Homogeneously enhanced Ti2AlNb alloy and preparation method and application thereof

Abstract

The invention discloses a homogeneously-enhanced Ti2AlNb alloy and a preparation method and application thereof, and belongs to the technical field of metal powder processing. The preparation method comprises the following steps: preparing spherical Ti2AlNb pre-alloyed powder and lamellar Ti2AlNb pre-alloyed powder with the same components through high-energy ball milling treatment; the spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder are mixed, and then the mixture is subjected to high-energy ball milling treatment, so that composite-state Ti2AlNb pre-alloyed powder is obtained; and the composite state Ti2AlNb pre-alloy powder is sequentially subjected to spark plasma sintering forming and double heat treatment, and the Ti2AlNb alloy is prepared. The method is used for solving the technical problems that when the Ti2AlNb alloy is prepared through combination of conventional powder metallurgy and an SPS technology, due to the fact that the number of equiaxed crystals is large, the durability is poor under the high-temperature condition of 650-750 DEG C, and the product performance is unstable due to introduction of a heterogeneous reinforcing phase.

Description

Technical Field

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

[0002] Ti2AlNb alloys, with their excellent specific strength, low thermal conductivity, and good corrosion resistance, are considered a candidate material to replace traditional nickel-based superalloys in the field of high-temperature titanium alloys, and have broad application prospects in hot-end components of aerospace engines. To prepare this type of alloy, the current common process is a combination of vacuum melting and casting. This involves fully mixing and solidifying the raw materials through arc melting or induction melting, followed by heat treatment to obtain the desired microstructure and properties. However, traditional vacuum melting processes face significant technical challenges in preparing highly alloyed Ti2AlNb alloys: due to the large difference in melting points and diffusion rates between Al and Nb, severe element segregation easily occurs during melting, resulting in uneven microstructure and affecting further use of the material; simultaneously, the melting temperature far exceeds the melting point of Al, easily causing element burn-off, leading to serious deviations from the composition design, damage to the microstructure, and even product scrap. Furthermore, conventional titanium alloy casting usually requires three vacuum melting processes, which is time-consuming and costly, and the unavoidable risers further increase melting costs.

[0003] To address the inherent limitations of the vacuum melting-casting process, researchers have increasingly turned their attention to powder metallurgy. Spark plasma sintering (SPS), a rapid densification method, has been widely applied to the preparation of Ti2AlNb alloys. SPS can achieve powder densification in a short time, effectively suppressing excessive grain growth and avoiding defects such as component segregation and element loss caused by melting, thus improving the material's mechanical properties to some extent. However, conventional powder metallurgy methods combined with SPS still have significant shortcomings: while improving alloy composition uniformity, the resulting alloy microstructure is predominantly equiaxed. Under continuous high load conditions, cracks easily initiate and propagate along grain boundaries, resulting in insufficient durability at high temperatures of 650℃~750℃, making it difficult to meet the stringent long-term service stability requirements of critical components in aero-engines. Studies have found that introducing suitable reinforcing phases into the Ti2AlNb alloy matrix can effectively improve the overall mechanical properties of the alloy, achieving a synergistic optimization of strength and toughness. Furthermore, the lamellar structure possesses excellent high-temperature strength and creep resistance, making it a preferred choice. Therefore, finding suitable lamellar reinforcing phases has become an effective way to solve the aforementioned technical challenges. However, the lamellar reinforcing phases currently used are usually heterogeneous materials, such as carbon-based materials or other titanium alloy systems. Although these materials can improve the mechanical properties of Ti2AlNb-based alloys to some extent, the significant differences between them and the matrix in physical parameters such as the coefficient of thermal expansion and elastic modulus easily lead to stress concentration at the interface, promoting microcrack initiation and inevitably adversely affecting the high-temperature creep resistance of the material. On the other hand, the interdiffusion between the heterogeneous reinforcing phase and the matrix alloying elements often induces the formation of brittle reactive phases that are difficult to control, resulting in large fluctuations in product performance between different batches, making it difficult to guarantee the stability of the final product's performance.

[0004] In summary, when preparing Ti2AlNb alloys using conventional powder metallurgy combined with SPS process, there are issues such as insufficient creep performance at high temperatures of 650℃~750℃ and unstable product performance caused by the introduction of heterogeneous reinforcing phases. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a homogeneous reinforced Ti2AlNb alloy, its preparation method and application, to solve the technical problem that when preparing Ti2AlNb alloy by conventional powder metallurgy combined with SPS process, the presence of more equiaxed crystals leads to poor creep performance under high temperature conditions of 650℃~750℃, and the introduction of heterogeneous reinforcement phase causes unstable product performance.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention provides a method for preparing a homogeneous reinforced Ti2AlNb alloy, comprising the following steps: Titanium powder, AlMo alloy powder, NbTi alloy powder, and AlNb alloy powder are mixed and formulated. A first high-energy ball milling process is then performed to prepare spherical Ti2AlNb pre-alloyed powder. This spherical Ti2AlNb pre-alloyed powder is then divided into two parts. The first part of the spherical Ti2AlNb pre-alloyed powder is kept for later use, while the second part of the spherical Ti2AlNb pre-alloyed powder undergoes a second high-energy ball milling process to prepare lamellar Ti2AlNb pre-alloyed powder. The composition of the first part of the spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder are the same. The spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder from the first part are mixed, and then subjected to a third high-energy ball milling treatment to obtain composite Ti2AlNb pre-alloyed powder; the lamellar Ti2AlNb pre-alloyed powder accounts for 3% to 5% of the mass of the composite Ti2AlNb pre-alloyed powder; Ti2AlNb alloy was obtained by sequentially subjecting composite Ti2AlNb pre-alloyed powder to spark plasma sintering and two heat treatments.

[0007] In one embodiment, the titanium powder has a purity of 99.99% and a particle diameter of 150 μm to 300 μm; the AlMo alloy powder has a powder diameter of 200 μm to 250 μm; the NbTi alloy powder has a powder diameter of 300 μm to 350 μm; and the AlNb alloy powder has a powder diameter of 150 μm to 200 μm. By mass percentage, the AlMo alloy powder contains 28% to 32% Al, with the balance being Mo; the NbTi alloy powder contains 75% to 80% Nb, with the balance being Ti; and the AlNb alloy powder contains 33% to 37% Al, with the balance being Nb. By atomic percentage, the spherical Ti2AlNb pre-alloyed powder, the first portion of the spherical Ti2AlNb pre-alloyed powder, and the lamellar Ti2AlNb pre-alloyed powder comprise 22% Al, 24% Nb, and 0.45%~0.55% Mo, with the balance being Ti and unavoidable impurity elements.

[0008] In one embodiment, the ball milling processes of the first, second, and third high-energy ball milling treatments are all carried out in an intermittent manner, with a single run time of 30 to 50 minutes and a single pause time of 3 to 5 minutes.

[0009] In one embodiment, during the first high-energy ball milling process, the ball-to-material ratio is 3~5:1, the rotation speed is 300r / min~350r / min, and the total milling time is 3h~5h. Based on the total mass of the grinding balls, the proportion of small balls with a diameter of 3mm is 30%~40%, the proportion of medium balls with a diameter of 5mm is 45%~50%, and the remainder is large balls with a diameter of 8mm.

[0010] In one embodiment, solid stearic acid is added as a process control agent during the second high-energy ball milling process, and the process control agent accounts for 1.5% to 3% of the total mass of the spherical Ti2AlNb pre-alloyed powder in the second part; In the second high-energy ball milling process, the ball-to-material ratio is 18~20:1, the rotation speed is 500r / min~800r / min, and the total milling time is 10h~15h. Based on the total mass of the grinding balls, the proportion of small balls with a diameter of 3mm is 5%~10%, the proportion of medium balls with a diameter of 5mm is 50%~60%, and the remainder is large balls with a diameter of 8mm.

[0011] In one embodiment, in the third high-energy ball milling process, the ball-to-material ratio is 5~10:1, the rotation speed is 300r / min~350r / min, and the total ball milling time is 1h~3h; based on the total mass of the grinding balls, the proportion of small balls with a diameter of 3mm is 10%~20%, the proportion of medium balls with a diameter of 5mm is 60%~80%, and the remainder is large balls with a diameter of 8mm.

[0012] In one embodiment, the process parameters for the spark plasma sintering are as follows: the target sintering temperature is 1050℃~1100℃, the heating method is a stepped heating method, and the stepped heating process is as follows: first, the temperature is raised to 900℃~1000℃ at a heating rate of 50℃ / min~70℃ / min, and then raised to the target sintering temperature at a heating rate of 5℃ / min~10℃ / min; the sintering pressure is 130MPa~150MPa, and the pressure is increased at a uniform rate during the stepped heating stage; the holding time is 20min~30min, and the sintering vacuum degree is ≤1×10 -3 Pa, the cooling method is circulating water cooling.

[0013] In one embodiment, the two heat treatments include a first heat treatment and a second heat treatment performed sequentially; the temperature of the first heat treatment is 950℃~970℃, the holding time is 1h~3h, the cooling method is oil cooling, and the transfer time from the end of the first heat treatment to the start of the second heat treatment is less than 30s; the temperature of the second heat treatment is 770℃~810℃, the holding time is 12h~30h, and the cooling method is air cooling.

[0014] This invention also provides a homogeneous reinforced Ti2AlNb alloy, prepared by the above-described method for preparing homogeneous reinforced Ti2AlNb alloy. The phase composition of the homogeneous reinforced Ti2AlNb alloy includes B2 phase, α2 phase, and O phase, with a fine-grained structure of lamellar structure distributed at the grain boundaries. The service temperature range of the homogeneous reinforced Ti2AlNb alloy is 650℃~750℃, and the high-temperature creep time of the homogeneous reinforced Ti2AlNb alloy under test conditions of 750℃ and 250MPa is not less than 25h.

[0015] This invention also provides an application of a homogeneous reinforced Ti2AlNb alloy in hot-end components of aerospace engines.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing a homogeneous reinforced Ti2AlNb alloy. In this method, lamellar Ti2AlNb pre-alloyed powder with the same composition but different morphology as spherical Ti2AlNb pre-alloyed powder is used as the homogeneous reinforcing phase. The method first prepares spherical and lamellar Ti2AlNb pre-alloyed powders with completely identical atomic ratios, then uniformly mixes them and densifies them using spark plasma sintering (SPS). Finally, a two-stage heat treatment process is applied to optimize its microstructure and properties. The application of high-energy ball milling technology effectively improves the problem of excessive equiaxed crystal formation in traditional powder metallurgy processes. By controlling process parameters such as the ball-to-powder ratio, a reinforcing phase with a lamellar morphology can be prepared, thereby directionally introducing lamellar structure into the microstructure. This not only improves the high-temperature creep resistance of the material but also inhibits abnormal grain growth. The specific process flow is as follows: The first high-energy ball milling process processes the initial raw material into spherical Ti2AlNb pre-alloyed powder. Subsequently, by increasing the ball-to-material ratio and rotation speed, the mechanical cutting action of the cemented carbide balls is enhanced. In the second high-energy ball milling process, the spherical Ti2AlNb pre-alloyed powder is transformed into lamellar Ti2AlNb pre-alloyed powder. The third high-energy ball milling process then composites the lamellar Ti2AlNb pre-alloyed powder as a homogeneous reinforcing phase with the spherical matrix powder. The introduction of this homogeneous reinforcing phase can construct a favorable lamellar reinforcement structure in the microstructure, while avoiding the formation of harmful phases at the interface and further inhibiting grain growth. On the other hand, the homogeneous reinforcing phase avoids the problems of uneven reaction and poor interfacial compatibility caused by other heterogeneous lamellar reinforcing phases (graphene, carbon nanotubes, etc.), making it more reliable when pursuing stable performance. Lamellar Ti2AlNb pre-alloyed powder accounts for 3%–5% of the mass of the composite Ti2AlNb pre-alloyed powder, and the addition amount of lamellar reinforcing phase is controlled at 3%–5%. This achieves effective strengthening while avoiding the potential decrease in plasticity caused by excessive lamellar phase. The SPS process, with its rapid densification characteristics, effectively limits grain growth and shortens the preparation cycle. Ti2AlNb, as a ternary alloy containing B2, O, and α2 phases, has its comprehensive mechanical properties controlled by adjusting the size and distribution of each phase through heat treatment. Therefore, this method, based on powder metallurgy forming, employs a two-stage heat treatment to further optimize the microstructure: the first stage, solution treatment, is located in the low-temperature range of the B2+α2+O three-phase region, aiming to promote the precipitation of micron-sized coarse lamellar O phase to improve alloy plasticity; the second stage, aging treatment, is carried out in the B2+O two-phase region to induce the precipitation of nano-sized fine needle-like O phase in the B2 phase, thereby improving alloy strength. The combination of these two methods significantly improves the high-temperature creep resistance while maintaining the alloy's high strength and toughness.

[0017] In addition, this process has the advantages of low production cost, fast forming speed and energy saving and environmental protection. It also avoids the cutting and machining of complex components, reduces raw material waste, and is suitable for producing expensive titanium alloy workpieces.

[0018] This invention also provides a homogeneous reinforced Ti2AlNb alloy prepared by the above-described method, which exhibits excellent high-temperature creep resistance and can be stably used for a long time in the temperature range of 650℃ to 750℃. The alloy is composed of phases consisting of B2 phase, α2 phase, and O phase, with a lamellar fine-grained structure distributed at the grain boundaries. Under continuous high load conditions, this lamellar structure has a strong interfacial pinning effect, which can effectively transfer the load. Moreover, the structure is stable and does not easily coarsen or grow at high temperatures. Furthermore, the internal fine-grained structure can deflect cracks and slow down their propagation rate, thus synergistically improving the high-temperature creep resistance of the Ti2AlNb alloy.

[0019] The homogeneous reinforced Ti2AlNb alloy prepared by the above-described method is suitable for use in hot-end components of aerospace engines. Firstly, this alloy exhibits excellent high-temperature creep resistance, maintaining good structural stability even under high stress conditions (650℃~750℃), effectively extending the service life of key engine components and meeting the stringent requirements of aero-engines for long-term reliable operation. Secondly, this alloy has a low density, offering significant weight reduction advantages compared to traditional nickel-based high-temperature alloys, contributing to reduced engine weight and improved thrust-to-weight ratio, aligning with the aerospace industry's development direction of energy conservation, emission reduction, and improved flight efficiency. Furthermore, due to the stable interfacial structure constructed through homogeneous heterogeneous morphology composite and dual heat treatment processes, this alloy possesses high strength, good plasticity, and crack propagation resistance, maintaining structural integrity under complex thermo-mechanical coupling loads. This makes it suitable for hot-end components such as turbine blades, guide vanes, and combustion chamber liners that withstand severe temperature gradients and mechanical stresses. Attached Figure Description

[0020] Figure 1 This is a comparison chart of the high-temperature creep performance of the homogeneous reinforced Ti2AlNb alloys prepared in Examples 1 to 3 of the present invention and the Ti2AlNb alloys prepared in Comparative Examples 1 to 3. Figure 2 This is a microstructure diagram of the Ti2AlNb alloy block obtained in Example 1 of the present invention; Figure 3 This is a microstructure diagram of the Ti2AlNb alloy block obtained in Example 2 of the present invention; Figure 4 This is a microstructure diagram of the Ti2AlNb alloy block obtained in Example 3 of the present invention. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] 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.”

[0024] 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.

[0025] This invention provides a homogeneous reinforced Ti2AlNb alloy, its preparation method, and its application, to solve the technical problem that the presence of a large number of equiaxed crystals in the conventional powder metallurgy combined with SPS process results in poor creep performance at high temperatures of 650℃~750℃, and the instability of product performance caused by the introduction of heterogeneous reinforcement phases.

[0026] To address this problem, this invention designs a novel powder metallurgy process. On one hand, spherical Ti2AlNb pre-alloyed powder is used as the matrix phase, and lamellar Ti2AlNb pre-alloyed powder is introduced as a reinforcing phase through high-energy ball milling to construct a homogeneous composite powder system with heterogeneous morphology. On the other hand, Ti2AlNb, as a typical three-phase intermetallic compound, exhibits comprehensive mechanical properties highly dependent on the relative content, size distribution, and spatial orientation of the B2, O, and α2 phases. Existing research has confirmed that a reasonable heat treatment regime can regulate the precipitation behavior of the three phases, especially promoting the orderly precipitation of lath O phase and the formation of interfaces, thereby improving comprehensive performance and achieving the ultimate goal of strengthening and toughening. Therefore, this invention, combined with a dual heat treatment process, achieves the controllable construction of the lamellar microstructure within the material. Ultimately, through the synergistic effect of interface strengthening and microstructure optimization, the high-temperature creep performance of Ti2AlNb alloys is significantly improved.

[0027] On one hand, this invention provides a method for preparing a homogeneous reinforced Ti2AlNb alloy. First, by adjusting a high-energy ball milling process, spherical Ti2AlNb pre-alloyed powder and lamellar Ti2AlNb pre-alloyed powder are prepared sequentially. Then, the two morphologies of pre-alloyed powder are mixed and subjected to high-energy ball milling to obtain a uniformly dispersed homogeneous heterogeneous composite powder system. Finally, spark plasma sintering is used, followed by two subsequent heat treatment processes, to controllably form a lamellar interface structure within the alloy, thus preparing a homogeneous reinforced Ti2AlNb alloy, i.e., a Ti2AlNb alloy with a lamellar interface structure. This effectively improves the high-temperature creep resistance of the Ti2AlNb alloy. The specific steps are as follows: (1) Titanium powder, AlMo alloy powder, NbTi alloy powder and AlNb alloy powder are mixed and prepared. First, a high-energy ball milling process is performed to prepare spherical Ti2AlNb pre-alloy powder. Then, the spherical Ti2AlNb pre-alloy powder is divided into two parts. The first part of the spherical Ti2AlNb pre-alloy powder is reserved for use. The second part of the spherical Ti2AlNb pre-alloy powder is subjected to a second high-energy ball milling process to prepare lamellar Ti2AlNb pre-alloy powder. The composition of the first part of the spherical Ti2AlNb pre-alloy powder and the lamellar Ti2AlNb pre-alloy powder is the same. (2) The spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder of the first part are mixed and then subjected to a third high-energy ball milling process to obtain composite Ti2AlNb pre-alloyed powder. (3) The composite Ti2AlNb pre-alloyed powder was sintered into Ti2AlNb alloy bulk material by spark plasma sintering process; (4) The Ti2AlNb alloy bulk is subjected to two heat treatments to prepare a homogeneous reinforced Ti2AlNb alloy.

[0028] Before use, the above-mentioned titanium powder, AlMo alloy powder, NbTi alloy powder and AlNb alloy powder are sieved to remove large particles and agglomerated powder.

[0029] The cemented carbide balls used in the first, second, and third high-energy ball milling processes mentioned above are made of ZrO2. The diameter of the small balls is 3 mm, the diameter of the medium balls is 5 mm, and the diameter of the large balls is 8 mm.

[0030] The ball milling processes of the first, second, and third high-energy ball milling treatments were all carried out in an intermittent manner. The single run time of the intermittent operation was 30 min to 50 min, and the single pause time of the intermittent operation was 3 min to 5 min.

[0031] In step (1), the titanium powder has a purity of 99.99% and a particle diameter of 150μm~300μm; the AlMo alloy powder has a powder diameter of 200μm~250μm; the NbTi alloy powder has a powder diameter of 300μm~350μm; the AlNb alloy powder has a powder diameter of 150μm~200μm; and by mass percentage, the AlMo alloy powder contains 28%~32% Al, with the balance being Mo; the N... The bTi alloy powder contains 75%~80% Nb, with the balance being Ti; the AlNb alloy powder contains 33%~37% Al, with the balance being Nb; by atomic percentage, the spherical Ti2AlNb pre-alloy powder, the first part of the spherical Ti2AlNb pre-alloy powder and the lamellar Ti2AlNb pre-alloy powder contain 22% Al, 24% Nb and 0.45%~0.55% Mo, with the balance being Ti and unavoidable impurity elements.

[0032] More preferably, by atomic percentage, the spherical Ti2AlNb pre-alloyed powder, the first portion of the spherical Ti2AlNb pre-alloyed powder, and the lamellar Ti2AlNb pre-alloyed powder comprise 22% Al, 24% Nb, and 0.5% Mo, with the balance being Ti and unavoidable impurity elements.

[0033] The process of the first high-energy ball milling treatment for preparing spherical Ti2AlNb pre-alloyed powder in step (1) is as follows: the ball-to-material ratio is 3~5:1, the rotation speed is 300r / min~350r / min, and the total ball milling time is 3h~5h; based on the total mass of the grinding balls, the proportion of small balls in the grinding balls used is 30%~40%, the proportion of medium balls is 45%~50%, and the remainder is large balls.

[0034] In step (1), solid stearic acid is added as a process control agent in the second high-energy ball milling process. The process control agent accounts for 1.5% to 3% of the total mass of the spherical Ti2AlNb pre-alloyed powder in the second part.

[0035] The second high-energy ball milling process for preparing the lamellar Ti2AlNb pre-alloyed powder in step (1) is as follows: the ball-to-material ratio is 18~20:1, the rotation speed is 500r / min~800r / min, and the total ball milling time is 10h~15h; based on the total mass of the grinding balls, the proportion of small balls in the grinding balls used is 5%~10%, the proportion of medium balls is 50%~60%, and the remainder is large balls.

[0036] In step (2), the lamellar Ti2AlNb pre-alloyed powder accounts for 3% to 5% of the mass of the composite Ti2AlNb pre-alloyed powder.

[0037] The third high-energy ball milling process for preparing composite Ti2AlNb pre-alloyed powder in step (2) is as follows: the ball-to-material ratio is 5~10:1, the rotation speed is 300r / min~350r / min, and the total ball milling time is 1h~3h; based on the total mass of the grinding balls, the proportion of small balls in the grinding balls used is 10%~20%, the proportion of medium balls is 60%~80%, and the remainder is large balls.

[0038] The process parameters for the spark plasma sintering process in step (3) are as follows: the target sintering temperature is 1050℃~1100℃, the heating method is step heating, and the step heating process is as follows: first, the temperature is raised to 900℃~1000℃ at a heating rate of 50℃ / min~70℃ / min, and then raised to the target sintering temperature at a heating rate of 5℃ / min~10℃ / min; the sintering pressure is 130MPa~150MPa, and the pressure is increased at a uniform rate during the step heating stage; the holding time is 20min~30min, and the sintering vacuum degree is ≤1×10 -3 Pa, the cooling method is circulating water cooling.

[0039] The two-stage heat treatment process in step (4) includes a first heat treatment and a second heat treatment performed sequentially; the temperature of the first heat treatment is 950℃~970℃, the holding time is 1h~3h, the cooling method is oil cooling, and the transfer time from the end of the first heat treatment to the start of the second heat treatment is less than 30s; the temperature of the second heat treatment is 770℃~810℃, the holding time is 12h~30h, and the cooling method is air cooling.

[0040] On the other hand, the present invention provides a homogeneous reinforced Ti2AlNb alloy prepared by the above-mentioned method for preparing a homogeneous reinforced Ti2AlNb alloy, wherein the service temperature range of the alloy is 650℃~750℃, and the high temperature creep time under test conditions of 750℃ and 250MPa is not less than 25h.

[0041] This preparation method introduces a homogeneous lamellar reinforcing phase into the Ti2AlNb alloy microstructure through powder metallurgy and heat treatment processes, thereby improving the alloy's high-temperature creep resistance. The phase composition of this homogeneously reinforced Ti2AlNb alloy includes B2 phase, α2 phase, and O phase. The alloy microstructure has B2 phase as the matrix phase, in which lamellar or banded α2 phase is distributed. Two forms of O phase also exist: one is the micron-sized coarse lamellar O phase precipitated after a first heat treatment, and the other is the nano-sized fine lamellar O phase further precipitated after a second heat treatment. In addition, a fine-grained microstructure with lamellar structure characteristics can be observed at and near the grain boundaries of the alloy.

[0042] Furthermore, the present invention also provides the application of the aforementioned homogeneous reinforced Ti2AlNb alloy in hot-end components of aerospace engines.

[0043] 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.

[0044] 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.

[0045] In the following embodiments, the cemented carbide balls used in the first, second, and third high-energy ball milling processes are made of ZrO2, with the small ball having a diameter of 3 mm, the medium ball having a diameter of 5 mm, and the large ball having a diameter of 8 mm.

[0046] In the following embodiments, the ball milling processes of the first, second, and third high-energy ball milling treatments are all carried out in an intermittent manner. The single run time of the intermittent operation is 30 min to 50 min, and the single pause time of the intermittent operation is 3 min to 5 min.

[0047] Example 1: The materials used in this embodiment are titanium powder, AlMo alloy powder, NbTi alloy powder, and AlNb alloy powder. These materials were sieved in a closed sieve before use to remove large particles and agglomerates. After sieving, the titanium powder had a particle diameter of 150 μm to 300 μm and a purity of 99.99%; the AlMo alloy powder had a particle diameter of 200 μm to 250 μm; the NbTi alloy powder had a particle diameter of 300 μm to 350 μm; and the AlNb alloy powder had a particle diameter of 150 μm to 200 μm.

[0048] By mass percentage, the AlMo alloy powder contains 28% Al and the balance is Mo; the NbTi alloy powder contains 80% Nb and the balance is Ti; and the AlNb alloy powder contains 33% Al and the balance is Nb.

[0049] A method for preparing a homogeneous reinforced Ti2AlNb alloy includes the following steps: Step 1) Weigh and mix titanium powder, AlMo alloy powder, NbTi alloy powder and AlNb alloy powder according to the atomic ratio Ti-22Al-24Nb-0.5Mo. First, perform a first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder. Then, divide the spherical Ti2AlNb pre-alloyed powder into two parts. The first part of the spherical Ti2AlNb pre-alloyed powder is reserved for later use. The second part of the spherical Ti2AlNb pre-alloyed powder is subjected to a second high-energy ball milling treatment to prepare lamellar Ti2AlNb pre-alloyed powder. The process for the first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 3:1, rotation speed 300 r / min, total ball milling time 5 h, 30 min per milling, and 3 min pause; based on the total mass of the grinding balls, small balls account for 30%, medium balls account for 45%, and the remainder are large balls. The second high-energy ball milling process for preparing the lamellar Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 20:1, rotation speed 500 r / min, total milling time 10 h, milling for 30 min per cycle, with a 3 min pause; based on the total mass of the milling balls, small balls account for 5%, medium balls account for 50%, and the remainder are large balls; solid stearic acid is added as a process control agent in the second high-energy ball milling process, and the process control agent accounts for 1.5% of the total mass of the spherical Ti2AlNb pre-alloyed powder in the second part; Step 2) The spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder from the first part are mixed and then subjected to a third high-energy ball milling process to obtain composite Ti2AlNb pre-alloyed powder; the lamellar Ti2AlNb pre-alloyed powder accounts for 5% of the mass of the composite Ti2AlNb pre-alloyed powder; The third high-energy ball milling process for preparing composite Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 5:1, rotation speed 300 r / min, total ball milling time 3 h, 30 min per milling, and 3 min pause; based on the total mass of the grinding balls, small balls account for 10%, medium balls account for 80%, and the remainder are large balls. Step 3) The composite Ti2AlNb pre-alloyed powder was sintered into Ti2AlNb alloy bulk material using spark plasma sintering (SPSS). The process parameters for SPSS were as follows: target sintering temperature of 1050℃, step-by-step heating, with the following steps: first, heating to 900℃ at a rate of 50℃ / min, then heating to 1050℃ at a rate of 5℃ / min; sintering pressure of 150MPa; uniform pressure increase during the step-by-step heating phase; holding time of 30min; and sintering vacuum degree ≤1×10⁻⁶. -3 Pa, the cooling method is circulating water cooling; Step 4) The Ti2AlNb alloy block is subjected to two heat treatments. The first heat treatment is to hold at 950℃ for 3 hours and then oil-cool it. The second heat treatment is to hold at 810℃ for 24 hours and then air-cool it. The heat treatment is completed, and the homogeneous reinforced Ti2AlNb alloy is obtained.

[0050] like Figure 2 As shown in the microstructure diagram of the Ti2AlNb alloy block prepared in Example 1, lamellar Ti2AlNb is uniformly distributed at the grain boundaries of spherical Ti2AlNb.

[0051] The mechanical properties of the homogeneous reinforced Ti2AlNb alloy were tested, and the results are shown in Table 1. It can be seen that the homogeneous reinforced Ti2AlNb alloy prepared in Example 1 exhibits excellent comprehensive mechanical properties, with a tensile strength of 1158 MPa, a yield strength of 996 MPa, an elongation of 8.3%, and a high-temperature creep rupture performance of 25.2 h at 750℃ and 250 MPa.

[0052] Table 1 Mechanical properties of the homogeneous reinforced Ti2AlNb alloy prepared in Example 1

[0053] Example 2: The materials used in this embodiment are titanium powder, AlMo alloy powder, NbTi alloy powder, and AlNb alloy powder. These materials were sieved in a closed sieve before use to remove large particles and agglomerates. After sieving, the titanium powder had a particle diameter of 150 μm to 300 μm and a purity of 99.99%; the AlMo alloy powder had a particle diameter of 200 μm to 250 μm; the NbTi alloy powder had a particle diameter of 300 μm to 350 μm; and the AlNb alloy powder had a particle diameter of 150 μm to 200 μm.

[0054] By mass percentage, the AlMo alloy powder contains 30% Al and the balance is Mo; the NbTi alloy powder contains 78% Nb and the balance is Ti; and the AlNb alloy powder contains 35% Al and the balance is Nb.

[0055] A method for preparing a homogeneous reinforced Ti2AlNb alloy includes the following steps: Step 1) Weigh and mix titanium powder, AlMo alloy powder, NbTi alloy powder and AlNb alloy powder according to the atomic ratio Ti-22Al-24Nb-0.5Mo. First, perform a first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder. Then, divide the spherical Ti2AlNb pre-alloyed powder into two parts. The first part of the spherical Ti2AlNb pre-alloyed powder is reserved for later use. The second part of the spherical Ti2AlNb pre-alloyed powder is subjected to a second high-energy ball milling treatment to prepare lamellar Ti2AlNb pre-alloyed powder. The process for the first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 4:1, rotation speed 350 r / min, total ball milling time 5 h, 40 min per milling, and 4 min pause; based on the total mass of the grinding balls, small balls account for 35%, medium balls account for 50%, and the remainder are large balls. The second high-energy ball milling process for preparing the lamellar Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 19:1, rotation speed 800 r / min, total milling time 13 h, milling for 40 min per cycle, with a 4 min pause; based on the total mass of the milling balls, small balls account for 8%, medium balls account for 55%, and the remainder are large balls; solid stearic acid is added as a process control agent in the second high-energy ball milling process, and the process control agent accounts for 2% of the total mass of the spherical Ti2AlNb pre-alloyed powder in the second part; Step 2) The spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder from the first part are mixed and then subjected to a third high-energy ball milling process to obtain composite Ti2AlNb pre-alloyed powder; the lamellar Ti2AlNb pre-alloyed powder accounts for 3% of the mass of the composite Ti2AlNb pre-alloyed powder; The third high-energy ball milling process for preparing composite Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 8:1, rotation speed 350 r / min, total ball milling time 1 h, 40 min per milling, 4 min pause; based on the total mass of the grinding balls, small balls account for 15%, medium balls account for 70%, and the remainder are large balls. Step 3) The composite Ti2AlNb pre-alloyed powder was sintered into Ti2AlNb alloy bulk material using spark plasma sintering (SPSS). The process parameters for SPSS were as follows: target sintering temperature of 1100℃, step-by-step heating, with the temperature initially increased to 1000℃ at a rate of 60℃ / min, then increased to 1100℃ at a rate of 10℃ / min. The sintering pressure was 130MPa, with uniform pressure increase during the step-by-step heating phase. The holding time was 25min, and the sintering vacuum degree was ≤1×10⁻⁶. -3 Pa, the cooling method is circulating water cooling; Step 4) The Ti2AlNb alloy block is subjected to two heat treatments. The first heat treatment is to hold at 960℃ for 1 hour and then oil-cool. The second heat treatment is to hold at 770℃ for 30 hours and then air-cool. The heat treatment is completed, and the homogeneous reinforced Ti2AlNb alloy is obtained.

[0056] like Figure 3 As shown in the microstructure diagram of the Ti2AlNb alloy block prepared in Example 2, lamellar Ti2AlNb is uniformly distributed at the grain boundaries of spherical Ti2AlNb.

[0057] The mechanical properties of the homogeneous reinforced Ti2AlNb alloy were tested, and the results are shown in Table 2. It can be seen that the homogeneous reinforced Ti2AlNb alloy prepared in Example 2 exhibits excellent comprehensive mechanical properties, with a tensile strength of 1123 MPa, a yield strength of 964 MPa, an elongation of 9.6%, and a high-temperature creep rupture performance of 27.3 h at 750℃ and 250 MPa.

[0058] Table 2 Mechanical properties of the homogeneous reinforced Ti2AlNb alloy prepared in Example 2

[0059] Example 3: The materials used in this embodiment are titanium powder, AlMo alloy powder, NbTi alloy powder, and AlNb alloy powder. These materials were sieved in a closed sieve before use to remove large particles and agglomerates. After sieving, the titanium powder had a particle diameter of 150 μm to 300 μm and a purity of 99.99%; the AlMo alloy powder had a particle diameter of 200 μm to 250 μm; the NbTi alloy powder had a particle diameter of 300 μm to 350 μm; and the AlNb alloy powder had a particle diameter of 150 μm to 200 μm.

[0060] By mass percentage, the AlMo alloy powder contains 32% Al and the balance is Mo; the NbTi alloy powder contains 75% Nb and the balance is Ti; and the AlNb alloy powder contains 37% Al and the balance is Nb.

[0061] A method for preparing a homogeneous reinforced Ti2AlNb alloy includes the following steps: Step 1) Weigh and mix titanium powder, AlMo alloy powder, NbTi alloy powder and AlNb alloy powder according to the atomic ratio Ti-22Al-24Nb-0.5Mo. First, perform a first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder. Then, divide the spherical Ti2AlNb pre-alloyed powder into two parts. The first part of the spherical Ti2AlNb pre-alloyed powder is reserved for later use. The second part of the spherical Ti2AlNb pre-alloyed powder is subjected to a second high-energy ball milling treatment to prepare lamellar Ti2AlNb pre-alloyed powder. The process for the first high-energy ball milling treatment to prepare spherical Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 5:1, rotation speed 330 r / min, total ball milling time 3 h, 50 min per milling, and 5 min pause; based on the total mass of the grinding balls, small balls account for 40%, medium balls account for 47%, and the remainder are large balls. The second high-energy ball milling process for preparing the lamellar Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 18:1, rotation speed 600 r / min, total milling time 15 h, with a 5 min pause between milling cycles; based on the total mass of the milling balls, small balls account for 10%, medium balls account for 60%, and the remainder are large balls; solid stearic acid is added as a process control agent during the second high-energy ball milling process, and the process control agent accounts for 3% of the total mass of the spherical Ti2AlNb pre-alloyed powder in the second part. Step 2) The spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder from the first part are mixed and then subjected to a third high-energy ball milling process to obtain composite Ti2AlNb pre-alloyed powder; the lamellar Ti2AlNb pre-alloyed powder accounts for 4% of the mass of the composite Ti2AlNb pre-alloyed powder; The third high-energy ball milling process for preparing composite Ti2AlNb pre-alloyed powder is as follows: ball-to-material ratio 10:1, rotation speed 330 r / min, total ball milling time 3 h, 50 min per milling, and 5 min pause; based on the total mass of the grinding balls, small balls account for 20%, medium balls account for 60%, and the remainder are large balls. Step 3) The composite Ti2AlNb pre-alloyed powder was sintered into Ti2AlNb alloy bulk material using spark plasma sintering (SPSS). The process parameters for SPSS were as follows: target sintering temperature of 1070℃, step-by-step heating, with the temperature initially increased to 950℃ at a rate of 70℃ / min, followed by a rate of 8℃ / min to 1070℃. The sintering pressure was 140MPa, with uniform pressure increase during the step-by-step heating phase. The holding time was 20min, and the sintering vacuum degree was ≤1×10⁻⁶. -3 Pa, the cooling method is circulating water cooling; Step 4) The Ti2AlNb alloy block is subjected to two heat treatments. The first heat treatment is to hold at 970℃ for 2 hours and then oil-cool. The second heat treatment is to hold at 790℃ for 12 hours and then air-cool. The heat treatment is completed, and the homogeneous reinforced Ti2AlNb alloy is obtained.

[0062] like Figure 4 As shown in the microstructure diagram of the Ti2AlNb alloy block prepared in Example 3, lamellar Ti2AlNb is uniformly distributed at the grain boundaries of spherical Ti2AlNb.

[0063] The mechanical properties of the homogeneous reinforced Ti2AlNb alloy were tested, and the results are shown in Table 1. It can be seen that the homogeneous reinforced Ti2AlNb alloy prepared in Example 3 exhibits excellent comprehensive mechanical properties, with a tensile strength of 1096 MPa, a yield strength of 903 MPa, an elongation of 10.6%, and a high-temperature creep rupture performance of 26.2 h at 750℃ and 250 MPa.

[0064] Table 3 Mechanical properties of the homogeneous reinforced Ti2AlNb alloy prepared in Example 3

[0065] Comparative Example 1: Comparative Example 1 is identical to Example 1 in all other conditions, except that: Step 1) Weigh and mix titanium powder, AlMo alloy powder, NbTi alloy powder and AlNb alloy powder according to the atomic ratio Ti-22Al-24Nb-0.5Mo, and perform a first high-energy ball milling process to prepare spherical Ti2AlNb pre-alloyed powder. Step 2) The spherical Ti2AlNb pre-alloyed powder is then subjected to a third high-energy ball milling process to obtain composite Ti2AlNb pre-alloyed powder; Steps 3) and 4) are the same as in Example 1.

[0066] In step 2), the powders used to prepare the composite Ti2AlNb pre-alloyed powder were all spherical Ti2AlNb pre-alloyed powders. The mechanical properties of the Ti2AlNb alloy prepared in this comparative example are shown in Table 4. Under the conditions of 750℃ and 250MPa, the high-temperature creep rupture was only 10.3h, indicating poor performance.

[0067] This is because no lamellar Ti2AlNb alloy powder was added in this comparative example, resulting in a lack of lamellar structure in the microstructure. After SPS sintering, the microstructure is mostly equiaxed, and cracks are prone to propagate along grain boundaries, resulting in low alloy plasticity and poor high-temperature creep performance.

[0068] Table 4 Mechanical properties of Ti2AlNb alloy prepared in Comparative Example 1

[0069] Comparative Example 2: Comparative Example 2 is identical to Example 1 in all other conditions except that, in step 2), the lamellar Ti2AlNb pre-alloy powder accounts for 6% of the mass of the composite Ti2AlNb pre-alloy powder. The mechanical properties of the Ti2AlNb alloy prepared in this comparative example are shown in Table 5. The high-temperature creep rupture at 750℃ and 250MPa is 15.2h, but the yield strength is only 850MPa, which is poor.

[0070] This is because the Ti2AlNb alloy prepared in this comparative example has too many lamellar phases introduced into its microstructure. The lamellar structure has poor coordination deformation ability, resulting in a low alloy elongation.

[0071] Table 5 Mechanical properties of Ti2AlNb alloys prepared in Comparative Example 2

[0072] Comparative Example 3: Comparative Example 3 was identical to Example 1 in all other conditions except that, in step 1), the ball-to-material ratio in the second high-energy ball milling process for preparing the lamellar Ti2AlNb pre-alloyed powder was 15:1. The mechanical properties of the Ti2AlNb alloy obtained in this comparative example are shown in Table 6. The high-temperature creep rupture at 750℃ and 250MPa was 13.2h, indicating poor performance.

[0073] This is because the ball-to-material ratio is too low during ball milling, resulting in insufficient cutting force, which further leads to poor lamellarization of the spherical powder. After SPS sintering, there are not enough lamellar phases inside the alloy structure, resulting in poor high-temperature creep performance of the alloy.

[0074] Table 6 Mechanical properties of Ti2AlNb alloy prepared in Comparative Example 3

[0075] See Figure 1 As can be seen from the comparison chart of the high-temperature creep performance of the homogeneous reinforced Ti2AlNb alloys prepared in Examples 1 to 3 of the present invention and the Ti2AlNb alloys prepared in Comparative Examples 1 to 3, the high-temperature creep performance of the homogeneous reinforced Ti2AlNb alloys provided by the present invention is better than that of the Ti2AlNb alloys prepared in Comparative Examples 1 to 3.

[0076] This invention provides a method for preparing a homogeneous reinforced Ti2AlNb alloy to improve the high-temperature creep resistance of the Ti2AlNb alloy. The preparation method includes the following steps: (1) preparing spherical Ti2AlNb pre-alloy powder and lamellar Ti2AlNb pre-alloy powder by high-energy ball milling; (2) mixing the two types of spherical Ti2AlNb pre-alloy powder and lamellar Ti2AlNb pre-alloy powder evenly, and preparing a composite Ti2AlNb pre-alloy powder by high-energy ball milling; (3) shaping the composite Ti2AlNb alloy powder by spark plasma sintering to prepare a composite Ti2AlNb alloy bulk; (4) subjecting the Ti2AlNb alloy bulk to two heat treatments to obtain a homogeneous reinforced Ti2AlNb alloy. The Ti2AlNb alloy prepared by this process has an interfacial structure, high strength and high toughness, and excellent high-temperature creep resistance, which can meet the requirements of high-temperature use in aerospace and has good application prospects.

[0077] In summary, this invention prepares spherical and lamellar Ti2AlNb pre-alloyed powders through high-energy ball milling, and then combines them through high-energy ball milling followed by spark plasma sintering and two heat treatments to construct an interface structure based on the same composition. Specifically, the high-energy ball milling achieves morphology control by adjusting parameters such as the ball-to-powder ratio and rotation speed; low-intensity ball milling obtains spherical powder to ensure densification, while high-intensity ball milling produces a reinforcing phase with a lamellar morphology. After composite formation, rapid SPS sintering inhibits grain growth, and the two heat treatments promote the precipitation of lath O phase, forming a stable lamellar structure. This method successfully introduces a lamellar structure into the microstructure without introducing any new phase, constructing an interface that effectively hinders dislocation movement and crack propagation, thereby significantly improving high-temperature creep resistance.

[0078] 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 method for preparing a homogeneous reinforced Ti2AlNb alloy, characterized in that, Includes the following steps: Titanium powder, AlMo alloy powder, NbTi alloy powder, and AlNb alloy powder are mixed and formulated. A first high-energy ball milling process is then performed to prepare spherical Ti2AlNb pre-alloyed powder. This spherical Ti2AlNb pre-alloyed powder is then divided into two parts. The first part of the spherical Ti2AlNb pre-alloyed powder is kept for later use, while the second part of the spherical Ti2AlNb pre-alloyed powder undergoes a second high-energy ball milling process to prepare lamellar Ti2AlNb pre-alloyed powder. The composition of the first part of the spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder are the same. The spherical Ti2AlNb pre-alloyed powder and the lamellar Ti2AlNb pre-alloyed powder from the first part are mixed, and then subjected to a third high-energy ball milling treatment to obtain composite Ti2AlNb pre-alloyed powder; the lamellar Ti2AlNb pre-alloyed powder accounts for 3% to 5% of the mass of the composite Ti2AlNb pre-alloyed powder; Ti2AlNb alloy was obtained by sequentially subjecting composite Ti2AlNb pre-alloyed powder to spark plasma sintering and two heat treatments.

2. The method for preparing the homogeneous reinforced Ti2AlNb alloy according to claim 1, characterized in that, The titanium powder has a purity of 99.99% and a particle diameter of 150μm to 300μm; the AlMo alloy powder has a powder diameter of 200μm to 250μm; the NbTi alloy powder has a powder diameter of 300μm to 350μm; and the AlNb alloy powder has a powder diameter of 150μm to 200μm. By mass percentage, the AlMo alloy powder contains 28% to 32% Al, with the balance being Mo; the NbTi alloy powder contains 75% to 80% Nb, with the balance being Ti; and the AlNb alloy powder contains 33% to 37% Al, with the balance being Nb. Based on atomic percentage, the spherical Ti2AlNb pre-alloyed powder, the first portion of the spherical Ti2AlNb pre-alloyed powder, and the lamellar Ti2AlNb pre-alloyed powder comprise 22% Al, 24% Nb, and 0.45%~0.55% Mo, with the balance being Ti and impurity elements.

3. The method for preparing the homogeneous reinforced Ti2AlNb alloy according to claim 1, characterized in that, The ball milling processes of the first, second, and third high-energy ball milling treatments are all carried out in an intermittent manner. The single run time of the intermittent operation is 30 min to 50 min, and the single pause time of the intermittent operation is 3 min to 5 min.

4. The method for preparing the homogeneous reinforced Ti2AlNb alloy according to claim 3, characterized in that, In the first high-energy ball milling process, the ball-to-material ratio is 3~5:1, the rotation speed is 300r / min~350r / min, and the total milling time is 3h~5h. Based on the total mass of the grinding balls, the proportion of small balls with a diameter of 3mm is 30%~40%, the proportion of medium balls with a diameter of 5mm is 45%~50%, and the remainder is large balls with a diameter of 8mm.

5. The method for preparing the homogeneous reinforced Ti2AlNb alloy according to claim 3, characterized in that, Solid stearic acid is added as a process control agent in the second high-energy ball milling process, and the process control agent accounts for 1.5% to 3% of the total mass of the spherical Ti2AlNb pre-alloyed powder in the second part. In the second high-energy ball milling process, the ball-to-material ratio is 18~20:1, the rotation speed is 500r / min~800r / min, and the total milling time is 10h~15h. Based on the total mass of the grinding balls, the proportion of small balls with a diameter of 3mm is 5%~10%, the proportion of medium balls with a diameter of 5mm is 50%~60%, and the remainder is large balls with a diameter of 8mm.

6. The method for preparing the homogeneous reinforced Ti2AlNb alloy according to claim 3, characterized in that, In the third high-energy ball milling process, the ball-to-material ratio is 5~10:1, the rotation speed is 300r / min~350r / min, and the total ball milling time is 1h~3h. Based on the total mass of the grinding balls, the proportion of small balls with a diameter of 3mm is 10%~20%, the proportion of medium balls with a diameter of 5mm is 60%~80%, and the remainder is large balls with a diameter of 8mm.

7. The method for preparing the homogeneous reinforced Ti2AlNb alloy according to claim 1, characterized in that, The process parameters for the spark plasma sintering are as follows: the target sintering temperature is 1050℃~1100℃, the heating method is step heating, and the step heating process is as follows: first, the temperature is raised to 900℃~1000℃ at a heating rate of 50℃ / min~70℃ / min, and then the temperature is raised to the target sintering temperature at a heating rate of 5℃ / min~10℃ / min; the sintering pressure is 130MPa~150MPa, and the pressure is increased at a uniform rate during the step heating stage. The holding time is 20-30 minutes, and the sintering vacuum degree is ≤1×10⁻⁶. -3 Pa, the cooling method is circulating water cooling.

8. The method for preparing the homogeneous reinforced Ti2AlNb alloy 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 950℃~970℃, the holding time is 1h~3h, the cooling method is oil cooling, and the transfer time from the end of the first heat treatment to the start of the second heat treatment is less than 30s; the temperature of the second heat treatment is 770℃~810℃, the holding time is 12h~30h, and the cooling method is air cooling.

9. A homogeneous reinforced Ti2AlNb alloy, characterized in that, The Ti2AlNb alloy is prepared by the method of any one of claims 1 to 8, wherein the phase composition of the Ti2AlNb alloy includes B2 phase, α2 phase and O phase, and fine-grained structure with lamellar structure is distributed at the grain boundaries. The service temperature range of the homogeneous reinforced Ti2AlNb alloy is 650℃~750℃, and the high-temperature creep time of the homogeneous reinforced Ti2AlNb alloy under the test conditions of 750℃ and 250MPa is not less than 25h.

10. The application of a homogeneous reinforced Ti2AlNb alloy in hot-end components of aerospace engines, characterized in that, The homogeneous reinforced Ti2AlNb alloy is prepared by the method for preparing homogeneous reinforced Ti2AlNb alloy as described in any one of claims 1 to 8.

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