A high-entropy alloy-ceramic composite material, its preparation method and application

Abstract

This invention provides a high-entropy alloy-ceramic composite material, its preparation method, and its application. The method involves coating the surface of ceramic phase powder particles with a metal protective layer, followed by molding, debinding, and vacuum pre-sintering to obtain a pre-sintered body with a relative density not exceeding 90%. Then, at least two metal layers, including an innermost high-entropy alloy layer, are coated onto the surface of the pre-sintered body. The resulting material is then subjected to vacuum sintering, hot isostatic pressing (HIP) infiltration treatment, and annealing to obtain the high-entropy alloy-ceramic composite material. This invention, through the metal protective layer, prevents carbon, nitrogen, boron, or silicon atoms in the ceramic phase from damaging the high-entropy alloy phase structure. Furthermore, the subsequent HIP infiltration treatment solves the problem of easy agglomeration of the high-entropy alloy binder phase caused by traditional powder mixing methods. It also addresses the issues of incomplete infiltration and limitations imposed by product dimensions.

Description

Technical Field

[0001] This invention relates to the field of metal-ceramic composite materials technology, and in particular to a high-entropy alloy-ceramic composite material, its preparation method, and its application. Background Technology

[0002] Compared with traditional metal alloys, high-entropy alloys possess high strength, high toughness, high hardness, high wear resistance, excellent corrosion resistance, and good high-temperature stability and performance. Since their introduction, high-entropy alloys have found widespread application. Currently, the developed high-entropy alloy systems mainly include the following three categories: lightweight metal high-entropy alloy systems based on Al and fourth and fifth period elements such as Fe, Co, Ni, Cr, Cu, Mn, Sn, Zn, Li, Mg, Zr, and Ti; refractory metal high-entropy alloy systems based on refractory metal elements such as Mo, V, Nb, Hf, Ta, Cr, and W; and rare earth metal high-entropy alloy systems based on rare earth elements.

[0003] In the field of metal-ceramic composites, high-entropy alloys (HUA) possess excellent properties, and researchers have attempted to use them as the metal alloy phase to replace traditional metal alloy phases, thereby further improving the strength and toughness of metal-ceramic composites. However, the preparation of HUA-ceramic composites using traditional powder metallurgy methods faces the following technical challenges: Firstly, ceramic phase powders (such as carbides, borides, or nitrides) typically have a particle size of less than 2 μm, and are easily broken down during ball milling. Ultrafine HUA-ceramic alloy powders with a particle size of less than 5 μm are difficult to mass-produce. Even if finer HUA-ceramic alloy powders can be produced, cold welding easily occurs between particles during ball milling, causing agglomeration. Based on these factors, it is difficult to achieve uniform ball milling and mixing of ceramic phase powders and HUA-ceramic alloy powders. Secondly, during liquid-phase sintering, atoms such as carbon, boron, nitrogen, or silicon in the ceramic phase easily dissolve into the liquid phase of the HUA-ceramic alloy. During cooling, these atoms readily react with the metal components in the HUA-ceramic alloy and precipitate, leading to the destruction of the HUA-ceramic phase structure and preventing the HUA-ceramic alloy from fulfilling its intended function.

[0004] Based on the above analysis, how to obtain high-performance high-entropy alloy-ceramic composite materials with intact high-entropy alloy phase structure, non-agglomeration of high-entropy alloy phase, and controllable high-entropy alloy phase content is an urgent problem to be solved in this field. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a high-entropy alloy-ceramic composite material, its preparation method, and its application, so as to obtain a high-performance high-entropy alloy-ceramic composite material in which the high-entropy alloy phase structure is not destroyed, the high-entropy alloy phase does not agglomerate, and the high-entropy alloy content is controllable.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0008] A metal protective layer is coated on the surface of ceramic phase powder particles, and then the particles are shaped, degreased and vacuum pre-sintered to obtain a pre-sintered body with a relative density of no more than 90%.

[0009] The high-entropy alloy-ceramic composite material is obtained by coating the surface of the pre-sintered body with at least two metal layers, followed by vacuum sintering, hot isostatic pressing, and annealing.

[0010] The at least two metal layers include the innermost high-entropy alloy layer.

[0011] The vacuum sintering temperature T2, the hot isostatic pressing melting treatment temperature T3, and the annealing treatment temperature T4 are all lower than the melting point T of the metal protective layer. m1 .

[0012] The vacuum sintering temperature T2 is higher than the melting point T of the high-entropy alloy layer. m2 .

[0013] The melting point T of the outermost metal layer of the at least two metal layers m3 The melting point T of the metal protective layer is higher than that of the metal protective layer. m1 .

[0014] The preparation method provided by this invention involves coating the surface of ceramic phase powder particles with a metal protective layer to prevent carbon, nitrogen, boron, or silicon atoms in the ceramic phase powder from damaging the high-entropy alloy phase structure. Then, through molding, debinding, and vacuum pre-sintering, a porous pre-sintered body is obtained. Next, at least two metal layers, including the innermost high-entropy alloy layer, are uniformly coated onto the surface of the pre-sintered body. The surface of the pre-sintered body is then sealed by vacuum sintering. Finally, hot isostatic pressing (HIP) is used to allow the molten high-entropy alloy to diffuse along the pores and / or interfaces of the pre-sintered body into its interior, thereby obtaining a dense high-entropy alloy-ceramic composite material. By controlling the pressure of the HIP process, a high-entropy alloy-ceramic composite material with a gradient distribution of the high-entropy alloy phase or a high-entropy alloy-ceramic composite material with uniform composition can be obtained. Furthermore, the application of HIP solves the problem of easy agglomeration of the high-entropy alloy binder phase caused by traditional powder mixing methods, and also solves the problems of incomplete melting and infiltration and limitations imposed by product dimensions.

[0015] Preferably, the metal element in the metal protective layer includes any one or a combination of at least two of Co, Ni, or Fe.

[0016] Preferably, the melting point T of the high-entropy alloy layer is... m2 The temperature range is 600℃-1200℃.

[0017] Preferably, the metal elements in the high-entropy alloy layer include a combination of at least five of the following: Al, Fe, Co, Zn, Sn, Ni, Cr, Cu, Mn, Li, Mg, or Ti.

[0018] Preferably, the volume of the high-entropy alloy layer is not less than the total volume of pores in the pre-sintered body.

[0019] Preferably, the metal element in the outermost metal layer includes any one or a combination of at least two of Ti, Zr, Mo, Nb, or Ta.

[0020] Preferably, the thickness of the outermost metal layer is 0.1mm-0.3mm.

[0021] Preferably, the vacuum sintering temperature T2 is higher than the melting point T of the high-entropy alloy layer. m2 Temperatures can range from 25°C to 50°C.

[0022] Preferably, the vacuum sintering temperature T2 is higher than the melting point T of the metal protective layer. m1 Lower than 200℃.

[0023] Preferably, the holding time for vacuum sintering is 0.5h-1h.

[0024] Preferably, the pressure of the vacuum sintering is 10. -3 Below Pa.

[0025] Preferably, the hot isostatic pressing melting treatment is carried out in an inert atmosphere.

[0026] Preferably, the pressure of the hot isostatic pressing melt infiltration treatment is 5MPa-300MPa.

[0027] Preferably, the temperature T3 of the hot isostatic pressing melting treatment is equal to the temperature T2 of the vacuum sintering.

[0028] Preferably, the heat preservation and pressure holding time for the hot isostatic pressing melt infiltration treatment is 1h-3h.

[0029] Preferably, the annealing temperature T4 is lower than the melting point T of the high-entropy alloy layer. m2 .

[0030] Preferably, the annealing temperature T4 is higher than the melting point T of the high-entropy alloy layer. m2 100℃-200℃ lower.

[0031] Preferably, the annealing pressure is below 30 Pa.

[0032] Preferably, the temperature is increased from room temperature to the annealing temperature T4 at a heating rate of 0.5℃ / min-1℃ / min.

[0033] Preferably, the annealing treatment is carried out at a temperature T4 and the holding time is 1-3 hours.

[0034] Preferably, the annealing process is completed when the temperature T4 of the annealing treatment is cooled to room temperature at a cooling rate of 1℃ / min-2℃ / min.

[0035] In a second aspect, the present invention provides a high-entropy alloy-ceramic composite material, which is prepared by the preparation method described in the first aspect.

[0036] Preferably, when the pressure of the hot isostatic pressing melting treatment is above 5 MPa and below 80 MPa, a high-entropy alloy-ceramic composite material with a gradient distribution of high-entropy alloy phase is obtained, that is, the content of high-entropy alloy phase gradually decreases from the surface to the interior of the high-entropy alloy-ceramic composite material.

[0037] Preferably, when the pressure of the hot isostatic pressing melting treatment is higher than 80 MPa and lower than 300 MPa, a high-entropy alloy-ceramic composite material with uniform composition is obtained.

[0038] Thirdly, the present invention provides an application of a high-entropy alloy-ceramic composite material, which is used to prepare molds, cutting tools or wear-resistant parts.

[0039] The high-entropy alloy-ceramic composite material is prepared by the preparation method described in the first aspect, or is the high-entropy alloy-ceramic composite material described in the second aspect.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] The preparation method provided by this invention involves coating the surface of ceramic phase powder particles with a metal protective layer to prevent carbon, nitrogen, boron, or silicon atoms in the ceramic phase powder from damaging the high-entropy alloy phase structure. Then, through molding, debinding, and vacuum pre-sintering, a porous pre-sintered body is obtained. Next, at least two metal layers, including the innermost high-entropy alloy layer, are uniformly coated onto the surface of the pre-sintered body. The surface of the pre-sintered body is then sealed by vacuum sintering. Finally, hot isostatic pressing (HIP) infiltration treatment is used to allow the molten high-entropy alloy to diffuse along the pores and / or interfaces of the pre-sintered body into its interior, thereby obtaining a dense high-entropy alloy-ceramic composite material. By controlling the pressure of the HIP infiltration treatment, a high-entropy alloy-ceramic composite material with a gradient distribution of the high-entropy alloy phase or a high-entropy alloy-ceramic composite material with uniform composition can be obtained. Furthermore, the application of HIP infiltration treatment solves the problem of easy agglomeration of the high-entropy alloy binder phase caused by traditional powder mixing methods, while also avoiding incomplete infiltration and limitations imposed by product dimensions. Detailed Implementation

[0042] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0043] An embodiment of the present invention provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0044] A metal protective layer is coated on the surface of ceramic phase powder particles, and then the particles are shaped, degreased and vacuum pre-sintered to obtain a pre-sintered body with a relative density of no more than 90%.

[0045] The high-entropy alloy-ceramic composite material is obtained by coating the surface of the pre-sintered body with at least two metal layers, followed by vacuum sintering, hot isostatic pressing, and annealing.

[0046] The at least two metal layers include the innermost high-entropy alloy layer.

[0047] The vacuum sintering temperature T2, the hot isostatic pressing melting treatment temperature T3, and the annealing treatment temperature T4 are all lower than the melting point T of the metal protective layer. m1 .

[0048] The vacuum sintering temperature T2 is higher than the melting point T of the high-entropy alloy layer. m2 .

[0049] The melting point T of the outermost metal layer of the at least two metal layers m3 The melting point T of the metal protective layer is higher than that of the metal protective layer. m1 .

[0050] The preparation method provided by this invention involves coating the surface of ceramic phase powder particles with a metal protective layer to prevent carbon, nitrogen, boron, or silicon atoms in the ceramic phase powder from damaging the high-entropy alloy phase structure. Then, through molding, debinding, and vacuum pre-sintering, a porous pre-sintered body is obtained. Next, at least two metal layers, including the innermost high-entropy alloy layer, are uniformly coated onto the surface of the pre-sintered body. The surface of the pre-sintered body is then sealed by vacuum sintering. Finally, hot isostatic pressing (HIP) infiltration treatment is used to allow the molten high-entropy alloy to diffuse along the pores and / or interfaces of the pre-sintered body into its interior, thereby obtaining a dense high-entropy alloy-ceramic composite material. By controlling the pressure of the HIP infiltration treatment, a high-entropy alloy-ceramic composite material with a gradient distribution of the high-entropy alloy phase or a high-entropy alloy-ceramic composite material with uniform composition can be obtained. Furthermore, the application of HIP infiltration treatment solves the problem of easy agglomeration of the high-entropy alloy binder phase caused by traditional powder mixing methods, while also avoiding incomplete infiltration and limitations imposed by product dimensions.

[0051] In this invention, the temperature T1 of vacuum pre-sintering is not specifically limited. It is only necessary to ensure that the relative density of the pre-sintered body does not exceed 90%, that is, to control the total volume of pores in the pre-sintered body, and further control the content of high-entropy alloy phase in the high-entropy alloy-ceramic composite material.

[0052] In this invention, the relative density of the pre-sintered body refers to the ratio of the density of the pre-sintered body to the theoretical density of the metal-ceramic composite material composed of ceramic phase powder and metal protective layer.

[0053] In some embodiments, the relative density of the pre-sintered body is also related to the initial relative density of the molded body, typically the relative density of the molded body after molding is not less than 35%.

[0054] In some embodiments, the raw material powder of the ceramic phase powder comprises more than 50 vol% ceramic phase raw material and less than 50 vol% additive powder, by volume percentage.

[0055] In some embodiments, the ceramic phase powder includes any one or a combination of at least two of nitride ceramic phase powder, boride ceramic phase powder, or carbide ceramic phase powder. Typical but non-limiting combinations include combinations of nitride ceramic phase powder and boride ceramic phase powder, combinations of nitride ceramic phase powder and carbide ceramic phase powder, or combinations of nitride ceramic phase powder, boride ceramic phase powder, and carbide ceramic phase powder.

[0056] In some embodiments, the nitride ceramic phase powder comprises any one or a combination of at least two of TiCN, AlN, TiN, SiAlON, or BN.

[0057] In some embodiments, when the ceramic phase powder is a nitride ceramic phase powder, the additive powder includes WC, Cr3C2, VC, ZrC, TiC, Mo2C, TaC, NbC, SiC, and SiC. w Whiskers, B4C, ZrB, ZrB2, TiB, TiB2, WB, W2B, W2B5, CrB, ZrN, TiN, or rare earth metal borides, or any combination of at least two of them.

[0058] In some embodiments, the boride ceramic phase powder comprises ZrB2 and / or TiB2.

[0059] In some embodiments, when the ceramic phase powder is a boride ceramic phase powder, the additive powder includes WC, Cr3C2, VC, ZrC, TiC, TiCN, Mo2C, TaC, NbC, SiC, and SiC. w Whiskers, B4C, ZrB, TiB, WB, W2B, W2B5, CrB, SiAlON, BN, AlN, ZrN, TiN, or rare earth metal borides, or any combination of at least two of them.

[0060] In some embodiments, the carbide ceramic phase powder comprises any one or a combination of at least two of TiC, ZrC, SiC, or B4C.

[0061] In some embodiments, when the ceramic phase powder is a carbide ceramic phase powder, the additives include WC, Cr3C2, VC, Mo2C, TaC, NbC, and SiC. w Whiskers, ZrB, ZrB2, TiB, TiB2, WB, W2B, W2B5, CrB, SiAlON, BN, AlN, ZrN, TiCN, TiN, or rare earth metal borides, or any combination of at least two of them.

[0062] In some embodiments, the method for preparing the ceramic phase powder includes: placing the formulated amount of ceramic phase matrix powder, additive powder and grinding balls in a ball mill, then injecting anhydrous ethanol into the ball mill, and ball milling and mixing for more than 24 hours in a protective atmosphere to obtain a uniformly mixed ceramic phase powder.

[0063] In some embodiments, the grinding balls used in the ball milling mixture are made of silicon carbide, silicon nitride, or cemented carbide balls, and the mass ratio of the grinding balls to the raw material powder is 2:1 to 8:1, for example, it can be 2:1, 3:1, 4:1, 5:1, 6:1, 7:1 or 8:1, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0064] In some embodiments, the protective gas during ball milling includes nitrogen and / or an inert gas, wherein the inert gas includes any one or a combination of at least two of helium, neon, or argon.

[0065] In some embodiments, the method of coating the surface of ceramic phase powder particles with a metal protective layer includes chemical coating.

[0066] In some embodiments, the chemical coating method includes the following steps: activating the ceramic phase powder with an activating solution, placing it in a chemical plating solution for chemical coating, and then cleaning and vacuum drying to complete the chemical coating.

[0067] In some embodiments, the activation solution includes hydrofluoric acid (40 wt%), ammonium fluoride, nitric acid (65 wt%), and hydrochloric acid (36 wt%); wherein the amounts of hydrofluoric acid, ammonium fluoride, nitric acid, and hydrochloric acid in the activation solution are 30 mL / L-50 mL / L, 2 g / L-4 g / L, 20 mL / L-40 mL / L, and 10 mL / L-30 mL / L, respectively.

[0068] This invention removes impurities from the surface of ceramic phase powder particles by activating them, and at the same time modifies the microstructure of the ceramic phase powder particle surface, so as to generate micro-defects such as active stacking faults or dislocations on the surface of the ceramic phase powder particles, thereby helping to induce the deposition of binder phase metal ions on the particle surface and improve the bonding force.

[0069] In some embodiments, the activation includes ultrasonic stirring for 15-30 minutes, such as 15 minutes, 20 minutes, 25 minutes or 30 minutes, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0070] In some embodiments, the solid-liquid ratio during chemical coating is 150 g / L to 1500 g / L, for example, it can be 150 g / L, 300 g / L, 500 g / L, 800 g / L, 1000 g / L, 1200 g / L or 1500 g / L, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0071] In some embodiments, the electroless plating solution includes 20 g / L-30 g / L of a protective metal salt compound, 20 g / L-30 g / L of a reducing agent, 40 g / L-60 g / L of a complexing agent, and 20 g / L-30 g / L of a stabilizer.

[0072] In some embodiments, the protective metal salt compound includes a protective metal sulfate compound and / or a protective metal chloride compound.

[0073] In some embodiments, the protective metal salt compound includes any one or a combination of at least two of cobalt salt compounds, nickel salt compounds, or iron salt compounds.

[0074] In some embodiments, the reducing agent includes sodium hypophosphite.

[0075] In some embodiments, the complexing agent includes trisodium citrate.

[0076] In some embodiments, the stabilizer includes boric acid.

[0077] In some embodiments, the chemical coating is performed under ultrasonic stirring at a temperature of 40°C-60°C, such as 40°C, 45°C, 50°C, 55°C or 60°C, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0078] In some embodiments, the vacuum drying temperature during the chemical coating process is 60°C-120°C, for example, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or 120°C, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0079] In this invention, the metal elements in the metal protective layer need to have good compatibility with the ceramic phase powder, thereby improving the interfacial strength between the metal protective layer and the ceramic phase powder; the metal protective layer also needs to have good compatibility with the high-entropy alloy phase, thereby facilitating the melting and infiltration of the high-entropy alloy during hot isostatic pressing melting and infiltration treatment.

[0080] In some embodiments, the metal element in the metal protective layer includes any one or a combination of at least two of Co, Ni, or Fe. Typical but non-limiting combinations include combinations of Co and Ni, Co and Fe, Ni and Fe, or Co, Ni, and Fe.

[0081] The method of coating the surface of the pre-sintered body with at least two metal layers is a conventional method, as long as the metal layers can be non-airtightly coated on the surface of the pre-sintered body.

[0082] In some embodiments, the at least two metal layers include an innermost high-entropy alloy layer and an outermost metal layer. For example, a method of coating the innermost high-entropy alloy layer onto the surface of the pre-sintered body includes spraying or alloy thin-walled fitting.

[0083] In some embodiments, when coating the innermost high-entropy alloy layer, the spraying method includes: uniformly spraying a slurry containing coating high-entropy alloy powder onto the surface of the pre-sintered body, thereby forming the innermost high-entropy alloy coating layer.

[0084] In some embodiments, when covering the innermost high-entropy alloy layer, the method of fitting the thin-walled alloy components includes: preparing the high-entropy alloy to be covered into multiple thin-walled components with the same shape as the pre-sintered body; combining and fitting the multiple thin-walled components tightly against the surface of the pre-sintered body; and connecting the interfaces of the multiple thin-walled components through... The layers are connected to form the innermost high-entropy alloy layer.

[0085] An example method of covering the outermost metal layer includes wearing a thin-walled metal component.

[0086] In some embodiments, when covering the outermost metal layer, the method of fitting the thin-walled metal components includes: preparing the metal component to be covered into multiple thin-walled components with the same shape as the pre-sintered body already covered with the inner metal layer; combining and fitting the multiple thin-walled components tightly against the outer surface of the pre-sintered body already covered with the inner metal layer; and connecting the interfaces of the multiple thin-walled components through... The sleeves are connected to form the outermost metal cladding layer.

[0087] In some embodiments, the melting point T of the high-entropy alloy layer m2 The range is 600℃-1200℃, for example, it can be 600℃, 800℃, 900℃, 1000℃ or 1200℃, but is not limited to the listed values. Other unlisted values ​​within the range also apply.

[0088] In some embodiments, the metallic elements in the high-entropy alloy layer include a combination of at least five of the following: Al, Fe, Co, Zn, Sn, Ni, Cr, Cu, Mn, Li, Mg, or Ti.

[0089] In some embodiments, the volume of the high-entropy alloy layer is not less than the total volume of pores in the pre-sintered body.

[0090] In this invention, the volume of the high-entropy alloy layer is set to be no less than the total volume of pores in the pre-sintered body. The purpose is to ensure that the high-entropy alloy in the high-entropy alloy layer can fully fill the pores in the pre-sintered body, thereby obtaining a dense high-entropy alloy-ceramic composite material.

[0091] Let the density of the high-entropy alloy layer be ρ, the relative density of the pre-sintered body be D, and the volume of the pre-sintered body be V. Then the mass of the required high-entropy alloy layer is M≥ρ×V×(1-D).

[0092] In order to ensure the smooth progress of the preparation method provided by the present invention, the outermost metal layer can remain solid throughout the vacuum sintering, hot isostatic pressing and infiltration treatment and annealing treatment, thereby avoiding the loss of the high-entropy alloy layer due to gravity during the melting process, so as to ensure complete coverage and sealing of the pre-sintered body.

[0093] In some embodiments, the metal element in the outermost metal layer includes any one or at least two combinations of Ti, Zr, Mo, Nb, or Ta. Typical but non-limiting combinations include combinations of Ti and Zr, Mo and Nb, Mo, Nb, and Ta, Ti, Zr, Mo, Nb, and Ta.

[0094] The outermost metal layer can provide adequate protection. Generally, the thickness of the outermost metal layer increases with the increase of the volume of the high-entropy alloy layer.

[0095] In some embodiments, the thickness of the outermost metal layer is 0.1mm-0.3mm, for example, it can be 0.1mm, 0.15mm, 0.2mm, 0.25mm or 0.3mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0096] This invention uses vacuum sintering to melt the high-entropy alloy layer and cause a diffusion reaction on the surface of the pre-sintered body, forming a dense high-entropy alloy sealing layer on the surface of the pre-sintered body, thereby achieving complete sealing of the pre-sintered body.

[0097] In some embodiments, the vacuum sintering temperature T2 is higher than the melting point T of the high-entropy alloy layer. m2 The temperature range is 25℃-50℃, for example, it can be 25℃, 30℃, 35℃, 40℃, 45℃ or 50℃, but is not limited to the listed values. Other unlisted values ​​within the range also apply.

[0098] In some embodiments, the vacuum sintering temperature T2 is higher than the melting point T of the metal protective layer. m1 Lower than 200℃.

[0099] This invention controls the vacuum sintering temperature T2 to be higher than the melting point T of the high-entropy alloy layer. m2 The high temperature range of 25℃-50℃ allows the high-entropy alloy layer to fully melt and diffuse into the surface of the pre-sintered body through the pores and / or interfaces, thus effectively sealing the surface of the pre-sintered body. Simultaneously, the vacuum sintering temperature T2 is controlled to be higher than the melting point T of the metal protective layer. m1 Temperatures above 200°C ensure that the metal protective layer remains solid, preventing atoms such as carbon, nitrogen, boron, or silicon in the ceramic phase from diffusing across the metal protective layer and damaging the high-entropy alloy phase structure. Furthermore, vacuum sintering, performed under vacuum conditions, ensures that all gaseous phases fully react and are expelled from the pre-sintered body before the high-entropy alloy is melted and sealed.

[0100] In some embodiments, the holding time for vacuum sintering is 0.5h-1h, for example, it can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h or 1h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0101] In some embodiments, the vacuum sintering pressure is 10. -3 Below Pa.

[0102] After vacuum sintering, hot isostatic pressing is performed to infiltrate the material. Under the action of gas pressure, the molten high-entropy alloy diffuses into the interior of the pre-sintered body along the pores and / or interfaces to fill the pores in the pre-sintered body, thereby obtaining a completely dense high-entropy alloy-ceramic composite material.

[0103] In some embodiments, the hot isostatic pressing melting process is carried out in an inert atmosphere, wherein the gas in the inert atmosphere includes any one or at least two of nitrogen, helium or argon, and typical but non-limiting combinations include combinations of nitrogen and helium, helium and argon, nitrogen and argon, or nitrogen, helium and argon.

[0104] In some embodiments, the pressure of the hot isostatic pressing melt infiltration treatment is 5MPa-300MPa, for example, it can be 5MPa, 20MPa, 40MPa, 50MPa, 60MPa, 80MPa, 100MPa, 150MPa, 200MPa, 250MPa or 300MPa, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0105] The pressure of hot isostatic pressing (HIP) affects the melting and infiltration of molten high-entropy alloys into the pre-sintered body. When the HIP pressure is below 80 MPa, as the sintering temperature increases, the diffusion process of the high-entropy alloy liquid phase lags behind the densification process of the pre-sintered body, thus forming a high-entropy alloy-ceramic composite material with a gradient distribution of high-entropy alloy phase, i.e., the content of high-entropy alloy phase gradually decreases from the surface to the interior. However, when the HIP pressure is above 80 MPa but below 300 MPa, the diffusion and melting process of the high-entropy alloy liquid phase occurs almost simultaneously with the densification process of the pre-sintered body. Therefore, a high-entropy alloy-ceramic composite material with uniform composition can be obtained.

[0106] In some embodiments, the temperature T3 of the hot isostatic pressing melting treatment is equal to the temperature T2 of the vacuum sintering.

[0107] In some embodiments, the heat preservation and pressure holding time of the hot isostatic pressing melt infiltration treatment is 1h-3h, for example, it can be 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0108] In some embodiments, the annealing temperature T4 is lower than the melting point T of the high-entropy alloy layer. m2 .

[0109] This invention further optimizes the interfacial bonding force between the metal protective layer and the ceramic phase, as well as between the metal protective layer and the high-entropy alloy phase, through annealing treatment, thereby improving the strength of the high-entropy alloy-ceramic composite material; moreover, it can also effectively reduce internal stress and improve the toughness of the obtained high-entropy alloy-ceramic composite material.

[0110] In some embodiments, the annealing temperature T4 is higher than the melting point T of the high-entropy alloy layer. m2 The temperature range is 100℃-200℃ lower, for example, it can be 100℃, 120℃, 150℃, 160℃, 180℃ or 200℃, but is not limited to the listed values. Other unlisted values ​​within the range also apply.

[0111] In some embodiments, the annealing process is performed at a pressure of 30 Pa or less.

[0112] In some embodiments, the temperature is increased from room temperature to the annealing temperature T4 at a heating rate of 0.5℃ / min to 1℃ / min, for example, 0.5℃ / min, 0.6℃ / min, 0.7℃ / min, 0.8℃ / min, 0.9℃ / min or 1℃ / min, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0113] In some embodiments, the holding time at the annealing temperature T4 is 1h-3h, for example, it can be 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0114] In some embodiments, the annealing process is terminated when the temperature T4 of the annealing treatment is cooled to room temperature at a cooling rate of 1℃ / min-2℃ / min; the cooling rate may be 1℃ / min, 1.2℃ / min, 1.5℃ / min, 1.8℃ / min or 2℃ / min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0115] In some embodiments, the molding process includes at least one of compression molding, cold isostatic pressing, extrusion molding, injection molding, or 3D printing. This invention does not specifically limit the molding method, as long as a molded body of the desired shape can be obtained. When the desired shape cannot be obtained through a one-step molding process, the molding process further includes machining.

[0116] In some embodiments, the degreasing is performed by inert gas negative pressure degreasing or hydrogen positive pressure degreasing.

[0117] In some embodiments, if the shape of the degreased molded body is inconsistent with the shape of the target product, cutting processing is performed after degreasing.

[0118] In this invention, no specific limit is placed on the vacuum pre-sintering temperature T1; it is sufficient to obtain a pre-sintered body with a relative density not exceeding 90%. The aim is to ensure that most of the pores in the pre-sintered body are interconnected, thereby facilitating the melting and infiltration process of the high-entropy alloy.

[0119] In some embodiments, the holding time for vacuum pre-sintering is 1h-3h, for example, it can be 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0120] In some embodiments, the pressure of the vacuum pre-sintering is below 30 Pa.

[0121] One embodiment of the present invention provides a high-entropy alloy-ceramic composite material, which is prepared by the preparation method described in any embodiment.

[0122] In some embodiments, when the pressure of the hot isostatic pressing melting treatment is above 5 MPa and below 80 MPa, a high-entropy alloy-ceramic composite material with a gradient distribution of high-entropy alloy phase is obtained, that is, the content of high-entropy alloy phase gradually decreases from the surface to the interior of the high-entropy alloy-ceramic composite material.

[0123] In some embodiments, when the pressure of the hot isostatic pressing melting treatment is higher than 80 MPa and lower than 300 MPa, a high-entropy alloy-ceramic composite material with uniform composition is obtained.

[0124] One embodiment of the present invention provides an application of a high-entropy alloy-ceramic composite material, which is used to prepare molds, cutting tools or wear-resistant parts.

[0125] The high-entropy alloy-ceramic composite material is prepared by the preparation method described in any embodiment, or is the high-entropy alloy-ceramic composite material described in any embodiment.

[0126] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0127] The technical solution of the present invention will be described in detail below through specific embodiments and comparative examples.

[0128] Examples and Comparative Examples

[0129] Example 1

[0130] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0131] (1) In a nitrogen atmosphere, the raw material powder of the formula amount was placed in a ball mill and mixed by ball milling with cemented carbide grinding balls and anhydrous ethanol for 48 hours. The mass ratio of cemented carbide grinding balls to raw material powder was 4:1, and ceramic phase powder with an average particle size of about 0.2 μm was obtained.

[0132] The raw material powder comprises, by volume percentage, 98.45 vol% titanium carbide, 0.55 vol% tantalum carbide and 1 vol% niobium carbide, and the corresponding mass percentages of titanium carbide, tantalum carbide and niobium carbide are calculated to be 96.91 wt%, 1.57 wt% and 1.52 wt%, respectively.

[0133] (2) A metal protective layer is chemically coated onto the surface of the ceramic phase powder particles. The metal protective layer is made of cobalt (melting point T). m1 (1495℃):

[0134] The ceramic phase powder was placed in an activation solution and ultrasonically stirred for 25 minutes. It was then placed in a chemical plating solution at a solid-liquid ratio of 250 g / L and kept at 85°C until bubbles were generated. The powder was then ultrasonically stirred at 50°C for chemical plating. After no more bubbles were generated, the powder was rinsed with deionized water and vacuum dried at 100°C to complete the chemical plating. The resulting ceramic phase powder had a metal protective layer (approximately 1.31 wt%) on its surface.

[0135] Based on the original formulation amount of ceramic phase powder and the content of the coating metal protective layer, the theoretical density of the metal-ceramic composite material composed of these two components was calculated to be 5.074 g / cm³. 3 The densities of titanium carbide, tantalum carbide, niobium carbide, and cobalt are respectively taken as 4.93 g / cm³. 3 14.3g / cm 3 7.6g / cm 3 and 8.9g / cm 3 .

[0136] The activation solution includes hydrofluoric acid (40 wt%), ammonium fluoride, nitric acid (65 wt%), and hydrochloric acid (36 wt%); wherein the amounts of hydrofluoric acid, ammonium fluoride, nitric acid, and hydrochloric acid in the activation solution are 40 mL / L, 3 g / L, 30 mL / L, and 20 mL / L, respectively.

[0137] The electroless plating solution comprises 28 g / L cobalt sulfate, 25 g / L sodium hypophosphite, 50 g / L trisodium citrate, and 25 g / L boric acid.

[0138] (3) The ceramic phase powder with a metal protective layer on the particle surface is granulated and the molded body is obtained by cold isostatic pressing at 200MPa.

[0139] (4) The molded body is degreased in an argon atmosphere and then vacuum pre-sintered under a pressure of less than 30 Pa to obtain a pre-sintered body with a relative density D of 86%.

[0140] The vacuum pre-sintering temperature T1 is 1532℃, and the holding time is 2h.

[0141] (5) Two metal layers are coated on the surface of the pre-sintered body, and the innermost high-entropy alloy layer (melting point T) is coated by spraying. m2 (1042℃); the outermost metal layer is a 0.2mm thick titanium layer (melting point T) formed by using a thin-walled metal component. m3 (1668℃).

[0142] The high-entropy alloy layer is composed of Cu. 22.7 Zn 22.7 Mn 22.7 Ni 22.7 Al 9.2 .

[0143] The density of the high-entropy alloy layer is 7.36 g / cm³. 3 Based on the relative density D and volume V of the pre-sintered body, the mass M of the high-entropy alloy layer is obtained as ≥ 7.36 × V × (1 - D).

[0144] (6) At a pressure of 10 -3 Vacuum sintering is performed under conditions below Pa, and the vacuum sintering temperature T2 = T m2 +35℃ = 1077℃, keep warm for 0.5h.

[0145] (7) Under argon atmosphere, hot isostatic pressing melting treatment was carried out at a pressure of 10 MPa, a temperature T3 of 1077℃, and a holding time of 3h to obtain a high-entropy alloy-ceramic composite sintered body with gradient structure.

[0146] (8) The obtained high-entropy alloy-ceramic composite sintered body with gradient structure was annealed to optimize the interfacial bonding force between the ceramic phase grains and the metal protective layer and to reduce internal stress: the annealing was carried out under a pressure below 30 Pa, and the temperature was increased from room temperature to T4=T at a heating rate of 0.5℃ / min. m2-200℃ = 842℃, and the holding time is 1h; then, the temperature is reduced from T4 to room temperature at a cooling rate of 2℃ / min to obtain the high-entropy alloy-ceramic composite material.

[0147] Example 2

[0148] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0149] The steps for preparing the pre-sintered body in steps (1) to (5) are the same as in Example 1.

[0150] (6) At a pressure of 10 -3 Vacuum sintering is performed under conditions below Pa, and the vacuum sintering temperature T2 = T m2 +25℃ = 1067℃, keep warm for 1 hour.

[0151] (7) Under argon atmosphere, hot isostatic pressing melting treatment was carried out at a pressure of 5 MPa, a temperature T3 of 1067℃, and a holding time of 3 h to obtain a high entropy alloy-ceramic composite sintered body with gradient structure.

[0152] (8) The obtained high-entropy alloy-ceramic composite sintered body with gradient structure was annealed to optimize the interfacial bonding force between the ceramic phase and the metal protective layer and to reduce internal stress: the annealing was carried out under a pressure of less than 30 Pa, and the temperature was increased from room temperature to T4 = T at a heating rate of 0.5 °C / min. m2 -100℃ = 942℃, and the holding time is 1h; then, the temperature is reduced from T4 to room temperature at a cooling rate of 2℃ / min to obtain the high-entropy alloy-ceramic composite material.

[0153] Example 3

[0154] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0155] The steps for preparing the pre-sintered body in steps (1) to (5) are the same as in Example 1.

[0156] (6) When the pressure is below 10 -3 Vacuum sintering is performed under conditions of Pa, and the vacuum sintering temperature T2 = T m2 +50℃ = 1092℃, keep warm for 1 hour.

[0157] (7) Under argon atmosphere, hot isostatic pressing melting treatment was carried out at a pressure of 70 MPa and a temperature T3 of 1092 °C for 3 h to obtain a high entropy alloy-ceramic composite sintered body with gradient structure.

[0158] (8) The obtained high-entropy alloy-ceramic composite sintered body with gradient structure was annealed to optimize the interfacial bonding force between the ceramic phase grains and the metal protective layer and to reduce internal stress: the annealing was carried out under a pressure of less than 30 Pa, and the temperature was increased from room temperature to T4 = T at a heating rate of 0.5 °C / min. m2 -150℃ = 892℃, and the holding time is 1h; then, the temperature is reduced from T4 to room temperature at a cooling rate of 2℃ / min to obtain the high-entropy alloy-ceramic composite material.

[0159] Example 4

[0160] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0161] The step parameters in steps (1) to (6) are the same as in Example 1.

[0162] (7) Under argon atmosphere, hot isostatic pressing melting treatment was carried out at a pressure of 80 MPa, a temperature T3 of 1077℃, and a holding time of 3h to obtain a high-entropy alloy-ceramic composite sintered body with gradient structure.

[0163] (8) The obtained high-entropy alloy-ceramic composite sintered body with gradient structure is annealed to optimize the interfacial bonding force between the ceramic phase and the metal protective layer and reduce the internal stress, so as to obtain the high-entropy alloy-ceramic composite material; the annealing parameters are the same as those in Example 1.

[0164] Example 5

[0165] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material. Except for the hot isostatic pressing melting treatment pressure of 150 MPa, the rest is the same as in Example 4.

[0166] Example 6

[0167] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material. Except for the hot isostatic pressing melting treatment pressure of 300 MPa, the rest is the same as in Example 4.

[0168] Example 7

[0169] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material. Except for the vacuum sintering temperature T2 and the hot isostatic pressing melting and infiltration treatment temperature T3 being 1052℃, the rest are the same as in Example 5.

[0170] Example 8

[0171] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material. Except for the vacuum sintering temperature T2 and the hot isostatic pressing melting and infiltration treatment temperature T3 being 1102℃, the rest are the same as in Example 5.

[0172] Example 9

[0173] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material. Except for the annealing temperature T4 being 992℃, the rest is the same as in Example 5.

[0174] Example 10

[0175] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, which is the same as in Example 5 except that the annealing temperature T4 is 792℃.

[0176] Example 11

[0177] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0178] (1) In a nitrogen atmosphere, the raw material powder of the formula amount was placed in a ball mill and mixed by ball milling with cemented carbide grinding balls and anhydrous ethanol for 48 hours. The mass ratio of cemented carbide grinding balls to raw material powder was 4:1, and ceramic phase powder with an average particle size of about 0.2 μm was obtained.

[0179] The raw material powder comprises, by volume percentage, 98.45 vol% titanium carbide, 0.55 vol% tantalum carbide and 1 vol% niobium carbide, and the corresponding mass percentages of titanium carbide, tantalum carbide and niobium carbide are calculated to be 96.91 wt%, 1.57 wt% and 1.52 wt%, respectively.

[0180] (2) A metal protective layer is coated onto the surface of the ceramic phase powder particles using a chemical coating method. The metal protective layer is made of nickel (melting point T). m1 (1455℃):

[0181] The ceramic phase powder was placed in an activation solution and ultrasonically stirred for 25 minutes. It was then placed in a chemical plating solution at a solid-liquid ratio of 250 g / L and kept at 85°C until bubbles were generated. The powder was then ultrasonically stirred at 50°C for chemical plating. After no more bubbles were generated, the powder was rinsed with deionized water and vacuum dried at 100°C to complete the chemical plating. The resulting ceramic phase powder had a metal protective layer (1.31 wt%) on its surface.

[0182] Based on the original formulation amount of ceramic phase powder and the content of the coating metal protective layer, the theoretical density of the metal-ceramic composite material composed of these two components was calculated to be 5.074 g / cm³.3 The densities of titanium carbide, tantalum carbide, niobium carbide, and nickel are all taken as 4.93 g / cm³. 3 14.3g / cm 3 7.6g / cm 3 and 8.902 g / cm 3 .

[0183] The activation solution comprises hydrofluoric acid (40 wt%), ammonium fluoride, nitric acid (65 wt%), and hydrochloric acid (36 wt%); wherein the amounts of hydrofluoric acid, ammonium fluoride, nitric acid, and hydrochloric acid in the activation solution are 40 mL / L, 3 g / L, 30 mL / L, and 20 mL / L, respectively; and the solvent of the activation solution is deionized water.

[0184] The electroless plating solution comprises 28 g / L nickel sulfate, 25 g / L sodium hypophosphite, 50 g / L trisodium citrate, and 25 g / L boric acid.

[0185] (3) The ceramic phase powder with a metal protective layer on the particle surface is granulated and the molded body is obtained by cold isostatic pressing at 200MPa.

[0186] (4) The molded body is degreased in an argon atmosphere and then vacuum pre-sintered under a pressure of less than 30 Pa to obtain a pre-sintered body with a relative density D of 90%. The vacuum pre-sintering temperature T1 is 1552℃ and the temperature is held for 1 hour.

[0187] (5) Two metal layers are coated on the surface of the pre-sintered body, and the innermost high-entropy alloy layer (melting point T) is coated by spraying. m2 The outermost metal layer is a 0.1mm thick titanium layer (melting point T). m3 (1668℃).

[0188] The high-entropy alloy layer is composed of Al. 80 Li5Mg5Zn5Cu5.

[0189] The density of the high-entropy alloy layer is 3.08 g / cm³. 3 Based on the relative density D and volume V of the pre-sintered body, the mass M of the high-entropy alloy layer is obtained as ≥ 3.08 × V × (1 - D).

[0190] (6) At a pressure of 10 -3 Vacuum sintering is performed under conditions below Pa; the vacuum sintering temperature is T2 = T m2 +50℃ = 685℃, keep warm for 0.5h.

[0191] (7) Under argon atmosphere, hot isostatic pressing melting treatment was carried out at a pressure of 100 MPa, a temperature of 685 °C and a time of 2 h to obtain a high entropy alloy-ceramic composite sintered body with uniform composition.

[0192] (8) The obtained high-entropy alloy-ceramic composite sintered body with uniform composition was annealed to optimize the interfacial bonding force between the ceramic phase and the metal protective layer and to reduce internal stress: the annealing was carried out under a pressure of less than 30 Pa, and the temperature was increased from room temperature to T4 = T at a heating rate of 0.5 °C / min. m2 -150℃ = 485℃ and hold for 1 hour; then cool from T4 to room temperature at a cooling rate of 2℃ / min to obtain the high-entropy alloy-ceramic composite material.

[0193] Example 12

[0194] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0195] (1) In a nitrogen atmosphere, the raw material powder of the formula amount was placed in a ball mill and mixed by ball milling with cemented carbide grinding balls and anhydrous ethanol for 48 hours. The mass ratio of cemented carbide grinding balls to raw material powder was 4:1, and ceramic phase powder with an average particle size of about 0.2 μm was obtained.

[0196] The raw material powder comprises, by volume percentage, 98.45 vol% titanium carbide, 0.55 vol% tantalum carbide and 1 vol% niobium carbide, and the corresponding mass percentages of titanium carbide, tantalum carbide and niobium carbide are calculated to be 96.91 wt%, 1.57 wt% and 1.52 wt%, respectively.

[0197] (2) A metal protective layer is coated onto the surface of the ceramic phase powder particles using a chemical coating method. The metal protective layer is made of iron (melting point T). m1 (1538℃):

[0198] The ceramic phase powder was placed in an activation solution and ultrasonically stirred for 25 minutes. It was then placed in a chemical plating solution at a solid-liquid ratio of 250 g / L and kept at 85°C until bubbles were generated. The powder was then ultrasonically stirred at 50°C for chemical plating. After no more bubbles were generated, the powder was rinsed with deionized water and vacuum dried at 100°C to complete the chemical plating. The resulting ceramic phase powder had a metal protective layer (1.17 wt%) on its surface.

[0199] Based on the original formulation amount of ceramic phase powder and the content of the coating metal protective layer, the theoretical density of the metal-ceramic composite material composed of these two components was calculated to be 5.067 g / cm³. 3The densities of titanium carbide, tantalum carbide, niobium carbide, and iron are all taken as 4.93 g / cm³. 3 14.3g / cm 3 7.6g / cm 3 and 7.86 g / cm 3 .

[0200] The activation solution comprises hydrofluoric acid (40 wt%), ammonium fluoride, nitric acid (65 wt%), and hydrochloric acid (36 wt%); wherein the amounts of hydrofluoric acid, ammonium fluoride, nitric acid, and hydrochloric acid in the activation solution are 40 mL / L, 3 g / L, 30 mL / L, and 20 mL / L, respectively; and the solvent of the activation solution is deionized water.

[0201] The electroless plating solution comprises 28 g / L ferric sulfate, 25 g / L sodium hypophosphite, 50 g / L trisodium citrate, and 25 g / L boric acid.

[0202] (3) Granulate the ceramic phase powder with a metal protective layer on the particle surface, and obtain the molded body by cold isostatic pressing at 200MPa.

[0203] (4) The molded body is degreased in an argon atmosphere and then vacuum pre-sintered under a pressure of less than 30 Pa to obtain a pre-sintered body with a relative density D of 82%; the vacuum pre-sintering temperature T1 is 1506℃ and the temperature is held for 1h.

[0204] (5) Two metal layers are coated on the surface of the pre-sintered body, and the innermost high-entropy alloy layer (melting point T) is coated by spraying. m2 The outermost metal layer is a 0.1mm thick titanium layer (melting point T). m3 (1668℃);

[0205] The high-entropy alloy layer has the composition AlCoCrFeNiTi. 0.5 .

[0206] The density of the high-entropy alloy layer is 6.44 g / cm³. 3 Based on the relative density D and volume V of the pre-sintered body, the minimum required mass M of the high-entropy alloy layer is 6.44 × V × (1 - D).

[0207] (6) At a pressure of 10 -3 Vacuum sintering is performed under conditions below Pa; the vacuum sintering temperature is T2 = T m2 +35℃ = 1223℃, keep warm for 0.5h.

[0208] (7) Under argon atmosphere, hot isostatic pressing melting treatment was carried out at a pressure of 100 MPa, a temperature of 1223 °C and a time of 2 h to obtain a high entropy alloy-ceramic composite sintered body with uniform composition.

[0209] (8) The obtained high-entropy alloy-ceramic composite sintered body with uniform composition was annealed to optimize the interfacial bonding force between the ceramic phase and the metal protective layer and to reduce internal stress: the annealing was carried out under a pressure of less than 30 Pa, and the temperature was increased from room temperature to T4 = T at a heating rate of 0.5 °C / min. m2 -150℃ = 1038℃ and hold for 1 hour; then cool from T4 to room temperature at a cooling rate of 2℃ / min to obtain the high-entropy alloy-ceramic composite material.

[0210] Example 13

[0211] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0212] (1) In a nitrogen atmosphere, the raw material powder of the formula amount was placed in a ball mill and mixed by ball milling with silicon carbide grinding balls and anhydrous ethanol for 48 hours. The mass ratio of silicon carbide grinding balls to raw material powder was 6:1, and ceramic phase powder with an average particle size of about 0.6 μm was obtained.

[0213] The raw material powder comprises 60 vol% TiN, 25 vol% SiC, and 15 vol% AlN by volume percentage, and the corresponding mass percentages of TiN, SiC, and AlN are calculated to be 70.92 wt%, 18.05 wt%, and 11.03 wt%, respectively.

[0214] (2) A metal protective layer is coated onto the surface of the ceramic phase powder particles using a chemical coating method. The material of the metal protective layer is cobalt (melting point T). m1 (1495℃):

[0215] The ceramic phase powder was placed in an activation solution and ultrasonically stirred for 25 minutes. It was then placed in a chemical plating solution at a solid-liquid ratio of 250 g / L and kept at 85°C until bubbles were generated. The powder was then ultrasonically stirred at 50°C for chemical plating. After no more bubbles were generated, the powder was rinsed with deionized water and vacuum dried at 100°C to complete the chemical plating. The resulting ceramic phase powder had a metal protective layer (1.26 wt%) on its surface.

[0216] Based on the original formulation amount of ceramic phase powder and the content of the coating metal protective layer, the theoretical density of the metal-ceramic composite material composed of these two components was calculated to be 4.489 g / cm³. 3The densities of TiN, SiC, AlN, and Co are each taken as 5.24 g / cm³. 3 3.2g / cm 3 3.26 g / cm 3 and 8.9g / cm 3 .

[0217] The activation solution comprises hydrofluoric acid (40 wt%), ammonium fluoride, nitric acid (65 wt%), and hydrochloric acid (36 wt%); wherein the amounts of hydrofluoric acid, ammonium fluoride, nitric acid, and hydrochloric acid in the activation solution are 40 mL / L, 3 g / L, 30 mL / L, and 20 mL / L, respectively; and the solvent of the activation solution is deionized water.

[0218] The electroless plating solution comprises 30 g / L cobalt sulfate, 25 g / L sodium hypophosphite, 50 g / L trisodium citrate, and 25 g / L boric acid.

[0219] (3) Granulate the ceramic phase powder with a metal protective layer on the particle surface, and obtain the molded body by cold isostatic pressing at 200MPa.

[0220] (4) The molded body is degreased in an argon atmosphere and then vacuum pre-sintered under a pressure of less than 30 Pa to obtain a pre-sintered body with a relative density D of 88%; the vacuum pre-sintering temperature T1 is 1563℃ and the temperature is held for 1h.

[0221] (5) Two metal layers are coated on the surface of the pre-sintered body, and the innermost high-entropy alloy layer (melting point T) is coated by spraying. m2 The outermost metal layer is a 0.1 mm thick niobium layer (melting point T). m3 (2468℃);

[0222] The high-entropy alloy layer has the composition AlCoCrFeNiTi. 0.5 .

[0223] The density of the high-entropy alloy layer is 6.44 g / cm³. 3 Based on the relative density D and volume V of the pre-sintered body, the mass M of the high-entropy alloy layer is obtained as ≥ 6.44 × V × (1 - D).

[0224] (6) At a pressure of 10 -3 Vacuum sintering is performed under conditions below Pa; the vacuum sintering temperature is T2 = T m2 +35℃ = 1223℃, keep warm for 0.5h.

[0225] (7) Under argon atmosphere, hot isostatic melting and infiltration treatment was carried out at a pressure of 100 MPa, a temperature of 1223 °C and a time of 2 h to obtain a high entropy alloy-ceramic composite sintered body with uniform composition.

[0226] (8) The obtained high-entropy alloy-ceramic composite sintered body with uniform composition was annealed to optimize the interfacial bonding force between the ceramic phase and the metal protective layer and to reduce internal stress: the annealing was carried out under a pressure of less than 30 Pa, and the temperature was increased from room temperature to T4 = T at a heating rate of 0.5 °C / min. m2 -150℃ = 1038℃ and hold for 1 hour; then cool from T4 to room temperature at a cooling rate of 2℃ / min to obtain the high-entropy alloy-ceramic composite material.

[0227] Example 14

[0228] This embodiment provides a method for preparing a high-entropy alloy-ceramic composite material, the method comprising the following steps:

[0229] (1) In a nitrogen atmosphere, the raw material powder of the formula amount was placed in a ball mill and mixed with cemented carbide grinding balls and anhydrous ethanol. The ball milling time was 48h and the mass ratio of cemented carbide grinding balls to raw material powder was 4:1, resulting in ceramic phase powder with an average particle size of about 0.5μm.

[0230] The raw material powder comprises, by volume percentage, 75.5 vol% TiB2, 20 vol% B4C, 2.5 vol% SiC and 2 vol% Mo2C, with corresponding calculated mass percentages of 81.64 wt%, 12.06 wt%, 1.91 wt%, and 4.39 wt% for TiB2, B4C, SiC and Mo2C, respectively.

[0231] (2) A metal protective layer is coated onto the surface of the ceramic phase powder particles using a chemical coating method. The material of the metal protective layer is cobalt (melting point T). m1 (1495℃):

[0232] The ceramic phase powder was placed in an activation solution and ultrasonically stirred for 25 minutes. It was then placed in a chemical plating solution at a solid-liquid ratio of 250 g / L and kept at 85°C until bubbles were generated. The powder was then ultrasonically stirred at 50°C for chemical plating. After no more bubbles were generated, the powder was rinsed with deionized water and vacuum dried at 100°C to complete the chemical plating. The resulting ceramic phase powder had a metal protective layer (1.12 wt%) on its surface.

[0233] Based on the original formulation amount of ceramic phase powder and the content of the coating metal protective layer, the theoretical density of the metal-ceramic composite material composed of these two components was calculated to be 4.227 g / cm³. 3 The densities of TiB2, B4C, SiC, Mo2C, and Co are all taken as 4.52 g / cm³. 3 2.52g / cm 3 3.2g / cm 3 9.18 g / cm 3 and 8.9g / cm 3 .

[0234] The activation solution comprises hydrofluoric acid (40 wt%), ammonium fluoride, nitric acid (65 wt%), and hydrochloric acid (36 wt%); wherein the amounts of hydrofluoric acid, ammonium fluoride, nitric acid, and hydrochloric acid in the activation solution are 40 mL / L, 3 g / L, 30 mL / L, and 20 mL / L, respectively; and the solvent of the activation solution is deionized water.

[0235] The electroless plating solution comprises 30 g / L cobalt sulfate, 25 g / L sodium hypophosphite, 50 g / L trisodium citrate, and 25 g / L boric acid.

[0236] (3) The ceramic phase powder with a metal protective layer on the particle surface is granulated and the molded body is obtained by cold isostatic pressing at 200MPa.

[0237] (4) The molded body is degreased in an argon atmosphere and then vacuum pre-sintered under a pressure of less than 30 Pa to obtain a pre-sintered body with a relative density D of 84%; the vacuum pre-sintering temperature T1 is 1555℃ and the temperature is held for 1h.

[0238] (5) Two metal layers are coated on the surface of the pre-sintered body, and the innermost high-entropy alloy layer (melting point T) is coated by spraying. m2 The outermost metal layer is a 0.1 mm thick tantalum layer (melting point T). m3 (2996℃).

[0239] The high-entropy alloy layer has the composition AlCoCrFeNiTi. 0.5 .

[0240] The density of the high-entropy alloy layer is 6.44 g / cm³. 3 Based on the relative density D and volume V of the pre-sintered body, the mass M of the high-entropy alloy layer is obtained as ≥ 6.44 × V × (1 - D).

[0241] (6) At a pressure of 10 -3 Vacuum sintering is performed under conditions below Pa; the vacuum sintering temperature is T2 = Tm2 +35℃ = 1223℃, keep warm for 0.5h.

[0242] (7) Under argon atmosphere, hot isostatic pressing melting treatment was carried out at a pressure of 100 MPa, a temperature of 1223 °C and a time of 2 h to obtain a high entropy alloy-ceramic composite sintered body with uniform composition.

[0243] (8) The obtained high-entropy alloy-ceramic composite sintered body with uniform composition was annealed to optimize the interfacial bonding force between the ceramic phase and the metal protective layer and to reduce internal stress: the annealing was carried out under a pressure of less than 30 Pa, and the temperature was increased from room temperature to T4 = T at a heating rate of 0.5 °C / min. m2 -150℃ = 1038℃ and hold for 1 hour; then cool from T4 to room temperature at a cooling rate of 2℃ / min to obtain the high-entropy alloy-ceramic composite material.

[0244] Comparative Example 1

[0245] This comparative example provides a method for preparing a high-entropy alloy-ceramic composite material, which is the same as Example 5 except that the surface of the ceramic phase powder particles is not covered with a metal protective layer.

[0246] Since the surface of the ceramic phase powder particles is not covered with a metal protective layer, the sintering activity is greatly reduced at the same vacuum pre-sintering temperature T1 = 1532°C as in Example 5. The relative density D of the pre-sintered body obtained in this comparative example is 63%, and the mass M of the high-entropy alloy layer is adjusted according to the formula 7.36 × V × (1-D).

[0247] Comparative Example 2

[0248] This comparative example provides a method for preparing a high-entropy alloy-ceramic composite material, which is the same as in Example 5 except that the outermost metal layer is omitted.

[0249] Comparative Example 3

[0250] This comparative example provides a method for preparing a high-entropy alloy-ceramic composite material, which is the same as Example 5 except that no annealing treatment is performed.

[0251] Comparative Example 4

[0252] This comparative example provides a method for preparing a high-entropy alloy-ceramic composite material, which is the same as that in Example 5 except that the vacuum pre-sintering temperature T1 is 1563℃.

[0253] Because the vacuum pre-sintering temperature T1 = 1563℃ was increased, the relative density D of the pre-sintered body obtained in this comparative example is 92%, and the mass M of the high-entropy alloy layer is adjusted accordingly according to the formula 7.36×V×(1-D).

[0254] Comparative Example 5

[0255] This comparative example provides a method for preparing a high-entropy alloy-ceramic composite material. Except for the vacuum sintering temperature T2 and the hot isostatic pressing melting and infiltration treatment temperature T3 being 1500℃, the rest are the same as in Example 5.

[0256] The sintering density, hardness, flexural strength and fracture toughness of the high-entropy alloy-ceramic composite materials obtained in the above embodiments and comparative examples were measured, and the results are shown in Table 1.

[0257] The test method for sintering density is as follows: Since it involves the gradient structure and whether the melting is complete, the obtained high-entropy alloy-ceramic composite material sample is cut along the central region. After grinding and polishing the cut surface, the entire cut surface is observed and tested for sintering density using a metallographic microscope or a scanning electron microscope.

[0258] Hardness testing was conducted according to the national standard GB / T16534-2009 "Test Method for Room Temperature Hardness of Fine Ceramics". Due to the involvement of compositional gradient structure, based on the sampling method for detecting sintering density, hardness was measured on the cut surface after grinding and polishing. Assuming the distance from the edge of the cut surface to the center is L, the edge region was used as the starting point, and tests were conducted from the edge region towards the center region of the sample in four regions at distances of 0L, L / 3, 2L / 3, and L from the edge. At least three values ​​were measured in each region, and the average value was taken.

[0259] The flexural strength was tested according to the national standard GB / T4741-1999 "Test Method for Flexural Strength of Ceramic Materials". Due to the presence of compositional gradient structures, the flexural strength of these structures could not be tested. Therefore, flexural strength tests were not performed on samples with compositional gradient structures.

[0260] Fracture toughness testing was conducted according to the national standard GB / T23806-2009 "Test Method for Fracture Toughness of Fine Ceramics - Single-sided Precracked Beam (SEPB) Method". Due to the involvement of compositional gradient structures, the fracture toughness of gradient structures could not be tested. Therefore, fracture toughness testing was not performed on samples with compositional gradient structures.

[0261] Table 1. Test results of embodiments and comparative examples of the present invention.

[0262]

[0263]

[0264] As can be seen from Examples 1 to 6 in Table 1, as the pressure of hot isostatic pressing infiltration treatment increases, the composition gradient of the obtained high-entropy alloy-ceramic composite material gradually decreases. When the pressure is above 80 MPa, the composition gradient disappears, and a high-entropy alloy-ceramic composite material with uniform composition is obtained. At the same time, since the pressure increases, it is beneficial to promote the densification of the pre-sintered body, which will cause the content of high-entropy alloys infiltrated into the pre-sintered body to decrease. As a result, the hardness of the obtained high-entropy alloy-ceramic composite material increases and the fracture toughness decreases.

[0265] A comparison of Examples 5 and 7 in Table 1 shows that, due to the decrease in the vacuum sintering and hot isostatic pressing melting treatment temperature, the energy of sintering shrinkage is reduced, resulting in a slight increase in the high-entropy alloy content in the obtained high-entropy alloy-ceramic composite material. This leads to a slight decrease in hardness and flexural strength, while the toughness increases slightly. Conversely, a comparison of Examples 5 and 8 in Table 1 shows that, an increase in the vacuum sintering and hot isostatic pressing melting treatment temperature leads to a slight increase in the hardness and flexural strength of the obtained high-entropy alloy-ceramic composite material, while the fracture toughness decreases slightly.

[0266] As can be seen from the comparison of Example 5 with Examples 9 and 10 in Table 1, an excessively high annealing temperature will enhance the atomic diffusion ability and easily lead to changes in the phase structure of the high-entropy alloy. On the other hand, an excessively low annealing temperature will result in insufficient optimization of the interface and reduction of stress, both of which will lead to a decrease in the fracture toughness of the obtained high-entropy alloy-ceramic composite material.

[0267] As can be seen from the comparison between Example 5 and Comparative Example 1 in Table 1, the phase structure of the high-entropy alloy was severely damaged during vacuum sintering and hot isostatic pressing due to the lack of a metal protective layer. As a result, the hardness, flexural strength and fracture toughness of the obtained high-entropy alloy-ceramic composite material decreased sharply.

[0268] As can be seen from the comparison between Example 5 and Comparative Example 2 in Table 1, since the outermost metal layer was not covered, the molten high-entropy alloy layer during vacuum sintering was not protected, causing it to flow to the lower part of the product and the upper part was not well sealed. Therefore, the subsequent hot isostatic pressing melt infiltration process could not sinter it into a dense state.

[0269] As can be seen from the comparison between Example 5 and Comparative Example 3 in Table 1, the bending strength and fracture toughness of the obtained high-entropy alloy-ceramic composite material are reduced due to the lack of annealing treatment.

[0270] As can be seen from the comparison between Example 5 and Comparative Example 4 in Table 1, since the temperature of vacuum pre-sintering is much higher than the melting point of the metal protective layer, the relative density of the pre-sintered body reaches 92%, which means that the pores in the pre-sintered body are almost all closed pores. Therefore, during the subsequent vacuum sintering and hot isostatic pressing infiltration treatment, the molten high-entropy alloy is prevented from diffusing into the interior of the pre-sintered body, resulting in the inability to sinter densely.

[0271] As can be seen from the comparison between Example 5 and Comparative Example 5 in Table 1, since the temperature of vacuum sintering and the temperature of hot isostatic pressing infiltration treatment are higher than the melting point of the metal protective layer, the high-entropy alloy phase structure will also be destroyed, and the bending strength and fracture toughness of the obtained high-entropy alloy-ceramic composite material will be reduced.

[0272] In summary, this invention coats the surface of ceramic phase powder particles with a metal protective layer to prevent carbon, nitrogen, boron, or silicon atoms in the ceramic phase from damaging the high-entropy alloy phase structure. Then, through molding, debinding, and vacuum pre-sintering, a porous pre-sintered body is obtained. Next, at least two metal layers, including the innermost high-entropy alloy layer, are coated onto the surface of the pre-sintered body. The surface of the pre-sintered body is then sealed by vacuum sintering. Finally, hot isostatic pressing (HIP) infiltration treatment is used to allow the molten high-entropy alloy to diffuse along the pores and / or interfaces of the pre-sintered body into its interior, thereby obtaining a dense high-entropy alloy-ceramic composite material. Controlling the pressure of the HIP infiltration treatment allows for the production of high-entropy alloy-ceramic composite materials with a gradient distribution of the high-entropy alloy phase or with uniform composition. Furthermore, the application of HIP infiltration treatment solves the problem of easy agglomeration of the high-entropy alloy binder phase caused by traditional powder mixing methods, while also avoiding incomplete infiltration and limitations imposed by product dimensions.

[0273] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-entropy alloy-ceramic composite material, characterized in that, The preparation method includes the following steps: A metal protective layer is coated on the surface of ceramic phase powder particles, and then the particles are shaped, degreased and vacuum pre-sintered to obtain a pre-sintered body with a relative density of no more than 90%. The high-entropy alloy-ceramic composite material is obtained by coating the surface of the pre-sintered body with at least two metal layers, followed by vacuum sintering, hot isostatic pressing, and annealing. The at least two metal layers include an innermost high-entropy alloy layer and an outermost metal layer; The vacuum sintering temperature T2, the hot isostatic pressing melting treatment temperature T3, and the annealing treatment temperature T4 are all lower than the melting point T of the metal protective layer. m1 ; The vacuum sintering temperature T2 is higher than the melting point T of the high-entropy alloy layer. m2 ; The melting point T of the outermost metal layer of the at least two metal layers m3 The melting point T of the metal protective layer is higher than that of the metal protective layer. m1 ; The melting point T of the high-entropy alloy layer m2 The temperature range is 600℃-1200℃. The volume of the high-entropy alloy layer is not less than the total volume of the pores in the pre-sintered body; The thickness of the outermost metal layer is 0.1mm-0.3mm; The vacuum sintering temperature T2 is higher than the melting point T of the high-entropy alloy layer. m2 Temperatures can range from 25°C to 50°C. The vacuum sintering temperature T2 is higher than the melting point T of the metal protective layer. m1 Low than 200℃; The temperature T3 of the hot isostatic pressing melt infiltration treatment is equal to the temperature T2 of the vacuum sintering. The annealing temperature T4 is higher than the melting point T of the high-entropy alloy layer. m2 100℃-200℃ lower.

2. The preparation method according to claim 1, characterized in that, The metal element in the metal protective layer includes any one or a combination of at least two of Co, Ni, or Fe.

3. The preparation method according to claim 1, characterized in that, The metallic elements in the high-entropy alloy layer include a combination of at least five of the following: Al, Fe, Co, Zn, Sn, Ni, Cr, Cu, Mn, Li, Mg, or Ti.

4. The preparation method according to claim 1, characterized in that, The outermost metal layer contains any one or a combination of at least two of the following metal elements: Ti, Zr, Mo, Nb, or Ta.

5. The preparation method according to claim 1, characterized in that, The holding time for vacuum sintering is 0.5h-1h.

6. The preparation method according to claim 1, characterized in that, The vacuum sintering pressure is 10. -3 Below Pa.

7. The preparation method according to claim 1, characterized in that, The hot isostatic pressing melting treatment is carried out in an inert atmosphere.

8. The preparation method according to claim 1, characterized in that, The pressure of the hot isostatic pressing melt infiltration treatment is 5MPa-300MPa.

9. The preparation method according to claim 1, characterized in that, The heat preservation and pressure holding time for the hot isostatic pressing melt infiltration treatment is 1h-3h.

10. The preparation method according to claim 1, characterized in that, The annealing process is performed at a pressure of 30 Pa or less.

11. The preparation method according to claim 1, characterized in that, The temperature is increased from room temperature to the annealing temperature T4 at a heating rate of 0.5℃ / min-1℃ / min.

12. The preparation method according to claim 1, characterized in that, The annealing process is carried out at a temperature T4 for 1-3 hours.

13. The preparation method according to claim 1, characterized in that, The annealing process is completed when the temperature T4 of the annealing treatment is cooled to room temperature at a cooling rate of 1℃ / min-2℃ / min.

14. A high-entropy alloy-ceramic composite material, characterized in that, The high-entropy alloy-ceramic composite material is prepared by the preparation method according to any one of claims 1-13.

15. The high-entropy alloy-ceramic composite material according to claim 14, characterized in that, When the pressure of the hot isostatic pressing melting treatment is above 5 MPa and below 80 MPa, a high-entropy alloy-ceramic composite material with a gradient distribution of high-entropy alloy phase is obtained, that is, the content of high-entropy alloy phase gradually decreases from the surface to the interior of the high-entropy alloy-ceramic composite material.

16. The high-entropy alloy-ceramic composite material according to claim 14, characterized in that, When the pressure of the hot isostatic pressing melting treatment is higher than 80 MPa and lower than 300 MPa, a high-entropy alloy-ceramic composite material with uniform composition is obtained.

17. An application of a high-entropy alloy-ceramic composite material, characterized in that, The high-entropy alloy-ceramic composite material is used to prepare molds and cutting tools; The high-entropy alloy-ceramic composite material is prepared by the preparation method according to any one of claims 1-13.

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