Ultrahigh-temperature high-entropy carbide ceramic matrix composite, in-situ preparation method and application

Abstract

The application belongs to the field of high-entropy ceramics and high-temperature-resistant materials, and particularly relates to an ultrahigh-temperature high-entropy carbide ceramic matrix composite material, an in-situ preparation method and application. a Mo b Ta c W d M e D f )C g , wherein M is one or more of metal elements such as Ti, Zr and Hf, and D is a metalloid element. The high-entropy carbide matrix composite material takes high-entropy carbide ceramics as a matrix, and high-entropy alloys are distributed between the ceramic matrix to achieve the effect of reinforcement and toughening, and the organization can be regulated by changing the content of C. The application has the advantages of simple process, low cost, shorter preparation period, high density and purity of the prepared composite material, and excellent room temperature and high-temperature performance, wherein the room temperature strength is not less than 3500 MPa, and the strength at 2000 DEG C is not less than 400 MPa.

Description

Technical Field

[0001] This invention belongs to the field of high-entropy ceramics and high-temperature resistant materials, and particularly relates to an ultra-high temperature high-entropy carbide ceramic matrix composite material, its in-situ preparation method, and its application. Background Technology

[0002] Carbide ceramics, as a high-temperature structural material, possess a series of excellent comprehensive properties, such as high melting point, high strength, high hardness, low density, good thermal conductivity, electrical conductivity, and high-temperature stability. They are widely used in applications such as high-temperature nuclear reactors, aircraft engines, and surface thermal protection components. However, with the rapid development of my country's national defense and aerospace industries in recent years, the performance of traditional carbide ceramics has become insufficient to meet ever-increasing demands. Currently, there is an urgent need to develop ultra-high-temperature materials applicable to extreme service environments.

[0003] High-entropy ceramics are a new type of single-phase solid solution ceramic developed based on the unique design concept of multi-component ceramics. Thanks to the unique high-entropy effect, compared with single-component ceramic materials, high-entropy ceramics, which are composed of multiple metal elements and one non-metal element and have a simple crystal structure, have higher strength, hardness, modulus and better corrosion resistance. In particular, high-entropy carbide ceramics composed of multiple high-melting-point transition metal carbides have extremely outstanding ultra-high temperature performance and are an important development direction for the next generation of heat-resistant structural materials. Currently, most methods for preparing high-entropy ceramics employ powder metallurgy processes, using planetary ball mills combined with spark plasma sintering (SPS). For example, Castle et al. prepared (Hf,Ta,Zr,Nb)C high-entropy ceramics with a relative density of approximately 99% using SPS sintering, exhibiting excellent hardness and elastic modulus (Castle EG, Scientific Reports, 2018). Although this method can successfully synthesize dense and uniform carbide high-entropy ceramics, the preparation process is cumbersome, easily introducing more impurities during ball milling, and is limited by the capacity of the ball mill jar, making efficient preparation impossible.

[0004] High-entropy carbide ceramics possess excellent ultra-high temperature performance, but they also suffer from high brittleness and poor toughness. Currently, most methods improve the strength and toughness of ceramic materials by introducing suitable metallic binder phases to prepare cermet materials. For example, patent CN 110423930 A uses (MoTiWTaZr)C high-entropy ceramic as the hard phase and FeCoCrNiAl high-entropy alloy as the metallic binder phase, which improves performance to some extent. However, the powder metallurgy preparation process and the interface problems between the binder and hard phases limit further improvement in their overall performance. Therefore, developing high-entropy carbide ceramics or high-entropy ceramic matrix composites with excellent properties, as well as efficient and high-quality preparation methods, is of great significance. Summary of the Invention

[0005] The present invention discloses a super-high temperature refractory high-entropy alloy with a dual high-entropy effect, a preparation method and an application, so as to solve any one of the above and other potential problems in the prior art.

[0006] To achieve the above object, the technical solution of the present invention is: a super-high temperature high-entropy carbide ceramic matrix composite material, and the chemical formula of the super-high temperature high-entropy carbide ceramic matrix composite material is: (Nb a Mo b Ta c W d M e D f )C g , wherein, M is at least one of Ti, Zr, Hf, V, Cr, Fe, Co, Ni, Ir, Ru, Re, Rh, Y, La, Al; D is at least one of B, O, N, Si, Ge, and the atomic percentage content of each component is: 0 < a ≤ 35 at%, 0 < b ≤ 35 at%, 0 < c ≤ 40 at%, 0 < d ≤ 40 at%, 0 < e ≤ 35 at%, 0 < f ≤ 10 at%, 26 < g ≤ 50 at%, and a + b + c + d + e + f + g = 100.

[0007] Furthermore, the super-high temperature high-entropy carbide ceramic matrix composite material has a high-entropy carbide ceramic phase and a high-entropy alloy solid solution phase.

[0008] Furthermore, the super-high temperature high-entropy carbide ceramic phase is composed of a high-entropy carbide primary phase and a eutectic structure in which the primary phases are intertwined in a network pattern. The eutectic structure is composed of a high-entropy carbide phase and a high-entropy alloy solid solution phase arranged alternately in a lamellar pattern, and the phase interface is a semi-coherent interface.

[0009] Furthermore, the high-entropy carbide phase is (Nb,Mo,Ta,W,M)2C or (Nb,Mo,Ta,W,M)C containing transition refractory metal elements;

[0010] The high-entropy alloy solid solution phase is a disordered solid solution with a BCC structure composed of Nb, Mo, Ta, W and M elements.

[0011] Furthermore, when a = 10.0, b = 10.0, c = 22.5, d = 22.5, e = 2, f = 3, g = 30.0, the atomic percentage expression of the high-entropy carbide ceramic matrix composite material is Nb 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 , and the room temperature strength of the alloy is 4000 MPa, and the strength at 2000 °C is 480 MPa.

[0012] Furthermore, when a = 7.5, b = 7.5, c = 22.5, d = 22.5, e = 2, f = 3, and g = 35.0, the expression for the atomic percentage of the high-entropy carbide ceramic matrix composite material is Nb. 7.5 Mo 7.5 Ta 22.5 W 22.5 Hf2B3C 35 The alloy has a room temperature strength of 3500 MPa and a strength of 440 MPa at 2000℃.

[0013] Furthermore, when a = 10.0, b = 10.0, c = 17.5, d = 17.5, e = 2, f = 3, and g = 40.0, the expression for the atomic percentage of the high-entropy carbide ceramic matrix composite material is Nb. 10 Mo 10 Ta 17.5 W 17.5 Hf2B3C 40 The alloy has a room temperature strength of 3900 MPa and a strength of 460 MPa at 2000℃.

[0014] Furthermore, when a = 10.0, b = 10.0, c = 20.0, d = 20.0, e = 7, f = 3, and g = 30.0, the expression for the atomic percentage of the high-entropy carbide ceramic matrix composite material is Nb. 10 Mo 10 Ta 20 W 20 Hf7B3C 30 The alloy has a room temperature strength of 3500 MPa and a strength of 400 MPa at 2000℃.

[0015] Another object of the present invention is to provide a method for in-situ preparation of the above-mentioned ultra-high temperature high-entropy carbide ceramic matrix composite material, the method specifically including the following steps:

[0016] S1) Ingredients: Weigh out each raw material with a purity of not less than 99.9% according to the designed proportions;

[0017] S2) Discharge: Place the materials into the reaction vessel in the order of low melting point materials at the bottom and high melting point materials at the top, and set aside;

[0018] S3) Melting: The reaction vessel of S2) is smelted multiple times in an inert gas under vacuum conditions. High-purity argon is introduced and the melting current is 300-450A to ensure that all raw materials can be completely melted. The melting is carried out at least 5 times, and the electric arc is maintained for at least 1-3 minutes during each melting process. Before each melting, the ingot is flipped and tilted at 38-43° to finally obtain an ultra-high temperature high-entropy carbide ceramic matrix composite material.

[0019] The above-mentioned ultra-high temperature high-entropy carbide ceramic matrix composite material is applied to heat-end components that withstand ultra-high temperature service conditions in the aerospace and defense industries, and are resistant to softening.

[0020] The advantages of this invention are:

[0021] The series of ultra-high temperature high-entropy carbide ceramic matrix composite materials involved in this invention significantly improve ultra-high temperature strength while maintaining the strength of traditional single ceramics;

[0022] The composition can be adjusted over a wide range. By varying the carbon content, the content of high-entropy carbides and the proportion and microstructure of metal solid solutions in ceramic matrix composites can be flexibly adjusted to obtain high-temperature structural materials suitable for different application scenarios.

[0023] Fully leverage the slow diffusion mechanism of high entropy. Since this high-entropy carbide is a multi-principal-element carbide composed of various refractory metals, it exhibits a significant slow diffusion effect at high temperatures. Therefore, it can improve the high-temperature strength and microstructure stability of ceramic matrix composites during high-temperature deformation.

[0024] The preparation method is simple. Breaking through the traditional understanding of the design and preparation of single ceramics, the series of carbide ceramic matrix composites prepared by this invention have extremely high solubility for metalloid elements such as C and B. The bulk raw materials can be directly melted through processes such as arc melting and induction melting, achieving complete fusion of metalloid elements such as C and B with the matrix metal. This eliminates the need for large-scale carbon alloying through powder metallurgy, avoids the influence of other impurities, and significantly improves the production efficiency of ceramic matrix composites. Attached Figure Description

[0025] Figure 1 Nb is an embodiment of the present invention. 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 XRD patterns of ultra-high temperature high-entropy carbide ceramic matrix composites;

[0026] Figure 2 Nb is an embodiment of the present invention. 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 Scanning electron microscopy images of ultra-high temperature high-entropy carbide ceramic matrix composites;

[0027] Figure 3 Nb is an embodiment of the present invention. 10 Mo 10 Ta 22.5 W 22.5Hf2B3C 30 Room temperature compression curves of ultra-high temperature high-entropy carbide ceramic matrix composites;

[0028] Figure 4 Nb is an embodiment of the present invention. 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 High-temperature compression curves of ultra-high temperature high-entropy carbide ceramic matrix composites;

[0029] Figure 5 Nb is an embodiment of the present invention. 7.5 Mo 7.5 Ta 22.5 W 22.5 Hf2B3C 35 Scanning electron microscopy images of ultra-high temperature high-entropy carbide ceramic matrix composites. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0031] This invention provides an ultra-high temperature high-entropy carbide ceramic matrix composite material strengthened and toughened by high-entropy alloys, and its preparation method. Through a rational compositional design approach, the addition of carbon content is controlled to create a composite material with a multi-principal-element alloy carbide ceramic matrix and a uniformly distributed network of high-entropy alloy solid solution within the ceramic matrix as the binder phase, exhibiting excellent ultra-high temperature strength. This invention, through precise microstructure design, forms a certain content of network-like high-entropy alloy solid solution phase, which can suppress crack propagation during deformation and effectively improve the material's plasticity while maintaining the high strength of a single ceramic material.

[0032] Another objective of this invention is to provide an in-situ preparation method for the above-mentioned ultra-high temperature high-entropy carbide ceramic matrix composite material. This method uses high-purity elemental particles or carbide powder as raw materials and utilizes a simple electric arc melting process (or induction melting) to completely melt a large amount of metal elements such as C and B into the alloy matrix. This method is simple and efficient, and the prepared material has a uniformly dispersed distribution of each phase and excellent bonding strength at the phase interface.

[0033] To achieve the above objectives, the present invention provides an ultra-high temperature high-entropy carbide ceramic matrix composite material. The ceramic matrix composite material is obtained by optimizing the composition of the (Nb,Mo,Ta,W)C series ultra-high temperature high-entropy alloy matrix and selectively adding a certain amount of metal elements such as Ti, Zr, Hf and metal-like elements such as B, thereby obtaining a high-entropy ceramic matrix composite material with synergistic effect of metal solid solution, which significantly improves the mechanical properties of the ceramic matrix composite material.

[0034] The atomic percentage of the ultra-high temperature high-entropy carbide ceramic matrix composite material is expressed as (Nb a Mo b Ta c W d M e D f C g M is at least one of Ti, Zr, Hf, V, Cr, Fe, Co, Ni, Ir, Ru, Re, Rh, Y, La, and Al; D is at least one of B, O, N, Si, and Ge. The atomic percentage of each component is: 0 < a ≤ 35, 0 < b ≤ 35, 0 < c ≤ 40, 0 < d ≤ 40, 0 ≤ e ≤ 35, 0 ≤ f ≤ 15, 26 < g ≤ 50, and a + b + c + d + e + f + g = 100.

[0035] The present invention also provides a method for preparing the above-mentioned ceramic matrix composite material, specifically including the following steps:

[0036] S1) Ingredients: The raw materials Ta, Nb, Mo, W, etc. used above are elemental particles with a purity exceeding 99.9%. Raw material C is high-purity graphite or the aforementioned metal carbide powder, and B is small particles made from elemental boron. Before smelting, the oxide layer and impurities on the surface of the metal element particles are removed, and they are ultrasonically cleaned in ethanol or acetone. The high-purity graphite and elemental boron are cut into fine particles. Accurately weigh the required weights of Ta, Nb, Mo, W, and C raw materials for later use.

[0037] S2) Feeding: When the C content is high, high-purity niobium foil and tantalum foil can be used for Ta and Nb raw materials. Graphite particles, B particles, or carbide powder are wrapped in niobium foil and placed at the bottom of the water-cooled copper crucible. Based on the melting point and the difference in the morphology of the raw materials, they are placed in the water-cooled copper crucible of the non-consumable vacuum arc melting furnace in the order of low-melting-point raw materials at the bottom and high-melting-point raw materials at the top, ready for melting.

[0038] S3) Melting: Vacuum the furnace cavity; when the vacuum level is higher than 5×10 -3 After Pa, high-purity argon gas is introduced, and the melting current is 300–450 A to ensure that all raw materials are completely melted. Melting is performed 5–10 times, with the electric arc maintained for at least 1–3 minutes during each melting process. Before each melting, the ingot is flipped and tilted at approximately 38–43° to obtain a uniformly composed ultra-high temperature high-entropy carbide ceramic matrix composite ingot. This ingot can be used as raw material for subsequent machining, suction casting, and powder metallurgy processes.

[0039] By controlling the amount of carbon added through compositional regulation, the microstructure evolution of the alloy was discovered. High-entropy carbide ceramics, as the first precipitated phase, are distributed in the matrix in a spherical form, while a structure of metal-high-entropy carbide phases is formed around the high-entropy carbide.

[0040] The ultra-high temperature high-entropy carbide ceramic matrix composite material prepared by this invention exhibits high room temperature strength and plasticity, and excellent high temperature strength. The room temperature strength is approximately 4000 MPa, and the strength at 2000℃ exceeds 400 MPa. Therefore, it is believed that the ultra-high temperature high-entropy carbide ceramic matrix composite material of this invention possesses high mechanical properties in high-temperature service environments (800℃-2300℃).

[0041] Example 1

[0042] In this embodiment, Nb 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 The preparation method of ultra-high temperature high-entropy carbide ceramic matrix composite material includes the following steps:

[0043] 1) Raw Materials: The alloy smelting raw materials used in this invention are high-purity (≥99.9%) Nb, Mo, Ta, Hf, and W elements. The oxide scale of the raw materials is removed using a grinding wheel or similar means. The materials are precisely weighed and proportioned according to the molar ratio, and then cleaned in alcohol using ultrasonic vibration before being used for alloy smelting. Carbon blocks and boron particles are mechanically crushed into smaller particles, and C and B particles with a size of approximately 1 mm are screened using metal sieves.

[0044] 2) Loading: Place the raw materials in a water-cooled copper crucible in order of decreasing melting point. To lower the overall melting point of the alloy, place the above elements evenly in two different crucibles according to their melting point differences for pre-alloying. When arranging the elements, wrap the screened C and B particles with Nb foil or Ta foil and place them at the bottom of the crucible. Then, arrange the other metal elements in order of increasing melting point.

[0045] 3) Melting: The alloy is melted using a vacuum non-consumable tungsten electrode arc furnace. The sample chamber is evacuated, and the vacuum level is higher than 5*10. -3 After Pa, high-purity argon gas is introduced; to ensure uniform distribution of the pre-alloyed components, it is melted at least five times; then the pre-alloyed components are transferred to the same crucible and melted at least five times, so that a high-temperature high-entropy carbide ceramic matrix composite material with the designed composition is finally melted. During each melting process, the electric arc is maintained for at least 2 minutes, and the ingot is flipped and tilted at 38-43° before each melting process, so as to finally obtain a high-temperature high-entropy carbide ceramic matrix composite material with uniform composition.

[0046] The refined ultra-high temperature high-entropy carbide ceramic matrix composite material was prepared into high-entropy alloy samples of a certain size for testing and characterization.

[0047] Nb 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 The structural and property characterization of ultra-high temperature high-entropy carbide ceramic matrix composites are as follows:

[0048] 1) X-ray diffraction (XRD) testing and phase analysis

[0049] A 5*5*1.5 cm square was cut from the sample using wire cutting, and then polished smooth and glossy using 240#, 800#, 1000#, and 2000# metallographic sandpaper, respectively. Phase composition analysis of each sample was performed using X-ray diffraction with a scan step of 0.02 s. -1 The scanning angle 2θ ranges from 20° to 90°, and the scanning rate is 10° / min. Nb 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 XRD test results of ultra-high temperature high-entropy carbide ceramic matrix composites are as follows: Figure 1 As shown, the crystal structure of this ultra-high temperature high-entropy carbide ceramic matrix composite material is BCC solid solution and FCC carbide (MC). According to the diffraction pattern, the content of MC is significantly higher than that of BCC solid solution. Specific analysis shows that the elemental composition of MC is mainly high-entropy carbide crystal structure of FCC carbide formed by different types of metal elements.

[0050] 2) Microscopic tissue observation

[0051] The 5*5*1.5 square pieces obtained by wire cutting were ground smooth and shiny with metallographic sandpaper. Electrolytic polishing was then used to polish each component, and the metallographic structure was obtained through the action of an etching solution and electric current. The microstructure and microstructure evolution of this ultra-high temperature high-entropy carbide ceramic matrix composite were analyzed using scanning electron microscopy. Figure 2 For Nb 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30Scanning electron microscopy (SEM) images of ultra-high temperature high-entropy carbide ceramic matrix composites reveal that the composite material primarily exhibits a coexistence of high-entropy carbides and metal solid solutions. Spherical high-entropy carbides, as the dominant phase, are uniformly distributed within the matrix, while a certain volume fraction of metal solid solution phase is distributed around the spherical high-entropy carbides, forming a continuous network structure throughout the composite material. Analysis of the interface between the high-entropy carbides and the metal solid solution phases reveals a micrometer-scale transition region at the interface, ensuring a perfect bond between the interfacial lattice structures of the high-entropy carbides and the solid solution, thereby significantly improving the interfacial bonding strength of the material.

[0052] 3) Quasi-static compression test

[0053] Ultra-high temperature high-entropy carbide ceramic matrix composites were wire-cut into cylindrical specimens with a diameter of 2mm x 4mm. The wire-cut marks on the sides of the specimens were removed by grinding with metallographic sandpaper. After ultrasonic cleaning in acetone, the two end faces of the cylinders were smoothed with metallographic sandpaper. Room temperature compression tests were performed on an electronic universal testing machine, with a uniform compression rate of 2 × 10⁻⁶. -4 At least three samples should be selected for testing. Figure 3 For Nb 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 The room temperature compression curve of the ultra-high temperature high-entropy carbide ceramic matrix composite material is shown. This indicates that the material exhibits excellent room temperature strength, reaching 4000 MPa. Compared with the strength of traditional single carbide materials, this ceramic matrix composite material, despite containing a certain volume fraction of solid solution phase, still achieves a high level of strength.

[0054] 4) High-temperature compression test

[0055] The ultra-high temperature high-entropy carbide ceramic matrix composite material was machined into cylindrical specimens with a diameter of Φ4mm*8mm using wire cutting. The wire cutting marks on the sides of the specimens were removed by grinding with metallographic sandpaper. The specimens were then fixed in place using clamps of appropriate specifications, and the two end faces of the cylinders were smoothed with metallographic sandpaper. A high-temperature compression test was conducted at 2000℃ on a high-temperature electronic universal testing machine. To ensure uniform heating of the sample during compression, the temperature was increased at a rate of 20℃ / min, and held at 2000℃ for 15 minutes, followed by a further increase of 5×10⁻⁶. -3 s -1 The compression rate was used to begin the deformation test. Figure 4 For Nb 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30The high-temperature compression curve of the ultra-high temperature high-entropy carbide ceramic matrix composite material at 1600℃ shows that the high-temperature strength of this high-entropy ceramic matrix composite material exceeds 400MPa, exhibiting excellent high-temperature strength. This demonstrates that a certain content of carbides, as a high-temperature strengthening phase, can significantly improve the high-temperature resistance of the alloy during deformation at 2000℃.

[0056] Example 2

[0057] Nb 7.5 Mo 7.5 Ta 22.5 W 22.5 Hf2B3C 35 Preparation and characterization of ultra-high temperature high-entropy carbide ceramic matrix composites

[0058] 1) Raw materials: The alloy smelting raw materials used in this invention are high-purity (≥99.9%) Nb, Mo, Ta, Hf, and W elements. The oxide scale of the raw materials is removed by means of a grinding wheel and other methods, and they are cleaned by ultrasonic vibration in alcohol before being used for alloy smelting. Carbon blocks and boron particles are mechanically crushed into smaller particles, and C and B particles with a size of about 1 mm are screened out with metal sieves. The particles are then weighed and proportioned precisely according to the molar ratio.

[0059] 2) Loading: Place the raw materials in a water-cooled copper crucible in order of decreasing melting point. To lower the overall melting point of the alloy, place the above elements evenly in two different crucibles according to their melting point differences for pre-alloying. When arranging the elements, wrap the screened C and B particles with Nb foil or Ta foil and place them at the bottom of the crucible. Then, arrange the other metal elements in order of increasing melting point.

[0060] 3) Melting: A vacuum non-consumable tungsten electrode arc furnace is used for melting. The furnace cavity is evacuated, and the vacuum level is higher than 5*10. - 3 After Pa, high-purity argon gas is introduced; to ensure uniform distribution of the pre-alloyed components, it is melted at least five times; then the pre-alloyed components are transferred to the same crucible and melted at least five times, so that a high-temperature high-entropy carbide ceramic matrix composite material with the designed composition is finally melted. During each melting process, the electric arc is maintained for at least 2 minutes, and the ingot is flipped and tilted at 38-43° before each melting process, so as to finally obtain a high-temperature high-entropy carbide ceramic matrix composite material with uniform composition.

[0061] Nb 7.5 Mo 7.5 Ta 22.5 W 22.5 Hf2B3C 35 The structural and property characterization of ultra-high temperature high-entropy carbide ceramic matrix composites are as follows:

[0062] This case further increases the carbon content of ultra-high temperature high-entropy carbide ceramic matrix composites by using the preparation steps described in this invention, according to the predetermined alloy composition Nb. 7.5 Mo 7.5 Ta 22.5 W 22.5 Hf2B3C 35 Weighing and melting were performed to obtain an ultra-high temperature high-entropy carbide ceramic matrix composite material with high-entropy carbide reinforcement. Figure 5 The image shows Nb. 7.5 Mo 7.5 Ta 22.5 W 22.5 Hf2B3C 35 Scanning electron microscopy (SEM) images of the ultra-high temperature high-entropy carbide ceramic matrix composite reveal that it primarily exhibits a coexistence of high-entropy carbides and metal solid solutions. Spherical high-entropy carbides form the dominant phase, uniformly distributed within the matrix, while a certain volume fraction of metal solid solution phase is distributed around them, forming a continuous network structure throughout the composite. The content of high-entropy carbides gradually increases with increasing carbon content. Mechanical properties show that the alloy possesses a room temperature strength as high as 3500 MPa. Due to the high content of refractory metal carbides, it exhibits excellent ultra-high temperature strength.

[0063] Example 3

[0064] Nb 10 Mo 10 Ta 17.5 W 17.5 Hf2B3C 40 Preparation of ultra-high temperature high-entropy carbide ceramic matrix composites:

[0065] 1) Raw materials: The alloy smelting raw materials used in this invention are high-purity (≥99.9%) Nb, Mo, Ta, Hf, and W elements. The oxide scale of the raw materials is removed by means of a grinding wheel and other methods, and they are cleaned by ultrasonic vibration in alcohol before being used for alloy smelting. Carbon blocks and boron particles are mechanically crushed into smaller particles, and C and B particles with a size of about 1 mm are screened out with metal sieves. The particles are then weighed and proportioned precisely according to the molar ratio.

[0066] 2) Loading: Place the raw materials in a water-cooled copper crucible in order of decreasing melting point. To lower the overall melting point of the alloy, place the above elements evenly in two different crucibles according to their melting point differences for pre-alloying. When arranging the elements, wrap the screened C and B particles with Nb foil or Ta foil and place them at the bottom of the crucible. Then, arrange the other metal elements in order of increasing melting point.

[0067] 3) Melting: The alloy is melted using a vacuum non-consumable tungsten electrode arc furnace. The furnace cavity is evacuated, and the vacuum level is higher than 5*10. -3 After Pa, high-purity argon gas is introduced; to ensure uniform distribution of the pre-alloyed components, it is melted at least five times; then the pre-alloyed components are transferred to the same crucible and melted at least five times, so that a high-temperature high-entropy carbide ceramic matrix composite material with the designed composition is finally melted. During each melting process, the electric arc is maintained for at least 2 minutes, and the ingot is flipped and tilted at 38-43° before each melting process, so as to finally obtain a high-temperature high-entropy carbide ceramic matrix composite material with uniform composition.

[0068] Microstructural analysis reveals that the alloy primarily consists of MC with an FCC structure and a metallic solid solution with a BCC structure, with MC occupying a large volume fraction. Due to the high content of carbide phases, the alloy exhibits high strength; mechanical property testing shows that its room temperature mechanical strength reaches 3900 MPa.

[0069] Example 4

[0070] Nb 10 Mo 10 Ta 20 W 20 Hf7B3C 30 Preparation of ultra-high temperature high-entropy carbide ceramic matrix composites:

[0071] 1) Raw materials: The alloy smelting raw materials used in this invention are high-purity (≥99.9%) Nb, Mo, Ta, and W elements. The oxide scale of the raw materials is removed by means of a grinding wheel and other means, and they are cleaned by ultrasonic vibration in alcohol before being used for alloy smelting. The carbon blocks are mechanically crushed into smaller particles, and C particles with a size of about 1 mm are screened out with metal sieves. The particles are then weighed and proportioned precisely according to the molar ratio.

[0072] 2) Loading: Place the raw materials in a water-cooled copper crucible in order of decreasing melting point. To lower the overall melting point of the alloy, place the above elements evenly in two different crucibles according to their melting point differences for pre-alloying. When arranging the elements, wrap the screened C particles with Nb foil or Ta foil and place them at the bottom of the crucible. Then, arrange the other metal elements in order of increasing melting point.

[0073] 3) Melting: The alloy is melted using a vacuum non-consumable tungsten electrode arc furnace. The furnace cavity is evacuated, and the vacuum level is higher than 5*10. -3After Pa, high-purity argon gas is introduced; to ensure uniform distribution of the pre-alloyed components, it is melted at least five times; then the pre-alloyed components are transferred to the same crucible and melted at least five times to finally melt into an alloy ingot with the designed composition. During each melting process, the electric arc is maintained for at least 2 minutes, and the ingot is flipped and tilted at 38-43° before each melting process to finally obtain a uniformly composed ultra-high temperature high-entropy carbide ceramic matrix composite material.

[0074] Microstructural analysis shows that the alloy mainly consists of MC with an FCC structure and a BCC structure, with MC occupying a large volume fraction. Due to the high content of carbide phases, the alloy exhibits high strength; mechanical property tests show that the alloy's room temperature mechanical strength reaches 3500 MPa.

[0075] The above description is only a typical embodiment of the present invention and is not intended to limit the actual content of the present invention. Various modifications and changes can be made according to the actual application scenario for the application of the present invention.

Claims

1. A high-temperature, high-entropy carbide ceramic matrix composite material, characterized in that, The chemical formula of the high-entropy carbide ceramic matrix composite material is: (Nb a Mo b Ta c W d M e D f C g Wherein, M is at least one of Ti, Zr, Hf, V, Cr, Fe, Co, Ni, Ir, Ru, Re, Rh, Y, La, and Al; D is at least one of B, O, N, Si, and Ge, and the atomic percentage of each component is: 0 < a ≤ 35, 0 < b ≤ 35, 0 < c ≤ 40, 0 < d ≤ 40, 0 < e ≤ 35, 0 < f ≤ 10, 26 < g ≤ 50, and a + b + c + d + e + f + g = 100; The high-entropy carbide ceramic matrix composite material has a high-entropy carbide ceramic phase and a high-entropy alloy solid solution phase; The high-entropy carbide ceramic phase is composed of a high-entropy carbide primary phase and a eutectic structure in which the primary phase is interwoven in a network. The eutectic structure is composed of a lamellar alternating high-entropy carbide phase and a high-entropy alloy solid solution phase, and the phase interface is a semi-coherent interface. The high-entropy carbide phase is (Nb,Mo,Ta,W,M)2C or (Nb,Mo,Ta,W,M)C containing transition metal elements. The high-entropy alloy solid solution phase is a disordered solid solution with a BCC structure composed of Nb, Mo, Ta, W and M elements.

2. The high-entropy carbide ceramic matrix composite material according to claim 1, characterized in that, When a = 10.0, b = 10.0, c = 22.5, d = 22.5, e = 2, f = 3, and g = 30.0, the expression for the atomic percentage of the high-entropy carbide ceramic matrix composite material is Nb. 10 Mo 10 Ta 22.5 W 22.5 Hf2B3C 30 The alloy has a room temperature strength of 4000 MPa and a strength of 480 MPa at 2000℃.

3. The high-entropy carbide ceramic matrix composite material according to claim 1, characterized in that, When a = 7.5, b = 7.5, c = 22.5, d = 22.5, e = 2, f = 3, and g = 35.0, the atomic percentage of the high-entropy carbide ceramic matrix composite material is expressed as Nb. 7.5 Mo 7.5 Ta 22.5 W 22.5 Hf2B3C 35 The alloy has a room temperature strength of 3500 MPa and a strength of 440 MPa at 2000℃.

4. The high-entropy carbide ceramic matrix composite material according to claim 1, characterized in that, When a = 10.0, b = 10.0, c = 17.5, d = 17.5, e = 2, f = 3, and g = 40.0, the expression for the atomic percentage of the high-entropy carbide ceramic matrix composite material is Nb. 10 Mo 10 Ta 17.5 W 17.5 Hf2B3C 40 The alloy has a room temperature strength of 3900 MPa and a strength of 460 MPa at 2000℃.

5. The high-entropy carbide ceramic matrix composite material according to claim 1, characterized in that, When a = 10.0, b = 10.0, c = 20.0, d = 20.0, e = 7, f = 3, and g = 30.0, the atomic percentage of the high-entropy carbide ceramic matrix composite material is expressed as Nb. 10 Mo 10 Ta 20 W 20 Hf7B3C 30 The alloy has a room temperature strength of 3500 MPa and a strength of 400 MPa at 2000℃.

6. A method for in-situ preparation of the ultra-high temperature high-entropy carbide ceramic matrix composite material as described in any one of claims 1-5, characterized in that, The method specifically includes the following steps: S1) Ingredients: Weigh out each raw material with a purity of not less than 99.9% according to the designed proportions; S2) Discharge: Place the materials into the reaction vessel in the order of low melting point materials at the bottom and high melting point materials at the top, and set aside; S3) Melting: The reaction vessel of S2) is smelted multiple times in an inert gas under vacuum conditions. High-purity argon is introduced and the melting current is 300-450A to ensure that all raw materials can be completely melted. The melting is carried out at least 5 times, and the electric arc is maintained for at least 1-3 minutes during each melting process. Before each melting, the ingot is flipped and tilted at 38-43° to finally obtain an ultra-high temperature high-entropy carbide ceramic matrix composite material.

7. A high-temperature, high-entropy carbide ceramic matrix composite material as described in any one of claims 1-5, used in aerospace and defense industries for a softening-resistant hot-end component subjected to high-temperature service conditions.

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