High-entropy alloy composite material and preparation method thereof

Abstract

The invention provides a high-entropy alloy composite material and a preparation method thereof. Through reasonable component design, a nano precipitated phase is induced to be formed in a B2 phase, and meanwhile, the core-shell structure ceramic particles are synthesized through an in-situ reaction; the ceramic particles are of a double-layer structure with an Al2O3 core of an orthogonal crystal structure and TiC of a face-centered cubic crystal structure as a shell. According to the TiC-FCC composite material and the preparation method thereof, the TiC-FCC composite material has the advantages that the TiC-FCC composite material and a matrix interface are clean and good in combination, a # imgabs 0 # imgabs 1 # and [101] FCC / / [110] TiC orientation relation is formed by a shell TiC and an FCC phase, the crystal face mismatch degree is only 2.2%, and due to the coherent interface, stress concentration in the deformation process is effectively relieved, and the cooperative deformation capacity is improved; compared with an original AlCoCrFeNi2.1 high-entropy alloy, the prepared high-entropy alloy composite material has the advantages that the compression yield strength is improved by 60.6%, the plasticity is slightly reduced, and the engineering application range is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of alloy materials, and particularly relates to a high-entropy alloy composite material and a preparation method thereof. Background Art

[0002] Due to the well-known four core effects, high-entropy alloys have received extensive attention in the academic and industrial fields due to their excellent corrosion resistance and outstanding oxidation resistance. AlCoCrFeNi 2.1 As a new generation of high-entropy alloy with non-equiatomic ratio, AlCoCrFeNi high-entropy alloy has become a very promising candidate material for engineering applications in the fields of energy industry, aviation, aerospace, etc. due to its good castability and the ability to obtain a good balance of strength and toughness. The yield strength of the traditional AlCoCrFeNi high-entropy alloy produced by the casting method is less than 800 MPa, which is not enough to meet the performance requirements of structural materials. 2.1 The yield strength of the AlCoCrFeNi high-entropy alloy is less than 800 MPa and is not sufficient to meet the performance requirements of structural materials.

[0003] Based on the defects existing in the preparation of current high-entropy alloy materials, it is necessary to improve them. Summary of the Invention

[0004] The purpose of the present invention is to provide a high-entropy alloy composite material and a preparation method thereof for the problems and deficiencies existing in the prior art; in this method, AlCoCrFeNi alloy powder, Ti powder, and Cr3C2 powder are synchronously transported to the molten pool formed by the laser through three-channel coaxial powder feeding, and a novel ceramic particle-reinforced high-entropy alloy composite material with a core-shell structure is synthesized by in-situ reaction under preset process conditions. 2.1 To achieve the above purpose, the present invention adopts the following technical solutions:

[0005] In the first aspect, the present invention provides a preparation method of a high-entropy alloy composite material, including the following steps:

[0006] Using the laser directed energy deposition method, AlCoCrFeNi alloy powder, Ti powder, and Cr3C2 powder are synchronously fed into the molten pool formed by the laser by a three-channel powder feeder, and the three powders are melted and deposited on the surface of the substrate to obtain a high-entropy alloy composite material.

[0007] Preferably, during laser directed energy deposition, after each deposition layer is temporarily stopped and the temperature of the deposition layer is cooled to 280 - 300 °C, the laser focus is raised by 1.0 - 1.3 mm and then the next layer is deposited, and so on until the deposition thickness reaches the set value. 2.1 Preferably, during laser directed energy deposition, after each deposition layer is temporarily stopped and the temperature of the deposition layer is cooled to 280 - 300 °C, the laser focus is raised by 1.0 - 1.3 mm and then the next layer is deposited, and so on until the deposition thickness reaches the set value.

[0008] Preferably, during laser directed energy deposition, after each deposition layer is temporarily stopped and the temperature of the deposition layer is cooled to 280 - 300 °C, the laser focus is raised by 1.0 - 1.3 mm and then the next layer is deposited, and so on until the deposition thickness reaches the set value.

[0009] Preferably, the process parameters controlled for each deposited layer during laser directed energy deposition are as follows: the laser power is 1500 - 2500 W, the scanning speed is 10 - 16 mm / s, the spot diameter is 3 - 4 mm, and the scanning interval is 1.5 - 2.0 mm.

[0010] Preferably, a three-channel powder feeder is used to synchronously feed AlCoCrFeNi 2.1 alloy powder, Ti powder, and Cr3C2 powder into the molten pool formed by the laser. In this step, the powder feeding speed of the AlCoCrFeNi 2.1 alloy powder is 10 - 12 g / min, the powder feeding speed of the Ti powder is 0.5 - 0.8 g / min, and the powder feeding speed of the Cr3C2 powder is 0.5 - 0.8 g / min.

[0011] Preferably, the particle size of the AlCoCrFeNi 2.1 alloy powder is 50 - 150 μm;

[0012] the particle size of the Ti powder is 50 - 150 μm;

[0013] the particle size of the Cr3C2 powder is 50 - 150 μm.

[0014] Preferably, before melting and depositing the three powders on the substrate surface, surface pretreatment of the substrate is also included. The pretreatment includes:

[0015] Washing the substrate surface with ethanol, and then polishing the substrate surface with 400 - 1000 mesh sandpaper.

[0016] Preferably, before synchronously feeding the AlCoCrFeNi 2.1 alloy powder, Ti powder, and Cr3C2 powder into the molten pool formed by the laser, drying the AlCoCrFeNi 2.1 alloy powder, Ti powder, and Cr3C2 powder at 100 - 120 °C is also included.

[0017] In a second aspect, the present invention also provides a high-entropy alloy composite material prepared by using the described preparation method.

[0018] The high-entropy alloy composite material and its preparation method of the present invention have the following beneficial effects compared with the prior art:

[0019] The preparation method of the high-entropy alloy composite material of the present invention. The preparation method of the high-entropy alloy composite material of the present invention has the following advantages compared with the prior art:

[0020] 1. Through reasonable composition design (raw materials and their mass ratios), nano-precipitates are induced to form in the B2 phase, and at the same time, "core-shell" structure ceramic particles are synthesized by in-situ reaction. The ceramic particles have a double-layer structure with an Al2O3 core of orthorhombic crystal structure and a TiC shell of face-centered cubic crystal structure. The interface between the ceramic particles and the matrix is clean and well-bonded;

[0021] 2. The shell layer TiC of the "core-shell" structure ceramic particles forms and

[101] FCC / /

[110] TiC orientation relationship, and the lattice misfit degree is only 2.2%. This coherent interface effectively reduces the stress concentration during the deformation process and improves the co-deformation ability. Compared with the AlCoCrFeNi 2.1 high-entropy alloy, the compressive yield strength of the prepared high-performance high-entropy alloy composite material is increased by 60.6%, while the plasticity only decreases slightly, which is beneficial to expanding the scope of engineering applications;

[0022] 3. Compared with the traditional methods such as post-forming heat treatment and deformation, the laser directed energy deposition method is adopted. Through a short process synthesis process, the preparation of all high-performance composite materials can be completed in only one step, with extremely high production efficiency. Based on the advantages of the laser directed energy deposition method, relying on the multi-material synchronous powder feeding system and precise control of the melt pool composition, combined with the present invention, the continuous gradient distribution of material composition and mechanical properties can be realized, solving the key problems such as low interfacial bonding strength and thermal stress concentration of heterogeneous materials, and having important economic value and application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts based on these drawings.

[0024] Figure 1 It is the scanning electron microscope image of the high-entropy alloy composite material prepared in Example 1;

[0025] Figure 2 It is the morphology and element distribution map observed by transmission electron microscope of the high-entropy alloy composite material prepared in Example 1;

[0026] Figure 3 It is Figure 2 the scanning result map of Al element marked by the green line in

[0027] Figure 4 It is Figure 2Scanning result diagram of O element marked by green line;

[0028] Figure 5 is Figure 2 Scanning result diagram of Ti element marked by green line;

[0029] Figure 6 is Figure 2 Scanning result diagram of C element marked by green line;

[0030] Figure 7 is the selected area electron diffraction spot diagram corresponding to each phase in the high-entropy alloy composite material prepared in Example 1;

[0031] Figure 8 is the selected area electron diffraction spot diagram of the interface between FCC and TiC in the high-entropy alloy composite material prepared in Example 1;

[0032] Figure 9 is the compressive stress-strain curve diagram of the high-entropy alloy composite materials prepared in Example 1 and Comparative Example 1;

[0033] Figure 10 is the bright-field image obtained by transmission electron microscopy of the high-entropy alloy composite material prepared in Comparative Example 1. Detailed implementation manners

[0034] Next, in combination with the implementation manners of the present invention, the technical solutions in the implementation manners of the present invention will be clearly and completely described. Obviously, the described implementation manners are only a part of the implementation manners of the present invention, rather than all of the implementation manners. Based on the implementation manners in the present invention, all other implementation manners obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] In the description of the present invention, it should be understood that the relationships indicating orientations or positions such as "upper" are based on the orientations or positions shown in the drawings, or the orientations or positions in which the product of the present invention is usually placed during use, or the orientations or positions commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0036] The description order of the following embodiments does not limit the preferred order of the embodiments. Additionally, in the description of this application, the term "comprising" means "including but not limited to". The various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0037] An embodiment of the present application provides a method for preparing a high-entropy alloy composite material, comprising the following steps:

[0038] Using the laser directed energy deposition method, an AlCoCrFeNi 2.1 alloy powder, a Ti powder, and a Cr3C2 powder are synchronously fed into the molten pool formed by the laser by means of a three-channel powder feeder, and the three powders are melted and deposited on the surface of the substrate to obtain a high-entropy alloy composite material.

[0039] The method for preparing the high-entropy alloy composite material of the present invention uses the laser directed energy deposition method and synchronously transports an AlCoCrFeNi 2.1 alloy powder, a Ti powder, and a Cr3C2 powder into the molten pool formed by the laser through three-channel coaxial powder feeding, and a novel core-shell structure ceramic particle-reinforced high-entropy alloy composite material is synthesized by in-situ reaction under preset process conditions; the high-entropy alloy composite material prepared by the present invention mainly contains four phases, namely, the FCC phase (face-centered cubic structure), the B2 phase (ordered body-centered cubic structure), and core-shell structure ceramic particles (containing TiC and Al2O3); in the core-shell structure ceramic particles, Al2O3 with an orthorhombic crystal structure is used as the core layer, and TiC with a face-centered cubic crystal structure is used as the shell layer; additionally, a large number of short rod-shaped nanoparticles rich in Cr elements precipitate in the B2 phase. The high-entropy alloy composite material of the present invention has a compressive yield strength exceeding 1 GPa and good plasticity, and the core-shell structure ceramic particles in the material are evenly distributed and have good bonding with the matrix composed of FCC and BCC.

[0040] Specifically, the alloy system of the present invention mainly contains Al, Co, Cr, Fe, Ni, Ti, C, and trace amounts of O elements. Among them, Al has the strongest reducibility and is prone to in-situ reaction with O atoms to form Al2O3, and the reaction formula is: 2Al + 3O = Al2O3;

[0041] Since the melting point of Cr3C2 is only about 1810 °C, while the temperature of the molten pool formed by the process adopted in the present invention exceeds 3000 °C, the added Cr3C2 powder completely melts in the molten pool and releases C atoms; in this alloy system, there is the lowest binding enthalpy between C and Ti atom pairs, so the two are easy to combine to form a stable compound. The C atoms react in-situ with the added Ti atoms to form TiC; the reaction formula is: Ti + C = TiC.

[0042] The laser directed energy deposition technology of the present invention uses a high-energy density laser beam as a heat source to heat raw materials such as metal powders or wires to a molten state, and under computer control, layer by layer deposits the molten material on the substrate according to a pre-designed path and manner, and finally forms a three-dimensional solid part through layer-by-layer stacking. During the deposition process, the energy of the laser beam is highly concentrated, which can quickly melt and solidify the material, realizing precise material addition and forming. At the same time, the computer control system can precisely control parameters such as the scanning path, power, and scanning speed of the laser beam, as well as the feeding speed of the powder feeding or wire feeding system, so as to ensure that the shape, size, and performance of the deposited material meet the design requirements.

[0043] In some embodiments, during laser directed energy deposition, after each deposited layer is temporarily stopped and the temperature of the deposited layer is cooled to 280 - 300 °C, the laser focus is raised by 1.0 - 1.3 mm and then the next layer is deposited, and so on in a cycle until the deposition thickness reaches the set value.

[0044] In some embodiments, the process parameters controlled for each deposited layer during laser directed energy deposition are: the laser power is 1500 - 2500 W, the scanning speed is 10 - 16 mm / s, the spot diameter is 3 - 4 mm, and the scanning interval is 1.5 - 2.0 mm.

[0045] In some embodiments, a three-channel powder feeder is used to synchronously send AlCoCrFeNi 2.1 alloy powder, Ti powder, and Cr3C2 powder to the molten pool formed by the laser. In this step, the powder feeding speeds of each channel are adjusted so that the powder feeding speed of the AlCoCrFeNi2.1 alloy powder is 10 - 12 g / min, the powder feeding speed of the Ti powder is 0.5 - 0.8 g / min, and the powder feeding speed of the Cr3C2 powder is 0.5 - 0.8 g / min.

[0046] In some embodiments, the particle size of the AlCoCrFeNi 2.1 alloy powder is 50 - 150 μm;

[0047] The particle size of the Ti powder is 50 - 150 μm;

[0048] The particle size of the Cr3C2 powder is 50 - 150 μm.

[0049] In some embodiments, before melting and depositing the three powders on the substrate surface, it further includes pre-treating the substrate surface, and the pre-treatment includes:

[0050] Washing the substrate surface with ethanol, and then polishing the substrate surface with 400-1000 mesh sandpaper.

[0051] In some embodiments, before synchronously feeding the AlCoCrFeNi 2.1 alloy powder, Ti powder, and Cr3C2 powder into the molten pool formed by the laser, it further includes drying the AlCoCrFeNi 2.1 alloy powder, Ti powder, and Cr3C2 powder at 100-120 °C respectively.

[0052] In some embodiments, the substrate includes a substrate made of carbon steel or alloy steel.

[0053] In some embodiments, a method for preparing a high-entropy alloy composite material includes the following steps:

[0054] S1. Cut a metal substrate made of carbon steel or alloy steel into the required size, then wash the substrate surface with ethanol to remove surface oil stains, and polish the substrate surface flat with 400-mesh, 800-mesh, and 1000-mesh sandpapers respectively;

[0055] S2. Place the AlCoCrFeNi 2.1 powder with a particle size of 50-150 μm, Ti powder with a particle size of 50-150 μm, and Cr3C2 powder with a particle size of 50-150 μm in a vacuum drying oven and dry them at 100-120 °C for 2-3 h;

[0056] S3. Use a three-channel powder feeder to synchronously feed the three powders into the molten pool formed by the laser; adjust the powder feeding speed of each channel so that the powder feeding speed of the AlCoCrFeNi 2.1 alloy powder is 10-12 g / min, the powder feeding speed of Ti powder is 0.5-0.8 g / min, and the powder feeding speed of Cr3C2 powder is 0.5-0.8 g / min;

[0057] S4. Use laser directed energy deposition technology to melt and deposit the raw materials on the substrate surface under preset process parameters to form a high-entropy alloy composite material; pause for a period of time after each deposition layer, wait for the temperature of the deposition layer to cool to 280-300 °C, then raise the laser focus by 1.2-1.3 mm and deposit the next layer, and repeat this process until the required size and thickness are reached; the process parameters are a laser power of 1500-2500 W, a scanning speed of 10-16 mm / s, a spot diameter of 3-4 mm, and a scanning interval of 1.5-2 mm.

[0058] In some embodiments, the AlCoCrFeNi of the present invention 2.1 powder is prepared by existing conventional processes. For example, it is prepared by the following method:

[0059] S1. Mix and melt the elemental particles of Al, Co, Cr, Fe, and Ni according to the molar ratio of 1:1:1:1:2.1 for the preparation of the raw powder of the high-entropy alloy. During the melting process, turn it over to make the mixture uniform, so as to make the composition distribution uniform and produce a pre-alloyed ingot for preparing the powder.

[0060] S2. Prepare the AlCoCrFeNi 2.1 alloy powder from the alloy ingot in step S1 by gas atomization method. The specific operation steps are as follows: Generate high-pressure and high-speed argon through the atomization nozzle, quickly impact the molten metal stream, crush the molten metal stream into very fine droplets and quickly condense to obtain fine metal powder. Then place the obtained powder in a drying oven and dry it at 80 °C for 5 h to remove residual moisture, and obtain the AlCoCrFeNi 2.1 powder.

[0061] For the preparation method of the high-entropy alloy composite material of the present invention, compared with the prior art, the present invention has the following advantages:

[0062] (1) Through reasonable composition design, nano-precipitates are induced to form in the B2 phase (i.e., the short rod-shaped nano-particles rich in Cr element mentioned above), and at the same time, "core-shell" structure ceramic particles are synthesized by in-situ reaction. The ceramic particles have a double-layer structure with an Al2O3 core of orthorhombic crystal structure and a TiC shell of face-centered cubic crystal structure. The interface between the ceramic particles and the matrix is clean and well-bonded.

[0063] (2) The shell layer TiC of the "core-shell" structure ceramic particles forms and

[101] FCC / /

[110] TiC orientation relationship, and the lattice misfit degree is only 2.2%. This coherent interface effectively reduces the stress concentration during the deformation process and improves the co-deformation ability; compared with the AlCoCrFeNi 2.1 high-entropy alloy, the compressive yield strength of the prepared high-performance high-entropy alloy composite material is increased by 60.6%, while the plasticity only decreases slightly, which is beneficial to expanding the scope of engineering applications.

[0064] (2) Compared with traditional methods such as post - forming heat treatment and deformation, the laser directed energy deposition method can complete the preparation of all high - performance composite materials in only one step through a short - process synthesis process, with extremely high production efficiency. Based on the advantages of the laser directed energy deposition method, relying on the multi - material synchronous powder feeding system and precise control of the melt pool composition, combined with the present invention, it is possible to achieve a continuous gradient distribution of material composition and mechanical properties, solve key problems such as low interfacial bonding strength and thermal stress concentration of heterogeneous materials, and has important economic value and application potential.

[0065] Based on the same inventive concept, the present invention also provides a high - entropy alloy composite material prepared by the above - mentioned preparation method.

[0066] The following further illustrates the high - entropy alloy composite material and its preparation method of the present application with specific examples. This part further illustrates the content of the present invention in combination with specific examples, but should not be construed as a limitation to the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well - known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0067] In the following examples and comparative examples, the preparation method of AlCoCrFeNi 2.1 powder is as described above.

[0068] Example 1

[0069] This example provides a preparation method of a high - entropy alloy composite material, including the following steps:

[0070] S1. Cut the metal substrate made of carbon steel into the required size, then wash the surface of the substrate with ethanol to remove surface oil stains, and polish the surface of the substrate flat with 400 - mesh, 800 - mesh, and 1000 - mesh sandpapers respectively;

[0071] S2. Place the AlCoCrFeNi 2.1 powder with an average particle size of 100μm, Ti powder with an average particle size of 100μm, and Cr3C2 powder with an average particle size of 100μm in a vacuum drying oven and dry them at 120°C for 2h;

[0072] S3. Use a three - channel powder feeder to synchronously feed the three kinds of powders into the melt pool formed by the laser; use high - purity argon as the powder - carrying gas, and adjust the gas flow rate of each channel so that the powder feeding speed of the AlCoCrFeNi 2.1 alloy powder is 11g / min, the powder feeding speed of Ti powder is 0.7g / min, and the powder feeding speed of Cr3C2 powder is 0.7g / min;

[0073] S4. Using the laser directed energy deposition technique, the raw materials are melted and deposited on the surface of the substrate under preset process parameters to form a high-entropy alloy composite material (size: 25 mm × 25 mm × 12 mm, that is, the length is 25 mm, the width is 25 mm, and the thickness is 12 mm); pause for a period of time after each layer is deposited. After the temperature of the deposited layer cools to 300 °C, raise the laser focus by 1.2 mm and then deposit the next layer, and so on until the required size and thickness are reached; the process parameters used are a laser power of 1650 W, a scanning speed of 12 mm / s, a spot diameter of 3 mm, a scanning interval of 1.7 mm, and a deposition thickness of 1.2 mm for each layer.

[0074] Comparative Example 1

[0075] This comparative example provides a method for preparing a high-entropy alloy composite material. The same as Example 1, the difference is that it does not contain Ti powder and Cr3C2 powder, and specifically includes the following steps:

[0076] S1. Cut the metal substrate made of carbon steel into the required size, and then wash the surface of the substrate with ethanol to remove surface oil stains. Polish the surface of the substrate with 400-mesh, 800-mesh, and 1000-mesh sandpapers respectively;

[0077] S2. Place the AlCoCrFeNi 2.1 powder with an average particle size of 100 μm in a vacuum drying oven and dry it at 120 °C for 2 h;

[0078] S3. Use a single-channel powder feeder to send the AlCoCrFeNi 2.1 powder into the molten pool formed by the laser; use high-purity argon as the powder-carrying gas, and adjust the single-channel gas flow rate so that the powder feeding speed of the AlCoCrFeNi 2.1 alloy powder is 11 g / min;

[0079] S4. Using the laser directed energy deposition technique, the AlCoCrFeNi 2.1 powder is melted and deposited on the surface of the substrate under preset process parameters to form a high-entropy alloy composite material (size: 25 mm × 25 mm × 12 mm, that is, the length is 25 mm, the width is 25 mm, and the thickness is 12 mm); pause for a period of time after each layer is deposited. After the temperature of the deposited layer cools to 300 °C, raise the laser focus by 1.2 mm and then deposit the next layer, and so on until the required size and thickness are reached; the process parameters used are a laser power of 1650 W, a scanning speed of 12 mm / s, a spot diameter of 3 mm, a scanning interval of 1.7 mm, and a deposition thickness of 1.2 mm for each layer.

[0080] Performance Characterization

[0081] Figure 1Scanning electron microscope image of the high-entropy alloy composite prepared in Example 1.

[0082] The microstructure of the high-entropy alloy composite was observed by scanning electron microscope. It can be seen from Figure 1 that the microstructure of the high-entropy alloy composite prepared in Example 1 consists of FCC phase, B2 phase and uniformly distributed "core-shell" structure particles. The "core-shell" structure is composed of a gray-black shell (identified as TiC) surrounding a bright white circular core (identified as Al2O3). At the same time, a large number of short rod-shaped nano-precipitated particles can also be seen in the B2 phase.

[0083] For the high-entropy alloy composite prepared in Example 1, transmission electron microscope was used for morphology observation, element distribution test and selected area electron diffraction test to analyze and characterize the phase composition, phase crystal structure and element distribution of the composite. The results are as Figures 2 - 8 shown.

[0084] Similar to the structure observed under scanning electron microscope, the morphology and element distribution of the high-entropy alloy composite observed by transmission electron microscope are as Figure 2 shown, and also contain the above-mentioned FCC phase, B2 phase and "core-shell" structure particles.

[0085] Figures 3 - 6 is Figure 2 the scanning result diagram of Al, O, Ti, C elements marked by the green line in

[0086] Figure 2 The element surface distribution diagram in Figures 3 - 6 and the element line scanning result of

[0087] Figure 7 show that the "core" mainly contains Al and O elements (atomic ratio close to 2:3), and the "shell" mainly contains Ti and C elements (atomic ratio close to 1:1).

[0088] Figure 8 is the selected area electron diffraction spot diagram corresponding to each phase in the high-entropy alloy composite prepared in Example 1.

[0089] According to Figure 7 the selected area electron diffraction spots of each phase, the crystal structures of each phase can be accurately identified respectively. It is identified that TiC in the core-shell structure is face-centered cubic structure, while Al2O3 is orthorhombic structure.

[0090] Analysis of the TiC and FCC interface found that TiC and FCC phase form and

[101] FCC / /

[110] TiCOrientation relationship ( Figure 8 ), and the high-resolution results show that the crystal plane mismatch degree between the two is only 2.2%. This interface effectively alleviates the stress concentration at the interface during deformation, not only improving the strength but also enhancing the co-deformation ability, which is beneficial to maintaining good plasticity.

[0091] Figure 9 Figure 6 is the compressive stress-strain curve obtained by using a universal material testing machine for the high-entropy alloy composites prepared in Example 1 and Comparative Example 1. Specifically, the prepared high-entropy alloy composites were subjected to a compression experiment on a universal electronic mechanical testing machine, and the compression strain rate was 1×10 -3 / s. During the compression process, an electronic extensometer with a sampling frequency of 60 SPS (i.e., 60 samples were collected per second) and an accuracy of 0.001 mm was used to monitor the strain generated by the specimen during compression in real time. Figure 9 In the figure, the example is the high-entropy alloy composite prepared in Example 1, and the comparative example in the figure is the high-entropy alloy composite prepared in Comparative Example 1.

[0092] As can be seen from Figure 9 , for the high-entropy alloy composite prepared in Example 1, its yield strength and fracture strength are 1226.8 MPa and 2909.2 MPa respectively, and the fracture strain is 28.8%. However, the strength of the AlCoCrFeNi 2.1 alloy prepared in Comparative Example 1 decreased significantly. Compared with Comparative Example 1, the compression yield strength of the high-entropy alloy composite prepared in Example 1 increased by 60.6%, while the plasticity only decreased slightly.

[0093] Figure 10 Figure 21 is the bright-field image obtained by transmission electron microscopy of the high-entropy alloy composite prepared in Comparative Example 1.

[0094] As can be seen from Figure 10 , for the high-entropy alloy composite AlCoCrFeNi 2.1 prepared in Comparative Example 1, no "core-shell" structure was formed, nor were nanoparticles precipitated.

[0095] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a high entropy alloy composite material, characterized in that: The following steps are involved: Using laser directed energy deposition method, AlCoCrFeNi 2.1 Alloy powder, Ti powder and Cr3C2 powder are simultaneously sent to a molten pool formed by a laser, and the three powders are melted and deposited on the surface of a substrate to obtain a high entropy alloy composite material.

2. The method for preparing a high entropy alloy composite material according to claim 1, characterized in that: During laser directed energy deposition, after pausing after each layer is deposited, wait for the temperature of the deposited layer to cool to 280-300°C, then raise the laser focus by 1.0-1.3mm and deposit the next layer, and repeat this cycle until the deposition thickness reaches the set value.

3. The method for preparing a high entropy alloy composite material according to claim 1, characterized in that: The process parameters controlled for each layer of laser directed energy deposition are: laser power of 1500-2500W, scanning speed of 10-16mm / s, spot diameter of 3-4mm, and scanning interval of 1.5-2.0mm.

4. The method for preparing a high entropy alloy composite material according to claim 1, characterized in that: A three-channel powder feeder was used to feed AlCoCrFeNi 2.1 In the step of simultaneously feeding alloy powder, Ti powder and Cr3C2 powder into the molten pool formed by laser, AlCoCrFeNi 2.1 The feeding speed of alloy powder is 10-12 g / min, the feeding speed of Ti powder is 0.5-0.8 g / min, and the feeding speed of Cr3C2 powder is 0.5-0.8 g / min.

5. The method for preparing a high entropy alloy composite material according to claim 1, characterized in that: The AlCoCrFeNi 2.1 The particle size of the alloy powder is 50 to 150 μm; The particle size of the Ti powder is 50 to 150 μm; The particle size of the Cr3C2 powder is 50-150 μm.

6. The method for preparing a high entropy alloy composite material according to claim 1, characterized in that: Before melting and depositing the three powders on the substrate surface, the substrate surface is pre-treated, and the pre-treatment includes: The substrate surface was washed with ethanol, and then polished with 400-1000 grit sandpaper.

7. The method for preparing a high entropy alloy composite material according to claim 1, characterized in that: AlCoCrFeNi 2.1 Before the alloy powder, Ti powder and Cr3C2 powder are simultaneously sent to the molten pool formed by the laser, AlCoCrFeNi 2.1 The alloy powder, Ti powder and Cr3C2 powder are dried at 100-120°C.

8. A high entropy alloy composite material, characterized in that: The preparation method is as described in any one of claims 1 to 7.

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