Carbide reinforced 3D printing titanium-aluminum alloy composite material and preparation method

Abstract

The invention provides a carbide reinforced 3D printing titanium-aluminum alloy composite material and a preparation method, and relates to the technical field of 3D printing composite materials. The alloy comprises the following chemical components in atomic percent: 40-50 at% of Al, 2-10 at% of Nb, 0.2-1 at% of Mo, 0.05-2 at% of Si, 0.2-5 at% of C and the balance of Ti and inevitable impurity elements. The preparation method comprises the steps of carbon nanotube coating, TiC powder coating, laser directional energy deposition, thermal deformation and thermal treatment. According to the method, two kinds of titanium-aluminum alloy powder with different particle sizes are creatively subjected to surface coating modification, and the titanium-aluminum alloy powder with different particle sizes and subjected to surface coating modification is conveyed at the same time through double powder bins for laser directional energy deposition, so that the composite material with all parts uniformly enhanced in mechanical property is obtained; the method is high in resource utilization rate, low in production cost, short in process, easy to operate, high in efficiency, uniform in carbide reinforced particle distribution and beneficial to industrial large-scale production and popularization.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing composite materials, and particularly to a carbide-reinforced 3D printing titanium aluminide composite material and a preparation method thereof. Background Art

[0002] TiAl-based alloys are widely regarded as the best candidate materials to replace nickel-based superalloys due to their low density, high specific strength, excellent high-temperature oxidation resistance and creep resistance, and have broad application prospects especially in the aerospace field. However, TiAl-based alloys prepared by traditional processes have problems such as high internal stress, easy cracking, and difficulty in forming complex parts, and their room-temperature fracture toughness is low and ductility is insufficient, which limits their application in high-temperature environments.

[0003] In recent years, by combining in-situ self-generation technology and 3D printing technology, and adding reinforcing phase particles, the mechanical properties of TiAl-based alloys have been significantly improved. The application of 3D printing technology further enhances the performance of TiAl-based alloys, enabling them to meet the requirements of lightweight and high performance of aviation equipment.

[0004] Although particulate-reinforced titanium aluminide composite materials have shown significant effects in enhancing the strength, toughness and oxidation resistance of alloys, there are still some challenges and dilemmas in the actual application and production processes: 1) The uniform distribution of reinforcing phase particles is crucial, but due to the limited interfacial bonding strength between the titanium aluminide matrix and the reinforcing phase particles, problems such as interfacial debonding and crack propagation are likely to occur, thus affecting the overall performance of the material; 2) The addition of particles often increases the brittleness of the alloy. Especially at lower temperatures, the ductility and toughness of TiAl-based alloys are still insufficient, which limits their application under complex stress conditions. Although particulate reinforcement improves the strength at high temperatures, when the temperature is above 850 °C, the strength of titanium aluminide alloys still decreases significantly and cannot fully meet the usage requirements of higher temperature environments.

[0005] In addition, the process control during the preparation process is difficult. Although 3D printing technology can efficiently prepare titanium aluminide composite materials with complex shapes, there are still challenges in controlling the uniform distribution of particles, the bonding between deposition layers, and the final microstructure. How to improve the process efficiency and reduce the production cost without affecting the material uniformity is still a technical problem to be solved.

[0006] For example, Chinese Patent CN109940165A discloses a method for preparing in-situ TiAl metal compounds by particle reinforcement SLM. This method obtains particle-reinforced titanium aluminide through mechanical alloying mixing, addition of reinforcing phase particles, and SLM technology. However, this process requires multiple steps of mechanical alloying and SLM processing, with complex processing, strict powder requirements, especially the particle size of the reinforcing phase particles needs to be less than 500 nm, otherwise it will affect the SLM forming quality. SLM technology requires precision equipment and high costs, and may not be suitable for large-scale production.

[0007] Chinese Patent CN116921697A discloses a method for preparing a biomimetic interpenetrating Ti2AlNb / TiAl matrix composite. This method uses selective laser melting technology to 3D print a Ti2AlNb reinforcement skeleton, places the skeleton in a mold and fills it with TiAl powder, and cold presses it into shape; finally, a biomimetic interpenetrating Ti2AlNb / TiAl matrix composite is prepared by hot press sintering. However, the preparation process is complex, requiring high-precision equipment and strict process parameter control. There may be high residual stresses during the hot press sintering process, which may affect the final properties of the material.

[0008] Chinese Patent CN117399637A discloses a near-net shaping method for high-performance in-situ Ti5Si3 phase-reinforced titanium aluminide matrix composites. This method obtains Ti5Si3 reinforcement and a titanium aluminide matrix through electron beam dual-wire 3D printing technology. However, during the additive process, parameters such as wire feeding speed, electron beam focus, and cooling speed need to be precisely controlled, and the process window is narrow, which easily leads to process instability. In addition, the temperature gradient during preheating and deposition may cause thermal stress, resulting in microcracks inside the material and affecting the mechanical properties of the material. Even though the material properties can be regulated by adjusting the proportion of the Ti5Si3 reinforcement, this requires high process experience from the operators and it is difficult to maintain consistency in large-scale industrial production.

[0009] Chinese Patent CN110205536A discloses a titanium / carbide core-shell structure-reinforced aluminum matrix composite and its preparation method. It is composed of a pure aluminum or aluminum alloy matrix and titanium / carbide core-shell particle reinforcements. The reinforcement has titanium as the core and a titanium carbide ceramic layer as the shell, and the size of the titanium carbide particles inside the shell shows a gradient change; this method obtains the required composite by adding the reinforcing particles to the matrix alloy melt and stirring evenly. To increase the interfacial bonding strength between the matrix alloy and the reinforcing phase particles, the reinforcing phase needs to be specially prepared; and the regulation between different matrix alloys and reinforcing phase particles, as well as the structure and composition of the reinforcing phase, are difficult to anticipate for the staff.

[0010] Chinese Patent CN114480942A discloses a method for preparing a silicon carbide reinforced aluminum matrix composite material, which is prepared by infiltrating SiC particles with an aluminum base alloy in a high gravity field; obviously, this preparation method has a high cost and is not suitable for industrial production; moreover, there is agglomeration of SiC particles during the infiltration process, so that the SiC particles cannot be evenly distributed in the prepared composite material, and only some parts are strengthened, increasing the risk of internal stress and fracture. Summary of the Invention

[0011] In order to solve the technical problems existing in the preparation method of particulate reinforced 3D printed titanium aluminum alloy composite materials in the prior art, such as the mixing of titanium powder and aluminum powder, first preparing a reinforcing body skeleton and then filling titanium aluminum alloy powder in a mold for cold pressing, too many process parameters are too difficult to control, the requirements for the preparation device and control accuracy are very high, the temperature gradient during the preparation process causes thermal stress, and the particulate structure is complex and requires special preparation, etc.; therefore, the embodiments of the present invention provide a carbide reinforced 3D printed titanium aluminum alloy composite material and a preparation method that can synergistically improve the strength, toughness and oxidation resistance of titanium aluminum alloy. The technical solutions are as follows:

[0012] A carbide reinforced 3D printed titanium aluminum alloy composite material, the chemical composition of the carbide reinforced 3D printed titanium aluminum alloy composite material is calculated by atomic percentage as follows: Al 40-50at%, Nb 2-10at%, Mo 0.2-1at%, Si 0.05-2at%, C 0.2-5at%, and the balance is Ti and inevitable impurity elements.

[0013] Optionally, the metallographic composition of the carbide reinforced 3D printed titanium aluminum alloy composite material is 60-80% γ phase + 1-10% α2 phase + 5-30% carbide H phase.

[0014] Optionally, the carbide reinforced 3D printed titanium aluminum alloy composite material contains lamellar tissue, equiaxed crystals around the lamellar cluster and carbides; among them, the shape of the lamellar tissue is circular, and the average size is 50-200μm; the shape of the equiaxed crystals around the lamellar cluster is prototype, and the average size is 1-10μm; the shape of the carbides is elliptical and irregular, and the average size is 5-20μm.

[0015] Optionally, the density of the carbide reinforced 3D printed titanium aluminum alloy composite material is 3.9-4.3g / cm 3 , the tensile strength is not less than 600MPa, the yield strength is not less than 400MPa, the elongation is not less than 1%, the tensile strength at 850°C is not less than 500MPa, the yield strength is not less than 300MPa, and the elongation is not less than 3%.

[0016] A preparation method of a carbide-reinforced 3D printed titanium aluminide composite material based on the above, the method for the carbide-reinforced 3D printed titanium aluminide composite material comprises the following steps:

[0017] S1. Carbon nanotube coating: The titanium aluminide coarse powder and carbon nanotubes are subjected to high-energy ball milling together by high-energy ball milling to obtain titanium aluminide coarse powder coated with carbon nanotubes;

[0018] S2. TiC powder coating: The titanium aluminide fine powder and TiC powder are mechanically mixed by mechanical mixing to obtain titanium aluminide fine powder coated with TiC powder;

[0019] S3. Laser directed energy deposition: The titanium aluminide coarse powder coated with carbon nanotubes in S1 and the titanium aluminide fine powder coated with TiC powder in S2 are respectively loaded into two powder barrels for laser directed energy deposition, and powder feeding parameters are selected according to actual needs for powder feeding and laser directed energy deposition to obtain a deposited sample;

[0020] S4. Hot deformation and heat treatment: The deposited sample in S3 is subjected to hot isostatic pressing and heat treatment to obtain a carbide-reinforced 3D printed titanium aluminide composite material.

[0021] Optionally, in S1, the average particle size of the titanium aluminide coarse powder is 50 - 150 μm; the carbon nanotubes are multi-walled carbon nanotubes with an average diameter of 10 - 20 nm and a length of 1 - 10 μm; the mass ratio of the titanium aluminide coarse powder to the carbon nanotubes is 90 - 98:10 - 2; the grinding balls for high-energy ball milling are stainless steel balls or zirconia balls with a diameter of 5 - 10 mm, and the ball-to-powder ratio of the high-energy ball mill is 10 - 8:1.

[0022] Optionally, in S1, the rotation speed of high-energy ball milling is 300 - 400 rpm, and the ball milling time is 4 - 8 h; during high-energy ball milling, the ball milling is stopped for 10 min every 30 min, and mild sintering treatment is carried out under argon protection at a temperature of 500 - 600 °C for a holding time of 1 - 2 h.

[0023] Optionally, in S2, the average particle size of the titanium aluminide fine powder is 10 - 50 μm; the particle size of the TiC powder is 1 - 10 μm; the mass ratio of the titanium aluminide fine powder to the TiC powder is 85:15 - 95:5; the grinding balls for mechanical mixing are zirconia or tungsten carbide balls with a diameter of 3 - 10 mm, accounting for 50 - 60% of the total volume of the ball mill tank, the vibration frequency is 1000 - 1500 rpm, the ball-to-powder ratio is 10:1 - 20:1, the mechanical mixing time is 2 - 4 h, and intermittent ball milling or a cooling device is adopted.

[0024] Optionally, the powder feeding rate of the powder bucket loaded with the carbon nanotube-coated titanium aluminide coarse powder in S3 is 3-7 g / min, and the powder feeding rate of the powder bucket loaded with the titanium aluminide fine powder coated with TiC powder is 0.5-2 g / min; the laser power of laser directed energy deposition is 800-1200 W, the scanning rate is 6-12 mm / s, and the spot diameter is 2-4 mm.

[0025] Optionally, in S4, the heating and holding temperature of hot isostatic pressing is 1140-1300 °C, the pressure is 140-190 MPa, and the time is 3-8 h; the heating and holding temperature of heat treatment is 1240-1340 °C, and the time is 0.5-4 h.

[0026] The above technical solution has at least the following beneficial effects compared with the prior art:

[0027] In the above solution, the present invention provides a carbide-reinforced 3D printed titanium aluminide composite material, which can solve the technical problems existing in the preparation method of particle-reinforced 3D printed titanium aluminide composite materials in the prior art, such as the mixing of titanium powder and aluminum powder, first preparing a reinforcing body skeleton and then filling titanium aluminide powder in a mold for cold pressing, too many process parameters are difficult to control, the requirements for the preparation device and control accuracy are very high, the temperature gradient during the preparation process causes thermal stress, and the particulate structure is complex and requires special preparation.

[0028] The present invention conducts surface coating modification on two different particle size titanium aluminide powders, and uses the addition and uniform distribution of carbides of different scales to overall strengthen 3D printed titanium aluminide, and can achieve the effect of uniformly strengthening the mechanical properties of all parts of the whole.

[0029] The present invention realizes that the same raw material can generate multiple different components, carbides and coating structures simultaneously by feeding powder from two powder bins, making the preparation of titanium aluminide more suitable for different performance requirements. The products produced cover all aspects of titanium aluminide. Not only are products with simple shapes easy to produce, but also products with complex shapes are easy to produce, and the production difficulty will not change significantly due to the change of product shape.

[0030] Due to the fact that the solidification rate of the large molten pool of laser directed energy deposition in the present invention is less than that of SLM and EBM, sufficient time can be provided for the precipitation of carbides, so the precipitation is relatively sufficient and the distribution in the melt is also uniform, thereby obtaining excellent overall strengthening effects of all parts of the material.

[0031] The whole process of the present invention is carried out under argon protection to better avoid the influence of oxidation. For example, the unpacking, weighing, canning, etc. of titanium aluminide powder and carbon nanotubes need to be carried out in a glove box to isolate the influence of oxygen, and ball milling is carried out in an argon environment, which effectively prevents the increase of oxygen content during the whole preparation process.

[0032] Through hot isostatic pressing treatment and heat treatment, the present invention can effectively eliminate the printing defects inside the material, that is, eliminate pores and internal stresses, and ensure the fatigue performance, mechanical properties and other properties of the material.

[0033] The density of the carbide-reinforced 3D printed titanium aluminide composite material prepared by the present invention is 3.9-4.3 g / cm 3 , the tensile strength is not less than 600 MPa, the yield strength is not less than 400 MPa, the elongation is not less than 1%, the tensile strength at 850 °C is not less than 500 MPa, the yield strength is not less than 300 MPa, and the elongation is not less than 3%.

[0034] In summary, compared with other traditional methods, the method of the present invention creatively conducts surface coating modification on titanium aluminide powders with two different particle sizes, and simultaneously transports the surface-coated modified titanium aluminide powders with different particle sizes through a double powder bin for laser directed energy deposition to obtain a composite material with uniformly enhanced mechanical properties in all parts; this method has high resource utilization rate, low production cost, short process, easy operation, high efficiency, and uniform distribution of carbide reinforcement particles, which is conducive to large-scale industrial production and promotion. Description of the Drawings

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0036] Figure 1 It is a schematic structural diagram of the device used in the method for preparing a carbide-reinforced 3D printed titanium aluminide composite material of the present invention;

[0037] Figure 2 It is a BSD scanning electron microscope image of the carbide-reinforced 3D printed titanium aluminide composite material in Example 1 of the present invention;

[0038] Figure 3 It is a BSD scanning electron microscope image of the carbide-reinforced 3D printed titanium aluminide composite material in Example 2 of the present invention;

[0039] Figure 4 It is a BSD scanning electron microscope image of the carbide-reinforced 3D printed titanium aluminide composite material in Example 3 of the present invention. Detailed Embodiments

[0040] The following will describe the technical solutions in the present invention in conjunction with the drawings.

[0041] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to give examples, illustrations or explanations. Any embodiment or design described as an "example" in the present invention should not be construed as being more preferred or having more advantages than other embodiments or designs. Rather, the use of the word "example" is intended to present concepts in a specific manner. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one of the two.

[0042] In the embodiments of the present invention, "image" and "picture" can sometimes be used interchangeably. It should be noted that when the difference is not emphasized, the meanings they express are the same. "Of", "corresponding" and "corresponding to" can sometimes be used interchangeably. It should be noted that when the difference is not emphasized, the meanings they express are the same.

[0043] In the embodiments of the present invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meanings they express are the same.

[0044] To make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0045] A carbide-reinforced 3D printing titanium-aluminum alloy composite material, the chemical composition of the carbide-reinforced 3D printing titanium-aluminum alloy composite material is calculated by atomic percentage as follows: Al 40-50 at%, Nb 2-10 at%, Mo 0.2-1 at%, Si 0.05-2 at%, C 0.2-5 at%, and the balance is Ti and inevitable impurity elements.

[0046] Specifically, the metallographic composition of the carbide-reinforced 3D printing titanium-aluminum alloy composite material is 60-80% γ phase + 1-10% α2 phase + 5-30% carbide H phase.

[0047] Specifically, the carbide-reinforced 3D printing titanium-aluminum alloy composite material contains lamellar tissue, equiaxed crystals around the lamellar clusters and carbides; among them, the shape of the lamellar tissue is circular, and the average size is 50-200 μm; the shape of the equiaxed crystals around the lamellar clusters is circular, and the average size is 1-10 μm; the shape of the carbides is elliptical and irregular, and the average size is 5-20 μm.

[0048] Specifically, the density of the carbide-reinforced 3D printing titanium-aluminum alloy composite material is 3.9-4.3 g / cm 3 , the tensile strength is not less than 600 MPa, the yield strength is not less than 400 MPa, the elongation is not less than 1%, the tensile strength at 850 °C is not less than 500 MPa, the yield strength is not less than 300 MPa, and the elongation is not less than 3%.

[0049] A preparation method of a carbide-reinforced 3D printed titanium aluminide composite based on the above, and the structure of the device used is as Figure 1 shown. The method for preparing the carbide-reinforced 3D printed titanium aluminide composite is as follows:

[0050] S1. Carbon nanotube coating: The titanium aluminide coarse powder and carbon nanotubes are subjected to high-energy ball milling together by high-energy ball milling to obtain titanium aluminide coarse powder coated with carbon nanotubes;

[0051] S2. TiC powder coating: The titanium aluminide fine powder and TiC powder are mechanically mixed by mechanical mixing to obtain titanium aluminide fine powder coated with TiC powder;

[0052] S3. Laser directed energy deposition: The titanium aluminide coarse powder coated with carbon nanotubes in S1 and the titanium aluminide fine powder coated with TiC powder in S2 are respectively loaded into two powder barrels of laser directed energy deposition, and the powder feeding parameters are selected according to actual needs for powder feeding and laser directed energy deposition to obtain a deposited sample;

[0053] S4. Hot deformation and heat treatment: The deposited sample in S3 is subjected to hot isostatic pressing and heat treatment to obtain a carbide-reinforced 3D printed titanium aluminide composite.

[0054] Specifically, in S1, the average particle size of the titanium aluminide coarse powder is 50 - 150 μm; the carbon nanotubes are multi-walled carbon nanotubes with an average diameter of 10 - 20 nm and a length of 1 - 10 μm; the mass ratio of the titanium aluminide coarse powder to the carbon nanotubes is 90 - 98:10 - 2; the grinding balls for high-energy ball milling are stainless steel balls or zirconia balls with a diameter of 5 - 10 mm, and the ball-to-powder ratio of the high-energy ball mill is 10 - 8:1.

[0055] Specifically, in S1, the rotation speed of high-energy ball milling is 300 - 400 rpm, and the ball milling time is 4 - 8 h; during high-energy ball milling, the ball milling is stopped for 10 min every 30 min, and mild sintering treatment is carried out under argon protection at a temperature of 500 - 600 °C for a holding time of 1 - 2 h.

[0056] Specifically, in S2, the average particle size of the titanium aluminide fine powder is 10 - 50 μm; the particle size of the TiC powder is 1 - 10 μm; the mass ratio of the titanium aluminide fine powder to the TiC powder is 85:15 - 95:5; the grinding balls for mechanical mixing are zirconia or tungsten carbide balls with a diameter of 3 - 10 mm, accounting for 50 - 60% of the total volume of the ball mill tank, the vibration frequency is 1000 - 1500 rpm, the ball-to-powder ratio is 10:1 - 20:1, the mechanical mixing time is 2 - 4 h, and intermittent ball milling or a cooling device is adopted.

[0057] Specifically, the powder feeding rate of the powder barrel loaded with the titanium aluminum alloy coarse powder coated with carbon nanotubes in S3 is 3-7 g / min, and the powder feeding rate of the powder barrel loaded with the titanium aluminum alloy fine powder coated with TiC powder is 0.5-2 g / min; the laser power of laser directed energy deposition is 800-1200 W, the scanning rate is 6-12 mm / s, and the spot diameter is 2-4 mm.

[0058] Specifically, the heating and holding temperature of hot isostatic pressing in S4 is 1140-1300 °C, the pressure is 140-190 MPa, and the time is 3-8 h; the heating and holding temperature of heat treatment is 1240-1340 °C, and the time is 0.5-4 h.

[0059] Example 1

[0060] A carbide-reinforced 3D printed titanium aluminum alloy composite material, the shape of the carbide-reinforced 3D printed titanium aluminum alloy composite material is square, the size is 35 mm in height and 15 mm in thickness, and the chemical composition is calculated by atomic percentage as: Al 43.5 at%, Nb 4 at%, Mo 0.5 at%, Si 0.2 at%, C 2 at%, and the balance is Ti and unavoidable impurity elements.

[0061] A preparation method of the carbide-reinforced 3D printed titanium aluminum alloy composite material based on the above, the method for the carbide-reinforced 3D printed titanium aluminum alloy composite material is as follows:

[0062] S1. Carbon nanotube coating: Select the raw materials and process parameters for coating the titanium aluminum alloy coarse powder. The average particle size of the titanium aluminum alloy coarse powder is 100 μm; the carbon nanotubes are multi-walled carbon nanotubes with an average diameter of 15 nm and a length of 8 μm; the mass ratio of the titanium aluminum alloy coarse powder to the carbon nanotubes is 98:2; the grinding balls for high-energy ball milling are zirconia balls with a diameter of 5 mm, and the ball-to-powder ratio of the high-energy ball mill is 10:1; the rotation speed of the high-energy ball mill is 300 rpm, and the ball milling time is 6 h; during high-energy ball milling, the ball milling is stopped for 10 min every 30 min to prevent the equipment from overheating and maintain the structural integrity of the carbon nanotubes. After-treatment is used to further improve the bonding effect, and mild sintering treatment is carried out under argon protection at a temperature of 500 °C for a holding time of 1 h;

[0063] The titanium aluminum alloy coarse powder and the carbon nanotubes are subjected to high-energy ball milling together by the high-energy ball milling method to obtain the titanium aluminum alloy coarse powder coated with carbon nanotubes;

[0064] S2. Coating with TiC Powder: Select the raw materials and process parameters for coating the fine titanium-aluminum alloy powder. The average particle size of the fine titanium-aluminum alloy powder is 30 μm; the particle size of the TiC powder is 5 μm; the mass ratio of the fine titanium-aluminum alloy powder to the TiC powder is 95:5; the grinding balls for mechanical mixing are zirconia or tungsten carbide balls with a diameter of 10 mm, accounting for 60% of the total volume of the ball mill tank, the vibration frequency is 1500 rpm, the ball-to-powder ratio is 10:1, the mechanical mixing time is 4 h, and an intermittent ball mill or a cooling device is used;

[0065] Mechanically mix the fine titanium-aluminum alloy powder and the TiC powder by mechanical mixing method to obtain the fine titanium-aluminum alloy powder coated with TiC powder;

[0066] S3. Laser Directed Energy Deposition: Load the carbon nanotube-coated coarse titanium-aluminum alloy powder of S1 and the TiC powder-coated fine titanium-aluminum alloy powder of S2 into two powder barrels for laser directed energy deposition respectively. Select the powder feeding parameters according to actual needs for powder feeding and laser directed energy deposition to obtain the as-deposited sample; among them: the powder feeding rate of the powder barrel loaded with the carbon nanotube-coated coarse titanium-aluminum alloy powder is 3 g / min, and the powder feeding rate of the powder barrel loaded with the TiC powder-coated fine titanium-aluminum alloy powder is 0.5 g / min; the laser power for laser directed energy deposition is 800 W, the scanning rate is 6 mm / s, and the spot diameter is 2 mm;

[0067] S4. Hot Deformation and Heat Treatment: Perform hot isostatic pressing and heat treatment on the as-deposited sample of S3. The heating and holding temperature for hot isostatic pressing is 1240 °C, the pressure is 160 MPa, and the time is 3 h; the heating and holding temperature for heat treatment is 1270 °C, and the time is 0.5 h to obtain the carbide-reinforced 3D printed titanium-aluminum alloy composite material.

[0068] The metallographic composition of the carbide-reinforced 3D printed titanium-aluminum alloy composite material prepared in this example is 68% γ phase + 2% α2 phase + 30% carbide H phase, as Figure 2 shown. A large number of carbides are evenly distributed on the titanium-aluminum alloy matrix. The types of carbides are Ti2AlC and TiC, and the morphology of the carbides is elliptical.

[0069] In the carbide-reinforced 3D printed titanium-aluminum alloy composite material prepared in this example, the shape of the lamellar tissue group is circular, and the average size is 120 μm; the shape of the equiaxed grains around the lamellar group is prototype, and the average size is 5 μm; the shape of the carbides is elliptical and irregular, and the average size is 12 μm.

[0070] The density of the carbide-reinforced 3D printed titanium-aluminum alloy composite material prepared in this example is 4.0 g / cm 3, Tensile strength: 730 MPa, yield strength: 688 MPa, elongation: 1.2%, tensile strength at 850 °C: 621 MPa, yield strength at 850 °C: 546 MPa, elongation at 850 °C: 6.0%.

[0071] Example 2

[0072] A carbide-reinforced 3D printed titanium-aluminum alloy composite material. The carbide-reinforced 3D printed titanium-aluminum alloy composite material is in the shape of a cube, with a height of 50 mm and a thickness of 20 mm. The chemical composition in atomic percentage is: Al 44 at%, Nb 6 at%, Mo 0.6 at%, Si 0.1 at%, C 5 at%, and the balance is Ti and inevitable impurity elements.

[0073] A preparation method of the above-mentioned carbide-reinforced 3D printed titanium-aluminum alloy composite material. The method for the carbide-reinforced 3D printed titanium-aluminum alloy composite material comprises the following steps:

[0074] S1. Carbon nanotube coating: Select the raw materials and process parameters for coating the titanium-aluminum alloy coarse powder. The average particle size of the titanium-aluminum alloy coarse powder is 120 μm; the carbon nanotubes are multi-walled carbon nanotubes with an average diameter of 10 nm and a length of 6 μm; the mass ratio of the titanium-aluminum alloy coarse powder to the carbon nanotubes is 95:5; the grinding balls for high-energy ball milling are zirconia balls with a diameter of 6 mm, and the ball-to-powder ratio of the high-energy ball mill is 9:1; the rotation speed of the high-energy ball mill is 350 rpm, and the ball milling time is 4 h; during high-energy ball milling, the ball milling is stopped for 10 min every 30 min to prevent the equipment from overheating and maintain the structural integrity of the carbon nanotubes. After-treatment is used to further improve the bonding effect, and mild sintering treatment is carried out under argon protection at a temperature of 550 °C for a holding time of 1.5 h;

[0075] The titanium-aluminum alloy coarse powder and the carbon nanotubes are subjected to high-energy ball milling together by the high-energy ball milling method to obtain the titanium-aluminum alloy coarse powder coated with carbon nanotubes;

[0076] S2. TiC powder coating: Select the raw materials and process parameters for coating the titanium-aluminum alloy fine powder. The average particle size of the titanium-aluminum alloy fine powder is 20 μm; the particle size of the TiC powder is 3 μm; the mass ratio of the titanium-aluminum alloy fine powder to the TiC powder is 90:10; the grinding balls for mechanical mixing are zirconia or tungsten carbide balls with a diameter of 8 mm, accounting for 55% of the total volume of the ball milling tank, the vibration frequency is 1250 rpm, the ball-to-powder ratio is 15:1, and the mechanical mixing time is 3 h. Intermittent ball milling or a cooling device is adopted;

[0077] The titanium-aluminum alloy fine powder and the TiC powder are mechanically mixed by the mechanical mixing method to obtain the titanium-aluminum alloy fine powder coated with TiC powder;

[0078] S3. Laser Directed Energy Deposition: The coarse powder of titanium aluminide coated with carbon nanotubes in S1 and the fine powder of titanium aluminide coated with TiC powder in S2 are respectively loaded into two powder barrels for laser directed energy deposition. Select the powder feeding parameters according to actual needs for powder feeding and laser directed energy deposition to obtain a deposited sample. Among them: the powder feeding rate of the powder barrel loaded with the coarse powder of titanium aluminide coated with carbon nanotubes is 5 g / min, and the powder feeding rate of the powder barrel loaded with the fine powder of titanium aluminide coated with TiC powder is 1 g / min; the laser power for laser directed energy deposition is 1000 W, the scanning rate is 8 mm / s, and the spot diameter is 3 mm.

[0079] S4. Hot Deformation and Heat Treatment: The deposited sample in S3 is subjected to hot isostatic pressing and heat treatment. The heating and holding temperature for hot isostatic pressing is 1290 °C, the pressure is 170 MPa, and the time is 6 h; the heating and holding temperature for heat treatment is 1320 °C, and the time is 2 h to obtain a carbide-reinforced 3D printed titanium aluminide composite.

[0080] The metallographic composition of the carbide-reinforced 3D printed titanium aluminide composite prepared in this example is 68% γ phase + 5% α2 phase + 27% carbide H phase. As Figure 3 shown, a large number of carbides are evenly distributed on the titanium aluminide matrix. The types of carbides are Ti2AlC and TiC, and the morphology of the carbides is irregular.

[0081] In the carbide-reinforced 3D printed titanium aluminide composite prepared in this example, the shape of the lamellar tissue group is circular, and the average size is 60 μm; the shape of the equiaxed grains around the lamellar tissue group is prototype, and the average size is 3 μm; the shape of the carbides is elliptical and irregular, and the average size is 18 μm.

[0082] The density of the carbide-reinforced 3D printed titanium aluminide composite prepared in this example is 3.9 g / cm 3 , the tensile strength is 697 MPa, the yield strength is 538 MPa, the elongation is 1.4%, the tensile strength at 850 °C is 565 MPa, the yield strength is 316 MPa, and the elongation is 7%.

[0083] Example 3

[0084] A carbide-reinforced 3D printed titanium aluminide composite, the shape of the carbide-reinforced 3D printed titanium aluminide composite is square, the size is 50 mm in height and 50 mm in thickness, and the chemical composition is calculated by atomic percentage as: Al 45 at%, Nb 8 at%, Mo 0.5 at%, Si 0.05 at%, C 4 at%, and the balance is Ti and inevitable impurity elements.

[0085] A preparation method of a carbide-reinforced 3D printing titanium-aluminum alloy composite based on the above, and the method for preparing the carbide-reinforced 3D printing titanium-aluminum alloy composite is as follows:

[0086] S1. Carbon nanotube coating: Select the raw materials and process parameters for coating the titanium-aluminum alloy coarse powder. The average particle size of the titanium-aluminum alloy coarse powder is 80 μm; the carbon nanotubes are multi-walled carbon nanotubes with an average diameter of 12 nm and a length of 4 μm; the mass ratio of the titanium-aluminum alloy coarse powder to the carbon nanotubes is 92:8; the grinding balls for high-energy ball milling are zirconia balls with a diameter of 5 mm, and the ball-to-powder ratio of the high-energy ball mill is 8:1; the rotation speed of the high-energy ball mill is 300 rpm, and the ball milling time is 6 h; during high-energy ball milling, the ball milling is stopped for 10 min every 30 min to prevent the equipment from overheating and maintain the structural integrity of the carbon nanotubes. Post-treatment is used to further improve the bonding effect, and mild sintering treatment is carried out under argon protection at a temperature of 600 °C for a holding time of 2 h to further improve the bonding strength between the carbon nanotubes and the titanium-aluminum alloy powder;

[0087] The titanium-aluminum alloy coarse powder and the carbon nanotubes are subjected to high-energy ball milling together by the high-energy ball milling method to obtain the titanium-aluminum alloy coarse powder coated with carbon nanotubes;

[0088] S2. TiC powder coating: Select the raw materials and process parameters for coating the titanium-aluminum alloy fine powder. The average particle size of the titanium-aluminum alloy fine powder is 25 μm; the particle size of the TiC powder is 4.5 μm; the mass ratio of the titanium-aluminum alloy fine powder to the TiC powder is 85:15; the grinding balls for mechanical mixing are zirconia or tungsten carbide balls with a diameter of 8 mm, accounting for 50% of the total volume of the ball milling tank, the vibration frequency is 1400 rpm, the ball-to-powder ratio is 20:1, and the mechanical mixing time is 4 h. Intermittent ball milling or a cooling device is adopted;

[0089] The titanium-aluminum alloy fine powder and the TiC powder are mechanically mixed by the mechanical mixing method to obtain the titanium-aluminum alloy fine powder coated with TiC powder;

[0090] S3. Laser directed energy deposition: The titanium-aluminum alloy coarse powder coated with carbon nanotubes in S1 and the titanium-aluminum alloy fine powder coated with TiC powder in S2 are respectively loaded into two powder barrels for laser directed energy deposition, and the powder feeding parameters are selected according to actual needs for powder feeding and laser directed energy deposition to obtain a deposited sample; among them: the powder feeding rate of the powder barrel loaded with the titanium-aluminum alloy coarse powder coated with carbon nanotubes is 6 g / min, and the powder feeding rate of the powder barrel loaded with the titanium-aluminum alloy fine powder coated with TiC powder is 2 g / min; the laser power of the laser directed energy deposition is 1100 W, the scanning rate is 5 mm / s, and the spot diameter is 3 mm;

[0091] S4, Hot Deformation and Heat Treatment: The sample in the as-deposited state of S3 is subjected to hot isostatic pressing and heat treatment. The heating and holding temperature for hot isostatic pressing is 1270 °C, the pressure is 180 MPa, and the time is 7 h; the heating and holding temperature for heat treatment is 1340 °C, and the time is 3 h, obtaining a carbide-reinforced 3D printed titanium aluminide composite material.

[0092] The metallographic composition of the carbide-reinforced 3D printed titanium aluminide composite material prepared in this example is 69% γ-phase + 6% α2-phase + 25% carbide H-phase. As Figure 4 shown, a large number of carbides are evenly distributed on the titanium aluminide matrix. The types of carbides are Ti2AlC and TiC, and the morphology of the carbides is elliptical.

[0093] In the carbide-reinforced 3D printed titanium aluminide composite material prepared in this example, the shape of the lamellar tissue group is circular, and the average size is 90 μm; the shape of the equiaxed grains around the lamellar group is prototype, and the average size is 6 μm; the shapes of the carbides are elliptical and irregular, and the average size is 10 μm.

[0094] The density of the carbide-reinforced 3D printed titanium aluminide composite material prepared in this example is 4.2 g / cm 3 , the tensile strength is 746 MPa, the yield strength is 637 MPa, the elongation is 1.7%, the tensile strength at 850 °C is 698 MPa, the yield strength is 610 MPa, and the elongation is 12%.

[0095] In the above solution, the present invention provides a carbide-reinforced 3D printed titanium aluminide composite material, which can solve the technical problems existing in the preparation method of the particle-reinforced 3D printed titanium aluminide composite material in the prior art, such as the mixing of titanium powder and aluminum powder, first preparing the reinforcement skeleton and then filling the titanium aluminide powder in the mold for cold pressing, too many process parameters are difficult to regulate, the requirements for the preparation device and regulation accuracy are very high, the temperature gradient in the preparation process causes thermal stress, and the particulate structure is complex and requires special preparation.

[0096] The present invention conducts surface coating modification on titanium aluminide powders with two different particle sizes, and uses the addition and uniform distribution of carbides with different scales to overall strengthen 3D printed titanium aluminide, which can achieve the effect of uniformly strengthening the mechanical properties of all parts of the whole.

[0097] The present invention realizes that the same raw material can simultaneously generate a variety of different compositions, carbides and coating structures by feeding powder from two powder bins at the same time, making the preparation of titanium aluminide more suitable for different performance requirements. The products produced cover all aspects of titanium aluminide. Not only are products with simple shapes easy to produce, but also products with complex shapes are easy to produce, and the production difficulty will not change significantly due to the change of product shape.

[0098] Due to the fact that the solidification rate of the large molten pool in the present invention by laser directed energy deposition is less than that of SLM and EBM, it enables sufficient time for the precipitation of carbides. Therefore, the precipitation is relatively sufficient and the distribution in the melt is also uniform, thereby obtaining an excellent effect of overall strengthening of each part of the material.

[0099] The entire process of the present invention is carried out under argon protection to better avoid the influence of oxidation. For example, the unpacking, weighing, and canning of titanium-aluminum alloy powder and carbon nanotubes all need to be carried out in a glove box to isolate the influence of oxygen. Ball milling is carried out in an argon environment, which effectively prevents the increase of oxygen content during the entire preparation process.

[0100] Through hot isostatic pressing treatment and heat treatment, the present invention can effectively eliminate the printing defects inside the material, that is, eliminate pores and internal stress, and ensure the fatigue performance, mechanical properties and other properties of the material.

[0101] The density of the carbide-reinforced 3D printed titanium-aluminum alloy composite material prepared by the present invention is 3.9 - 4.3 g / cm 3 , the tensile strength is not less than 600 MPa, the yield strength is not less than 400 MPa, the elongation is not less than 1%, the tensile strength at 850 °C is not less than 500 MPa, the yield strength is not less than 300 MPa, and the elongation is not less than 3%.

[0102] In summary, compared with other traditional methods, the method of the present invention creatively conducts surface coating modification on titanium-aluminum alloy powders with two different particle sizes, and transports the surface-coated modified titanium-aluminum alloy powders with different particle sizes through two powder bins simultaneously for laser directed energy deposition to obtain a composite material with uniformly enhanced mechanical properties in each part of the whole; this method has high resource utilization rate, low production cost, short process, easy operation, high efficiency, uniform distribution of carbide-reinforced particles, and is conducive to large-scale industrial production and promotion.

[0103] It should be understood that the term "and / or" in this article is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Among them, A and B can be singular or plural. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after, but it may also represent an "and / or" relationship, which can be specifically understood with reference to the context before and after.

[0104] In the present invention, "at least one" means one or more, and "a plurality of" means two or more. "At least one of the following" or a similar expression means any combination of these items, including any combination of single item(s) or plural item(s). For example, at least one of a, b, or c may represent: a, b, c, a - b, a - c, b - c, or a - b - c, where a, b, and c may be single or plural.

[0105] It should be understood that in various embodiments of the present invention, the magnitudes of the serial numbers of the above - mentioned processes do not imply the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.

[0106] As described above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A carbide-reinforced 3D printed titanium aluminide composite material, characterized in that, The chemical composition of the carbide-reinforced 3D printed titanium aluminide composite material is as follows in atomic percentage: Al 40 - 50 at%, Nb 2 - 10 at%, Mo 0.2 - 1 at%, Si 0.05 - 2 at%, C 0.2 - 5 at%, and the balance is Ti and inevitable impurity elements.

2. The 3D printed titanium-aluminum alloy composite material according to claim 1, characterized in that The metallographic composition of the carbide-reinforced 3D printed titanium aluminide composite material is 60 - 80% γ phase + 1 - 10% α2 phase + 5 - 30% carbide H phase.

3. The carbide-reinforced 3D printed titanium aluminide composite material according to claim 2, characterized in that, The carbide-reinforced 3D printed titanium aluminide composite material contains lamellar tissue, equiaxed grains around the lamellar clusters, and carbides; among them, the shape of the lamellar tissue is circular, with an average size of 50 - 200 μm; the shape of the equiaxed grains around the lamellar clusters is round, with an average size of 1 - 10 μm; the shape of the carbides is elliptical and irregular, with an average size of 5 - 20 μm.

4. The carbide-reinforced 3D printed titanium aluminide composite material according to claim 1, characterized in that, The density of the carbide-reinforced 3D printed titanium aluminide composite material is 3.9 - 4.3 g / cm 3 , the tensile strength is not less than 600 MPa, the yield strength is not less than 400 MPa, the elongation is not less than 1%, and the tensile strength at 850 °C is not less than 500 MPa, the yield strength is not less than 300 MPa, and the elongation is not less than 3%.

5. A method for preparing a carbide-reinforced 3D printing titanium aluminide composite material according to claim 1, characterized in that, The method for the carbide-reinforced 3D printed titanium aluminide composite material is as follows: S1. Carbon nanotube coating: The coarse titanium aluminide powder and carbon nanotubes are subjected to high-energy ball milling together by high-energy ball milling method to obtain the coarse titanium aluminide powder coated with carbon nanotubes. S2. TiC powder coating: The fine titanium aluminide powder and TiC powder are mechanically mixed by mechanical mixing method to obtain the fine titanium aluminide powder coated with TiC powder. S3. Laser directed energy deposition: The coarse titanium aluminide powder coated with carbon nanotubes in S1 and the fine titanium aluminide powder coated with TiC powder in S2 are respectively loaded into two powder barrels for laser directed energy deposition. Select the powder feeding parameters according to actual needs for powder feeding and laser directed energy deposition to obtain a deposited sample. S4. Hot deformation and heat treatment: The deposited sample in S3 is subjected to hot isostatic pressing and heat treatment to obtain the carbide-reinforced 3D printed titanium aluminide composite material.

6. The preparation method of the carbide-reinforced 3D printed titanium aluminide composite material according to claim 5, characterized in that, In S1, the average particle size of the coarse titanium aluminide powder is 50 - 150 μm; the carbon nanotubes are multi-walled carbon nanotubes with an average diameter of 10 - 20 nm and a length of 1 - 10 μm; the mass ratio of the coarse titanium aluminide powder to the carbon nanotubes is 90 - 98:10 - 2; the grinding balls for high-energy ball milling are stainless steel balls or zirconia balls with a diameter of 5 - 10 mm, and the ball-to-powder ratio of the high-energy ball mill is 10 - 8:

1.

7. The preparation method of the carbide-reinforced 3D printed titanium aluminide composite material according to claim 5, characterized in that, In S1, the rotation speed of high-energy ball milling is 300 - 400 rpm, and the ball milling time is 4 - 8 h; during high-energy ball milling, the ball milling is stopped for 10 min every 30 min, and mild sintering treatment is carried out under argon protection at a temperature of 500 - 600 °C for a holding time of 1 - 2 h.

8. The preparation method of the carbide-reinforced 3D printed titanium aluminide composite material according to claim 5, characterized in that, In S2, the average particle size of the fine titanium aluminide powder is 10 - 50 μm; the particle size of the TiC powder is 1 - 10 μm; the mass ratio of the fine titanium aluminide powder to the TiC powder is 85:15 - 95:5; the grinding balls for mechanical mixing are zirconia or tungsten carbide balls with a diameter of 3 - 10 mm, accounting for 50 - 60% of the total volume of the ball mill tank, the vibration frequency is 1000 - 1500 rpm, the ball-to-powder ratio is 10:1 - 20:1, and the mechanical mixing time is 2 - 4 h. Intermittent ball milling or a cooling device is used.

9. The preparation method of the carbide-reinforced 3D printed titanium aluminide composite material according to claim 5, characterized in that, In S3, the powder supply rate of the powder bucket loaded with the titanium aluminum alloy coarse powder coated with carbon nanotubes is 3 - 7 g / min, and the powder supply rate of the powder bucket loaded with the titanium aluminum alloy fine powder coated with TiC powder is 0.5 - 2 g / min; the laser power of laser directed energy deposition is 800 - 1200 W, the scanning rate is 6 - 12 mm / s, and the spot diameter is 2 - 4 mm.

10. The preparation method of the carbide-reinforced 3D printed titanium aluminide composite material according to claim 5, characterized in that, In S4, the heating and holding temperature of hot isostatic pressing is 1140 - 1300 °C, the pressure is 140 - 190 MPa, and the time is 3 - 8 h; the heating and holding temperature of heat treatment is 1240 - 1340 °C, and the time is 0.5 - 4 h.

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