Ti-CN-based cermet

Abstract

A kind of six-element high-entropy alloy is titanium-based cermet material for bonding phase, is with Ti-CN as hard phase, with six-element high-entropy alloy as bonding phase, with Mo2C as reinforcing phase, is mixed ball milling, pretreatment, pre-pressing and high-temperature sintering in turn is obtained.The ball milling powder is pretreated by electric field auxiliary and low-temperature pre-sintering in the application, effectively improve the overall performance of the cermet after SPS, the hardness of the prepared Ti-CN cermet reaches HV1920, the fracture toughness reaches 15.9 MPa·m¹ / ², the bending strength reaches 2400Mpa, has excellent wear resistance and corrosion resistance, and the wear rate is as low as 1.2×10 ‑7 mm 3 / N·m, the corrosion rate is as low as 0.0012 g / (m 2 ·h).

Description

[0001] This patent is a divisional application of invention number 202510990931.9, entitled "A titanium-based cermet material with a high-entropy alloy as the binder phase and its preparation method". Technical Field

[0002] This invention relates to the field of metal-ceramic material preparation technology, specifically to a Ti-CN-based metal-ceramic. Background Technology

[0003] Traditional titanium-based cermets typically use one or a few elements as additives, with Ni / Co as the binder phase, but their performance improvement faces bottlenecks. In terms of hardness, traditional binder phases (such as Ni and Co) soften easily at high temperatures, leading to a significant decrease in the material's strength and hardness, making it difficult to meet the requirements of applications such as high-hardness cutting tools. Regarding toughness, they are prone to brittle fracture under impact loads, limiting their use in some complex working conditions. Ti-CN-based cermets are prone to interfacial oxidation in high-temperature oxidizing environments, forming a loose oxide layer and accelerating material failure. Simultaneously, traditional binders have limited resistance to corrosive media, making them unsuitable for complex working conditions. The Co / Ni binder phase has poor wettability with the Ti (C,N) ceramic phase, resulting in weak interfacial bonding after sintering. This makes the material prone to chipping or delamination under impact or thermal stress, and its toughness and flexural strength are insufficient for high-end applications. With the increasing demands of modern industry on material performance, such as the comprehensive requirements of lightweight, high strength, and high toughness in the aerospace field, and the requirements of high conductivity and stability in the electronics field, existing titanium-based metal ceramic materials are unable to meet these stringent conditions in terms of comprehensive performance.

[0004] High-entropy alloys, composed of five or more metallic / non-metallic elements, have gained increasing attention due to their unique multi-principal element design, exhibiting advantages such as high strength, high hardness, good wear resistance, and corrosion resistance. However, research applying the concept of high-entropy alloys to titanium-based cermet materials is relatively limited, and numerous challenges remain in preparation processes and performance optimization. While high-entropy ceramics offer advantages in hardness and oxidation resistance, the multi-component nature of high-entropy alloys makes their interfacial reactions with TiCN more complex. Furthermore, their complex multi-component composition easily leads to local component segregation, forming low-entropy phases or brittle intermetallic compounds, disrupting the continuity of the binder phase and causing deterioration of the material's mechanical properties. In addition, Ti-CN has a low coefficient of thermal expansion (CTE, approximately 7~9×10⁻⁶). -6 The difference between the CTE of the high-entropy alloy and the CTE of the high-entropy alloy is too large, which will generate significant internal stress during sintering and cooling, leading to microcracks or interface peeling.

[0005] In addition, the multi-component nature of high-entropy alloys leads to higher raw material costs, and even small fluctuations in the composition ratio can have a significant impact on the overall performance of the material. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a Ti-CN-based cermet material with a hexa-element high-entropy alloy as the binder phase. Through unique elemental design and microstructure control during the preparation process, it exhibits excellent comprehensive properties, including high hardness, high toughness, good wear resistance, and corrosion resistance, thereby meeting the demands of modern industry for high-performance materials.

[0007] Another objective of this invention is to provide a method for preparing the aforementioned titanium-based cermet material. This objective is achieved through the following technical solution: A Ti-CN-based cermet material is characterized by being prepared by sequentially mixing and ball milling, pretreatment, pre-pressing and molding, and high-temperature sintering using Ti-CN as the hard phase, a hexa-element high-entropy alloy as the binder phase, and Mo2C as the reinforcing phase.

[0008] Furthermore, by mass percentage, Ti-CN accounts for 50-60%, hexa-element high-entropy alloy accounts for 30-45%, and Mo2C accounts for 5-10%.

[0009] Furthermore, the hexa-element high-entropy alloy is composed of Cr, Fe, Co, Al, V and Ta, with the atomic percentages being 24-26% for Cr, 22-25% for Fe, 15-20% for Co, 15-18% for Al, 7-9% for V and 7-9% for Ta.

[0010] Furthermore, the pretreatment is a two-step pretreatment. The first step is electric field-assisted pretreatment, which involves applying a DC electric field of 200~350V / cm to the ball milled powder and treating it at 200~400℃ for 20~30min. The second step is low-temperature pre-calcination treatment, which involves performing low-temperature pre-calcination treatment at 600~700℃ for 30~50min.

[0011] Furthermore, the high-temperature sintering is spark plasma sintering, specifically, the blank is placed in a graphite mold and sintered in a vacuum environment. First, the temperature is increased to 1000-1200℃ at 20-30℃ / min and held for 10-15 min, with a sintering pressure of 15-25 MPa. Then, the temperature is increased to 1300-1450℃ at 50-60℃ / min and held for 5-10 min, with a sintering pressure of 40-50 MPa.

[0012] The high-entropy alloy used in this invention exhibits multiple strengthening mechanisms, including solid solution strengthening (Al, V, Ta), precipitation strengthening (V, Ta carbides), and grain refinement (Fe, Cr), which collectively enhance the material's strength and toughness.

[0013] Ti-CN, as a hard phase, is easily oxidized at high temperatures (>800℃) to form TiO2 and CO / NO. x This leads to surface peeling and performance degradation. Al's high reactivity causes it to react with oxygen preferentially over elements like Ti and Cr, forming a dense Al₂O₃ oxide film at lower temperatures (melting point 2072℃, thermal expansion coefficient close to that of Ti-CN). Cr oxidizes at high temperatures to form Cr₂O₃, which together with Al₂O₃ forms a double oxide film, effectively blocking oxygen diffusion and protecting Ti-CN particles from oxidation. However, in SPS sintering, low-melting-point Al melts prematurely and migrates, while other high-melting-point elements remain in the solid state, leading to localized enrichment (such as Al clusters) and the formation of an uneven microstructure. Simultaneously, Al readily reacts with C (from Ti-CN), O (environmental or powder impurities), or other metals (such as Cr and Fe) to form brittle phases (such as Al₄C₃, Al₂O₃, FeAl₃, etc.), resulting in decreased interfacial bonding strength and deteriorated material toughness.

[0014] Good wettability between the binder phase and the hard phase (Ti-CN) is a prerequisite for ensuring the density and mechanical properties of cermets. Poor wettability prevents the high-entropy alloy from effectively filling the gaps between Ti-CN particles, easily leading to porosity. Fe, as a transition metal, has a surface energy (approximately 2.9 J / m²) that closely matches the surface energy of Ti-CN (approximately 3.1 J / m²). Its addition can reduce the interfacial energy between the high-entropy alloy and Ti-CN, thereby improving the density of the cermet. However, Fe has a high diffusion coefficient and easily penetrates into the Ti-CN hard phase, leading to hard phase decomposition (e.g., Ti in Ti-CN being replaced by Fe) or the formation of brittle intermetallic compounds (e.g., Fe-Ti phase), thus compromising the integrity of the hard phase.

[0015] The Ti-CN ceramic phase (surface energy of approximately 1.2-1.5 J / m²) exhibits extremely poor wettability with the high-entropy alloy binder phase, directly resulting in the difficulty of the metal phase spreading on the Ti-CN surface during sintering and low interfacial bonding strength.

[0016] To address the aforementioned issues, this invention performs an electric field-assisted pretreatment on the ball-milled powder before pressing and molding. Through low-temperature energy activation and electric field-directed driving, the electronegativity differences of elements induce the directional agglomeration and enrichment of high-entropy alloying elements on the surface of Ti-CN particles. Subsequently, a low-temperature pre-sintering treatment promotes the preferential reaction of Al and N to form an AlN barrier, blocking the reaction between Al and C. AlN acts as a transition layer, improving the lattice matching degree between the binder phase and the hard phase, thereby enhancing the interfacial bonding strength. Furthermore, because Al, Cr, V, and Ta in the high-entropy alloy have low and similar electronegativity, they form atomic-level contact interfaces under electric field polarization. During low-temperature pre-sintering, these interfaces preferentially react and diffuse at lower temperatures, generating stable and uniformly distributed intermetallic compounds. This avoids the reaction of Al with the hard phase to form a brittle phase during the SPS process and also limits the diffusion of Fe. The electric field alters the diffusion direction of Fe through the "electromigration effect." As a transition metal, Fe is prone to forming local low-energy regions due to electron enrichment in the electric field, which weakens its diffusion drive to the Ti-CN interface. At the same time, Fe and Co have similar electronegativity, and after they are enriched under the action of the electric field, they form Fe-Co solid solution during the pre-calcination process, which further inhibits the diffusion of Fe into the body.

[0017] A method for preparing a titanium-based cermet material with a hexa-element high-entropy alloy as the binder phase is characterized by: using Ti-CN as the hard phase, a hexa-element high-entropy alloy as the binder phase, and Mo2C as the reinforcing phase, ball milling is used to obtain ball milled powder; the ball milled powder is pretreated, then pre-pressed, and finally subjected to spark plasma sintering; wherein the pretreatment involves sequentially subjecting the ball milled powder to electric field-assisted pretreatment and low-temperature pre-sintering.

[0018] Furthermore, the hexa-element high-entropy alloy is composed of Cr, Fe, Co, Al, V and Ta, with the atomic percentages being 24-26% for Cr, 22-25% for Fe, 15-20% for Co, 15-18% for Al, 7-9% for V and 7-9% for Ta.

[0019] Furthermore, by mass percentage, Ti-CN accounts for 50-60%, hexa-element high-entropy alloy accounts for 30-45%, and Mo2C accounts for 5-10%.

[0020] Furthermore, the electric field-assisted pretreatment involves applying a DC electric field of 200~350V / cm to the ball-milled powder and treating it at 200~400℃ for 20~30min.

[0021] Furthermore, the low-temperature pre-firing treatment is carried out at 600~700℃ for 30~50 minutes.

[0022] Furthermore, the mixed ball milling involves weighing Ti-CN powder and the metal powder or metal oxide powder corresponding to the six high-entropy elements according to the stoichiometric ratio, adding them to a ball mill, using anhydrous ethanol as the ball milling medium, a ball-to-material ratio of 10:1, a ball milling speed of 300~500 r / min, a ball milling time of 24~48 h, and then vacuum drying to obtain a uniformly mixed ball milled powder.

[0023] Furthermore, the pre-compression molding involves pre-compressing the pretreated powder under a pressure of 100-200 MPa to form a blank.

[0024] Furthermore, the discharge plasma sintering involves placing the blank in a graphite mold and sintering it under vacuum. First, the temperature is increased to 1000-1200℃ at a rate of 20-30℃ / min and held for 10-15 min at a sintering pressure of 15-25 MPa. Then, the temperature is increased to 1300-1450℃ at a rate of 50-60℃ / min and held for 5-10 min at a sintering pressure of 40-50 MPa.

[0025] A method for preparing a titanium-based cermet material with a hexa-element high-entropy alloy as the binder phase, characterized by comprising the following steps: S1. Composition Design: By mass percentage, Ti-CN is used as the hard phase, accounting for 50-60% by mass; high-entropy alloy is used as the binder phase, accounting for 30-45% by mass; and Mo2C is used as the reinforcing phase, accounting for 5-10% by mass. The high-entropy alloy is CrFeCoAlVTa, with atomic percentages of Cr 24-26%, Fe 22-25%, Co 15-20%, Al 15-18%, V 7-9%, and Ta 7-9%, respectively. S2. Mixed ball milling: Ti-CN powder and the corresponding metal powders or metal oxide powders of the six high-entropy elements were weighed according to the stoichiometric ratio and added to a ball mill. Anhydrous ethanol was used as the ball milling medium, the ball-to-material ratio was 10:1, the ball milling speed was 300~500 r / min, and the ball milling time was 24~48 h. Then, the mixture was vacuum dried to obtain a uniformly mixed ball-milled powder. The purity of the Ti-CN powder was ≥99%, and the particle size was 1~5 μm; the purity of the metal powder was ≥99%, and the particle size was 2~8 μm; the purity of the metal oxide powder was ≥99%, and the particle size was 3~10 μm. S3. Pretreatment of ball milled powder: The pretreatment is divided into two steps. The first step is to apply a DC electric field of 200~350V / cm to the ball milled powder and treat it at 200~400℃ for 20~30min. The second step is to perform low-temperature pre-calcination treatment at 600~700℃ for 30~50min to obtain pretreated powder. S4. Pre-compression molding: The pretreated powder is pre-compressed under a pressure of 100-200MPa to form a blank; S5. Sintering treatment: The spark plasma sintering (SPS) process is adopted. The green body is placed in a graphite mold and sintered in a vacuum environment. First, the temperature is raised to 1000-1200℃ at 20-30℃ / min and held for 10-15 min. The sintering pressure is 15-25 MPa. Then, the temperature is raised to 1300-1450℃ at 50-60℃ / min and held for 5-10 min. The sintering pressure is 40-50 MPa.

[0026] The transition phase AlN forms a buffer layer during the SPS process, reducing direct reactions between the hard phase and the binder phase. In the first stage of the SPS process, binder phase aggregation is effectively prevented, and the interfacial reaction rate and uniform diffusion of components are controlled, allowing the binder phase and the Ti-CN hard phase to form a uniform and stable interfacial bond under controlled diffusion. In the second stage, rapid densification is achieved, preventing abnormal growth of the hard phase. This two-step SPS process reduces the internal temperature gradient of the billet, thereby alleviating stress concentration.

[0027] The present invention has the following technical effects: In this invention, the pretreatment of ball-milled powder by combining electric field assistance and low-temperature pre-sintering effectively improves the overall performance of the cermet after SPS (Silicon-Performance Synthesis). The prepared Ti-CN-based cermet achieves a hardness of HV1920, a fracture toughness of 15.9 MPa·m¹ / ², and a flexural strength of 2400 MPa. It also exhibits excellent wear resistance and corrosion resistance, with a wear rate as low as 1.2 × 10⁻⁶. -7 mm 3 / N·m, corrosion rate as low as 0.0012 g / (m 2 ·h). Attached Figure Description

[0028] Figure 1 : Compositional energy spectrum of Ti-CN-based cermet material prepared in Example 1.

[0029] Figure 2 SEM image of the pretreated ball-milled powder in Example 1.

[0030] Figure 3 SEM microstructure of Ti-CN-based cermet material prepared in Example 1.

[0031] Figure 4 The hardness uniformity test results of the Ti-CN-based cermet material prepared in Example 1. Detailed Implementation

[0032] The present invention will be specifically described below through embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0033] Example 1 A method for preparing a Ti-CN-based cermet material includes the following steps: S1. Composition Design: By mass percentage, Ti-CN is the hard phase, accounting for 55% by mass; high-entropy alloy is the binder phase, accounting for 38% by mass; and Mo2C is the reinforcing phase, accounting for 7% by mass. The high-entropy alloy is CrFeCoAlVTa, with atomic percentages of Cr 25%, Fe 23%, Co 19%, Al 17%, V 8%, and Ta 8%, respectively. S2. Mixed ball milling: Ti-CN powder and the corresponding metal powders or metal oxide powders of six high-entropy elements were weighed according to the stoichiometric ratio and added to a ball mill. Anhydrous ethanol was used as the ball milling medium, the ball-to-material ratio was 10:1, the ball milling speed was 400 r / min, and the ball milling time was 36 h. Then, the mixture was vacuum dried to obtain a uniformly mixed ball-milled powder. The purity of the Ti-CN powder was ≥99%, and the particle size was 1~5 μm; the purity of the metal powder was ≥99%, and the particle size was 2~8 μm; the purity of the metal oxide powder was ≥99%, and the particle size was 3~10 μm. S3. Pretreatment of ball milled powder: The pretreatment is divided into two steps. The first step is to apply a DC electric field of 300V / cm to the ball milled powder and treat it at 300℃ for 25min. The second step is to perform low-temperature pre-calcination treatment at 650℃ for 40min to obtain pretreated powder. S4. Pre-compression molding: The pre-treated powder is pre-compressed under a pressure of 150MPa to form a blank; S5. Sintering treatment: The spark plasma sintering (SPS) process is adopted. The green body is placed in a graphite mold and sintered in a vacuum environment. First, the temperature is increased to 1100℃ at 25℃ / min and held for 12 min. The sintering pressure is 20 MPa. Then, the temperature is increased to 1400℃ at 55℃ / min and held for 6 min. The sintering pressure is 45 MPa.

[0034] The SEM image of the pretreated powder prepared in this embodiment is shown below. Figure 2 As shown.

[0035] The microstructure of the metal-ceramic material prepared in this embodiment is as follows: Figure 3 As shown, the material surface is uniformly distributed and has a dense structure, without any cracks, holes or other defects.

[0036] Comparative Example 1 Compared with Example 1, after mixing and ball milling, the pretreatment of the powder only performed the first step of pretreatment, without the second step of pretreatment, and the remaining steps were the same as in Example 1.

[0037] Comparative Example 2 Compared with Example 1, after mixing and ball milling, the pretreatment of the powder was only the second pretreatment step, without the first pretreatment step, and the remaining steps were the same as in Example 1.

[0038] Comparative Example 3 Compared with Example 1, after ball milling, the pretreatment of the powder only involves the first step of pretreatment, followed by the second step of pretreatment after pre-pressing. The remaining steps are the same as in Example 1.

[0039] Product performance testing: The properties of the Ti-CN-based cermet materials prepared in Example 1 and the comparative examples were tested.

[0040] (1) Hardness test: The Vickers hardness test was conducted according to GB / T 4340.1-2009, "Metallic materials - Vickers hardness test - Part 1: Test method". A Vickers hardness tester was used to apply a load (98.07 N) and hold it for 10-15 seconds, indenting the material surface. The Vickers hardness value (HV) was calculated using the formula by measuring the diagonal length of the indentation.

[0041] Wherein, HV: Vickers hardness value (unit: kgf / mm²); F: test load (unit: kgf); d: arithmetic mean of the lengths of the two diagonals of the indentation (unit: mm). To ensure data accuracy, at least 5 tests were performed at different locations on the material, and the average value was taken as the material's hardness value.

[0042] (2) Fracture toughness test: The test was conducted according to GB / T 2358-1994, "Test Method for Crack Tip Opening Displacement in Metallic Materials". The material was machined into a standard compact tensile specimen and loaded onto a universal testing machine. The fracture toughness value (K0) of the material was calculated by measuring the load-displacement curve during crack propagation and using the following formula. IC ):

[0043] in, Critical load (N); B: Specimen thickness (mm); W: Specimen width (distance from the center of the loading hole to the edge of the specimen, mm). Crack length (distance from the crack tip to the center of the loading hole, in mm). To ensure data accuracy, at least 5 tests were performed at different locations on the material, and the average value was taken as the fracture toughness value of the material.

[0044] (3) Strength test: The bending strength test follows the standard GB / T 38514-2020 "Determination of Transverse Fracture Strength of Hard Alloy". The material is processed into a standard bending specimen (such as a rectangular cross-section three-point bending specimen), loaded at a specified rate on a universal testing machine, and the maximum load at fracture is recorded. The bending strength is calculated according to the formula. ):

[0045] Where F is the maximum fracture load, L is the span, b is the specimen width, and h is the specimen thickness. Five parallel tests were performed, and the average value was taken to ensure the representativeness of the data.

[0046] (4) Abrasion resistance test Wear resistance was tested using a pin-disc wear testing machine. The material was made into pin-shaped specimens and subjected to friction tests against a rotating disc specimen (made of GCr15 steel) under a certain load (50 N) and rotation speed (200 r / min). During the test, the wear rate was calculated by measuring the volume loss of the pin-shaped specimen after sliding a certain distance using the following formula:

[0047] Δ V Wear volume loss (unit: mm) 3 ); F Normal load (unit: N); S Total sliding distance (unit: m); K Wear rate (unit: mm) 3 / N·m ).

[0048] (5) Corrosion resistance test The national standard adopted is GB / T 10124-2021, "Metallic Materials - Laboratory Method for Uniform Corrosion Immersion Test". Electrodynamic polarization curves were tested using an electrochemical workstation, according to ASTM G5-94, "Standard Procedure for Measurement of Electrodynamic Polarization". The sample was completely immersed in a specific corrosive medium (3.5% NaCl solution). The sample was periodically removed, and loose corrosion products on the surface were removed with a soft brush (avoiding scratching the substrate). The sample was then rinsed with deionized water, dehydrated with alcohol, dried, and weighed. mt The corrosion rate is calculated using the following formula:

[0049] In the formula: v Corrosion rate (unit: g / (m)) 2 ·h)); S The surface area of ​​the sample (unit: m²) 2 ); t Soaking time (unit: h).

[0050] The product performance test results are shown in Table 1. The CK group is a metal ceramic prepared without any pretreatment of the ball-milled powder compared to Example 1.

[0051] Table 1:

[0052] Compared to the control group (CK) with no pretreatment of the ball-milled powder, the cermet material prepared in Example 1, which underwent ball-milled powder pretreatment, showed significantly increased hardness, toughness, and flexural strength, exhibiting excellent mechanical properties. Wear resistance and corrosion resistance were also significantly improved. In Comparative Example 1, the high-entropy alloy underwent some segregation and enrichment after electric field-assisted pretreatment, and the lack of subsequent low-temperature pre-firing to promote reaction and diffusion resulted in a significant decrease in the final product's toughness, strength, and other mechanical properties.

[0053] from Figure 4 As can be seen from the results, the material prepared in Example 1 exhibits excellent uniformity in hardness.

[0054] The effect of different high-entropy alloy compositions on the mechanical properties of materials: During the experiment, adjustments were also made to the composition of the high-entropy alloys. Specifically, the following high-entropy alloys were used: a pentagonal high-entropy alloy CrFeCoAlTa (i.e., V removed from the high-entropy alloy in Example 1), a hexaagonal high-entropy alloy CrFeCoAlVNb (i.e., Nb completely replaces Ta in the high-entropy alloy in Example 1), and a heptagonal high-entropy alloy CrFeCoAlVTaNb (i.e., Nb is added to the high-entropy alloy in Example 1 to replace 50% of Ta). These alloys were used to replace the high-entropy alloys in Example 1, respectively. The effect of the composition of high-entropy alloys on the mechanical properties of the final material is shown in Table 2.

[0055] Table 2:

[0056] As can be seen from the table above, under the preparation process of the present invention, the elemental composition of the high-entropy alloy binder phase has a significant impact on the performance of the final metal ceramic. In the present invention, the high-entropy alloy composition CrFeCoAlVTa effectively improves the mechanical properties of the material, such as hardness and toughness. On this basis, adding other components or reducing components will significantly reduce the mechanical properties of the material.

[0057] Example 2 A method for preparing a Ti-CN-based cermet material includes the following steps: S1. Composition Design: By mass percentage, Ti-CN is used as the hard phase, accounting for 50% of the mass; high-entropy alloy is used as the binder phase, accounting for 45% of the mass; and Mo2C is used as the reinforcing phase, accounting for 5% of the mass. The high-entropy alloy is CrFeCoAlVTa, with atomic percentages of Cr 24%, Fe 25%, Co 20%, Al 15%, V 7%, and Ta 9%. S2. Mixed ball milling: Ti-CN powder and the corresponding metal powders or metal oxide powders of six high-entropy elements were weighed according to the stoichiometric ratio and added to a ball mill. Anhydrous ethanol was used as the ball milling medium, the ball-to-material ratio was 10:1, the ball milling speed was 500 r / min, and the ball milling time was 24 h. Then, the mixture was vacuum dried to obtain a uniformly mixed ball-milled powder. The purity of the Ti-CN powder was ≥99%, and the particle size was 1~5 μm; the purity of the metal powder was ≥99%, and the particle size was 2~8 μm; the purity of the metal oxide powder was ≥99%, and the particle size was 3~10 μm. S3. Pretreatment of ball milled powder: The pretreatment is divided into two steps. The first step is to apply a DC electric field of 200V / cm to the ball milled powder and treat it at 400℃ for 20min. The second step is to perform low-temperature pre-calcination treatment at 700℃ for 30min to obtain pretreated powder. S4. Pre-compression molding: The pretreated powder is pre-compressed under a pressure of 200MPa to form a blank; S5. Sintering treatment: The spark plasma sintering (SPS) process is adopted. The green body is placed in a graphite mold and sintered in a vacuum environment. First, the temperature is increased to 1200℃ at 20℃ / min and held for 10 min. The sintering pressure is 15 MPa. Then, the temperature is increased to 1300℃ at 60℃ / min and held for 10 min. The sintering pressure is 50 MPa.

[0058] Tests showed that the Ti-CN-based cermet product prepared in this embodiment had a hardness of HV1940, a fracture toughness of 15.6 MPa·m¹ / ², and a bending strength of 2370 MPa.

[0059] Example 3 A method for preparing a Ti-CN-based cermet material includes the following steps: S1. Composition Design: By mass percentage, Ti-CN is used as the hard phase, accounting for 60% of the total mass; high-entropy alloy is used as the binder phase, accounting for 30% of the total mass; and Mo2C is used as the reinforcing phase, accounting for 10% of the total mass. The high-entropy alloy is composed of CrFeCoAlVTa, with atomic percentages of Cr 26%, Fe 20%, Co 20%, Al 18%, V 9%, and Ta 7%, respectively. S2. Mixed ball milling: Ti-CN powder and the corresponding metal powders or metal oxide powders of six high-entropy elements were weighed according to the stoichiometric ratio and added to a ball mill. Anhydrous ethanol was used as the ball milling medium, the ball-to-material ratio was 10:1, the ball milling speed was 300 r / min, and the ball milling time was 48 h. Then, the mixture was vacuum dried to obtain a uniformly mixed ball-milled powder. The purity of the Ti-CN powder was ≥99%, and the particle size was 1~5 μm; the purity of the metal powder was ≥99%, and the particle size was 2~8 μm; the purity of the metal oxide powder was ≥99%, and the particle size was 3~10 μm. S3. Pretreatment of ball milled powder: The pretreatment is divided into two steps. The first step is to apply a DC electric field of 350V / cm to the ball milled powder and treat it at 200℃ for 30min. The second step is to perform low-temperature pre-calcination treatment at 600℃ for 50min to obtain pretreated powder. S4. Pre-compression molding: The pretreated powder is pre-compressed under a pressure of 100 MPa to form a blank; S5. Sintering treatment: The spark plasma sintering (SPS) process is adopted. The green body is placed in a graphite mold and sintered in a vacuum environment. First, the temperature is increased to 1000℃ at 30℃ / min and held for 15 min. The sintering pressure is 25 MPa. Then, the temperature is increased to 1450℃ at 50℃ / min and held for 5 min. The sintering pressure is 40 MPa.

[0060] Tests showed that the Ti-CN-based cermet product prepared in this embodiment had a hardness of HV1900, a fracture toughness of 15.8 MPa·m¹ / ², and a bending strength of 2350 MPa.

Claims

1. A Ti-CN-based cermet material, characterized in that: It is made by using Ti-CN as the hard phase, a hexa-element high-entropy alloy as the binder phase, and Mo2C as the reinforcing phase, through sequential mixing and ball milling, pretreatment, pre-pressing and molding and high-temperature sintering.

2. The Ti-CN-based cermet material as described in claim 1, characterized in that: By mass percentage, Ti-CN accounts for 50-60%, hexa-element high-entropy alloys account for 30-45%, and Mo2C accounts for 5-10%.

3. A Ti-CN-based cermet material as described in claim 1 or 2, characterized in that: The hexa-element high-entropy alloy is composed of Cr, Fe, Co, Al, V and Ta, with the following atomic percentages: Cr 24-26%, Fe 22-25%, Co 15-20%, Al 15-18%, V 7-9%, and Ta 7-9%.

4. A Ti-CN-based cermet material as described in any one of claims 1-3, characterized in that: The pretreatment is a two-step pretreatment. The first step is electric field-assisted pretreatment, which involves applying a DC electric field of 200~350V / cm to the ball milled powder and treating it at 200~400℃ for 20~30min. The second step is low-temperature pre-calcination treatment, which involves pre-calcining at 600~700℃ for 30~50min.

5. A Ti-CN-based cermet material as described in any one of claims 1-4, characterized in that: The high-temperature sintering is spark plasma sintering, specifically, the temperature is first raised to 1000-1200℃ at 20-30℃ / min and held for 10-15 min, with a sintering pressure of 15-25 MPa, and then raised to 1300-1450℃ at 50-60℃ / min and held for 5-10 min, with a sintering pressure of 40-50 MPa.

6. A method for preparing a Ti-CN-based cermet material, comprising the following steps: S1. Composition Design: By mass percentage, Ti-CN is the hard phase, accounting for 55% by mass; high-entropy alloy is the binder phase, accounting for 38% by mass; and Mo2C is the reinforcing phase, accounting for 7% by mass. The high-entropy alloy is CrFeCoAlVTa, with atomic percentages of Cr 25%, Fe 23%, Co 19%, Al 17%, V 8%, and Ta 8%, respectively. S2. Mixed ball milling: Ti-CN powder and the corresponding metal powders or metal oxide powders of six high-entropy elements were weighed according to the stoichiometric ratio and added to a ball mill. Anhydrous ethanol was used as the ball milling medium, the ball-to-material ratio was 10:1, the ball milling speed was 400 r / min, and the ball milling time was 36 h. Then, the mixture was vacuum dried to obtain a uniformly mixed ball-milled powder. The purity of the Ti-CN powder was ≥99%, and the particle size was 1~5 μm; the purity of the metal powder was ≥99%, and the particle size was 2~8 μm; the purity of the metal oxide powder was ≥99%, and the particle size was 3~10 μm. S3. Pretreatment of ball milled powder: The pretreatment is divided into two steps. The first step is to apply a DC electric field of 300V / cm to the ball milled powder and treat it at 300℃ for 25min. The second step is to perform low-temperature pre-calcination treatment at 650℃ for 40min to obtain pretreated powder. S4. Pre-compression molding: The pretreated powder is pre-compressed under a pressure of 150MPa to form a blank; S5. Sintering treatment: The spark plasma sintering (SPS) process is adopted. The green body is placed in a graphite mold and sintered in a vacuum environment. First, the temperature is increased to 1100℃ at 25℃ / min and held for 12 min. The sintering pressure is 20 MPa. Then, the temperature is increased to 1400℃ at 55℃ / min and held for 6 min. The sintering pressure is 45 MPa.

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