Method for enhancing mechanical properties of laser metal deposition TiAl alloy by micro-nano TiC particles

Abstract

This invention belongs to the field of additive manufacturing technology for metal materials, and discloses a method for enhancing the mechanical properties of laser-deposited TiAl alloys using micro / nano TiC particles. The method includes the following steps: micron-sized TiC powder, nano-sized TiC powder, and TiAl alloy powder are added to a powder jar and sequentially subjected to ball milling and ultrasonic dispersion to obtain a mixed powder; the mixed powder is then shaped using laser metal deposition technology to obtain a shaped alloy part; the shaped alloy part is subjected to cyclic heat treatment to obtain a TiAl alloy with enhanced properties. The TiAl alloy of this invention achieves improvements in strength, hardness, wear resistance, and high-temperature performance, overcoming the limitations of single-scale particle reinforcement.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology for metal materials, and more specifically relates to a method for preparing titanium carbide (TiC) particle-reinforced titanium-aluminum (TiAl) alloys using laser metal deposition (LMD) technology. Background Technology

[0002] TiAl alloy is a novel, lightweight, high-temperature resistant structural material with broad application prospects and great development potential. TiAl alloy possesses high melting point, low density, high elastic modulus, excellent high-temperature strength (700–900℃), and strong flame retardancy, making it suitable for extreme environments such as high temperatures. It has wide applications in the aerospace, aviation, and automotive industries.

[0003] The main processing technologies for TiAl alloys include ingot metallurgy, precision casting, and powder metallurgy. However, traditional machining and casting techniques are insufficient for manufacturing parts with complex structures such as internal channels and cavities. Furthermore, as intermetallic compounds, TiAl-based alloys exhibit poor room-temperature plasticity and are difficult to process due to the strong directional bonding of the matrix γ-TiAl phase and its low symmetry based on ordered structural deformation behavior. With the rapid development of modern aerospace technology, the requirements for lightweight and functional engine components are constantly increasing, leading to increasingly complex structures in high-temperature components. This makes traditional manufacturing and processing methods unsuitable for the production of TiAl-based alloy parts. Therefore, there is an urgent need for new and efficient forming and manufacturing technologies to solve these problems.

[0004] Additive manufacturing, as an emerging manufacturing process, can form complex metal parts in a single process, solving the problems of high cost, long cycle time, and low efficiency associated with traditional processes such as casting, forging, and powder metallurgy. Laser metal deposition (LMD), a highly efficient additive manufacturing technology using a laser beam as a heat source, melts metal alloy powder fed by a synchronous powder feeding shaft, forming a molten pool in the desired deposition area. The molten pool rapidly solidifies to form a deposition layer. Based on a pre-designed 3D CAD model, the virtual design is transformed into a physical part through an advanced process of layer-by-layer stacking and accumulation, achieving precise transformation from design to manufacturing. LMD offers a spacious forming space and high printing efficiency, making it suitable for forming and repairing large components. Furthermore, this process requires only a small amount of powder to manufacture workpieces, making it ideal for optimizing new alloys and developing processes. LMD typically employs coaxial powder feeding and mechanical transmission, resulting in a relatively low scanning speed and thus a slower cooling rate, effectively reducing residual stress and suppressing the formation of brittle phases. However, the deposition layer is prone to heating and partial remelting, leading to inhomogeneity in the microstructure within the deposited sample. To prepare samples with excellent overall performance, heat treatment is generally used to optimize the microstructure.

[0005] Ceramic reinforcing phases are ceramic particles, whiskers, fibers, or nanoparticles dispersed in a metal, alloy, or ceramic matrix to improve the overall properties of the material. They are essentially a hard, high-strength second phase that improves the shortcomings of the matrix material through specific strengthening mechanisms (such as load bearing and deformation resistance). Since TiAl alloys often operate at high temperatures, the reinforcing phases selected for use and processing in titanium-aluminum matrix composites must be thermodynamically stable and compatible with the matrix. Adding ceramic reinforcing phases to TiAl alloy powder is an effective way to improve its high-temperature strength, hardness, wear resistance, and creep resistance. In ceramic reinforcing phases, TiC has good chemical compatibility with the TiAl matrix and is more stable than other materials. Moreover, TiC particles have an extremely high melting point (about 3160℃) and good high-temperature stability, which can effectively pin dislocations and hinder grain boundary slip. This allows the composite material to maintain high strength and excellent creep resistance at temperatures of 750℃ or even higher. At the same time, TiC is an ultra-hard ceramic (hardness much higher than the TiAl matrix), and its dispersed distribution significantly improves the surface hardness of the composite material. During friction and wear, the hard particles bear the main load, effectively protecting the matrix and greatly improving wear resistance.

[0006] Heat treatment plays a crucial role in improving the properties of TiAl alloys formed by laser metal deposition. The inherently high cooling rate and complex thermal cycle of the laser metal deposition process can lead to problems such as residual stress, inhomogeneous microstructure, non-equilibrium phases, and possible elemental segregation within the material. Heat treatment is an essential means to optimize its microstructure, eliminate residual stress, improve mechanical properties (especially room temperature plasticity and fracture toughness), and obtain the desired equilibrium phase.

[0007] Therefore, developing a method to significantly improve the mechanical properties of TiAl alloys is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0008] In view of this, the present invention provides a method for enhancing the mechanical properties of laser-deposited TiAl alloys using micro / nano TiC particles. The present invention employs a step-by-step processing method, including powder mixing, laser metal deposition, and post-treatment, thereby improving the mechanical properties of the TiAl alloy. This technology significantly enhances the mechanical properties of TiAl alloys and is suitable for the manufacture of high-temperature components such as aerospace engine blades and automotive turbochargers.

[0009] This invention simultaneously adds nano-sized and micron-sized TiC particles to Ti45Al8Nb powder, achieving multi-scale synergistic strengthening while leveraging the advantages of both nano- and micron-sized particles. The powder is uniformly mixed using a combination of ball milling and ultrasonic dispersion, ensuring that the TiC powder adheres evenly to the surface of TiAl powder spheres. The alloy is then formed using laser metal deposition. During laser metal deposition, appropriate laser power, scanning speed, and powder feed rate are employed to ensure the quality and performance of the alloy. Finally, a specific cyclic heat treatment process is used to strengthen the alloy component.

[0010] This invention provides a method for enhancing the mechanical properties of laser-deposited TiAl alloys using micro / nano TiC particles, comprising the following steps:

[0011] (1) Micron-sized TiC powder, nano-sized TiC powder and TiAl alloy powder are put into a powder tank and subjected to ball milling and ultrasonic dispersion to obtain mixed powder;

[0012] (2) The mixed powder is formed by laser metal deposition technology to obtain a molded alloy part;

[0013] (3) The formed alloy parts are subjected to cyclic heat treatment to obtain a TiAl alloy with enhanced performance.

[0014] Furthermore, in step (1), the content of the micron-sized TiC powder is 0.5%-1.5%wt and the content of the nano-sized TiC powder is 0.5%-1.5%wt, based on the weight of the TiAl alloy powder.

[0015] Furthermore, the TiAl alloy powder has a particle size of 50-150 μm; the micron-sized TiC powder has a particle size of 2-10 μm; and the nano-sized TiC powder has a particle size of 45-55 nm.

[0016] Furthermore, the TiAl alloy powder is Ti45Al8Nb, and the purity of the TiC powder is ≥99.5%.

[0017] TiC particles have a high melting point, good high-temperature stability, and high hardness. They can maintain high strength and excellent creep resistance even at high temperatures. Adding them to Ti45Al8Nb powder can effectively improve the material's hardness, wear resistance, strength, high-temperature creep resistance, and thermal stability.

[0018] Nano-TiC particles, densely dispersed in the matrix powder, generate strong Orowan dislocation bypass strengthening, significantly improving yield strength. They also pin grain boundaries, inhibiting high-temperature grain growth and enhancing microstructural stability. Micron-sized TiC particles, acting as a hard support phase, directly resist wear, significantly improving wear resistance. The simultaneous addition of nano- and micron-sized particles enables multi-scale synergistic strengthening, combining the advantages of both while reducing the risk of agglomeration of nano-particles and premature fracture caused by micron-sized particles, thus achieving the optimal balance of overall alloy performance.

[0019] Furthermore, in step (1), the ball milling process uses SiO2 grinding balls with a diameter of 5-15 mm, lasts for 2-6 hours, and rotates at a speed of 300-500 r / min. Ball milling, through the collision and shearing force of the grinding balls, can achieve large-scale pulverization of materials (to the nanometer or micrometer scale) while simultaneously promoting the uniform mixing of different components.

[0020] Furthermore, in step (1), the ultrasonic dispersion treatment time is 1-4 hours and the power is 800-1500W. Ultrasonic dispersion utilizes the ultrasonic cavitation effect (high pressure and micro-jet generated by bubble collapse) to strongly break particle agglomeration and achieve uniform distribution of particles in the liquid. The ultrasonic dispersion time is 1-4 hours and the power is 800-1500W.

[0021] First, the coarse particles or agglomerates are mechanically crushed by ball milling to solve the problem that ultrasound cannot handle large-sized hard materials. Then, ultrasonic dispersion is performed to further deagglomerate the ball-milled particles, overcoming the limitations of ball milling in small-scale dispersion.

[0022] Furthermore, in step (2), the laser metal deposition technology involves melting and depositing the mixed powder layer by layer onto the substrate.

[0023] Laser metal deposition (LMD) offers advantages such as high precision, rapid manufacturing, high material utilization, strong repairability, and the ability to fabricate complex-shaped parts, making it suitable for the preparation of TiAl alloys. Inhomogeneously mixed powders are prone to compositional segregation during the LMD powder feeding process. The uniform composite powder obtained through ball milling and ultrasonication significantly reduces this segregation tendency. This means that uniformly dispersed reinforcing phase particles are less affected by heating and melt flow after entering the molten pool, reducing the possibility of reinforcing phase aggregation.

[0024] Furthermore, the operation of the laser metal deposition technology is as follows: first, the substrate is preheated to 350-400°C to reduce the temperature difference between the substrate and the working area during the deposition process, which can effectively reduce thermal stress and prevent cracking, and then layer-by-layer deposition is performed.

[0025] The parameters for laser metal deposition are: laser power of 800-1200W, scanning speed of 400-700mm / min, and powder feeding rate of 5-10g / min.

[0026] Higher laser power and corresponding scanning speed can not only form a deeper molten pool, promote interlayer remelting, eliminate fusion defects and thus improve the density of alloy parts, but also reduce the cooling rate, reduce thermal stress and inhibit cracking, further ensuring the forming quality and performance stability of the alloy, so that the prepared TiAl alloy can meet the high requirements of practical applications for the comprehensive performance of materials.

[0027] Furthermore, in step (3), the operation of the cyclic heat treatment is as follows: first, heat from 1000℃ to 1200℃ and hold for 10 minutes, then cool down to 1000℃ and hold for 10 minutes, and repeat the above operation 5 times; after the cycle is completed, first air cool to room temperature, then heat to 1250℃ and hold for 10 minutes, and then cool with air.

[0028] Cyclic heat treatment plays a crucial role in improving the performance of TiC-reinforced laser metal-deposited TiAl alloy parts. The inherent high temperature gradient and rapid cooling of the laser metal deposition process generate significant thermal residual stresses within the parts, which can lead to deformation and cracking. Cyclic heat treatment, through multiple heating and cooling processes, can more fully utilize the volume changes during thermal expansion and contraction and phase transformation, promoting dislocation slip and climb, thereby more effectively relaxing and redistributing, or even eliminating, these residual stresses.

[0029] The overall process of the method for enhancing the mechanical properties of laser-deposited TiAl alloys using micro / nano TiC particles according to the present invention is as follows: powder mixing using a combination of ball milling and ultrasonic dispersion → forming the mixed powder by laser metal deposition → cyclic heat treatment of the formed alloy parts, comprising three stages. The first stage uses a combination of ball milling and ultrasonic dispersion for powder mixing. Ball milling provides a "macroscopic force field," i.e., impact and shear, while ultrasound applies a "microscopic force field," i.e., cavitation and microjets. These two methods cover different scales, and the resulting composite powder typically exhibits good flowability, which is crucial for the stability and continuous powder feeding of laser metal deposition, improving the consistency and surface quality of the deposited layer. The second stage uses laser metal deposition to form the powder mixed by ball milling and ultrasonic dispersion, achieving ultra-high mixing uniformity, excellent dispersion effect, and significantly improved powder flowability and molten pool stability. Suitable process parameters can significantly reduce defects in the alloy parts, improving their strength, wear resistance, and other properties. The third stage, cyclic heat treatment of the formed alloy parts, effectively eliminates residual thermal stress within the material caused by the rapid melting and solidification involved in laser metal deposition. It promotes atomic diffusion, facilitates a more complete phase transformation process, and yields a more uniform phase composition closer to equilibrium. Furthermore, it promotes relaxation and bonding at the interface between TiC particles and the TiAl matrix, potentially forming a more stable interface structure. These three stages, closely integrated and synergistic, break through the performance limitations of traditional TiAl alloys, expanding their application range to critical components operating at higher temperatures, higher stresses, and greater wear.

[0030] As can be seen from the above technical solution, compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0031] 1. This invention enhances the performance of laser metal deposition TiAl alloys by adding TiC particles. TiC particles have a high melting point, good high-temperature stability, and high hardness. They can maintain high strength and excellent creep resistance even at high temperatures. Adding them to TiAl powder can effectively improve the material's hardness, wear resistance, strength, and thermal stability.

[0032] 2. This invention uses a combination of nano- and micro-scale TiC particles. Nano-scale particles can pin dislocations and refine grains to improve strength, while micro-scale particles can enhance high-temperature wear resistance and creep resistance. The combination of the two improves the strength, hardness, wear resistance and high-temperature performance of TiAl alloy, overcoming the limitations of single-scale particle reinforcement.

[0033] 3. This invention uses a combination of ball milling and ultrasonic dispersion to mix TiC and TiAl powders, covering different scales. The resulting composite powder typically exhibits good flowability. Forming the powder using laser metal deposition with this ball-milled and ultrasonically dispersed mixture achieves ultra-high mixing uniformity, excellent dispersion effect, and significantly improved powder flowability and molten pool stability for both TiC and TiAl powders. This not only reduces defects in the deposited alloy parts but also lowers the segregation tendency, resulting in alloys with superior performance.

[0034] 4. This invention applies cyclic heat treatment to laser-deposited alloy parts. Through multiple heating and cooling processes, cyclic heat treatment can more effectively redistribute or even eliminate residual stress generated during laser metal deposition. Furthermore, cyclic heat treatment can improve the uniformity of the microstructure, refine grains, optimize phase composition and morphology, and promote the formation of a more stable and better-bonded interface between the TiC and TiAl matrix through multiple phase transformations and diffusions. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0036] Figure 1 A process flow diagram of a method for enhancing the properties of laser-deposited TiAl alloys with TiC particles;

[0037] Figure 2 This is a flow chart of the compound powder mixing process;

[0038] Figure 3 This is a schematic diagram of a laser metal deposition process;

[0039] Figure 4 Design drawing for a cyclic heat treatment process;

[0040] Figure 5 This is a gold-to-gold comparison chart of Example 1 and Comparative Example 1;

[0041] Figure 6 This is a comparison chart of Vickers hardness between Example 1 and Comparative Example 1;

[0042] Figure 7 This is a comparison diagram of compressive stress and strain between Example 1 and Comparative Example 1. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0044] A method for enhancing the mechanical properties of laser-deposited TiAl alloys using micro / nano TiC particles, such as... Figure 1 As shown, the steps are as follows:

[0045] (1) Raw material input;

[0046] Add 2-10μm TiC powder, 45-55nm TiC powder, and 50-150μm Ti45Al8Nb powder together into the powder container;

[0047] (2) Ball milling and powder mixing;

[0048] Relying on the collision and shearing force of the grinding media, coarse particles or agglomerates are mechanically crushed to solve the problem of large-sized hard materials that are difficult to process. During the ball milling process, the grinding media is SiO2 grinding beads with a diameter of 5-15mm, the ball milling time is 2-6h, and the rotation speed is 200-500r / min.

[0049] (3) Ultrasonic dispersion and mixing;

[0050] Relying on the ultrasonic cavitation effect, the particle agglomeration is strongly destroyed, and the particles after ball milling are further deagglomerated. The ultrasonic dispersion time is 1-4 hours and the power is 800-1500W.

[0051] (4) The mixed powder is shaped by laser metal deposition;

[0052] A high-power laser beam is focused onto the substrate surface to form a tiny molten pool. Powder is injected into the center of the molten pool through a coaxial nozzle using inert gas. Upon entering the molten pool, the powder melts instantly and mixes with the molten area of ​​the substrate to form a liquid metal mixture. The relative movement between the laser head and the substrate is controlled by a CNC system, and this process is repeated until a three-dimensional structure is completed. Before forming, the substrate is heated to 350-400℃ before laser metal deposition. The parameters for the laser metal deposition process are: laser power of 800-1200W, scanning speed of 400-700mm / min, and powder feed rate of 5-10g / min.

[0053] (5) Heat treatment is performed on the formed alloy parts;

[0054] By relying on repeated heating and cooling in cyclic heat treatment, the volume changes during thermal expansion and contraction and phase transformation can be utilized more fully, promoting the slip and climb of dislocations. This allows for more effective relaxation and redistribution, and even the elimination of these residual stresses, improving the dimensional stability and service reliability of parts. The cyclic heat treatment process involves heating from 1000℃ to 1200℃ five times, and finally heating to 1250℃ and holding for 10 minutes. That is, heating from 1000℃ to 1200℃ and holding for 10 minutes, then cooling to 1000℃ and holding for 10 minutes constitutes one cycle. After five cycles, the parts are first air-cooled to room temperature, then heated to 1250℃ and held for 10 minutes before being cooled with air.

[0055] The present invention will now be described, with reference to specific examples, the method of enhancing the mechanical properties of laser-deposited TiAl alloys with micro / nano TiC particles.

[0056] Example 1

[0057] Powder mixing: 0.9% wt nano-sized TiC powder (particle size 45-55 nm), 0.9% wt micron-sized TiC powder (particle size 2-10 μm), and Ti45Al8Nb powder (particle size 50-150 μm) were mixed. Ball milling time was 4 h at 200 r / min; ultrasonic dispersion time was 1 h at 1000 W.

[0058] Laser metal deposition: The laser power is 1400W, the scanning speed is 360mm / min, and the powder feeding rate is 8g / min. The mixed powder is melted and deposited layer by layer on the substrate.

[0059] Post-treatment: The formed alloy parts are subjected to cyclic heat treatment, which involves heating from 1000℃ to 1200℃ and holding for 10 minutes, then cooling to 1000℃ and holding for another 10 minutes as one cycle, and repeating the cycle 5 times. Then, the parts are heated to 1250℃ and held for 10 minutes.

[0060] Example 2

[0061] Powder mixing: 0.5% wt nano-sized TiC powder (particle size 45-55 nm), 0.5% wt micron-sized TiC powder (particle size 2-10 μm), and Ti45Al8Nb powder (particle size 50-150 μm) were mixed. Ball milling time was 2 h at 400 r / min; ultrasonic dispersion time was 1 h at 1000 W.

[0062] Laser metal deposition: The laser power is 1400W, the scanning speed is 360mm / min, and the powder feeding rate is 7.5g / min. The mixed powder is melted and deposited layer by layer on the substrate.

[0063] Post-treatment: The formed alloy parts are subjected to cyclic heat treatment, which involves heating from 1000℃ to 1200℃ and holding for 10 minutes, then cooling to 1000℃ and holding for another 10 minutes as one cycle, and repeating the cycle 5 times. Then, the parts are heated to 1250℃ and held for 10 minutes.

[0064] Example 3

[0065] Powder mixing: 1.2% wt nano-sized TiC powder (particle size 45-55 nm), 1.2% wt micron-sized TiC powder (particle size 2-10 μm), and Ti45Al8Nb powder (particle size 50-150 μm) were mixed. Ball milling time was 2 h at 400 r / min; ultrasonic dispersion time was 1 h at 1000 W.

[0066] Laser metal deposition: The laser power is 1600W, the scanning speed is 400mm / min, and the powder feeding rate is 8g / min. The mixed powder is melted and deposited onto the substrate layer by layer.

[0067] Post-treatment: The formed alloy parts are subjected to cyclic heat treatment, which involves heating from 1000℃ to 1200℃ and holding for 10 minutes, then cooling to 1000℃ and holding for another 10 minutes as one cycle, and repeating the cycle 5 times. Then, the parts are heated to 1250℃ and held for 10 minutes.

[0068] Comparative Example 1

[0069] No powder mixing is used; Ti45Al8Nb powder without added TiC particles is employed.

[0070] Laser metal deposition: The laser power is 1400W, the scanning speed is 360mm / min, and the powder feeding rate is 8g / min. The powder is melted and deposited onto the substrate layer by layer.

[0071] Post-treatment: The formed alloy parts are subjected to cyclic heat treatment, which involves heating from 1000℃ to 1200℃ and holding for 10 minutes, then cooling to 1000℃ and holding for another 10 minutes as one cycle, and repeating the cycle 5 times. Then, the parts are heated to 1250℃ and held for 10 minutes.

[0072] from Figure 5 As can be seen, compared with Comparative Example 1, the microstructure of Example 1 shows a significant refinement effect. A large number of fine white granular and blocky substances are distributed in the matrix, the overall microstructure is more uniform, and the grain size is significantly reduced. This is because the addition of TiC particles can achieve a synergistic effect of grain refinement, dispersion strengthening, and segregation suppression, thereby improving the hardness, strength, and wear resistance of LMD-molded TiAl alloy.

[0073] Comparative Example 2

[0074] Powder mixing: 0.9% wt nano-sized TiC powder (particle size 45-55 nm) was mixed with Ti45Al8Nb powder (particle size 50-150 μm). The ball milling time was 4 h at a speed of 200 r / min; the ultrasonic dispersion time was 1 h at a power of 1000 W.

[0075] Laser metal deposition: The laser power is 1400W, the scanning speed is 360mm / min, and the powder feeding rate is 8g / min. The mixed powder is melted and deposited layer by layer on the substrate.

[0076] Post-treatment: The formed alloy parts are subjected to cyclic heat treatment, which involves heating from 1000℃ to 1200℃ and holding for 10 minutes, then cooling to 1000℃ and holding for another 10 minutes as one cycle, and repeating the cycle 5 times. Then, the parts are heated to 1250℃ and held for 10 minutes.

[0077] Comparative Example 3

[0078] Powder mixing: 0.9% wt micron-sized TiC powder (particle size 2-10 μm) was mixed with Ti45Al8Nb powder (particle size 50-150 μm). The ball milling time was 4 h at a speed of 200 r / min; the ultrasonic dispersion time was 1 h at a power of 1000 W.

[0079] Laser metal deposition: The laser power is 1400W, the scanning speed is 360mm / min, and the powder feeding rate is 8g / min. The mixed powder is melted and deposited layer by layer on the substrate.

[0080] Post-treatment: The formed alloy parts are subjected to cyclic heat treatment, which involves heating from 1000℃ to 1200℃ and holding for 10 minutes, then cooling to 1000℃ and holding for another 10 minutes as one cycle, and repeating the cycle 5 times. Then, the parts are heated to 1250℃ and held for 10 minutes.

[0081] The TiAl alloys prepared in the above examples were tested and found to have improved hardness, strength, and wear resistance compared to the comparative examples. Compared to TiAl alloys prepared by existing technologies, their mechanical properties were significantly improved.

[0082] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for enhancing the mechanical properties of laser-deposited TiAl alloys using micro / nano TiC particles, characterized in that, Includes the following steps: (1) Micron-sized TiC powder, nano-sized TiC powder and TiAl alloy powder are put into a powder jar and subjected to ball milling and ultrasonic dispersion treatment in sequence to obtain mixed powder; (2) The mixed powder is formed by laser metal deposition technology to obtain a molded alloy part; (3) The formed alloy parts are subjected to cyclic heat treatment to obtain a TiAl alloy with enhanced performance; The TiAl alloy powder has a particle size of 50-150 μm; the micron-sized TiC powder has a particle size of 2-10 μm; and the nano-sized TiC powder has a particle size of 45-55 nm. In step (3), the operation of the cyclic heat treatment is as follows: first, heat from 1000℃ to 1200℃ and hold for 10 minutes, then cool down to 1000℃ and hold for 10 minutes. Repeat the above operation 5 times. After the cycle is completed, first air cool to room temperature, then heat to 1250℃ and hold for 10 minutes.

2. The method for enhancing the mechanical properties of laser-deposited TiAl alloys with micro / nano TiC particles according to claim 1, characterized in that, In step (1), the content of micron-sized TiC powder is 0.5%-1.5%wt and the content of nano-sized TiC powder is 0.5%-1.5%wt, based on the weight of TiAl alloy powder.

3. The method for enhancing the mechanical properties of laser-deposited TiAl alloys with micro / nano TiC particles according to claim 1, characterized in that, The TiAl alloy powder is Ti45Al8Nb, and the purity of the TiC powder is ≥99.5%.

4. The method for enhancing the mechanical properties of laser-deposited TiAl alloys with micro / nano TiC particles according to claim 1, characterized in that, In step (1), the ball milling process uses SiO2 ball milling beads with a diameter of 5-15 mm, the time is 2-6 h, and the rotation speed is 300-500 r / min.

5. The method for enhancing the mechanical properties of laser-deposited TiAl alloys with micro / nano TiC particles according to claim 1, characterized in that, In step (1), the ultrasonic dispersion treatment time is 1-4 h and the power is 800-1500 W.

6. The method for enhancing the mechanical properties of laser-deposited TiAl alloys with micro / nano TiC particles according to claim 1, characterized in that, In step (2), the laser metal deposition technology is to melt and coat the mixed powder layer by layer on the substrate.

7. The method for enhancing the mechanical properties of laser-deposited TiAl alloys with micro / nano TiC particles according to claim 6, characterized in that, The operation of the laser metal deposition technology is as follows: the substrate is preheated to 350-400℃ and then deposited layer by layer. The laser power is 800-1200 W, the scanning speed is 400-700 mm / min, and the powder feeding rate is 5-10 g / min.

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