TiC-reinforced high-entropy alloy-based wear-resistant composite material based on three-dimensional continuous structure and preparation method thereof

Abstract

The invention provides an AlCoCrFeNi2.1-based wear-resistant composite material based on three-dimensional continuous TiC reinforcement and a preparation method of the AlCoCrFeNi2.1-based wear-resistant composite material, and belongs to the technical field of wear-resistant composite materials. Core-shell structure powder is constructed through a physical crosslinking reaction, the surfaces of AlCoCrFeNi2.1 eutectic high-entropy alloy matrix particles are evenly coated with TiC, and the AlCoCrFeNi2.1-based wear-resistant composite material is obtained; and then a spark plasma sintering method is used for controlling TiC to be distributed in the AlCoCrFeNi2.1 eutectic high-entropy alloy in a controllable three-dimensional continuous net shape. The construction of the three-dimensional continuous structure of the AlCoCrFeNi2.1-based wear-resistant composite material improves the wide-temperature-range wear-resistant characteristic of the high-entropy alloy-based composite material, and has a wide application prospect in the field of wear-resistant materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of wear-resistant composite materials, and particularly relates to a high-entropy alloy-based wear-resistant composite material reinforced by three-dimensional continuous structure TiC and a preparation method thereof. Background Art

[0002] With the development of modern industrial equipment towards high efficiency, stability and long-term operation, the service conditions of wear-resistant materials have become increasingly harsh, such as high temperature, high speed, high pressure and heavy load, etc. However, due to their own limitations, traditional single materials are difficult to meet the harsh, complex and changeable service conditions. For example, metal materials inevitably have a sharp drop in strength due to high-temperature softening, and ceramic materials are extremely prone to catastrophic failures such as fracture and fragmentation under high temperature and external load impact. Therefore, it is urgent to develop new wear-resistant composite materials with good anti-wear functions in a wide temperature range.

[0003] High-entropy alloys are new alloys developed in the past ten years. Their unique four core effects make high-entropy alloys exhibit better mechanical properties, wear resistance and good high-temperature oxidation resistance than traditional alloys. Therefore, high-entropy alloys have become promising candidate materials for reducing damage and energy loss caused by wear in extreme environments. On this basis, it is imperative to develop high-entropy alloy-based wear-resistant composite materials to further improve their wear resistance and meet the comprehensive service performance requirements in extreme environments.

[0004] At present, most of the research on high-entropy alloy-based wear-resistant composite materials is to directly and homogenously add various ceramic reinforcing particles to high-entropy alloys to improve their wear resistance. However, when the content of the reinforcing phase is too high, it is easy to induce crack initiation. At the same time, due to the poor interfacial bonding between ceramic particles and the alloy matrix, the peeling of ceramic particles during wear may deteriorate the wear resistance of the material. By regulating the spatial distribution state of the reinforcing phase so that the ceramic reinforcing phase is distributed in a three-dimensional continuous structure, the initiation of cracks and the peeling of particles during friction can be effectively inhibited, which helps to give full play to the load-bearing and anti-wear effects of the reinforcing phase to a greater extent.

[0005] Therefore, it is urgent to develop a method for constructing a three-dimensional continuous structure of a new high-entropy alloy-based wear-resistant composite material, control the reinforcing phase to be distributed in a controllable three-dimensional continuous network in the alloy matrix, break through the limitations of current wear-resistant materials, and provide a simple, economical and practical method for preparing wear-resistant composite materials with excellent comprehensive properties. Summary of the Invention

[0006] To solve the above technical problems, the present invention proposes a high-entropy alloy-based wear-resistant composite material reinforced by three-dimensional continuous TiC and a preparation method thereof. By means of a physical cross-linking reaction, a core-shell structure powder is constructed, so that the TiC powder is uniformly coated on the surface of the high-entropy alloy matrix particles, and the discharge plasma sintering method is used to control TiC in AlCoCrFeNi 2.1It is distributed in a controllable three-dimensional continuous network in the eutectic high-entropy alloy, giving full play to the load-bearing and anti-wear effects of the reinforcing phase, thereby improving the wear resistance of the composite material in a wide temperature range.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A kind of AlCoCrFeNi-based wear-resistant composite material reinforced by three-dimensional continuous TiC 2.1 mainly constructs a core-shell structure powder through a physical cross-linking reaction, so that the TiC powder is uniformly coated on the surface of the AlCoCrFeNi 2.1 eutectic high-entropy alloy matrix particles, and then uses the spark plasma sintering method to control the three-dimensional continuous network distribution of TiC in the AlCoCrFeNi 2.1 eutectic high-entropy alloy.

[0009] The TiC powder is irregular particles with a particle size of 40 nm, and the powder particles of the AlCoCrFeNi 2.1 eutectic high-entropy alloy are spherical particles with a particle size of 15 - 53 μm.

[0010] The above-mentioned AlCoCrFeNi-based wear-resistant composite material reinforced by three-dimensional continuous TiC 2.1 its preparation method includes the following steps:

[0011] (1) Powder surface modification: Add a certain amount of spherical AlCoCrFeNi 2.1 eutectic high-entropy alloy powder into a polyvinyl alcohol (PVA) solution, and stir magnetically for 40 min, thereby modifying PVA (AlCoCrFeNi 2.1 @PVA) on the surface of the high-entropy alloy particles; add a certain amount of nano-TiC powder into a sodium carboxymethyl cellulose (CMC-Na) solution, and stir magnetically for 40 min, thereby modifying CMC-Na (TiC@CMC-Na) on the surface of the TiC powder; then filter out the excess PVA solution and CMC-Na solution, wash with deionized water, put it into an oven for drying, crushing and sieving to obtain the AlCoCrFeNi 2.1 @PVA powder and TiC@CMC-Na powder surface-modified with PVA and CMC-Na respectively.

[0012] (2) Wet ball milling and mixing: Wet mill the AlCoCrFeNi 2.1 @PVA and TiC@CMC-Na powders obtained in step (1) in an acetone solution, with a ball-to-material ratio of 5:1, a rotation speed of 180 rpm / min, ball mill for 5 min, pause for 2 min to cool down, and use this as a ball milling cycle, with a total ball milling time of 418 min.

[0013] (3) Powder treatment before sintering: Filter the liquid after wet milling and mixing in step (2), dry it at room temperature for 6 - 10 h, and sieve it after complete drying to obtain core-shell structured AlCoCrFeNi 2.1 @TiC powder.

[0014] (4) Spark plasma sintering: According to the size parameters of the required composite material block, take the core-shell structured powder obtained in step (3) and conduct spark plasma sintering in a high-purity argon atmosphere. The heating and cooling rates are 100 °C / min, and control the TiC to be in a controllable three-dimensional continuous network distribution in the AlCoCrFeNi 2.1 eutectic high-entropy alloy.

[0015] In the above method, the concentration of the PVA solution is 4 wt.%. The preparation process is as follows: Weigh 4 g of polyvinyl alcohol (PVA) powder and put it into a beaker, add 100 ml of deionized water, heat it to about 70 °C and stir magnetically for 30 min until the PVA powder is completely dissolved to obtain a transparent PVA aqueous solution with a concentration of 4 wt.%.

[0016] In the above method, the concentration of the CMC-Na solution is 2 wt.%. The preparation process is as follows: Weigh 1 g of sodium carboxymethyl cellulose (CMC-Na) powder and put it into a beaker, add 50 ml of deionized water, stir magnetically for 30 min until the CMC-Na powder is completely dissolved to obtain a transparent CMC-Na aqueous solution with a concentration of 2 wt.%.

[0017] During the wet ball milling, the addition ratio of the TiC@CMC-Na powder is 5 wt.% - 10 wt.% of the mass of the AlCoCrFeNi 2.1 @PVA powder.

[0018] The spark plasma sintering process is as follows:

[0019] First, place the core-shell structured powder in a graphite mold with an inner diameter of 30 mm and cold press it for 10 min under a pressure of 28 kN;

[0020] Then, keep it at a temperature of 600 °C for 10 min under a pressure of 3 kN and a power of 9 - 11 kW;

[0021] Subsequently, keep it at a temperature of 1200 °C for 10 min under a pressure of 28 kN and a power of 14 - 16 kW;

[0022] Finally, cool it down to room temperature to obtain a three-dimensional continuous TiC-reinforced AlCoCrFeNi 2.1 matrix wear-resistant composite material.

[0023] The preferred preparation method includes the following steps:

[0024] (1) Preparation of PVA solution and CMC-Na solution: Weigh 4 g of polyvinyl alcohol (PVA) powder and put it into a beaker. Add 100 ml of deionized water and heat it to about 70 °C, then stir magnetically for 30 min until the PVA powder is completely dissolved, obtaining a transparent PVA aqueous solution with a concentration of 4 wt.%. Weigh 1 g of sodium carboxymethyl cellulose (CMC-Na) powder and put it into a beaker. Add 50 ml of deionized water and stir magnetically for 30 min until the CMC-Na powder is completely dissolved, obtaining a transparent CMC-Na aqueous solution with a concentration of 2 wt.%.

[0025] The beneficial effects achieved by the above technical solution are as follows: Polyvinyl alcohol (PVA) is a water-soluble polymer that can be dissolved in water at a certain temperature. PVA is formed by bridging vinyl alcohol units through ethoxy groups, and each unit has a hydroxyl group (-OH). Sodium carboxymethyl cellulose (CMC-Na) is a water-soluble polymer compound, which is obtained by chemically modifying cellulose molecules. Its structure retains some hydroxyl groups (-OH) and also contains carboxylate (-COO - ) groups. Hydrogen bonds can be formed between PVA and CMC-Na through hydroxyl and carboxylate groups. In addition, the concentrations of the PVA solution and the CMC-Na solution should be appropriate. If the concentration is too low, the coating state on the powder surface is not ideal, while if the concentration is too high, the viscosity of the solution is too high and it is not easy to perform filtration separation. Therefore, the concentrations of the PVA solution and the CMC-Na solution are set at 4 wt.% and 2 wt.% respectively. It should be noted that during the dissolution process of PVA, bubbles may appear in the solution. This phenomenon is normal and can be eliminated by standing for a period of time. The stirring speed does not need to be too fast, otherwise it is also easy to cause the appearance of a large number of bubbles.

[0026] (2) Surface modification of powder: Add a certain amount of spherical AlCoCrFeNi 2.1 eutectic high-entropy alloy powder into the polyvinyl alcohol (PVA) solution and stir magnetically for 40 min, so as to modify PVA (AlCoCrFeNi 2.1 @PVA) on the surface of the high-entropy alloy particles; add a certain amount of nano-TiC powder into the sodium carboxymethyl cellulose (CMC-Na) solution and stir magnetically for 40 min, so as to modify CMC-Na (TiC@CMC-Na) on the surface of the TiC powder; then filter out the excess PVA solution and CMC-Na solution, wash with deionized water, put it into an oven for drying, crushing and sieving to obtain AlCoCrFeNi 2.1 @PVA powder and TiC@CMC-Na powder surface-modified with PVA and CMC-Na respectively.

[0027] The beneficial effects achieved by the above technical solution are as follows: In AlCoCrFeNi 2.1The surfaces of eutectic high-entropy alloy powder and TiC powder are respectively modified with PVA and CMC-Na. By using the physical cross-linking reaction between the two, namely hydrogen bonding, nano-TiC is uniformly coated on the surface of eutectic high-entropy alloy particles, successfully constructing core-shell structured powder. During the subsequent spark plasma sintering process, PVA and CMC-Na are decomposed and removed at high temperature. In addition, during the filtration and rinsing steps, ethanol should be avoided as the addition of ethanol solution will cause the appearance of flocculates.

[0028] (3) Calculate and weigh the modified powder: Weigh the corresponding mass of AlCoCrFeNi 2.1 @PVA powder and TiC@CMC-Na powder. The mass fraction of TiC@CMC-Na powder relative to AlCoCrFeNi 2.1 @PVA powder is 5 wt.% to 10 wt.%.

[0029] The beneficial effects achieved by the above technical solution are as follows: By regulating the content of the reinforcement, they are connected to each other in the high-entropy alloy matrix to form a three-dimensional continuous network structure. If the content of the reinforcement is too low, a completely continuous three-dimensional structure cannot be formed, and the load-bearing and anti-wear effects of the reinforcement cannot be fully exerted. On the contrary, if the content of the reinforcement is too high, the phenomenon of nano-TiC agglomeration will inevitably occur, which will lead to a decrease in the density of the sintered sample and even the appearance of pores.

[0030] (4) Wet ball milling and mixing: The weighed AlCoCrFeNi 2.1 @PVA powder and TiC@CMC-Na powder are wet milled in an acetone solution. The ball-to-material ratio is 5:1, the rotation speed is 180 rpm / min, ball milling is carried out for 5 min, and then paused for 2 min to cool down. This is taken as one ball milling cycle, and the total ball milling time is 418 min.

[0031] The beneficial effects achieved by the above technical solution are as follows: It should be noted that there are two conditions for the formation of hydrogen bonds. One is to have active hydrogen, that is, H is bonded to an atom with high electronegativity; the other is that the atom combined with the hydrogen bond has unshared electron pairs available. In the present invention, acetone is finally used as the solvent for wet ball milling for the following reasons: Although the oxygen atom on the carbonyl group of acetone has lone electron pairs, hydrogen bonds cannot be formed in acetone molecules. For this reason, the polar groups on the surface of TiC@CMC-Na can form hydrogen bonds with the hydroxyl groups on AlCoCrFeNi 2.1 @PVA as much as possible and bind together, rather than in other solvents such as deionized water or ethanol, where the polar groups on the surface of TiC@CMC-Na combine with the hydroxyl groups in the solvent, causing TiC@CMC-Na to be more dispersed in the solvent rather than in AlCoCrFeNi 2.1@PVA surface. In addition, acetone is volatile and has a lower boiling point (56.5 °C) than deionized water and ethanol, making it easier to dry and saving the preparation time. Further, the ball milling parameters defined in the present invention can ensure that the modified reinforcement and matrix particles are uniformly dispersed in the acetone solution, improving the coating rate of the reinforcement particles on the matrix particles without damaging the morphology and structure of the reinforcement and matrix particles, and reducing the possibility of agglomeration of the nano-reinforcement particles.

[0032] (5) Powder treatment before sintering: Filter the liquid after wet milling and mixing, dry it at room temperature for 6 - 10 h, and sieve it through a 100 - 200 mesh sieve after complete drying to obtain the core-shell structured AlCoCrFeNi 2.1 @TiC powder.

[0033] (6) Spark plasma sintering: Determine the size parameters of the sintered product. After calculation, weigh a certain mass of AlCoCrFeNi 2.1 @TiC powder, pour it into a graphite mold, place it in a spark plasma sintering furnace, and first cold press it at a pressure of 28 kN for 10 min; then keep it warm for 10 min at a pressure of 3 kN, a power of 9 - 11 kW, and a temperature of 600 °C; subsequently, keep it warm for 10 min at a temperature of 1200 °C, a pressure of 28 kN, and a power of 14 - 16 kW; finally, cool it to room temperature to obtain the three-dimensional continuous TiC-reinforced AlCoCrFeNi 2.1 matrix wear-resistant composite material.

[0034] The beneficial effects achieved by the above technical solution are as follows: In order to remove PVA and CMC-Na added in the core-shell structure powder, the usual process is to heat it in a tube furnace for a period of time to decompose it first, and then sinter the mixed powder after removing PVA and CMC-Na into a shape, which requires two steps to complete the preparation of the sample. However, the present invention hopes to use the SPS equipment to complete the removal of PVA and CMC-Na and the sintering and densification into a shape at one time. Because the heating principle of SPS is different from that of traditional hot press sintering, plasma is generated during the heating process, which can clean the particle surface, reduce surface oxides and other impurities. Therefore, in the SPS sintering process of the present invention, it is first kept at 600 °C for 10 min to remove PVA and CMC-Na. The discharge plasma sintering process defined by the present invention can ensure the successful preparation of a wear-resistant composite material based on TiC-reinforced eutectic high-entropy alloy with a high degree of three-dimensional continuity. If the pressure is insufficient, it will bring a high porosity, resulting in a reduction in the performance of the prepared material. If the pressure is too high, it may exceed the tolerance threshold of the graphite mold, causing damage to the graphite mold and thus resulting in sintering failure. When the temperature is higher than 1200 °C, it will promote the spheroidization of the eutectic high-entropy alloy and there may be a risk of the matrix alloy melting and flowing out. When the temperature is lower than 1200 °C, it will cause poor densification of the ceramic reinforcement skeleton and poor interfacial bonding between the ceramic skeleton and the matrix alloy. Keeping it at 1200 °C for 10 min can ensure a higher densification and good interfacial bonding of the material.

[0035] Further, during the entire discharge plasma sintering process, the heating and cooling rates are both 100 °C / min.

[0036] Further, the discharge plasma sintering process needs to be evacuated first, and the vacuum degree is less than 5×10 -2 mbar, and then argon is filled to prevent oxidation during the sintering process.

[0037] Compared with the prior art, the present invention has the following advantages and technical effects:

[0038] 1. The existing core-shell structure powder construction technology mainly directly ball-mills and mixes the matrix and reinforcement powders, and relies on the mutual collision between the long-time grinding balls to make the reinforcement adhere to the surface of the matrix particles. This method easily damages the morphology and structure of the matrix and reinforcement particles, and the reinforcement particles are prone to agglomeration. In the present invention, PVA and CMC-Na are respectively used to coat the matrix phase and the reinforcement phase particles, and the physical cross-linking effect between the hydroxyl groups on PVA and the groups on CMC-Na is utilized to make TiC uniformly coat the surface of the eutectic high-entropy alloy particles, without damaging the morphology and structure of the reinforcement and matrix particles. Finally, a wear-resistant composite material based on high-entropy alloy with a three-dimensional continuous structure distribution of the reinforcement is prepared by the discharge plasma sintering method.

[0039] 2. The wear-resistant composite material based on three-dimensional continuous TiC-reinforced high-entropy alloy provided by the present invention. The construction of its three-dimensional continuous reinforcement structure can not only play a role in hindering crack propagation and bearing strain, but also is not easy to peel off during the friction process, and has excellent wear resistance in a wide temperature range, showing broad application prospects in the field of wear-resistant materials.

[0040] 3. The raw materials of the present invention are easily obtained, the preparation method is simple and easy to operate, with strong controllability and high efficiency, showing broad industrial application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] The drawings forming a part of this application are used to provide a further understanding of this application. The schematic embodiments and descriptions thereof of this application are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0042] Figure 1 is the pure AlCoCrFeNi 2.1 eutectic high-entropy alloy (Comparative Example 1), the high-entropy alloy-based composite material directly homogenously compounded with TiC reinforcement (Comparative Example 2), and the XRD schematic diagrams of the wear-resistant composite materials based on high-entropy alloys with different contents of three-dimensional continuous TiC reinforcement (Example 1, Example 2) prepared in the present invention;

[0043] Figure 2 (a), (b), (c), (d) are respectively the pure AlCoCrFeNi 2.1 eutectic high-entropy alloy (Comparative Example 1), the high-entropy alloy-based composite material directly homogenously compounded with TiC reinforcement (Comparative Example 2), and the SEM microstructural schematic diagrams of the wear-resistant composite materials based on high-entropy alloys with different contents of three-dimensional continuous TiC reinforcement (Example 1, Example 2) prepared in the present invention;

[0044] Figure 3 is the pure AlCoCrFeNi 2.1 eutectic high-entropy alloy (Comparative Example 1), the high-entropy alloy-based composite material directly homogenously compounded with TiC reinforcement (Comparative Example 2), and the comparison diagrams of the friction coefficients of the wear-resistant composite materials based on high-entropy alloys with different contents of three-dimensional continuous TiC reinforcement (Example 1, Example 2) at test temperatures of room temperature, 300 °C, 600 °C, and 900 °C;

[0045] Figure 4 is the pure AlCoCrFeNi 2.1 eutectic high-entropy alloy (Comparative Example 1), the high-entropy alloy-based composite material directly homogenously compounded with TiC reinforcement (Comparative Example 2), and the comparison diagrams of the wear rates of the wear-resistant composite materials based on high-entropy alloys with different contents of three-dimensional continuous TiC reinforcement (Example 1, Example 2) at test temperatures of room temperature, 300 °C, 600 °C, and 900 °C; Detailed implementation mode

[0046] The present invention will be further elaborated in detail below in combination with specific examples. This detailed description should not be construed as a limitation of the present invention, but rather as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0047] It should be understood that the terms described in the present invention are only for describing specific implementation modes and are not used to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0048] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0049] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation modes of the present invention specification, which are obvious to those skilled in the art. Other implementation modes obtained from the present invention specification are obvious to those skilled in the art. The present invention specification and examples are only exemplary.

[0050] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, that is, they mean including but not limited to.

[0051] Example 1

[0052] Spherical AlCoCrFeNi 2.1 eutectic high-entropy alloy powder and nano-TiC powder are used as raw materials. First, surface modification is carried out on the two powders respectively, then wet milling and mixing are carried out to construct core-shell structured powder, and finally, the core-shell structured powder is sintered by spark plasma to prepare three-dimensional continuous TiC-reinforced AlCoCrFeNi 2.1 matrix composite material. Among them, the particle size of the AlCoCrFeNi 2.1 eutectic high-entropy alloy powder is 15 - 53 μm, and the size of the TiC particles is 40 nm.

[0053] All raw materials used in the examples of the present invention are obtained by purchasing commercially.

[0054] In the following examples, room temperature refers to 25 °C.

[0055] The specific steps are as follows:

[0056] S1. Prepare PVA solution and CMC-Na solution: Weigh 4 g of polyvinyl alcohol (PVA) powder and put it into a beaker, add 100 ml of deionized water, heat to about 70 °C and stir magnetically for 30 min until the PVA powder is completely dissolved to obtain a transparent PVA aqueous solution with a concentration of 4 wt.%; Weigh 1 g of sodium carboxymethyl cellulose (CMC-Na) powder and put it into a beaker, add 50 ml of deionized water, stir magnetically for 30 min until the CMC-Na powder is completely dissolved to obtain a transparent CMC-Na aqueous solution with a concentration of 2 wt.%.

[0057] S2. Surface modification of powders: Add 32 g of spherical AlCoCrFeNi 2.1 eutectic high-entropy alloy powder (15 - 53 μm) into 4 wt.% PVA solution and stir magnetically for 40 min; Add 2 g of nano-TiC powder (40 nm) into 2 wt.% CMC-Na solution and stir magnetically for 40 min; Then filter out the excess PVA solution and CMC-Na solution, wash with deionized water, put it in an oven at 60 °C and dry for 3 h, crush and sieve to obtain AlCoCrFeNi 2.1 @PVA powder and TiC@CMC-Na powder surface-modified with PVA and CMC-Na respectively.

[0058] S3. Calculate and weigh the modified powders: Weigh 30 g of AlCoCrFeNi 2.1 @PVA powder and 1.5 g of TiC@CMC-Na powder. The mass fraction of TiC@CMC-Na powder relative to AlCoCrFeNi 2.1 @PVA powder is 5 wt.%.

[0059] S4. Wet ball milling and mixing: Wet mill the weighed AlCoCrFeNi 2.1 @PVA powder and TiC@CMC-Na powder in acetone solution. The acetone solution just covers the powders. The ball-to-material ratio is 5:1, the rotation speed is 180 rpm / min, ball mill for 5 min, pause for 2 min to cool down. This is taken as one ball milling cycle, and the total ball milling time is 418 min.

[0060] S5. Pretreatment of powders before sintering: Filter the liquid after wet ball milling and mixing, dry at room temperature for 6 - 10 h, and sieve with a 100 - 200 mesh sieve after complete drying to obtain about 30 g of core-shell structured AlCoCrFeNi 2.1 @TiC powder.

[0061] S6. Spark plasma sintering: weigh 30g of AlCoCrFeNi 2.1 The TiC powder was poured into a graphite mold and placed in a spark plasma sintering furnace for cold pressing at 28 kN for 10 min. The spark plasma sintering furnace was then evacuated to a vacuum level of less than 5 × 10 -2 mbar, and after repeated gas washing 2-3 times, ensure that the furnace chamber is in an argon protective atmosphere with a mass concentration of more than 99.9%. The specific spark plasma sintering process is: keep warm at a pressure of 3kN, a power of 9-11kW, and a temperature of 600℃ for 10min; then keep warm at a temperature of 1200℃, a pressure of 28kN, and a power of 14-16kW for 10min; finally cool to room temperature to obtain a cylindrical composite material block with a diameter of 30mm and a height of about 6mm. The heating and cooling rates during the sintering process are both 100℃ / min.

[0062] The AlCoCrFeNi based on three-dimensional continuous TiC reinforcement obtained in this embodiment 2.1 The wear-resistant composite materials were characterized by XRD, such as Figure 1 The results show that the composite material obtained in Example 1 is composed of three phases: FCC phase, BCC phase and TiC phase, and no impurity phase is precipitated.

[0063] Scanning electron microscopy was used to analyze the microstructure of the composite materials, such as Figure 2 As shown in (c), TiC is distributed in a three-dimensional continuous network in the high entropy alloy matrix, and the network size is 15-53μm, which is similar to the original matrix high entropy alloy particle size. The existence of the network structure restricts the grains in the high entropy alloy matrix to grow in a network unit and cannot grow further into the adjacent matrix. This shows that the three-dimensional continuous TiC-enhanced AlCoCrFeNi 2.1 Wear-resistant composite materials.

[0064] The AlCoCrFeNi based on three-dimensional continuous TiC reinforcement obtained in this embodiment 2.1 The wear-resistant composite material is machined into long strips of friction samples and polished with 200 to 2000 mesh metallographic sandpaper from small to large. The friction and wear properties of the samples are tested using a high temperature friction and wear tester, and the test is repeated at least three times. Figure 3 As shown, the results show that the friction coefficient of the wear-resistant composite material of this embodiment is lower than 0.47 at all temperatures and is between 0.25 and 0.47. Figure 4 As shown in the figure, the wear rates of the wear-resistant composite material of this embodiment at room temperature, 300°C, 600°C and 900°C are 1.74×10 -6 mm 3 / Nm, 1.80×10-4 mm 3 / Nm, 7.31×10 -5 mm 3 / Nm and 3.66×10 -6 mm 3 / Nm. The above results indicate that the wear-resistant composite material prepared by the present invention exhibits excellent friction and wear performance in a wide temperature range.

[0065] Example 2

[0066] The difference from Example 1 is that in S2, 3.5 g of nano-TiC powder (40 nm) was added to 2 wt.% CMC-Na solution and magnetically stirred for 40 min; in S3, 30 g of AlCoCrFeNi 2.1 @PVA powder and 3 g of TiC@CMC-Na powder were weighed. The mass fraction of TiC@CMC-Na powder relative to AlCoCrFeNi 2.1 @PVA powder was 10 wt.%.

[0067] The AlCoCrFeNi 2.1 -based wear-resistant composite material reinforced by three-dimensional continuous TiC obtained in this example was characterized by XRD, as Figure 1 shown. The results show that the composite material obtained in Example 1 is composed of three phases: FCC, BCC phases and TiC phase. In addition, no impurity phase precipitates.

[0068] The microstructure of the composite material was analyzed by scanning electron microscope, as Figure 2 (d) shown. TiC is distributed in a three-dimensional continuous network in the high-entropy alloy matrix. When the TiC content increases to 10 wt.%, the three-dimensional continuous network structure becomes clearer and the width at the boundary also becomes significantly wider; in addition, the eutectic high-entropy alloy lamellar structure in the matrix is clearly visible. It shows that the AlCoCrFeNi 2.1 -based wear-resistant composite material reinforced by three-dimensional continuous TiC was successfully prepared.

[0069] The AlCoCrFeNi 2.1 -based wear-resistant composite material reinforced by three-dimensional continuous TiC obtained in this example was machined into long strip-shaped friction samples and polished with metallographic sandpaper from 200 to 2000 meshes from small to large. The friction and wear performance of the samples was tested by a high-temperature friction and wear testing machine, and the test was repeated at least three times. As Figure 3 shown, the results show that the wear-resistant composite material in this example has the highest friction coefficient at room temperature, which is 0.52, and the friction coefficients at other temperatures are all lower than 0.46 and are between 0.26 and 0.46. As Figure 4As shown, the results indicate that the wear rates of the wear-resistant composite material in this example at room temperature, 300 °C, 600 °C, and 900 °C are 1.28×10 -5 mm 3 / Nm, 2.12×10 -4 mm 3 / Nm, 6.7×10 -5 mm 3 / Nm, and 1.32×10 -6 mm 3 / Nm, respectively. The above results show that the wear-resistant composite material prepared by the present invention exhibits excellent friction and wear performance in a wide temperature range.

[0070] Comparative Example 1

[0071] In this comparative example, a pure AlCoCrFeNi 2.1 eutectic high-entropy alloy bulk was prepared. The difference from Example 1 is that no three-dimensional continuous TiC was added, that is, steps S1 to S5 were not carried out. In addition, the specific process of step S6 is as follows: Weigh 30 g of AlCoCrFeNi 2.1 eutectic high-entropy alloy powder, pour it into a graphite mold, place it in a spark plasma sintering furnace, first cold press it under a pressure of 28 kN for 10 min, then evacuate the spark plasma sintering furnace until the vacuum degree in the furnace cavity is less than 5×10 -2 mbar, and after flushing 2 to 3 times repeatedly, ensure that the furnace cavity is in an argon protection atmosphere with a mass concentration of more than 99.9%. The specific spark plasma sintering process is as follows: Keep it at a temperature of 1200 °C, a pressure of 28 kN, and a power of 14 - 16 kW for 10 min; finally cool it to room temperature to obtain a cylindrical high-entropy alloy bulk with a diameter of 30 mm and a height of about 6 mm. The heating and cooling rates during the sintering process are both 100 °C / min. Other conditions are the same as in Example 1.

[0072] The obtained AlCoCrFeNi 2.1 eutectic high-entropy alloy was characterized by XRD, as Figure 1 shown. The results show that Comparative Example 1 consists of two phases, FCC and BCC phases.

[0073] The microstructure of the eutectic high-entropy alloy was analyzed by scanning electron microscopy, as Figure 2 (a) shows. The AlCoCrFeNi 2.1 eutectic high-entropy alloy exhibits a regular lamellar eutectic structure.

[0074] The obtained AlCoCrFeNi 2.1The eutectic high-entropy alloy was machined into long strip-shaped friction samples and polished with metallographic sandpapers of 200 to 2000 meshes from small to large. The friction and wear properties of the samples were tested using a high-temperature friction and wear testing machine, and the tests were repeated at least three times. As Figure 3 shown, the results show that AlCoCrFeNi 2.1 eutectic high-entropy alloy has a relatively high friction coefficient of 0.51 at room temperature, and the friction coefficients at other temperatures are between 0.29 and 0.47. As Figure 4 shown, the results show that AlCoCrFeNi 2.1 eutectic high-entropy alloy has wear rates of 3.39×10 - 5 mm 3 / Nm, 4.18×10 -4 mm 3 / Nm, 1.82×10 -4 mm 3 / Nm and 1.14×10 -4 mm 3 / Nm at room temperature, 300 °C, 600 °C and 800 °C respectively.

[0075] Comparative Example 2

[0076] This comparative example is a preparation method of a TiC-embedded eutectic high-entropy alloy matrix composite material without any modification and coating treatment. The difference from Example 1 is that no powder surface modification treatment and core-shell structure powder construction were carried out, and the AlCoCrFeNi 2.1 powder and TiC powder were directly ball-milled and mixed, and finally a homogeneous TiC particle-reinforced AlCoCrFeNi 2.1 matrix composite material was prepared by SPS sintering.

[0077] The specific steps are as follows:

[0078] S1. Calculate and weigh the original powders: Weigh 30 g of AlCoCrFeNi 2.1 powder and 1.5 g of nano-TiC powder in a glove box protected by inert gas, and uniformly mix them in a stainless steel ball milling tank. The mass fraction of TiC powder relative to AlCoCrFeNi 2.1 powder is 5 wt.%.

[0079] S2. Dry ball milling and mixing: The ball milling tank filled with the mixed powders was installed on a high-energy ball mill for high-energy ball milling. The ball-to-material ratio was 10:1, the rotation speed was 300 rpm / min, and the ball milling was carried out for 5 min, then paused for 2 min to cool down. This was taken as one ball milling cycle, and the total ball milling time was 418 min.

[0080] S3. Spark plasma sintering: Weigh 30 g of AlCoCrFeNi2.1 The -TiC mixed powder was poured into a graphite mold and placed in a spark plasma sintering furnace. It was first cold - pressed at a pressure of 28 kN for 10 min. Then, the spark plasma sintering furnace was evacuated to a vacuum degree in the furnace cavity less than 5×10 -2 mbar. After flushing 2 - 3 times repeatedly, an argon - protection atmosphere with a mass concentration of more than 99.9% was ensured in the furnace cavity. The specific spark plasma sintering process was as follows: it was kept warm for 10 min at a temperature of 1200 °C, a pressure of 28 kN, and a power of 14 - 16 kW. Finally, it was cooled to room temperature to obtain a cylindrical composite block with a diameter of 30 mm and a height of about 6 mm. The heating and cooling rates during the sintering process were both 100 °C / min.

[0081] The homogeneous - structure TiC - particle - reinforced AlCoCrFeNi 2.1 matrix composite obtained in this comparative example was characterized by XRD, as Figure 1 shown. The results showed that the composite obtained in Comparative Example 2 was composed of three phases: FCC, BCC phases, and TiC phase. In addition, no impurity phases were precipitated.

[0082] The microstructure of the composite was analyzed by scanning electron microscopy, as Figure 2 (b) shown. TiC was scattered irregularly like "pockmarks" in the high - entropy alloy matrix and was isolated around the original eutectic high - entropy alloy matrix particles, unable to form a continuous network structure.

[0083] The homogeneous - structure TiC - particle - reinforced AlCoCrFeNi 2.1 matrix composite obtained in this comparative example was machined into a long - strip friction sample and polished with metallographic sandpaper from 200 to 2000 meshes from small to large. The friction and wear properties of the sample were tested using a high - temperature friction and wear testing machine, and the test was repeated at least three times. As Figure 3 shown, the results showed that the composite in this comparative example had the highest friction coefficient at room temperature, which was 0.52, and the friction coefficients at other temperatures were between 0.27 and 0.45. As Figure 4 shown, the results showed that the wear rates of the solid - lubricating composite in this example at room temperature, 300 °C, 600 °C, and 900 °C were 2.54×10 -5 mm 3 / Nm, 2.85×10 -4 mm 3 / Nm, 1.45×10 -4 mm 3 / Nm, and 5.55×10 - 6 mm 3 / Nm, respectively.

[0084] The above are only the preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A three-dimensional continuous TiC-reinforced AlCoCrFeNi 2.1 A wear-resistant composite material, characterized in that: The core-shell structure powder is constructed by physical cross-linking reaction, so that TiC powder is evenly coated on AlCoCrFeNi 2.1 The surface of eutectic high entropy alloy matrix particles is then controlled by spark plasma sintering method to control the TiC on AlCoCrFeNi 2.1 It is distributed in a controllable three-dimensional continuous network in the eutectic high entropy alloy.

2. The three-dimensional continuous TiC reinforced AlCoCrFeNi according to claim 1 2.1 A wear-resistant composite material, characterized in that: The TiC powder is irregular particles with a particle size of 40 nm. 2.1 The powder particles of the eutectic high entropy alloy are spherical particles with a particle size of 15-53 μm.

3. AlCoCrFeNi based on three-dimensional continuous TiC reinforcement according to claim 1 or 2 2.1 A wear-resistant composite material, characterized in that: The preparation method comprises the following steps: (1) Powder surface modification: a certain amount of spherical AlCoCrFeNi 2.1 Eutectic high entropy alloy powder was added to polyvinyl alcohol (PVA) solution and magnetically stirred for 40 min to modify PVA (AlCoCrFeNi) on the surface of high entropy alloy particles. 2.1 @PVA); a certain amount of nano-TiC powder was added to sodium carboxymethyl cellulose (CMC-Na) solution and magnetically stirred for 40 min to modify CMC-Na on the surface of TiC powder (TiC@CMC-Na); then the excess PVA solution and CMC-Na solution were filtered out, washed with deionized water, dried in an oven, crushed and sieved to obtain AlCoCrFeNi 2.1 @PVA powder and TiC@CMC-Na powder; (2) Wet ball milling: The AlCoCrFeNi 2.1 @PVA and TiC@CMC-Na powders were wet-milled in acetone solution with a ball-to-powder ratio of 5:1 and a rotation speed of 180 rpm / min. The milling time was 5 min and then paused for 2 min to cool down. This was considered a milling cycle, and the total milling time was 418 min. (3) Powder treatment before sintering: The liquid after wet grinding and mixing in step (2) is filtered, dried at room temperature for 6 to 10 hours, and sieved after complete drying to obtain a core-shell structure AlCoCrFeNi 2.1 @TiC powder; (4) Spark plasma sintering: According to the size parameters of the required composite material block, the core-shell structure powder obtained in step (3) is taken and spark plasma sintered in a high-purity argon atmosphere at a heating and cooling rate of 100°C / min to control the TiC content in AlCoCrFeNi 2.1 It is distributed in a controllable three-dimensional continuous network in the eutectic high entropy alloy.

4. AlCoCrFeNi based on three-dimensional continuous TiC reinforcement according to claim 3 2.1 A wear-resistant composite material, characterized in that: The concentration of the PVA solution in the preparation method is 4wt.%, and the preparation process is as follows: weigh 4g of polyvinyl alcohol (PVA) powder and put it into a beaker, add 100ml of deionized water, heat to about 70°C and stir magnetically for 30min until the PVA powder is completely dissolved to obtain a transparent PVA aqueous solution with a concentration of 4wt.%.

5. The AlCoCrFeNi based on three-dimensional continuous TiC reinforcement according to claim 3 2.1 A wear-resistant composite material, characterized in that: The concentration of the CMC-Na solution in the preparation method is 2wt.%, and the preparation process is as follows: weigh 1g of sodium carboxymethyl cellulose (CMC-Na) powder and put it into a beaker, add 50ml of deionized water, and stir magnetically for 30min until the CMC-Na powder is completely dissolved to obtain a transparent CMC-Na aqueous solution with a concentration of 2wt.%.

6. The AlCoCrFeNi based on three-dimensional continuous TiC reinforcement according to claim 3 2.1 A wear-resistant composite material, characterized in that: During the wet ball milling process described in the preparation method, the addition ratio of TiC@CMC-Na powder is AlCoCrFeNi 2.1 @5wt.%~10wt.% of PVA powder mass.

7. The AlCoCrFeNi based on three-dimensional continuous TiC reinforcement according to claim 3 2.1 Based wear-resistant composite material, characterized in that Polyvinyl alcohol (PVA) is used as AlCoCrFeNi 2.1 The material for powder surface modification is sodium carboxymethyl cellulose (CMC-Na) as the material for surface modification of nano-TiC powder, and acetone solution is used as the solvent during wet grinding.

8. The AlCoCrFeNi based on three-dimensional continuous TiC reinforcement according to claim 3 2.1 Based wear-resistant composite material, characterized in that The spark plasma sintering process described in the preparation method is: First, the core-shell structure powder was placed in a graphite mold with an inner diameter of 30 mm and cold pressed at a pressure of 28 kN for 10 min. Then, keep the temperature at 600℃ for 10 minutes at a pressure of 3kN, a power of 9-11kW, and a temperature of 600℃; Then, the temperature was kept at 1200°C, the pressure was 28kN, and the power was 14-16kW for 10 minutes; Finally, it was cooled to room temperature to obtain a three-dimensional continuous TiC-reinforced AlCoCrFeNi 2.1 Wear-resistant composite materials.

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