNb pre-alloyed powder in step (2) is as follows: the ball-to-material ratio is (8~10):1, the rotation speed is 400r / min~450r / min, the total ball milling time is 8h~10h, and the intermittent operation is adopted: every 30min~45min, pause for 5min~10min, and cycle until the total ball milling time is reached; by mass percentage, the proportions of small balls, medium balls and large balls are 45%~50%, 25%~30% and 20%~30%, respectively.

[0032] The second high-energy ball milling process for preparing the lamellar morphology of the reinforcing phase powder in step (3) is as follows: the ball-to-material ratio is (20~25):1, the rotation speed is 500r / min~800r / min, the total ball milling time is 5h~8h, and the intermittent operation is adopted: every 30min~45min, pause for 5min~10min, and cycle until the total ball milling time is reached; by mass percentage, the proportions of small balls, medium balls and large balls are 5%~10%, 25%~30% and 60%~70%, respectively. In the second high-energy ball milling process, 3%~5% stearyl alcohol by mass fraction is added as a process control agent.

[0033] In step (4), the stress-relief annealing process is carried out in an argon atmosphere at a temperature of 750℃~800℃ for 30min~60min.

[0034] In step (5), the ball milling process of wet high-energy ball milling is wet milling, the medium is anhydrous ethanol, the mass ratio of the medium to the total mass of the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder is (8~10):1, the ball-to-material ratio is (3~5):1, the rotation speed is 300r / min~400r / min, and the ball milling time is 1h~3h; by mass percentage, the proportions of small balls, medium balls and large balls are 60%~65%, 20%~25% and 10%~20%, respectively.

[0035] After the wet high-energy ball milling process in step (5) is completed, the Ti2AlNb-based composite material powder slurry is placed in a vacuum drying oven and dried at a temperature of 60℃~80℃. Then it is sieved to obtain Ti2AlNb-based composite material powder.

[0036] The discharge plasma sintering process in step (6) is as follows: first, the temperature is raised to 825℃~960℃ at a heating rate of 80℃ / min~100℃ / min, and then raised to the target sintering temperature of 1100℃~1200℃ at a heating rate of 10℃ / min~15℃ / min. At the target sintering temperature of 1100℃~1200℃, a sintering pressure of 130MPa~150MPa and a pressure of ≤1×10⁻⁶ are maintained. -3 The vacuum degree is set at 50 MPa, and the temperature is maintained for 15 to 30 minutes. After the temperature maintenance is completed, the sintering pressure is reduced to 50 MPa to 70 MPa, and then the temperature is cooled by circulating water cooling.

[0037] The two-stage heat treatment process in step (7) is as follows: the first stage heat treatment is to hold the temperature at 20℃~30℃ above the phase transition point of the three-phase region of B2, O and α2 for 2h~4h, and then cool it with oil. The time from taking it out of the furnace to transferring it into the cooling box after the first stage heat treatment is less than 30s; the second stage heat treatment is to hold the temperature at 770℃~810℃ in the phase region for 12h~24h, and then air cool it.

[0038] On the other hand, a high-uniformity Ti2AlNb alloy prepared by the powder metallurgy method of the above-mentioned high-uniformity Ti2AlNb alloy is provided. The microstructure of the high-uniformity Ti2AlNb alloy consists of B2 matrix phase, O phase and α2 phase, wherein the O phase and α2 phase are lath-shaped and uniformly distributed. The microstructure morphology of the edge region, half radius and central region of the cross section of the high-uniformity Ti2AlNb alloy is similar.

[0039] On the other hand, this invention provides an application of a Ti2AlNb alloy with high microstructure uniformity prepared by the powder metallurgy method described above in hot-end components of aerospace engines.

[0040] In summary, this invention introduces a lamellar reinforcing phase powder obtained by high-energy ball milling of TiMo and NbTi master alloy powders, and utilizes wet high-energy ball milling to achieve its uniform distribution within the matrix powder (spherical Ti2AlNb pre-alloyed powder). During SPS sintering, by controlling element diffusion behavior, Nb expands the presence range of the O phase, while Mo provides solid solution strengthening, promoting the precipitation of lamellar O / α2 phases at grain boundaries, thereby alleviating local embrittlement and optimizing the interface structure and mechanical properties. As an intermetallic compound system composed of B2, O, and α2 phases, the comprehensive mechanical properties of Ti2AlNb alloys are highly dependent on the size, morphology, and spatial distribution of each phase. Based on this, this invention controls the initial microstructure of the material through powder metallurgy and employs precise heat treatment processes to achieve synergistic optimization of the three-phase composition and distribution, ultimately obtaining a Ti2AlNb alloy with high microstructure uniformity. This alloy possesses both high strength and high toughness, providing key material support for next-generation aerospace propulsion systems.

[0041] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined in this application.

[0042] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0043] Example 1: This embodiment provides a powder metallurgy preparation method for Ti2AlNb alloy with high microstructure uniformity, including the following steps: Step 1) Pretreatment: Titanium powder, AlNb master alloy powder, AlMo master alloy powder, TiMo master alloy powder, and NbTi master alloy powder are sieved through a closed sieve to remove large particles and clumps.

[0044] The titanium powder has a particle diameter of 75μm~150μm and a purity of 99.99%. The AlNb master alloy powder has a particle diameter of 80μm~120μm, and the AlMo master alloy powder has a particle diameter of 80μm~100μm. By mass ratio, the Al element accounts for 20% of the composition of the AlNb master alloy powder and 90% of the composition of the AlMo master alloy powder. The TiMo master alloy powder has a particle diameter of 100μm~120μm, and the NbTi master alloy powder has a particle diameter of 100μm~150μm. By mass ratio, the Mo element accounts for 25% of the composition of the TiMo master alloy powder and 50% of the composition of the NbTi master alloy powder.

[0045] Step 2) Prepare spherical Ti2AlNb pre-alloyed powder. Weigh the pretreated titanium powder, AlNb master alloy powder and AlMo master alloy powder according to the atomic ratio of Ti-22Al-24Nb-0.5Mo, and then perform a first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder.

[0046] The first high-energy ball milling process for preparing spherical Ti2AlNb pre-alloyed powder is as follows: the ball-to-material ratio is 8:1, the rotation speed is 400 r / min, the total ball milling time is 10 h, and the ball mill is paused for 5 min every 30 min of operation; by mass percentage, the proportions of small balls, medium balls and large balls are 45%, 25% and 30%, respectively.

[0047] Step 3) Prepare the reinforcing phase powder with lamellar morphology. Mix the pretreated TiMo master alloy powder and NbTi master alloy powder, and then perform a second high-energy ball milling treatment to obtain the reinforcing phase powder with lamellar morphology.

[0048] The TiMo master alloy powder accounts for 15% of the mass of the reinforcing phase powder, and the aspect ratio of the reinforcing phase powder is 5:1. The second high-energy ball milling process for preparing the lamellar morphology of the reinforcing phase powder is as follows: the ball-to-material ratio is 20:1, the rotation speed is 500 r / min, the total ball milling time is 8 h, the ball mill is paused for 8 min every 40 min of operation, and 3% stearyl alcohol process control agent is added during the process. By mass percentage, the proportions of small balls, medium balls and large balls are 5%, 25% and 70%, respectively.

[0049] Step 4) In an argon atmosphere, the spherical Ti2AlNb pre-alloy powder is subjected to stress-relief annealing at 750°C for 60 min, and then cooled to room temperature in the furnace to obtain annealed spherical Ti2AlNb pre-alloy powder; in an argon atmosphere, the reinforcing phase powder is subjected to stress-relief annealing at 750°C for 60 min, and then cooled to room temperature in the furnace to obtain annealed reinforcing phase powder.

[0050] Step 5) Prepare Ti2AlNb-based composite powder. Mix the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder, and then perform wet high-energy ball milling to obtain Ti2AlNb-based composite powder slurry. Then place the Ti2AlNb-based composite powder slurry in a vacuum drying oven at 80°C to dry it, and then sieve it to obtain Ti2AlNb-based composite powder.

[0051] In this process, the reinforcing phase powder after annealing accounts for 10% of the mass of the Ti2AlNb-based composite powder. The wet grinding medium in the wet high-energy ball milling process is anhydrous ethanol. The mass ratio of the medium to the total mass of the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder is 10:1. The ball-to-material ratio is 3:1. The rotation speed is 300 r / min. The ball milling time is 3 h. By mass percentage, the mass proportions of small balls, medium balls and large balls are 60%, 20% and 20%, respectively.

[0052] Step 6) Prepare Ti2AlNb alloy bulk material: The Ti2AlNb-based composite material powder is sintered and formed by spark plasma sintering process to obtain Ti2AlNb alloy bulk material.

[0053] The spark plasma sintering process is as follows: first, the temperature is increased to 880℃ at a heating rate of 80℃ / min, then increased to the target sintering temperature of 1100℃ at a heating rate of 10℃ / min. At the target sintering temperature of 1100℃, a sintering pressure of 150MPa and a pressure ≤1×10⁻⁶ are maintained. -3 The vacuum level was set to 50 MPa, and the temperature was maintained for 15 minutes. After the temperature maintenance was completed, the sintering pressure was reduced to 50 MPa, and then the temperature was cooled by circulating water cooling.

[0054] Step 7) Prepare a uniformly structured Ti2AlNb alloy. The phase transformation point temperature of the B2+O+α2 three-phase region of the prepared Ti2AlNb alloy is 947℃. The Ti2AlNb alloy block is subjected to two heat treatments. The first heat treatment is to hold at 967℃ for 2 hours and then oil-cool. The second heat treatment is to hold at 810℃ for 24 hours and then air-cool. The heat treatment is then complete.

[0055] Mechanical properties of the heat-treated Ti2AlNb alloy bulk were tested. The room temperature test conditions were 0.5 mm / min before yielding and 3.5 mm / min after yielding. The high temperature test conditions were 750℃, 0.5 mm / min before yielding and 2.5 mm / min after yielding. The test results are shown in Table 1. It can be seen that the uniformly structured Ti2AlNb alloy prepared in Example 1 exhibits excellent comprehensive mechanical properties.

[0056] Figure 1 The image shows the microstructure of the Ti2AlNb alloy with high microstructure uniformity obtained in Example 1 of this invention. After two heat treatments, the microstructure consists of a B2 matrix, lath O / α2 phase, and fine needle-like O phase. The microstructure morphology of the edge region, the half-radius region, and the central region is generally consistent, showing high uniformity.

[0057] Table 1 Mechanical properties of the high-uniformity Ti2AlNb alloy prepared in Example 1

[0058] Example 2: This embodiment provides a powder metallurgy preparation method for Ti2AlNb alloy with high microstructure uniformity, including the following steps: Step 1) Pretreatment: Titanium powder, AlNb master alloy powder, AlMo master alloy powder, TiMo master alloy powder, and NbTi master alloy powder are sieved through a closed sieve to remove large particles and clumps.

[0059] The titanium powder has a particle diameter of 75μm~150μm and a purity of 99.99%. The AlNb master alloy powder has a particle diameter of 80μm~120μm, and the AlMo master alloy powder has a particle diameter of 80μm~100μm. By mass ratio, the Al element accounts for 25% of the composition of the AlNb master alloy powder and 85% of the composition of the AlMo master alloy powder. The TiMo master alloy powder has a particle diameter of 100μm~120μm, and the NbTi master alloy powder has a particle diameter of 100μm~150μm. By mass ratio, the Mo element accounts for 28% of the composition of the TiMo master alloy powder and 45% of the composition of the NbTi master alloy powder.

[0060] Step 2) Prepare spherical Ti2AlNb pre-alloyed powder. Weigh the pretreated titanium powder, AlNb master alloy powder and AlMo master alloy powder according to the atomic ratio of Ti-22Al-24Nb-0.5Mo, and then perform a first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder.

[0061] The first high-energy ball milling process for preparing spherical Ti2AlNb pre-alloyed powder is as follows: the ball-to-material ratio is 9:1, the rotation speed is 430 r / min, the total ball milling time is 9 h, and the ball mill is paused for 8 min every 35 min of operation; by mass percentage, the proportions of small balls, medium balls and large balls are 47%, 27% and 26%, respectively.

[0062] Step 3) Prepare the reinforcing phase powder with lamellar morphology. Mix the pretreated TiMo master alloy powder and NbTi master alloy powder, and then perform a second high-energy ball milling treatment to obtain the reinforcing phase powder with lamellar morphology.

[0063] The TiMo master alloy powder accounts for 25% of the mass of the reinforcing phase powder, and the aspect ratio of the reinforcing phase powder is 4:1. The second high-energy ball milling process for preparing the lamellar morphology of the reinforcing phase powder is as follows: the ball-to-material ratio is 22:1, the rotation speed is 700 r / min, the total ball milling time is 6 h, the ball mill is paused for 5 min every 30 min of operation, and 4% stearyl alcohol process control agent is added during the process. By mass percentage, the proportions of small balls, medium balls and large balls are 10%, 30% and 60%, respectively.

[0064] Step 4) In an argon atmosphere, the spherical Ti2AlNb pre-alloy powder is subjected to stress-relief annealing at 770°C for 40 min, and then cooled to room temperature in the furnace to obtain annealed spherical Ti2AlNb pre-alloy powder; in an argon atmosphere, the reinforcing phase powder is subjected to stress-relief annealing at 770°C for 40 min, and then cooled to room temperature in the furnace to obtain annealed reinforcing phase powder.

[0065] Step 5) Prepare Ti2AlNb-based composite powder. Mix the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder, and then perform wet high-energy ball milling to obtain Ti2AlNb-based composite powder slurry. Then place the Ti2AlNb-based composite powder slurry in a vacuum drying oven at 70°C to dry it, and then sieve it to obtain Ti2AlNb-based composite powder.

[0066] The annealed reinforcing phase powder accounts for 8% of the mass of the Ti2AlNb-based composite powder. The wet grinding medium in the wet high-energy ball milling process is anhydrous ethanol. The mass ratio of the medium to the total mass of the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder is 9:1. The ball-to-material ratio is 4:1. The rotation speed is 350 r / min. The ball milling time is 2 h. By mass percentage, the small balls, medium balls and large balls account for 63%, 22% and 15% of the mass, respectively.

[0067] Step 6) Prepare Ti2AlNb alloy bulk material: The Ti2AlNb-based composite material powder is sintered and formed by spark plasma sintering process to obtain Ti2AlNb alloy bulk material.

[0068] The spark plasma sintering process is as follows: first, the temperature is increased to 885.5℃ at a heating rate of 90℃ / min, then increased to the target sintering temperature of 1150℃ at a heating rate of 13℃ / min. At the target sintering temperature of 1150℃, a sintering pressure of 140MPa and a pressure of ≤1×10⁻⁶ are maintained. -3 The vacuum level was set at 60 MPa, and the temperature was maintained for 13 minutes. After the temperature maintenance was completed, the sintering pressure was reduced to 60 MPa, and then the temperature was cooled by circulating water cooling.

[0069] Step 7) Prepare a uniformly structured Ti2AlNb alloy. The phase transformation point temperature of the B2+O+α2 three-phase region of the prepared Ti2AlNb alloy is 945℃. The Ti2AlNb alloy block is subjected to two heat treatments. The first heat treatment is to hold at 970℃ for 3 hours and then oil-cool. The second heat treatment is to hold at 790℃ for 18 hours and then air-cool. The heat treatment is then complete.

[0070] Mechanical properties of the heat-treated Ti2AlNb alloy bulk were tested. The room temperature test conditions were 0.5 mm / min before yielding and 3.5 mm / min after yielding. The high temperature test conditions were 750℃, 0.5 mm / min before yielding and 2.5 mm / min after yielding. The test results are shown in Table 2. It can be seen that the uniformly structured Ti2AlNb alloy prepared in Example 2 exhibits excellent comprehensive mechanical properties.

[0071] Figure 2 The image shows the microstructure of the Ti2AlNb alloy with high microstructure uniformity obtained in Example 2 of this invention. After two heat treatments, the microstructure consists of a B2 matrix, lath O / α2 phase, and fine needle-like O phase. The microstructure morphology of the edge region, the half-radius region, and the central region is generally consistent, showing high uniformity.

[0072] Table 2 Mechanical properties of the high-uniformity Ti2AlNb alloy prepared in Example 2

[0073] Example 3: This embodiment provides a powder metallurgy preparation method for Ti2AlNb alloy with high microstructure uniformity, including the following steps: Step 1) Pretreatment: Titanium powder, AlNb master alloy powder, AlMo master alloy powder, TiMo master alloy powder, and NbTi master alloy powder are sieved through a closed sieve to remove large particles and clumps.

[0074] The titanium powder has a particle diameter of 75μm~150μm and a purity of 99.99%. The AlNb master alloy powder has a particle diameter of 80μm~120μm, and the AlMo master alloy powder has a particle diameter of 80μm~100μm. By mass ratio, the Al element accounts for 30% of the composition of the AlNb master alloy powder, and the Al element accounts for 80% of the composition of the AlMo master alloy powder. The TiMo master alloy powder has a particle diameter of 100μm~120μm, and the NbTi master alloy powder has a particle diameter of 100μm~150μm. By mass ratio, the Mo element accounts for 30% of the composition of the TiMo master alloy powder, and the Nb element accounts for 40% of the composition of the NbTi master alloy powder.

[0075] Step 2) Prepare spherical Ti2AlNb pre-alloyed powder. Weigh the pretreated titanium powder, AlNb master alloy powder and AlMo master alloy powder according to the atomic ratio of Ti-22Al-24Nb-0.5Mo, and then perform a first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder.

[0076] The first high-energy ball milling process for preparing spherical Ti2AlNb pre-alloyed powder is as follows: the ball-to-material ratio is 10:1, the rotation speed is 450 r / min, the total ball milling time is 8 h, and the ball mill is paused for 10 min every 45 min of operation; by mass percentage, the proportions of small balls, medium balls and large balls are 50%, 30% and 20%, respectively.

[0077] Step 3) Prepare the reinforcing phase powder with lamellar morphology. Mix the pretreated TiMo master alloy powder and NbTi master alloy powder, and then perform a second high-energy ball milling treatment to obtain the reinforcing phase powder with lamellar morphology.

[0078] The TiMo master alloy powder accounts for 30% of the mass of the reinforcing phase powder, and the aspect ratio of the reinforcing phase powder is 3:1. The second high-energy ball milling process for preparing the lamellar morphology of the reinforcing phase powder is as follows: the ball-to-material ratio is 25:1, the rotation speed is 800 r / min, the total ball milling time is 5 h, and the ball mill is paused for 10 min every 45 min of operation. During the process, 5% stearyl alcohol process control agent is added. By mass percentage, the proportions of small balls, medium balls and large balls are 8%, 27% and 65%, respectively.

[0079] Step 4) In an argon atmosphere, the spherical Ti2AlNb pre-alloy powder is subjected to stress-relief annealing at 800°C for 30 minutes, and then cooled to room temperature in the furnace to obtain annealed spherical Ti2AlNb pre-alloy powder; in an argon atmosphere, the reinforcing phase powder is subjected to stress-relief annealing at 800°C for 30 minutes, and then cooled to room temperature in the furnace to obtain annealed reinforcing phase powder.

[0080] Step 5) Prepare Ti2AlNb-based composite powder. Mix the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder, and then perform wet high-energy ball milling to obtain Ti2AlNb-based composite powder slurry. Then place the Ti2AlNb-based composite powder slurry in a vacuum drying oven at 60°C to dry it, and then sieve it to obtain Ti2AlNb-based composite powder.

[0081] In this process, the reinforcing phase powder after annealing accounts for 5% of the mass of the Ti2AlNb-based composite powder. The wet grinding medium in the wet high-energy ball milling treatment is anhydrous ethanol. The mass ratio of the medium to the total mass of the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder is 8:1. The ball-to-material ratio is 5:1. The rotation speed is 400 r / min. The ball milling time is 1 h. By mass percentage, the mass proportions of small balls, medium balls, and large balls are 65%, 25%, and 10%, respectively.

[0082] Step 6) Prepare Ti2AlNb alloy bulk material: The Ti2AlNb-based composite material powder is sintered and formed by spark plasma sintering process to obtain Ti2AlNb alloy bulk material.

[0083] The spark plasma sintering process is as follows: first, the temperature is increased to 900℃ at a heating rate of 100℃ / min, then increased to the target sintering temperature of 1200℃ at a heating rate of 15℃ / min. At the target sintering temperature of 1200℃, a sintering pressure of 130MPa and a pressure ≤1×10⁻⁶ are maintained. -3 The vacuum level was set to 70 MPa, and the temperature was maintained for 10 minutes. After the temperature maintenance was completed, the sintering pressure was reduced to 70 MPa, and then the temperature was cooled by circulating water cooling.

[0084] Step 7) Prepare a uniformly structured Ti2AlNb alloy. The phase transformation point temperature of the B2+O+α2 three-phase region of the prepared Ti2AlNb alloy is 955℃. The Ti2AlNb alloy block is subjected to two heat treatments. The first heat treatment is to hold at 985℃ for 4 hours and then oil-cool. The second heat treatment is to hold at 770℃ for 12 hours and then air-cool. The heat treatment is then complete.

[0085] Mechanical properties of the heat-treated Ti2AlNb alloy bulk were tested. The room temperature test conditions were 0.5 mm / min before yielding and 3.5 mm / min after yielding. The high temperature test conditions were 750℃, 0.5 mm / min before yielding and 2.5 mm / min after yielding. The test results are shown in Table 3. It can be seen that the uniformly structured Ti2AlNb alloy prepared in Example 3 exhibits excellent comprehensive mechanical properties.

[0086] Figure 3 The image shows the microstructure of the Ti2AlNb alloy with high microstructure uniformity obtained in Example 3 of this invention. After two heat treatments, the microstructure consists of a B2 matrix, lath O / α2 phase, and fine needle-like O phase. The microstructure morphology of the edge region, the half-radius region, and the central region is generally consistent, showing high uniformity.

[0087] Table 3 Mechanical properties of the high-uniformity Ti2AlNb alloy prepared in Example 3

[0088] Comparative Example 1: Comparative Example 1 was identical to Example 1 in all other conditions except that the reinforcing phase powder was a mixture of spherical TiMo master alloy powder and spherical NbTi master alloy powder obtained without a second high-energy ball milling process, which was used as the reinforcing phase. The mechanical properties of the resulting Ti2AlNb alloy are shown in Table 4, and the properties are poor.

[0089] The reason is that during the SPS sintering process, spherical particles inevitably have pores, resulting in poor compactness of the alloy after sintering, which further affects the mechanical properties of the material.

[0090] Table 4 Mechanical properties of Ti2AlNb alloy prepared in Comparative Example 1

[0091] Comparative Example 2: Comparative Example 2 was conducted under the same conditions as Example 1, except that the Ti2AlNb-based composite powder was prepared by dry grinding. The mechanical properties of the resulting Ti2AlNb alloy are shown in Table 5, and the properties were poor.

[0092] The reason is that the ball milling time was too long and dry milling was used, which caused severe cold welding between the powder and the ball milling jar, resulting in the loss of Al element. In addition, the ball milling jar also contaminated the alloy composition, further affecting the mechanical properties of the material.

[0093] Table 5 Mechanical properties of Ti2AlNb alloy prepared in Comparative Example 2

[0094] Comparative Example 3: Comparative Example 3 was identical to Example 1 in all other conditions except that TiMo master alloy powder accounted for 10% of the mass of the reinforcing phase powder. The mechanical properties of the resulting Ti2AlNb alloy are shown in Table 6, and the properties were poor.

[0095] The reason is that adding too much Mo leads to an excessive amount of B2 phase in the alloy. Although the finished product has good plasticity, its strength does not meet the standard and its uniformity is also insufficient.

[0096] Table 6 Mechanical properties of Ti2AlNb alloy prepared in Comparative Example 3

[0097] Comparative Example 4: Comparative Example 4 was conducted under the same conditions as Example 1, except that the aspect ratio of the reinforcing phase powder was 6:1. The mechanical properties of the resulting Ti2AlNb alloy are shown in Table 7, and the properties were poor.

[0098] The reason is that if the aspect ratio of the reinforcing phase is too large, although it improves the mechanical properties of the material, the end face of the reinforcing phase is prone to become a crack initiation point, which impairs the plasticity of the material.

[0099] Table 7 Mechanical properties of Ti2AlNb alloy prepared in Comparative Example 4

[0100] Comparative Example 5: Comparative Example 5 was identical to Example 1 in all other conditions except that the reinforcing phase powder accounted for 4% of the mass of the Ti2AlNb-based composite powder after annealing. The mechanical properties of the resulting Ti2AlNb alloy are shown in Table 8, and the properties were poor.

[0101] The reason is that the content of the reinforcing phase powder is too low, resulting in a higher Al content at the grain boundaries, poor material uniformity, and low strength.

[0102] Table 8 Mechanical properties of Ti2AlNb alloy prepared in Comparative Example 5

[0103] Comparative Example 6: Comparative Example 6 was identical to Example 1 in all other conditions except that the reinforcing phase powder accounted for 11% of the mass of the Ti2AlNb-based composite powder after annealing. The mechanical properties of the resulting Ti2AlNb alloy are shown in Table 9, and the properties were poor.

[0104] The reason is that the content of reinforcing phase powder is too high, resulting in too much B2 phase in the material, poor strength, and insufficient uniformity.

[0105] Table 9 Mechanical properties of Ti2AlNb alloy prepared in Comparative Example 6

[0106] This invention provides a powder metallurgy preparation method for a Ti2AlNb alloy with high microstructure uniformity to improve the microstructure uniformity of the Ti2AlNb alloy. The method includes the following steps: (1) preparing spherical Ti2AlNb pre-alloy powder and lamellar reinforcing phase powder respectively; (2) subjecting the spherical Ti2AlNb pre-alloy powder and lamellar reinforcing phase powder to stress-relief annealing treatment respectively, and then cooling them to obtain annealed spherical Ti2AlNb pre-alloy powder and annealed reinforcing phase powder; (3) mixing the annealed spherical Ti2AlNb pre-alloy powder and annealed reinforcing phase powder, and then sequentially performing wet high-energy ball milling treatment, drying and sieving to obtain Ti2AlNb-based composite material powder; (4) sintering the Ti2AlNb-based composite material powder using spark plasma sintering process to prepare Ti2AlNb alloy bulk; (5) subjecting the Ti2AlNb alloy bulk to double heat treatment to obtain a Ti2AlNb alloy with high microstructure uniformity. Compared to traditional casting processes, the Ti2AlNb alloy prepared by this process has high microstructure uniformity and good density. Compared to conventional powder metallurgy, it can give fuller play to the role of the reinforcing phase and improve the performance of the alloy.

[0107] In summary, this invention provides an innovative powder metallurgy solution to address the problem of poor mechanical properties caused by the formation of Al-rich brittle phases during the preparation of Ti2AlNb alloys using powder metallurgy combined with SPS. The core of this solution lies in using novel lamellar TiMo and NbTi master alloys as reinforcing phases, introducing β-stabilizing elements Nb and Mo at the interface, and then inducing the formation of beneficial O / α2 phases at the interface through a dual heat treatment process after SPS sintering. This effectively suppresses the formation of brittle phases and significantly improves the overall mechanical properties of the alloy.

[0108] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A powder metallurgy preparation method for a Ti2AlNb alloy with high microstructure uniformity, characterized in that, Includes the following steps: Titanium powder, AlNb master alloy powder and AlMo master alloy powder are mixed and then subjected to a first high-energy ball milling process to obtain spherical Ti2AlNb pre-alloyed powder. TiMo master alloy powder and NbTi master alloy powder are mixed and then subjected to a second high-energy ball milling treatment to obtain a lamellar reinforcing phase powder; wherein, the TiMo master alloy powder accounts for 15% to 30% of the mass of the reinforcing phase powder; and the aspect ratio of the reinforcing phase powder is (3 to 5):

1. Spherical Ti2AlNb pre-alloyed powder and reinforcing phase powder were subjected to stress-relief annealing and then cooled to obtain annealed spherical Ti2AlNb pre-alloyed powder and annealed reinforcing phase powder. Annealed spherical Ti2AlNb pre-alloyed powder and annealed reinforcing phase powder were mixed, and then subjected to wet high-energy ball milling, drying and sieving to obtain Ti2AlNb-based composite powder; wherein the annealed reinforcing phase powder accounted for 5% to 10% of the mass of the Ti2AlNb-based composite powder; Ti2AlNb-based composite powder was subjected to spark plasma sintering and two heat treatments in sequence to obtain a Ti2AlNb alloy with high microstructure uniformity.

2. The powder metallurgy preparation method of the Ti2AlNb alloy with high microstructure uniformity according to claim 1, characterized in that, The titanium powder has a particle diameter of 75μm to 150μm; the AlNb master alloy powder has an Al content of 20% to 30% by mass and a particle diameter of 80μm to 120μm; the AlMo master alloy powder has an Al content of 80% to 90% by mass and a particle diameter of 80μm to 100μm; by atomic percentage, the spherical Ti2AlNb pre-alloy powder comprises 22% Al, 24% Nb, and 0.45% to 0.55% Mo, with the balance being Ti and impurity elements; The TiMo master alloy powder contains 25% to 30% Mo by mass and has a particle diameter of 100 μm to 120 μm; the NbTi master alloy powder contains 40% to 50% Nb by mass and has a particle diameter of 100 μm to 150 μm.

3. The powder metallurgy preparation method of the Ti2AlNb alloy with high microstructure uniformity according to claim 1, characterized in that, In the stress-relief annealing process, the atmosphere is argon, the temperature is 750℃~800℃, and the time is 30min~60min.

4. The powder metallurgy preparation method of the Ti2AlNb alloy with high microstructure uniformity according to claim 1, characterized in that, The cemented carbide balls used in the first high-energy ball milling treatment, the second high-energy ball milling treatment, and the wet high-energy ball milling treatment are made of ZrO2. The diameter of the small balls is 3mm, the diameter of the medium balls is 5mm, and the diameter of the large balls is 8mm. The grinding jars used are made of titanium-based alloy.

5. The powder metallurgy preparation method of the Ti2AlNb alloy with high microstructure uniformity according to claim 4, characterized in that, In the first high-energy ball milling process, the ball-to-material ratio was (8~10):1, the rotation speed was 400r / min~450r / min, and the total ball milling time was 8h~10h. Intermittent operation was adopted: every 30min~45min of operation, there was a 5min~10min pause, and the cycle was repeated until the total ball milling time was reached. By mass percentage, the proportions of small balls, medium balls, and large balls were 45%~50%, 25%~30%, and 20%~30%, respectively. In the second high-energy ball milling process, the ball-to-material ratio was (20~25):1, the rotation speed was 500r / min~800r / min, and the total ball milling time was 5h~8h. Intermittent operation was adopted: every 30min~45min of operation, there was a 5min~10min pause, and the cycle was repeated until the total ball milling time was reached. By mass percentage, the proportions of small balls, medium balls, and large balls were 5%~10%, 25%~30%, and 60%~70%, respectively. The second high-energy ball milling process involves adding a process control agent with a mass fraction of 3% to 5%, wherein the process control agent is stearyl alcohol.

6. The powder metallurgy preparation method of the Ti2AlNb alloy with high microstructure uniformity according to claim 4, characterized in that, The medium used in the wet high-energy ball milling process is anhydrous ethanol. The mass ratio of the medium to the total mass of the annealed spherical Ti2AlNb pre-alloyed powder and the annealed reinforcing phase powder is (8~10):1, the ball-to-material ratio is (3~5):1, the rotation speed is 300 r / min~400 r / min, and the ball milling time is 1 h~3 h. By mass percentage, the proportions of small balls, medium balls, and large balls are 60%~65%, 20%~25%, and 10%~20%, respectively. The drying temperature is 60℃~80℃.

7. The powder metallurgy preparation method of the Ti2AlNb alloy with high microstructure uniformity according to claim 1, characterized in that, The process parameters for the spark plasma sintering are as follows: First, raise the temperature to 825℃~960℃ at a heating rate of 80℃ / min~100℃ / min, then raise it to the target sintering temperature of 1100℃~1200℃ at a heating rate of 10℃ / min~15℃ / min. At the target sintering temperature of 1100℃~1200℃, maintain a sintering pressure of 130MPa~150MPa and a pressure ≤1×10⁻⁶ MPa. -3 The vacuum degree is set at 50 MPa, and the temperature is maintained for 15 to 30 minutes. After the temperature maintenance is completed, the sintering pressure is reduced to 50 MPa to 70 MPa, and then the temperature is cooled by circulating water cooling.

8. The powder metallurgy preparation method of the Ti2AlNb alloy with high microstructure uniformity according to claim 1, characterized in that, The two-stage heat treatment includes a first heat treatment and a second heat treatment performed sequentially. The temperature of the first heat treatment is 20°C to 30°C above the phase transition point of the three-phase region of B2, O, and α2, the holding time is 2h to 4h, and the cooling method is oil cooling. The time from taking the product out of the furnace to transferring it to the cooling box after the first heat treatment is less than 30s. The temperature of the second heat treatment is 770°C to 810°C, the holding time is 12h to 24h, and the cooling method is air cooling.

9. A Ti2AlNb alloy with high microstructure uniformity, characterized in that, The high-uniformity Ti2AlNb alloy is prepared by powder metallurgy according to any one of claims 1 to 8; the microstructure of the high-uniformity Ti2AlNb alloy consists of a B2 matrix phase, an O phase and an α2 phase, wherein the O phase and the α2 phase are lath-shaped and uniformly distributed; the microstructure morphology of the edge region, the half-radius region and the center region of the cross-section of the high-uniformity Ti2AlNb alloy is similar.

10. The application of a Ti2AlNb alloy with high microstructure uniformity in hot-end components of aerospace engines, characterized in that, The high-uniformity Ti2AlNb alloy is prepared by the powder metallurgy preparation method of the high-uniformity Ti2AlNb alloy as described in any one of claims 1 to 8.

Images