Preparation method and application of high-entropy alloy TPMS network enhanced TiAl-based composite material

Abstract

The invention provides a preparation method and application of a high-entropy alloy TPMS network enhanced TiAl-based composite material, and relates to the technical field of metal-based composite materials. The method comprises the following steps that firstly, a TiAlV0. 5CrMo high-entropy alloy with a TPMS network structure is prepared through a selective laser melting technology, then gaps of the TPMS network structure are filled with TiAl4822 powder, finally, vacuum hot pressing sintering treatment is conducted, and a TiAlV0. 5CrMo phase in the prepared composite material is evenly distributed in a matrix in a continuous TPMS network form. According to the technical scheme, the TiAlV0. 5CrMo high-entropy alloy TPMS net structure is introduced into the TiAl matrix, so that organic combination of structural design and performance regulation and control is achieved, and the composite material is endowed with higher room-temperature and high-temperature strength and better toughness and thermal stability.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal matrix composites, in particular to a preparation method of a high-entropy-alloy TPMS network enhanced TiAl-based composite material and application thereof. BACKGROUND

[0002] With the continuous pursuit of performance limits in the fields of aerospace, national defense industry and other high-end equipment, almost stringent requirements are put forward for key hot-end component structural materials: excellent high specific strength, high specific stiffness and excellent creep resistance must be possessed under extreme high-temperature environment, and strict lightweight indicators must be met. The traditional titanium alloy and nickel-based high-temperature alloy face bottlenecks in such applications: the former has limited temperature resistance, and the latter has significantly high density and is difficult to balance high-temperature performance and weight reduction requirements.

[0003] Under this background, TiAl-based intermetallics with low density (about 3.7-4.3 g / cm 3 ) and high-temperature resistance (up to 1000 DEG C or above) are considered as one of the most potential new-generation lightweight high-temperature structural materials, which show great prospects in realizing equipment efficiency and lightweight. However, the inherent intrinsic brittleness of TiAl-based alloys leads to low room temperature ductility and damage tolerance, and easy brittle fracture, which seriously restricts the engineering application of the alloys in complex components.

[0004] To solve the above bottlenecks, modification of the TiAl matrix by adding alloying elements such as Nb has become a key technical approach to improve the performance of the material. The solid solution strengthening, fine grain strengthening and beta phase stabilization of Nb element can effectively improve the room temperature plasticity and high temperature strength of the alloy. However, this technical path faces double challenges: first, the addition amount of Nb needs to be accurately controlled, and excessive introduction not only forms a brittle phase (such as NbAl3) and damages the mechanical properties, but also weakens the lightweight advantage of the material due to the high density of Nb; secondly, and more importantly, the macro / microscopic segregation of Nb element is easily caused by using traditional melting or powder metallurgy process, and it is difficult to realize the uniform and continuous distribution of the strengthening phase, so that the alloying improvement effect cannot be stably and fully played, which has become the main technical obstacle for improving the performance of TiAl alloy by Nb element.

[0005] Therefore, it is necessary to design an improved preparation method of a high-entropy-alloy TPMS network enhanced TiAl-based composite material and application thereof to solve the above problems. SUMMARY

[0006] The purpose of the application is to provide a preparation method of a high-entropy-alloy TPMS network enhanced TiAl-based composite material and application thereof.

[0007] To achieve the above-mentioned purposes, in a first aspect, the application provides a preparation method of a high-entropy alloy TPMS network enhanced TiAl-based composite material, comprising the following steps:

[0008] S1, TiAlV 0.5 CrMo powder is filled into the SLM powder supply bin, and the TC4 substrate is smoothly placed on the forming table; after inert gas is introduced into the forming chamber, the TC4 substrate is heated to 300-600℃;

[0009] S2, TiAlV 0.5 CrMo powder is laid on the TC4 substrate, and selective laser melting technology is used to selectively scan and melt the laid powder layer, and the above powder laying and scanning and melting process is repeated to prepare a pre-alloy with a three-dimensional TPMS network structure;

[0010] S3, TiAl4822 powder is filled into the network structure of the pre-alloy prepared in step S2, and pre-compaction treatment is performed to prepare a composite blank; the composite blank is subjected to hot-pressing sintering treatment to prepare a TiAl-based composite material.

[0011] Preferably, in step S2, the process parameters of selective scanning and melting are as follows: laser power 70-100 W, scanning speed 600-1100 mm / s, scanning interval 60 μm, single layer thickness 25 μm, adjacent layer scanning path rotation angle 60-90°, and fan power 5-7 W.

[0012] Preferably, in step S3, the hot-pressing sintering treatment is carried out under a vacuum degree of not less than 1×10 -2 Pa or an argon protective atmosphere, a temperature of 1100-1250℃, a time of 30-120 min, and a hot-pressing pressure of 20-50 MPa.

[0013] Preferably, in step S1, the TiAlV 0.5 CrMo powder particles are spherical, with an average particle size of 15-53 μm, a particle size distribution of D10≤20.2 μm, D50≤35.8 μm, and D90≤49.6 μm, and a chemical composition as follows: Ti 33.0-35.0 wt.%, Al 30.0-32.0 wt.%, V 14.0-16.0 wt.%, Cr 9.0-11.0 wt.%, Mo 9.0-11.0 wt.%, and impurity content controlled as follows: O≤0.08 wt.%, C≤0.02 wt.%, N≤0.02 wt.%, H≤0.005 wt.%, Fe≤0.10 wt.%, and Ni≤0.05 wt.%.

[0014] Preferably, in step S3, the TiAl4822 powder particles are spheroidal, the average particle size is 15-53 mu m, the particle size distribution is D10<=18.2 mu m, D50<=38.6 mu m, D90<=50.8 mu m, and the chemical composition is as follows: Al 32.4-33.6 wt.%, Cr 2.4-2.8 wt.%, Nb 4.5-5.1 wt.%, O<=0.08 wt.%, C<=0.02 wt.%, N<=0.02 wt.%, H<=0.005 wt.%, Fe<=0.10 wt.%, Ni<=0.05 wt.%, and the balance is Ti.

[0015] Preferably, the laser power is 80-90 W, and the scanning speed is 800-900 mm / s.

[0016] Preferably, the sintering temperature is 1150-1200 DEG C, the time is 60-90 min, and the hot-pressing pressure is 30-45 MPa.

[0017] In a second aspect, the present application provides a high-entropy alloy TPMS network enhanced TiAl-based composite material, comprising:

[0018] The matrix is TiAl4822.

[0019] The reinforcing phase is TiAlV 0.5 The CrMo high-entropy alloy has a porosity of 30-90%, and is dispersed in the matrix, and the pore diameter of the TPMS network structure is 0.5-3 mm.

[0020] Preferably, the composite material has the following properties at room temperature:

[0021] The tensile strength is 820-850 MPa.

[0022] The yield strength is 730-760 MPa.

[0023] The elongation is 8-10%.

[0024] The reduction of area is 12-14%, and the elongation is not less than 8% in the range of 200-600 DEG C.

[0025] In a third aspect, the present application provides a high-entropy alloy TPMS network enhanced TiAl-based composite material in the field of new energy vehicles, unmanned aerial vehicles, aerospace and humanoid robots.

[0026] The present application has the following advantages:

[0027] 1. The high-entropy alloy TPMS network enhanced TiAl-based composite material provided by the present application is prepared by first using a selective laser melting technology to prepare TiAlV 0.5The CrMo high-entropy alloy TPMS network structure is prepared by vacuum hot-pressing sintering. 0.5 The CrMo high-entropy alloy can be used as a reinforcing phase of the composite material, can significantly improve the room temperature plasticity and comprehensive mechanical properties of the TiAl matrix while keeping the material lightweight as a whole; in addition, the TiAlV 0.5 The CrMo high-entropy alloy has good matching in chemical composition and lattice structure with the TiAl matrix, which is helpful to form a stable metallurgical bonding interface and avoid the generation of brittle reaction phases, and meanwhile, the TiAlV 0.5 The high plasticity characteristics of the CrMo high-entropy alloy are beneficial to improve the brittleness of the TiAl alloy, and by designing the high-entropy alloy as a continuous triple periodic minimal surface network structure (TPMS), the efficient load transmission and stress uniform distribution can be realized, so that the fracture toughness and ductility of the TiAl alloy are significantly improved.

[0028] 2. The structural advantages of the TPMS proposed in the application: in the selective laser melting (SLM) forming process, the forming mechanism of the TPMS structure is mainly derived from the continuous smooth minimal surface characteristics. The structure avoids the geometric mutation at the traditional rod or node, so that the load and thermal stress are uniformly transmitted along the curved surface in the forming process, thereby effectively reducing the local stress concentration and improving the overall stress state. At the same time, the uniform stress and temperature distribution helps to alleviate the thermal-mechanical coupling instability generated in the rapid melting-solidification process, and provides a basic condition for stable forming. On this basis, the continuously changing curved surface of the TPMS structure forms a natural self-supporting geometry in the building direction, and the local overhanging angle is generally less than the critical forming angle allowed by the SLM process, so that the molten layer can be stacked stably layer by layer relying on the formed entity, instead of relying only on loose powder support, which fundamentally avoids the problems of collapse, warping and local deformation of the horizontal rod in the truss structure. In addition, the self-supporting forming behavior is also beneficial to the stable spreading of the molten pool and uniform solidification, reduces the generation of forming defects, and significantly improves the forming stability and overall forming quality of the complex porous structure.

[0029] 3. The preparation method proposed in the application introduces the continuously distributed TiAlV 0.5 The CrMo high-entropy alloy TPMS network structure, combined with the selective laser melting (SLM) and vacuum hot-pressing sintering (HPS) process, realizes the significant improvement of the material in the aspects of organizational uniformity and interface bonding strength. In addition, by adjusting the process parameters of selective laser melting and vacuum hot-pressing sintering, the high-entropy alloy phase forms a continuous and uniform reinforcing network in the matrix, and meanwhile, the porosity of the TPMS structure can be controlled and adjusted, so that the high strength and lightweight characteristics are considered, and the prepared composite material has higher room temperature and high temperature strength, better toughness and thermal stability, and meanwhile, the density is relatively low (about 3.9-4.3 g / cm 3), which significantly improves the comprehensive mechanical properties and application reliability of the TiAl-based alloy.

[0030] 4、The preparation method provided by the application can realize high-quality compounding of the high-entropy alloy TPMS structure and the TiAl matrix by adopting high-precision selective laser melting technology and powder metallurgy combined interface reaction control process, ensures continuous, uniform and stable distribution of the reinforcing phase, and thus improves the plasticity of the TiAl alloy, so as to meet the application of the TiAl alloy in the fields of new energy vehicles, unmanned aerial vehicles, aerospace and humanoid robot technology. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 A preparation flowchart of the high-entropy alloy TPMS network enhanced TiAl-based composite material provided by the application is shown in the figure.

[0032] Figure 2 A structure diagram of the TiAl-based composite material provided by the application is shown in the figure.

[0033] Figure 3 TiAlV 0.5 SEM diagram of the CrMo and TiAl4822 combination. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the application clearer, the application will be described in detail below with reference to the drawings and specific embodiments.

[0035] Here, it also needs to be explained that, in order to avoid the application being obscured by unnecessary details, only the structures and / or processing steps closely related to the scheme of the application are shown in the drawings, and other details not closely related to the application are omitted.

[0036] In addition, it also needs to be explained that the term “comprise”, “include” or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such a process, method, article or device.

[0037] In one aspect, the application provides a high-entropy alloy TPMS network enhanced TiAl-based composite material, which comprises:

[0038] The matrix is composed of TiAl4822.

[0039] The reinforcing phase is TiAlV 0.5 The CrMo high-entropy alloy is composed of TiAlV 0.5The CrMo is prepared by laser melting, and has a porosity of 30-90%, which is dispersed in the matrix; the porosity diameter of the TPMS network structure is 0.5-3 mm. Specifically, the porosity diameter is of Gyroid, Schwarz D or Diamond type.

[0040] The composite material has the following properties at room temperature:

[0041] The tensile strength is 820-850 MPa;

[0042] The yield strength is 730-760 MPa;

[0043] The elongation is 8-10%;

[0044] The reduction of area is 12-14%, and the elongation is not less than 8% in the range of 200-600 DEG C. The TiAl-based composite material with the above properties can be applied to the fields of new energy vehicles, unmanned aerial vehicles, aerospace and humanoid robots.

[0045] In the above technical solution, TiAlV 0.5 The CrMo is used as a high-entropy alloy reinforcing phase, and is highly compatible with the TiAl matrix with Ti and Al as main framework elements, so that the chemical composition and the crystal lattice structure of the TiAl matrix are well matched. The multi-main element elements V, Cr and Mo introduced can significantly improve the mixing entropy of the system, inhibit the generation of brittle intermetallic compounds, promote the formation of stable solid solution phases, and thus improve the strength and thermal stability of the composite material. In addition, the TiAlV 0.5 The matching of the CrMo and the TiAl matrix in the lattice constant and the thermal expansion coefficient enables the two to form a stable metallurgical bond in the sintering process, avoids the generation of interface stress concentration and reaction layer, and ensures that the high-entropy alloy TPMS network structure forms a continuous and uniform reinforcing network in the matrix, thereby providing a reliable structural guarantee for the high strength and high toughness of the composite material.

[0046] In addition, by using the TiAlV 0.5 The CrMo high-entropy alloy TPMS network structure can fully utilize the excellent high-temperature strength and heat resistance of the high-entropy alloy, and effectively improve the high-temperature mechanical properties of the TiAl matrix; in addition, the TiAlV 0.5 The density of the CrMo high-entropy alloy is only 4.7 g / cm 3 , which is much lower than that of Nb, so that the composite material can maintain the lightweight feature, and has the properties of high strength, high toughness and lightweight.

[0047] Further, the application also provides a preparation method of the TiAl-based composite material reinforced by the high-entropy alloy TPMS network, and a specific preparation process is shown in Figure 1 , comprising the following steps:

[0048] S1, fill TiAlV 0.5 CrMo powder is filled into the SLM powder supply bin, and the TC4 substrate is placed stably on the forming table; after inert gas is introduced into the forming chamber, the substrate is heated to 300-600°C;

[0049] S2, TiAlV 0.5 CrMo powder is laid on the TC4 substrate, and selective laser melting technology is used to selectively scan and melt the powder layer according to the preset three-dimensional model path. The process of laying powder and scanning and melting is repeated to obtain a pre-alloy with a three-dimensional TPMS network structure;

[0050] S3, after cooling the pre-alloy prepared in step S2 in an inert atmosphere, TiAl4822 powder is uniformly filled into the network structure gap of the pre-alloy, and pre-compaction treatment is performed to obtain a composite blank; the composite blank is subjected to hot-pressing sintering treatment to obtain a TiAl-based composite material.

[0051] In the above technical solution, by constructing TiAlV 0.5 The continuous TPMS network structure of CrMo high-entropy alloy and the porosity thereof are controlled to realize the synergistic optimization of enhancement and lightweight. The obtained composite material has excellent high-temperature strength, thermal stability and oxidation resistance, and low density (about 3.9-4.3 g / cm 3 ), which is significantly higher than the density (about 4.4-4.8 g / cm 3 ) of conventional titanium alloy (Ti6Al4V) while maintaining the lightweight feature, and can be widely used in aerospace engine key components, high-speed unmanned aerial vehicle structural parts, new energy vehicle hot end systems, and high-performance humanoid robot joint driving components.

[0052] In some embodiments, in step S1, the TC4 substrate serves as a forming carrier and structural template for the TPMS skeleton, which needs to be cleaned before use to remove oil stains on its surface, such as acetone, and then dried and stored in an inert gas for standby. In other embodiments, other materials can also be used as long as the corresponding purpose is achieved, which is not limited here.

[0053] In some embodiments, in step S1, the inert gas is helium, argon or the like, preferably argon.

[0054] In some embodiments, in steps S1 and S3, TiAlV 0.5 Before use, the TiAlV0.5 The CrMo powder particles are spheroidal, with an average particle size of 15-53 μm, a particle size distribution of D10≤20.2 μm, D50≤35.8 μm, and D90≤49.6 μm, and a chemical composition of Ti 33.0-35.0 wt.%, Al 30.0-32.0 wt.%, V 14.0-16.0 wt.%, Cr 9.0-11.0 wt.%, Mo 9.0-11.0 wt.%, and impurities controlled to O≤0.08 wt.%, C≤0.02 wt.%, N≤0.02 wt.%, H≤0.005 wt.%, Fe≤0.10 wt.%, and Ni≤0.05 wt.%. The TiAl4822 powder particles are spheroidal, with an average particle size of 15-53 μm, a particle size distribution of D10≤18.2 μm, D50≤38.6 μm, and D90≤50.8 μm, and a chemical composition of Al 32.4-33.6 wt.%, Cr 2.4-2.8 wt.%, Nb 4.5-5.1 wt.%, O≤0.08 wt.%, C≤0.02 wt.%, N≤0.02 wt.%, H≤0.005 wt.%, Fe≤0.10 wt.%, Ni≤0.05 wt.%, and the balance Ti. More specifically, the TiAlV 0.5 The CrMo powder and the TiAl4822 powder are prepared by a high-purity inert gas atomization method. After alloy raw materials are melted under vacuum induction melting conditions, the alloy raw materials are atomized by high-pressure argon and rapidly cooled and solidified to form near-spherical powder. The powder is then dried in a vacuum drying box at 60-80 °C for 6-12 h, with a target oxygen content of O<500 ppm.

[0055] In the above technical solution, by controlling the performance of the raw material powder within the above range, the precision of the TPMS network structure prepared by selective laser melting can be improved, and the density of the TiAl can be improved, further improving the mechanical properties of the composite material.

[0056] In some embodiments, in step S2, the process parameters of selective scanning melting are: laser power 70-100 W, scanning speed 600-1100 mm / s, scanning pitch 60 μm, single layer thickness 25 μm, adjacent layer scanning path rotation angle 60-90°, and fan power 5-7 W. The laser power is preferably 80-90 W, and the scanning speed is preferably 800-900 mm / s. Under the above conditions, the obtained three-dimensional TPMS network structure can be stably formed, and the surface of the pre-alloy sample has no obvious cracks and collapse defects, the interlayer bonding is dense, and the overall forming quality shows more excellent and good consistency. In some embodiments, in step S3, the hot-pressing sintering treatment is performed at a vacuum degree of not less than 1×10 -2The sintering and hot-pressing process is carried out under a Pa or high-purity argon protective atmosphere, at a temperature of 1100-1250℃, for a time of 30-120min, at a hot-pressing pressure of 20-50MPa, and the temperature is raised at a rate of 5-10℃ / min from room temperature (25℃) to the target temperature. Preferably, the sintering temperature is 1150-1200℃, the time is 60-90min, the hot-pressing pressure is 30-45MPa, and the temperature is raised at a rate of 8-10℃ / min. It should be noted that the purpose of the pre-compaction treatment before the hot-pressing sintering treatment is to fully fill the TiAl4822 powder in the voids of the network structure, and the specific conditions can be selected according to actual needs, which are not limited herein.

[0057] The preparation method of the high-entropy alloy TPMS network enhanced TiAl-based composite material and the application thereof will be further described below in combination with specific examples:

[0058] Example 1

[0059] In this example, a high-entropy alloy TPMS network enhanced TiAl-based composite material is prepared, and the specific preparation method comprises the following steps:

[0060] The TiAl4822 powder and the TiAlV -2 CrMo powder are dried in a vacuum environment (<10 0.5 Pa) at 80℃ for 8h; the original purity of the TiAl4822 powder and the TiAlV 0.5 CrMo powder is greater than 99.9%, the average particle size of the TiAl4822 powder is 45μm, and the chemical composition is (wt.%): Al is 32.4%, Cr is 2.5%, Nb is 4.6%, O is 0.06%, C is 0.015%, N is 0.015%, H is 0.002%, Fe is 0.07%, Ni is 0.04%, and the balance is Ti; the average particle size of the TiAlV 0.5 CrMo powder is 45μm, and the density is 5.87 g / cm 3 ; and the chemical composition is (wt.%): Ti is 33.6%, Al is 30.5%, V is 14.8%, Cr is 10.5%, Mo is 9.8%, and the balance is impurities;

[0061] TC4 alloy is used as the substrate, the plate thickness is 25mm, the size is 100mm×100mm, the surface is sandblasted, cleaned with acetone solution and dried, and then placed in the forming cavity of the EOS M290 selective laser melting system; argon gas is introduced into the cavity to form a positive pressure protection environment, ensuring that the oxygen content is not higher than 0.05ppm, the distance between the substrate heating device and the substrate surface is adjusted to enable the substrate to be uniformly and efficiently heated, stable heat conduction is achieved, and the substrate heating temperature is 400℃;

[0062] Laying TiAlV on a substrate 0.5 The CrMo powder is firstly modeled with a three-dimensional Gyroid TPMS network structure by using a selective laser melting (SLM) process, and slicing processing is completed, on the basis of which process parameters such as a scanning speed are set, and a Diamond scanning path generated according to the slicing is used to selectively melt the powder layer (30 μm in thickness) to form a pre-alloy with a continuous network structure of the Gyroid TPMS, the powder layer is laid and scanned and melted layer by layer by using a high-energy laser, the thickness of each powder layer is 30 μm, and the specific number of layers can be adjusted according to actual conditions, the melted part is rapidly solidified and stacked layer by layer, and finally the pre-alloy with the continuous network structure of the Gyroid TPMS is formed; wherein the process parameters of the laser melting are as follows: a laser power of 80 W, a scanning speed of 700 mm / s, a scanning interval of 60 μm, a single-layer powder laying thickness of 25 μm, a rotation angle of the scanning path of adjacent layers of 90°, and a fan power of 7 W.

[0063] The pre-alloy is taken off from the forming table by using a wire cutting method, and the residual powder and impurities in the structure are removed by using compressed gas blowing or ultrasonic cleaning to ensure that the pores are unobstructed; the cleaned pre-alloy is fixed in a mold, TiAl4822 powder is uniformly filled into the structure gap by using vibration assistance and vacuum infiltration, so that the powder is fully filled, and a composite blank is prepared; the composite blank is placed in an OTF-1200X-VHP vacuum hot-pressing sintering furnace, and is heated to 1200℃ at a rate of 10℃ / min under a vacuum degree of not less than 1×10 -2 Pa or a high-purity argon protective atmosphere, 30 MPa hot pressing is applied and heat preservation is performed for 60 min, so that the composite blank is densified and TiAlV 0.5 CrMo network structure is metallurgically combined, that is, a TiAl-based composite material is prepared, the TiAlV 0.5 The component ratio of the CrMo network structure and the TiAl4822 is 25:75 (mass fraction ratio). It should be noted that, unless otherwise specified, the reagents and raw materials used in the embodiments of the present application can be obtained by market purchase.

[0064] The specific structure of the TiAl-based composite material prepared in this embodiment is as follows: Figure 2As shown, it exhibits excellent load-carrying capacity and toughness balance at room temperature, with an ultimate tensile strength of up to 830 MPa, a yield strength range of about 750 MPa, which is significantly higher than the ultimate tensile strength (about 600 MPa) of TiAl4822 alloy prepared by traditional selective laser melting technology; at the same time, the elongation of the composite is stable at 8%, indicating that it has good plastic deformation capacity, and the reduction of area (Z) of the composite can reach 12%, showing excellent fracture toughness and energy absorption capacity. The SEM image of the bonding interface of the TiAl-based composite is shown in Figure 3 As shown, the left side of the figure is TiAl4822 alloy, and the right side is TiAlV 0.5 CrMo alloy, the results show that both of them realize high-quality metallurgical composite, and the interface is clean and well combined; secondly, the microstructure on both sides of the interface is in sharp contrast, the left side of TiAl4822 alloy presents uniform and smooth microstructure, while the right side of TiAlV 0.5 CrMo alloy exhibits a complex network structure composed of different lamellar structures. In addition, the interface line of the bonding interface is straight and narrow, indicating that the element diffusion between the two alloys is effectively controlled during the composite preparation process, and no thick and brittle diffusion reaction zone is formed, indicating that the composite preparation process adopted can not only realize high-quality solid-state diffusion connection or metallurgical combination between the two TiAl alloys, but also will not introduce harmful interface phases or defects.

[0065] Example 2

[0066] In this embodiment, a TiAl-based composite reinforced by a high-entropy alloy TPMS network is prepared, and the specific preparation method comprises the following steps:

[0067] The TiAl4822 powder and TiAlV -2 CrMo powder are dried in a vacuum environment (<10 0.5 Pa) at 80℃ for 8h; the original purity of the TiAl4822 powder and TiAlV 0.5 CrMo powder is greater than 99.9%, the average particle size of the TiAl4822 powder is 45μm, and the chemical composition is (wt.%): Al is 33%, Cr is 2.5%, Nb is 4.6%, O is 0.06%, C is 0.015%, N is 0.015%, H is 0.002%, Fe is 0.07%, Ni is 0.04%, the balance is Ti, 0.05%, and the balance is Ti; the average particle size of the TiAlV 0.5 CrMo powder is 45μm, and the chemical composition is (wt.%): Ti is 33.6%, Al is 30.5%, V is 14.8%, Cr is 10.5%, Mo is 9.8%, and the balance is impurities;

[0068] TC4 alloy as the substrate, the plate thickness is 25 mm, the size is 100 mm x 100 mm, the surface is sandblasted, cleaned with acetone solution and dried, and placed in the forming cavity of the EOS M290 selective laser melting system; argon gas is introduced into the cavity to form a positive pressure protection environment, ensuring that the oxygen content is not higher than 0.05 ppm, the distance between the substrate heating device and the substrate surface is adjusted to uniformly and efficiently heat the substrate, realize stable heat conduction, and the substrate heating temperature is 400℃;

[0069] TiAlV 0.5 CrMo powder, using selective laser melting (SLM) process, after modeling and slice processing of three-dimensional Diamond type TPMS network structure, combining with process parameters such as scanning speed, the corresponding scanning track is established, according to the generated Diamond type path, the powder layer is selectively melted layer by layer, the powder layer laid by high-energy laser is selectively melted layer by layer, the process of laying powder and scanning melting is repeated, the melted part is rapidly solidified and stacked layer by layer, and finally the pre-alloy of Diamond type TPMS continuous network structure with continuous network topology characteristics is formed; wherein, the process parameters of laser melting are as follows: laser power 90W, scanning speed 1000mm / s, scanning interval 60μm, single layer powder laying thickness 25μm, adjacent layer scanning path rotation angle 67°, and fan power 7w;

[0070] The pre-alloy is taken off from the forming table by wire cutting, and the residual powder and impurities in the structure are removed by compressed gas blowing or ultrasonic cleaning to ensure the porosity; the cleaned pre-alloy is fixed in the mold, and TiAl4822 powder is uniformly filled into the structure gap by vibration assistance and vacuum infiltration, so that the powder is fully filled, and a composite blank is prepared; the composite blank is placed in an OTF-1200X-VHP type vacuum hot pressing sintering furnace, heated to 1100℃ at a rate of 10℃ / min under a vacuum degree not less than 1×10 -2 Pa or high-purity argon protection atmosphere, 50MPa hot pressing is applied and heat preservation is carried out for 90min, the densification of the composite blank and the metallurgical bonding of TiAlV 0.5 CrMo network structure are realized, that is, a TiAl-based composite material is prepared, and the component ratio of TiAlV 0.5 CrMo and TiAl4822 is 30:70 (mass fraction ratio).

[0071] The composite material prepared in the embodiment exhibits excellent load-carrying capacity and toughness balance at room temperature, the tensile strength of which can reach 840 MPa, and the yield strength is about 750 MPa, which is significantly improved compared with traditional TiAl alloy; at the same time, the elongation of the composite material is stable at 10%, indicating that it has good plastic deformation capacity, and the reduction of area (Z) of the composite material can reach 14%, showing excellent fracture toughness and energy absorption capacity.

[0072] The above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A method for preparing a high-entropy alloy TPMS network enhanced TiAl matrix composite material, characterized in that, The method comprises the following steps: S1, TiAlV 0.5 CrMo powder is filled into the SLM powder supply bin, and the TC4 substrate is placed smoothly on the forming table. After inert gas is introduced into the forming chamber, the TC4 substrate is heated to 300-600℃; S2, TiAlV in the SLM powder supply bin 0.5 CrMo powder is laid on a TC4 substrate, and the laid powder layer is selectively scanned and melted by selective laser melting technology. The process of laying powder and scanning and melting is repeated to obtain a pre-alloy with a three-dimensional TPMS network structure. S3, filling TiAl4822 powder in the network structure of the pre-alloy prepared in step S2, and performing pre-compaction treatment to obtain a composite blank; and performing hot-pressing sintering treatment on the composite blank to obtain a TiAl-based composite material.

2. The production method according to claim 1, characterized by, In step S2, the process parameters of selective scanning melting are as follows: laser power 70-100 W, scanning speed 600-1100 mm / s, scanning interval 60 μm, single-layer thickness 25 μm, adjacent layer scanning path rotation angle 60-90°, and fan power 5-7 W.

3. The production method according to claim 1, characterized by, In step S3, the hot-press sintering process is carried out under a vacuum degree of not less than 1 x 10 -2 under a vacuum degree of not less than 1 x 10 -6 Pa or an argon protective atmosphere, at a temperature of 1100-1250°C, for a time of 30-120 min, and under a hot-press pressure of 20-50 MPa.

4. The production method according to claim 1, characterized by, In step S1, TiAlV 0.5 The CrMo powder particles are spheroidal with an average particle size of 15-53 pm, a particle size distribution of D10 < 20.2 pm, D50 < 35.8 pm, D90 < 49.6 pm, and the following chemical composition: Ti 33.0-35.0 wt.%, Al 30.0-32.0 wt.%, V 14.0-16.0 wt.%, Cr 9.0-11.0 wt.%, Mo 9.0-11.0 wt.%, and the following impurities: O < 0.08 wt.%, C < 0.02 wt.%, N < 0.02 wt.%, H < 0.005 wt.%, Fe < 0.10 wt.%, Ni < 0.05 wt.%.

5. The method of claim 1, wherein the step of forming the first and second layers is performed by a method selected from the group consisting of: sputtering, evaporation, and chemical vapor deposition. In step S3, the TiAl4822 powder particles are spherical, the average particle size is 15-53 μm, the particle size distribution is D10≤18.2 μm, D50≤38.6 μm, and D90≤50.8 μm, and the chemical composition is as follows: Al 32.4-33.6 wt.%, Cr 2.4-2.8 wt.%, Nb 4.5-5.1 wt.%, O≤0.08 wt.%, C≤0.02 wt.%, N≤0.02 wt.%, H≤0.005 wt.%, Fe≤0.10 wt.%, Ni≤0.05 wt.%, and the balance is Ti.

6. The method of claim 2, wherein the step of forming the first and second layers is performed by a method comprising: The laser power is 80-90 W, and the scanning speed is 800-900 mm / s.

7. The method of claim 3, wherein the step of forming the first and second layers is performed by a method comprising: The sintering temperature is 1150-1200℃, the time is 60-90 min, and the hot-pressing pressure is 30-45 MPa.

8. A high-entropy alloy TPMS network-reinforced TiAl-based composite material prepared by the preparation method of any one of claims 1-7, characterized in that, The method comprises the following steps: The matrix is TiAl4822; Reinforcing phase: it is TiAlV with a TPMS network structure 0.5 CrMo high-entropy alloy with a porosity of 30-90% dispersed in the matrix, the pores of the TPMS network structure having a diameter of 0.5-3 mm.

9. The composite material of claim 8, wherein The composite material has the following properties at room temperature: The tensile strength is 820-850 MPa; The yield strength is 730-760 MPa; The elongation is 8-10%; The reduction of area is 12-14%, and the elongation is not less than 8% in the range of 200-600℃.

10. Application of the high-entropy alloy TPMS network reinforced TiAl-based composite material prepared by the preparation method of any one of claims 1-7 or the high-entropy alloy TPMS network reinforced TiAl-based composite material of claims 8-9 in the fields of new energy vehicles, unmanned aerial vehicles, aerospace, and humanoid robots.

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