A U3Si2-type multi-component boride-based high-entropy cermet and its preparation method

Abstract

The application provides a U3Si2 type structure multi-element boride-based high-entropy metal ceramic and a preparation method thereof, and belongs to the field of high-entropy metal ceramics.The multi-element boride-based high-entropy metal ceramic provided by the application is obtained by mixed sintering of a hard phase and a binder phase, the hard phase is a multi-element high-entropy boride, the crystal structure of the hard phase is U3Si2 type, the Wyckoff atom occupancy is B 4h (0.18, 0.68, 0.5), Fe 2a (0, 0, 0), M 4g (0.39, 0.89, 0), wherein the M 4g site element is 4 or 5 of Ti, V, Cr, Mn, Co, Ni, Zr, Nb, Hf, Ta, W and Mo, and the concentration (molar fraction) of each element is between 5% and 35%; and the binder phase in the high-entropy metal ceramic is Fe.The U3Si2 type structure multi-element boride-based high-entropy metal ceramic provided by the application has high hardness, high strength, high toughness and excellent wear resistance.The application further provides a preparation method of the multi-element boride-based high-entropy metal ceramic, and the method is simple to operate, stable in process and easy to popularize.

Description

Technical Field

[0001] This invention relates to the field of high-entropy metal ceramics technology, and in particular to a U3Si2-type multi-component boride-based high-entropy metal ceramic and its preparation method. Background Technology

[0002] Ceramic-metal composites are heterogeneous composite materials containing both tough metal and hard ceramic particles, with the ceramic phase typically comprising 15% to 85%. This combination gives them high hardness, strength, and wear resistance. Currently, they are widely used in mining, cutting tools, and wear-resistant coatings.

[0003] The concept of high entropy originated in the field of powder metallurgy, mainly referring to a composition of five or more elements, with each element's content ranging from 5% to 35%. When applied to the ceramics field, high entropy ceramics will possess many superior structural and performance characteristics. The preparation of high entropy cermets by combining them with metals has significant potential for performance enhancement. Boride-based cermets exhibit excellent hardness and strength, but their poor fracture toughness limits their further applications. Introducing the high entropy effect into boride-based cermet systems would contribute to further performance improvement. However, current research on boride-based high entropy cermets is relatively limited, especially the preparation of U3Si2-type multi-component boride-based high entropy cermets, which remains almost entirely unexplored. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a U3Si2-type multi-component boride-based high-entropy cermet and its preparation method. The U3Si2-type multi-component boride-based high-entropy cermet provided by this invention exhibits high hardness, high strength, high toughness, and excellent wear resistance.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solutions.

[0006] This invention provides a U3Si2-type multi-component boride-based high-entropy cermet, which is composed of a hard phase and a binder phase. The hard phase is a U3Si2-type multi-component high-entropy boride, and the binder phase is Fe.

[0007] The hard phase in the high-entropy cermet has a U3Si2 crystal structure with Wyckoff atoms occupying B 4h (0.18, 0.68, 0.5), Fe 2a (0, 0, 0), and M 4g (0.39, 0.89, 0). The M 4g site contains four or five elements selected from Ti, V, Cr, Mn, Co, Ni, Zr, Nb, Hf, Ta, W, and Mo, with each element concentration (mole fraction) ranging from 5% to 35%.

[0008] The mass fraction of the binder phase in the high-entropy cermet is 15% to 35%.

[0009] This invention also provides a method for preparing U3Si2-type structured multi-component boride-based high-entropy cermets, wherein the U3Si2-type structured multi-component boride-based high-entropy cermets are prepared by first sintering U3Si2-type structured multi-component high-entropy boride ceramic powder, and then mixing and sintering it with a binder phase to obtain U3Si2-type structured multi-component boride-based high-entropy cermet bulk material, comprising the following steps:

[0010] Metallic powders of the M 4g position elements of U3Si2 type structure multi-element high-entropy boride powder are mixed with Fe powder, FeB powder and B powder in a certain proportion, anhydrous ethanol is added and ball milling is performed, and then the ball-milled slurry is dried and sieved to obtain a mixed dry material.

[0011] The mixed dry material was sintered in an atmosphere, then cooled, crushed, and sieved to obtain a single-phase U3Si2 type multi-element high-entropy boride powder.

[0012] The single-phase U3Si2 type structure multi-component high-entropy boride powder was ball-milled and mixed with Fe powder, then pressed into blocks, and finally sintered under low pressure or by SPS to obtain multi-component boride-based high-entropy cermets. The obtained multi-component boride-based high-entropy cermets exhibit high hardness, high strength, high toughness, and excellent wear resistance.

[0013] The U3Si2-type multi-component boride-based high-entropy cermet has an element concentration (mole fraction) at the M4g position of its multi-component high-entropy boride hard phase ranging from 5% to 35%. The mass fraction of the hard phase is 65%–85%, and the mass fraction of the Fe binder phase is 15%–35%.

[0014] The ball milling is performed using a planetary ball mill wet milling method, and the amount of anhydrous ethanol added is 100% to 150% of the mass of the mixed powder.

[0015] The ball-to-material ratio in the ball mill is (5-8):1, the planetary ball mill speed is 250-400 rpm, and the ball milling time is 12-72 h.

[0016] The drying temperature is 60-80℃, and the drying time is 5-12 hours.

[0017] The sintering method for the U3Si2 type multi-element high-entropy boride powder is an atmosphere sintering method using flowing argon as a protective gas. The heating rate is 5-10℃ / min, and the intermediate holding stages are 600-650℃ for 10 min, 800-850℃ for 10 min, and 1100-1150℃ for 30 min. The sintering temperature is 1300-1400℃, and the holding time is 0.5-3 h.

[0018] The method for preparing U3Si2-type multi-component boride-based high-entropy cermets involves the following steps: During low-pressure sintering, the forming pressure of the briquette is 25–35 MPa, the holding time is 60–220 s, the heating rate during low-pressure sintering is 5–10 °C / min, the sintering temperature is 1200–1275 °C, and after reaching the target temperature, argon gas is introduced as an isostatic medium at a pressure of 2–10 MPa for a holding time of 30–90 min. During SPS sintering, the heating rate is 25–100 °C / min, the sintering temperature is 1200–1250 °C, the pressure is 10–100 MPa, and the holding time is 5–20 min.

[0019] This invention provides a U3Si2-type multi-component boride-based high-entropy cermet and its preparation method. The hard phase in the high-entropy cermet is a multi-component high-entropy boride with a U3Si2-type crystal structure. Wyckoff atoms occupy B 4h (0.18, 0.68, 0.5), Fe 2a (0, 0, 0), and M 4g (0.39, 0.89, 0), where the M 4g site elements are four or five of the following: Ti, V, Cr, Mn, Co, Ni, Zr, Nb, Hf, Ta, W, and Mo. Each major element in a high-entropy ceramic often possesses its own unique properties. For example, Cr can improve corrosion resistance, V can improve toughness, and Mn can improve hardness. By utilizing the synergistic effect between principal components, the hard phase grains are refined, the anisotropy of the hard phase is reduced, and the problem of poor wettability between the hard phase and the binder phase is improved. This effectively increases the interfacial bonding strength between the hard phase and the binder phase, thus enabling U3Si2-type multi-component boride-based high-entropy cermets to possess excellent comprehensive properties, exhibiting good comprehensive performance in both toughness and hardness.

[0020] Furthermore, the U3Si2-type multi-component boride-based high-entropy cermets provided by this invention exhibit controllable properties. By adjusting the type, quantity, and content of the M and 4g site elements, U3Si2-type multi-component boride-based high-entropy cermet materials meeting different requirements can be prepared. These materials possess thermodynamic high-entropy effects, kinetic hysteresis diffusion effects, structural lattice distortion effects, and a "cocktail" effect in performance. Therefore, the U3Si2-type multi-component boride-based high-entropy cermets provided by this invention typically exhibit excellent performance in terms of strength, hardness, toughness, high-temperature performance, wear resistance, and corrosion resistance, providing a new strategy for further optimizing the properties of cermets and meeting diverse service conditions.

[0021] Furthermore, adding 100%–150% anhydrous ethanol during ball milling can reduce the oxidation of elemental metal powders, reduce the introduction of impurities, make the powder mix uniformly, and improve ball milling efficiency.

[0022] Furthermore, a blower dryer is used to dry the mixed powder. The equipment is simple to operate, highly efficient, and shortens the preparation cycle of U3Si2 type structure multi-component boride-based high-entropy metal ceramics.

[0023] Furthermore, the sintering method is simple atmosphere sintering, using argon as a protective gas to prevent oxidation of the raw material powder. Atmosphere tube sintering furnaces are simple to operate and easy to industrialize and promote. Alternatively, hot pressing sintering or SPS sintering can be selected, offering a variety of sintering methods.

[0024] Furthermore, the method for preparing U3Si2-type multi-element high-entropy boride powder provided by the present invention employs segmented heat preservation during the sintering process, resulting in powder with controllable impurities and a single-phase U3Si2-type structure.

[0025] Furthermore, the molding pressure for briquetting is 25–35 MPa, and the holding time is 60–220 s. This ensures the strength of the blank while avoiding excessive pressure that could cause cracks, thus preparing the blank for subsequent sintering.

[0026] Compared with existing technologies, the U3Si2-type multi-component boride-based high-entropy cermets provided in this invention exhibit high hardness, high strength, high toughness, and excellent wear resistance. The preparation method is simple to operate, the process is stable, and it is easy to promote. Furthermore, by adjusting the type, quantity, and content of the M and 4g site elements, U3Si2-type multi-component boride-based high-entropy cermet materials meeting different requirements can be prepared, providing a new strategy for further expanding cermet systems, optimizing cermet performance, and meeting diverse service conditions. Attached Figure Description

[0027] Figure 1 The X-ray diffraction pattern of the U3Si2-type multi-element high-entropy boride powder prepared in Example 1 of this invention;

[0028] Figure 2 This is a SEM image of the U3Si2-type multi-element high-entropy boride powder prepared in Example 1 of this invention;

[0029] Figure 3 The X-ray diffraction pattern of the U3Si2-type multi-component boride-based high-entropy cermet prepared in Example 1 of this invention is shown below.

[0030] Figure 4 This is a SEM image of the U3Si2-type multi-component boride-based high-entropy cermet prepared in Example 1 of this invention. Detailed Implementation

[0031] This invention provides a U3Si2-type multi-component boride-based high-entropy cermet, wherein the high-entropy cermet is composed of a hard phase and a binder phase, wherein the hard phase in the high-entropy cermet is a multi-component high-entropy boride, and the binder phase in the high-entropy cermet is Fe.

[0032] The hard phase in the high-entropy cermet has a U3Si2 crystal structure with Wyckoff atoms occupying B 4h (0.18, 0.68, 0.5), Fe 2a (0, 0, 0), and M 4g (0.39, 0.89, 0). The M 4g site contains four or five elements selected from Ti, V, Cr, Mn, Co, Ni, Zr, Nb, Hf, Ta, W, and Mo, with each element concentration (mole fraction) ranging from 5% to 35%.

[0033] Unless otherwise specified, all the substances mentioned in this invention are commercially available products well known to those skilled in the art.

[0034] This invention also provides a method for preparing U3Si2-type multi-component boride-based high-entropy cermets, comprising the following steps:

[0035] S1, Mixing

[0036] The preparation of the U3Si2 type structure multi-element high-entropy boride powder involves mixing four or five of the following metal powders with a purity of not less than 99.0%: Ti, V, Cr, Mn, Co, Ni, Zr, Nb, Hf, Ta, W, and Mo, along with Fe powder, FeB powder, and B powder, in a certain proportion.

[0037] S2, ball mill

[0038] Place the mixed powder in S1 into a polyethylene ball mill jar, add 100% to 150% anhydrous ethanol by mass of the mixed powder, add hard alloy balls, the ball-to-powder ratio is (5 to 8):1, the ball mill speed is 250 to 400 rpm, and the ball milling time is 12 to 72 hours.

[0039] S3, Drying

[0040] The ball-milled slurry is placed in a forced-air drying oven for drying at a temperature of 60–80°C for 5–24 hours. The dried powder is then sieved through a 300-mesh sieve.

[0041] S4, sintering

[0042] The powder from S3 was placed in an alumina crucible and sintered in an atmosphere sintering furnace. The atmosphere sintering used flowing argon as the protective gas, with a heating rate of 5–10 °C / min. The intermediate holding stages were: 600–650 °C for 10 min, 800–850 °C for 10 min, and 1100–1150 °C for 30 min. The sintering temperature was 1300–1400 °C, and the holding time was 30–180 min. After furnace cooling, the crushed powder was sieved through a 300-mesh sieve to obtain U3Si2-type multi-element high-entropy boride powder.

[0043] S5, Mixing

[0044] The ingredients are mixed according to the following formula: 65% to 85% of the powder by weight, and 15% to 35% of Fe metal element with a purity of not less than 99.0% by weight.

[0045] S6, Ball Mill

[0046] Place the mixed powder from S5 into a polyethylene ball mill jar, add 100%–150% anhydrous ethanol by mass of the powder, add carbide balls, and the ball-to-material ratio is (5–8):1. The ball mill speed is 250–400 rpm, and the ball milling time is 12–72 h.

[0047] S7, Drying

[0048] The slurry after ball milling in S6 is placed in a forced-air drying oven for drying at a temperature of 60-80℃ for 5-24 hours. The dried powder is then sieved through a 300-mesh sieve.

[0049] S8, Pressing and Molding

[0050] The dried S7 powder is loaded into a mold for compression molding. The molding pressure is 25-35 MPa and the holding time is 60-220 s.

[0051] S9, Sintering

[0052] The S8 preform was placed in an alumina crucible for low-pressure sintering at a heating rate of 5–10 °C / min and a sintering temperature of 1200–1275 °C. After reaching the target temperature, argon gas was introduced as an isostatic medium at a pressure of 2–10 MPa and a holding time of 30–90 min. When SPS sintering was used, the dried S7 powder was placed in a mold in a sintering furnace at a pressure of 10–100 MPa, a heating rate of 25–100 °C / min, and a holding time of 5–20 min. After furnace cooling, a U3Si2 type multi-component boride-based high-entropy metal ceramic was obtained.

[0053] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of a U3Si2-type multi-component boride-based high-entropy cermet and its preparation method provided by the present invention, should not be construed as limiting the scope of protection of the present invention.

[0054] Example 1

[0055] (1) Powdering

[0056] 10.58 g of elemental B, 27.32 g of elemental Fe, 23.48 g of elemental Mo, 12.72 g of elemental Cr, 12.46 g of elemental V, and 13.44 g of elemental Mn were weighed and placed into a ball mill jar. Planetary ball milling was performed for 72 hours at a rotation speed of 250 rpm, a ball-to-material ratio of 8:1, and anhydrous ethanol as the milling medium. The milled slurry was dried in an oven at 60°C for 8 hours. The dried mixture was then sintered in a tubular furnace under a protective atmosphere of flowing argon gas. The heating rate was 10°C / min, with intermediate holding stages of 600°C for 10 minutes, 800°C for 10 minutes, and 1100°C for 30 minutes, followed by holding at 1400°C for 120 minutes. After furnace cooling, the powder was removed, crushed, and sieved to obtain a high-entropy powder with the composition (MoCrVMn)2FeB2. Its XRD pattern is shown in [Figure showing XRD pattern]. Figure 1 SEM Figure 2 .

[0057] (2) Mixing and molding

[0058] 17g of high-entropy ceramic powder and 3g of Fe metal powder were weighed and placed in a ball mill jar. The mixture was then ball-milled for 24 hours at a speed of 400 rpm, a ball-to-powder ratio of 5:1, and anhydrous ethanol as the milling medium. The milled slurry was dried in an oven at 80℃ for 5 hours, then sieved. It was then placed into a mold, pressed under a pressure of 28 MPa for 150 seconds, and shaped using a press.

[0059] (3) Sintering

[0060] The prepared compact was subjected to low-pressure sintering. The temperature was increased to 1250℃ at a rate of 10℃ / min, and then argon gas was introduced as the isostatic pressure medium at a pressure of 5 MPa. Sintering was held at this temperature for 30 min. After furnace cooling, (MoCrVMn)2FeB2-based high-entropy cermet was obtained. Its XRD pattern is shown in [Figure number missing]. Figure 3 SEM Figure 4 .

[0061] Example 2

[0062] (1) Powdering

[0063] 3.75g of elemental boron, 34.15g of FeB powder, 23.48g of elemental molybdenum, 12.72g of elemental Cr, 12.46g of elemental v, and 13.44g of elemental mn were weighed and placed into a ball mill jar. The mixture was ball-milled for 72 hours at a speed of 250 rpm, a ball-to-powder ratio of 7:1, and anhydrous ethanol as the milling medium. The milled slurry was dried in an oven at 60℃ for 7 hours. The dried mixture was then sintered in a tubular furnace under a protective atmosphere of flowing argon gas. The heating rate was 10℃ / min, with intermediate holding stages of 600℃ for 10 minutes, 800℃ for 10 minutes, and 1100℃ for 30 minutes. The temperature was then raised to 1350℃ and held for 120 minutes. After cooling in the furnace, the powder was removed, crushed, and sieved to obtain (MoCrVMn)2FeB2-based high-entropy ceramic powder.

[0064] (2) Mixing and molding

[0065] 17g of high-entropy ceramic powder and 3g of Fe metal powder were weighed and placed in a ball mill jar. The mixture was then ball-milled for 48 hours at a speed of 350 rpm, a ball-to-powder ratio of 6:1, and anhydrous ethanol as the milling medium. The milled slurry was then dried in an oven at 70℃ for 6 hours. Finally, it was placed in a mold and pressed into shape under a pressure of 32 MPa for 100 seconds.

[0066] (3) Sintering

[0067] The prepared compact was subjected to low-pressure sintering. The temperature was increased to 1200℃ at a heating rate of 7℃ / min, and then argon gas was introduced as an isostatic medium at a pressure of 4 MPa. The sintering was held at this temperature for 40 min. After furnace cooling, (MoCrVMn)2FeB2-based high-entropy cermet was obtained.

[0068] Example 3

[0069] (1) Powdering

[0070] 9.88g of elemental boron, 25.51g of elemental fetus, 10.93g of elemental titanium dioxide, 11.63g of elemental vanadium, 21.22g of elemental nitrogen, and 20.83g of elemental zirconium were weighed and placed into a ball mill jar. The mixture was ball-milled for 72 hours at a rotation speed of 250 rpm, a ball-to-material ratio of 7:1, and anhydrous ethanol as the milling medium. The milled slurry was then dried in an oven at 60℃ for 7 hours. The dried mixture was then sintered in a tubular furnace under a protective atmosphere of flowing argon gas. The heating rate was 8℃ / min, with intermediate holding stages of 610℃ for 10 minutes, 810℃ for 10 minutes, and 1110℃ for 30 minutes. The temperature was then raised to 1350℃ and held for 120 minutes. After cooling in the furnace, the powder was removed, crushed, and sieved to obtain (TiVNbZr)2FeB2-based high-entropy ceramic powder.

[0071] (2) Mixing and molding

[0072] 16g of high-entropy ceramic powder and 4g of Fe metal powder were weighed and placed in a ball mill jar. The mixture was then ball-milled for 24 hours at a speed of 350 rpm, a ball-to-powder ratio of 5:1, and anhydrous ethanol as the milling medium. The milled slurry was then dried in an oven at 75°C for 6 hours. Finally, it was placed in a mold and pressed into shape under a pressure of 25 MPa for 220 seconds.

[0073] (3) Sintering

[0074] The prepared compact was subjected to low-pressure sintering. The temperature was increased to 1250℃ at a heating rate of 8℃ / min, and then argon gas was introduced as an isostatic medium at a pressure of 6 MPa. The sintering was held at this temperature for 40 min. After furnace cooling, (TiVNbZr)2FeB2-based high-entropy cermet was obtained.

[0075] Example 4

[0076] 7.87g of elemental boron, 20.33g of elemental fetus, 10.69g of elemental nitrogen, 10.73g of elemental cobalt, 16.92g of elemental nitrogen, and 33.46g of elemental nitrogen were weighed and placed into a ball mill jar. The mixture was ball-milled for 48 hours at a speed of 300 rpm, a ball-to-material ratio of 6:1, and anhydrous ethanol as the milling medium. The milled slurry was dried in an oven at 70℃ for 6 hours. The dried mixture was then sintered in a tubular furnace under a protective atmosphere of flowing argon gas. The heating rate was 9℃ / min, with intermediate holding stages at 620℃ for 10 minutes, 820℃ for 10 minutes, and 1120℃ for 30 minutes. The temperature was then raised to 1400℃ and held for 30 minutes. After cooling in the furnace, the powder was removed, crushed, and sieved to obtain (NiCoNbW)2FeB2-based high-entropy ceramic powder.

[0077] (2) Mixing and molding

[0078] 15g of high-entropy ceramic powder and 5g of Fe metal powder were weighed and placed in a ball mill jar. The mixture was then ball-milled for 48 hours at a speed of 350 rpm, a ball-to-powder ratio of 6:1, and anhydrous ethanol as the milling medium. The milled slurry was then dried in an oven at 70℃ for 6 hours. Finally, it was placed in a mold, pressed at a pressure of 30 MPa for 120 seconds, and then shaped using a press.

[0079] (3) Sintering

[0080] The prepared compact was subjected to low-pressure sintering. The temperature was increased to 1200℃ at a heating rate of 7℃ / min, and then argon gas was introduced as an isostatic medium at a pressure of 7 MPa. The sintering was held at this temperature for 40 min. After furnace cooling, (NiCoNbW)2FeB2-based high-entropy cermet was obtained.

[0081] Example 5

[0082] 8.56g of elemental B, 22.11g of elemental Fe, 15.20g of elemental Mo, 8.24g of elemental Cr, 8.07g of elemental V, 8.70g of elemental Mn, and 29.12g of elemental W were weighed and placed into a ball mill jar. The mixture was ball-milled for 48 hours at a speed of 300 rpm, a ball-to-material ratio of 6:1, and anhydrous ethanol as the milling medium. The milled slurry was dried in an oven at 70℃ for 5 hours. The dried mixture was then sintered in a tubular furnace under a protective atmosphere of flowing argon gas. The heating rate was 6℃ / min, with intermediate holding stages of 630℃ for 10 minutes, 830℃ for 10 minutes, and 1130℃ for 30 minutes, followed by a final holding at 1400℃ for 60 minutes. After cooling in the furnace, the powder was removed, crushed, and sieved to obtain (MoCrVMnW)2FeB2-based high-entropy ceramic powder.

[0083] (2) Mixing and molding

[0084] 14g of high-entropy ceramic powder and 6g of Fe metal powder were weighed and placed in a ball mill jar. The mixture was then ball-milled for 48 hours at a speed of 300 rpm, a ball-to-powder ratio of 6:1, and anhydrous ethanol as the milling medium. The milled slurry was then dried in an oven at 70℃ for 7 hours. Finally, it was placed in a mold and pressed into shape under a pressure of 35 MPa for 60 seconds.

[0085] (3) Sintering

[0086] The prepared compact was subjected to low-pressure sintering. The temperature was increased to 1150℃ at a rate of 6℃ / min, and then argon gas was introduced as an isostatic medium at a pressure of 7 MPa. The sintering was held at this temperature for 50 min. After furnace cooling, (MoCrVMnW)2FeB2-based high-entropy cermet was obtained.

[0087] Example 6

[0088] 7.14g of elemental B, 18.44g of elemental Fe, 12.67g of elemental Mo, 6.32g of elemental Ti, 23.89g of elemental Ta, 7.26g of elemental Mn, and 24.28g of elemental W were weighed and placed into a ball mill jar. The mixture was ball-milled for 24 hours at a speed of 350 rpm, a ball-to-material ratio of 5:1, and anhydrous ethanol as the milling medium. The milled slurry was dried in an oven at 80℃ for 5 hours. The dried mixture was then sintered in a tubular furnace under a protective atmosphere of flowing argon gas. The heating rate was 6℃ / min, with intermediate holding stages of 640℃ for 10 minutes, 840℃ for 10 minutes, and 1140℃ for 30 minutes, followed by a holding at 1300℃ for 120 minutes. After cooling in the furnace, the powder was removed, crushed, and sieved to obtain (MoTiTaMnW)2FeB2-based high-entropy ceramic powder.

[0089] (2) Mixing and molding

[0090] 14g of the prepared high-entropy ceramic powder and 6g of Fe metal powder were weighed and placed in a ball mill jar. The mixture was then ball-milled for 72 hours at a speed of 250 rpm, a ball-to-powder ratio of 7:1, and anhydrous ethanol as the milling medium. The milled slurry was then dried in an oven at 65°C for 7 hours and then poured into a mold.

[0091] (3) Sintering

[0092] The mold containing the mixed powder was placed in a hot press sintering furnace. Under an applied external pressure of 60 MPa, the temperature was raised to 1250 °C at a heating rate of 50 °C / min. The sintering was held at this temperature for 20 min, and then cooled with the furnace to obtain (MoTiTaMnW)2FeB2-based high-entropy metal ceramics.

[0093] Example 7

[0094] 8.69 g of elemental B, 22.44 g of elemental Fe, 7.69 g of elemental Ti, 14.66 g of elemental Zr, 28.69 g of elemental Hf, 8.36 g of elemental Cr, and 9.47 g of elemental Co were weighed and placed into a ball mill jar. The mixture was ball-milled for 24 hours at a speed of 400 rpm, a ball-to-material ratio of 5:1, and anhydrous ethanol as the milling medium. The milled slurry was dried in an oven at 80°C for 4 hours. The dried mixture was then sintered in a tubular furnace under a protective atmosphere of flowing argon gas. The heating rate was 5°C / min, with intermediate holding stages of 650°C for 10 minutes, 850°C for 10 minutes, and 1150°C for 30 minutes. The temperature was then raised to 1400°C and held for 180 minutes. After cooling in the furnace, the powder was removed, crushed, and sieved to obtain (TiZrHfCrCo)2FeB2-based high-entropy ceramic powder.

[0095] (2) Mixing and molding

[0096] 13g of the prepared high-entropy ceramic powder and 7g of Fe metal powder were weighed and placed in a ball mill jar. The mixture was then ball-milled for 72 hours at a speed of 250 rpm, a ball-to-powder ratio of 8:1, and anhydrous ethanol as the milling medium. The milled slurry was then dried in an oven at 60°C for 8 hours and then poured into a mold.

[0097] (3) Sintering

[0098] The mold containing the mixed powder was placed in a hot press sintering furnace. Under an applied external pressure of 80 MPa, the temperature was raised to 1275 °C at a heating rate of 70 °C / min. The sintering was held at this temperature for 10 min, and then cooled with the furnace to obtain (TiZrHfCrCo)2FeB2-based high-entropy metal ceramics.

[0099] The mechanical properties of the U3Si2-type multi-component boride-based high-entropy cermets prepared in Examples 1-7 were tested. The test results are shown in Table 1, and the relative density of Examples 1-7 is also recorded.

[0100] Table 1. Mechanical properties and relative density of U3Si2-type multi-component boride-based high-entropy cermets described in Examples 1-7.

[0101]

[0102] In summary, the U3Si2-type multi-component boride-based high-entropy cermets provided by this invention exhibit high hardness, high strength, high toughness, and excellent wear resistance. The preparation method is simple to operate, the process is stable, and it is easy to promote. Furthermore, by adjusting the type, quantity, and content of the M and 4g-site elements, U3Si2-type multi-component boride-based high-entropy cermet materials meeting different requirements can be prepared, providing a new strategy for further expanding cermet systems, optimizing cermet performance, and meeting diverse service conditions.

[0103] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A U3Si2-type multi-component boride-based high-entropy cermet, characterized in that, The U3Si2-type multi-component boride-based high-entropy cermet consists of a hard phase and a binder phase. The hard phase is a multi-component high-entropy boride with a U3Si2-type crystal structure. The Wyckoff atom occupies B 4h (0.18, 0.68, 0.5), Fe 2a (0, 0, 0), and M 4g (0.39, 0.89, 0). The M 4g position element is 4 or 5 of the following: Ti, V, Cr, Mn, Co, Ni, Zr, Nb, Hf, Ta, W, and Mo. The specific multi-element high-entropy borides are (MoCrVMn)2FeB2, (TiVNbZr)2FeB2, (NiCoNbW)2FeB2, (MoCrVMnW)2FeB2, (MoTiTaMnW)2FeB2 or (TiZrHfCrCo)2FeB2; The binder phase is Fe; The molar concentration of each element at position M4g in the multi-element high-entropy boride is between 5% and 35%. The U3Si2-type structure multi-component boride-based high-entropy metal ceramic is prepared by first sintering U3Si2-type structure multi-component high-entropy boride ceramic powder, and then mixing it with the binder phase and sintering it to obtain U3Si2-type structure multi-component boride-based high-entropy metal ceramic block. The mass fraction of the multi-component high-entropy boride is 65%–85%, and the mass fraction of the binder phase is 15%–35%. The elemental metal powder of the M 4g position element of the multi-element high-entropy boride is mixed with Fe powder, FeB powder and B powder in a certain proportion, ball-milled, dried, sintered, crushed and sieved to obtain single-phase U3Si2 type structure multi-element high-entropy boride powder. The U3Si2-type multi-element high-entropy boride powder was prepared by atmospheric sintering with flowing argon as the protective gas. The heating rate was 5–10 °C / min, and the intermediate holding stages were 600–650 °C for 10 min, 800–850 °C for 10 min, and 1100–1150 °C for 30 min. The sintering temperature was 1300–1400 °C, and the holding time was 30–180 min.

2. The method for preparing the U3Si2-type multi-component boride-based high-entropy cermet as described in claim 1, characterized in that, The U3Si2-type structured multi-component boride-based high-entropy metal ceramic is prepared by first sintering U3Si2-type structured multi-component high-entropy boride ceramic powder, and then mixing it with a binder phase and sintering to obtain U3Si2-type structured multi-component boride-based high-entropy metal ceramic bulk material.

3. The preparation method according to claim 2, characterized in that, The U3Si2-type multi-component boride-based high-entropy cermet is prepared by ball milling and mixing U3Si2-type multi-component high-entropy boride powder with Fe powder, pressing into blocks, and then sintering under low pressure or by SPS sintering.

4. The preparation method according to claim 2, characterized in that, The ball milling adopts the planetary ball milling method, with a ball-to-material ratio of (5-8):1, a ball milling speed of 250-400 rpm, and a ball milling time of 12-72 h; the drying temperature is 60-80℃, and the drying time is 5-24 h.

5. The preparation method according to claim 3, characterized in that, The low-pressure sintering process involves forming blocks at a pressure of 25–35 MPa, holding time of 60–220 s, heating rate of 5–10 °C / min, and sintering temperature of 1200–1275 °C. After reaching the target temperature, argon gas is introduced as an isostatic medium at a pressure of 2–10 MPa, and the holding time is 30–90 min.

6. The preparation method according to claim 3, characterized in that, The SPS sintering process involves a heating rate of 25–100 °C / min, a sintering temperature of 1200–1250 °C, a sintering pressure of 10–100 MPa, and a holding time of 5–20 min.

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