Rare earth modified tungsten carbide alloy and preparation method thereof

Abstract

The invention discloses a rare earth modified tungsten carbide alloy and a preparation method thereof, and belongs to the technical field of tungsten carbide alloys. The rare earth modified tungsten carbide alloy comprises 80 wt.%-90 wt.% of a hard phase and 10 wt.%-20 wt.% of a matrix, and the hard phase is uniformly distributed in the matrix; the hard phase comprises a rare earth modified tungsten carbide inner core, the rare earth modified tungsten carbide inner core is coated with a nano tungsten carbide shell, the rare earth modified tungsten carbide inner core accounts for 85-95 wt.% of the mass of the hard phase, and the nano tungsten carbide shell accounts for 5-15 wt.% of the mass of the hard phase. By the adoption of the rare earth modified tungsten carbide alloy and the preparation method thereof, the problem that an existing tungsten carbide alloy is poor in hardness and abrasion resistance can be solved, and the toughness of the tungsten carbide alloy can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of tungsten carbide alloys, and particularly relates to a rare earth modified tungsten carbide alloy and a preparation method thereof. Background Art

[0002] Tungsten carbide-based hard alloys are widely used in fields such as cutting tools, mining tools, and wear-resistant components due to their high hardness, wear resistance, and thermal stability. In the field of machining, tungsten carbide tools can significantly improve the metal cutting efficiency; in the oil drilling industry, tungsten carbide drill bits can effectively cope with complex formation conditions and extend the service life. With the development of the manufacturing industry towards high precision, high efficiency, and high reliability, higher requirements are put forward for the comprehensive performance of tungsten carbide alloys. Traditional tungsten carbide alloys still have many technical bottlenecks in practical applications, and it is difficult to achieve an ideal balance between toughness and hardness. Conventional tungsten carbide-cobalt (WC-Co) alloys have high hardness, but are prone to brittle fracture when subjected to impact loads or alternating stresses, which limits their application under high-load and high-dynamic stress conditions.

[0003] The existing patent CN202311052539.7 discloses a tungsten carbide super wear-resistant hard alloy and a preparation method and application thereof. The tungsten carbide super wear-resistant hard alloy includes 90-97 wt% of tungsten carbide powder, 0.1-2.3 wt% of a restricting agent, 0.1-1.3 wt% of cobalt, and 0.1-1.5 wt% of rare earth metal. The restricting agent added to the tungsten carbide powder is a mixture of chromium and vanadium, and the mass ratio is 0.5-1.5:1. The preparation method includes: (1) mixing tungsten carbide powder with a restricting agent and rare earth metal, and adding alcohol for grinding; (2) discharging the slurry and drying it in vacuum; (3) sieving with a special sieve machine to obtain WC alloy powder; (4) placing the WC alloy powder in a mold and pressing it into shape with a cold isostatic press; (5) sintering the pressed blank in a vacuum sintering furnace; (6) naturally cooling the sintered blank to room temperature to obtain the tungsten carbide super wear-resistant hard alloy. The tungsten carbide super wear-resistant hard alloy of the present invention improves the wear resistance and reduces the production cost, and is suitable for large-scale industrial production. The above patent controls the growth of alloy crystals and improves the closure degree of alloy crystals by adding a restricting agent and rare earth metal to tungsten carbide. However, only by directly modifying tungsten carbide with rare earth metal and restricting agent, the hardness and wear resistance of the prepared tungsten carbide alloy are still relatively low, and the toughness of the tungsten carbide alloy is relatively poor. Summary of the Invention

[0004] The purpose of the present invention is to provide a rare earth modified tungsten carbide alloy and a preparation method thereof, to solve the problems of poor hardness and wear resistance of existing tungsten carbide alloys, and to improve the toughness of tungsten carbide alloys.

[0005] To achieve the above object, the present invention provides a rare earth modified tungsten carbide alloy, which includes a hard phase and a matrix. The mass percentage of the hard phase is 80wt.% - 90wt.%, and the mass percentage of the matrix is 10wt.% - 20wt.%. The hard phase is uniformly distributed in the matrix; the hard phase includes a rare earth modified tungsten carbide core, and the outer of the rare earth modified tungsten carbide core is coated with a nano tungsten carbide shell. The mass percentage of the rare earth modified tungsten carbide core in the hard phase is 85wt.% - 95wt.%, and the mass percentage of the nano tungsten carbide shell in the hard phase is 5wt.% - 15wt.%.

[0006] Preferably, the rare earth modified tungsten carbide core is spherical, and the particle size of the rare earth modified tungsten carbide core is 20μm - 30μm.

[0007] Preferably, the rare earth modified tungsten carbide core includes the following components by mass percentage: tungsten carbide particles with a particle size of 150nm - 200nm are 15wt.% - 20wt.%, tungsten carbide particles with a particle size of 1.0μm - 1.5μm are 50wt.% - 70wt.%, tungsten carbide particles with a particle size of 3μm - 5μm are 10wt.% - 20wt.%, rare earth oxide is 0.1wt.% - 0.5wt.%, and cobalt powder with a particle size of 1.0μm - 1.5μm is 8wt.% - 10wt.%.

[0008] Preferably, the particle size of the rare earth oxide is 0.5μm - 1.0μm, and the rare earth oxide is one of cerium oxide and yttrium oxide.

[0009] Preferably, the particle size of the nano tungsten carbide in the nano tungsten carbide shell is 0.2μm - 0.4μm, and the nano tungsten carbide shell includes 90wt.% - 95wt.% nano tungsten carbide, 5wt.% - 10wt.% cobalt and 1wt.% - 2wt.% sodium silicate by mass percentage.

[0010] Preferably, the matrix includes 80wt.% - 85wt.% tungsten carbide, 3wt.% - 5wt.% molybdenum carbide, 10wt.% - 15wt.% binder and 3wt.% - 5wt.% additive by mass percentage; the particle size of tungsten carbide in the matrix is 2μm - 3μm, the particle size of molybdenum carbide is 3μm - 5μm, the binder includes four elements of Fe, Co, Ni, and Cr with a molar ratio of 1:1:1:1, and the additive is one or a mixture of several of titanium, tantalum, and niobium.

[0011] The preparation method of the above rare earth modified tungsten carbide alloy includes the following steps: S1. Prepare the rare earth modified tungsten carbide core; S2. Coat the outer of the rare earth modified tungsten carbide core with a nano tungsten carbide shell to obtain the hard phase; S3. Prepare the matrix raw materials, add the hard phase to the matrix raw materials, mix evenly, press and mold, and then sinter to obtain a rare earth modified tungsten carbide alloy blank. S4. Heat-treat the hard tungsten carbide alloy blank to obtain a hard tungsten carbide alloy. The heat-treatment temperature is 1200°C - 1300°C, and the heat-treatment time is 4 hours - 6 hours.

[0012] Preferably, S1 includes the following steps: S11. Weigh tungsten carbide particles with a particle size of 150 nm - 200 nm, tungsten carbide particles with a particle size of 1.0 μm - 1.5 μm, tungsten carbide particles with a particle size of 3 μm - 5 μm, and cobalt powder according to the mass ratio, and perform ball milling and mixing to obtain a tungsten carbide mixed powder. S12. Weigh rare earth oxides according to the mass ratio, add the rare earth oxides and the tungsten carbide mixed powder to an aqueous copper sulfate solution with a mass concentration of 15% - 20%, and stir evenly to obtain a mixed solution. S13. Feed the mixed solution into an atomizing nozzle for atomization. The atomized droplets are sprayed into a reaction furnace at a temperature of 1200°C - 1300°C for reaction. After washing and drying the reactants, a rare earth modified tungsten carbide core is obtained.

[0013] Preferably, S2 includes the following steps: S21. Add nano tungsten carbide according to the mass ratio, mix the rare earth modified tungsten carbide core and nano tungsten carbide, add water glass, and perform ball milling and mixing in an alcohol medium at a ball-to-material ratio of 5:1 - 8:1. The ball milling speed is 300 r / min - 400 r / min, and the ball milling time is 12 h - 24 h to obtain a composite powder. S22. Put the composite powder into a heating furnace for presintering. The presintering temperature is 300°C - 500°C, and the presintering time is 1 h - 2 h. S23. Raise the temperature of the heating furnace to 1200°C - 1300°C and hold for 1 h - 2 h; then raise the temperature of the heating furnace to 1400°C - 1500°C, apply a pressure of 5 MPa - 10 MPa, and hold for 1 h - 2 h to obtain a sintered body. S24. Crush the sintered body, then perform ball milling and sieving to obtain hard phase particles.

[0014] Preferably, S3 includes the following steps: S31. Weigh Fe, Co, Ni, and Cr powders according to the composition ratio, and mix them evenly by ball milling to obtain a binder powder. S32. Mix and ball mill the binder powder, tungsten carbide, molybdenum carbide, titanium, tantalum, and niobium powders to obtain matrix raw materials. S33. Add the hard phase to the matrix raw materials, mix evenly by ball milling, then press into shape, and sinter in a spark plasma sintering furnace. After cooling, a rare earth modified tungsten carbide alloy blank is obtained. The sintering temperature is 1300°C - 1400°C, the sintering time is 20 min - 30 min, and the sintering pressure is 20 MPa - 40 MPa.

[0015] The advantages and positive effects of the rare earth modified tungsten carbide alloy and its preparation method described in this invention are as follows: 1. In this invention, the core of the rare earth modified tungsten carbide is micron-sized and is composed of tungsten carbide particles with different particle sizes mixed together. Different tungsten carbide particles form a multi-level grain distribution, and initial strengthening is achieved through the "mechanism of grain boundary hindering dislocation movement". The external nano tungsten carbide shell further enhances the surface hardness through the nano effect. The nano-scale grain size significantly increases the grain boundary density, greatly shortening the dislocation slip path, and higher stress is required to initiate plastic deformation, further improving the surface hardness and fracture toughness of the hard phase.

[0016] 2. Rare earth oxides are adsorbed on the WC grain boundaries during the sintering process, reducing the grain boundary energy and inhibiting abnormal grain growth. By adsorbing on the surfaces of nano tungsten carbide and micron tungsten carbide, rare earth oxides reduce the surface energy difference between tungsten carbide particles with different particle sizes, decrease the agglomeration tendency caused by the surface energy gradient, promote the uniform dispersion of particles of different scales, and improve the bonding strength between the core of the rare earth modified tungsten carbide and the nano tungsten carbide shell.

[0017] 3. Molybdenum carbide in the matrix is uniformly distributed as a hard second phase in the tungsten carbide and the binder phase of the matrix. It hinders dislocation movement through the dispersion strengthening mechanism, improving the toughness and hardness of the matrix. Cobalt in the nano tungsten carbide and molybdenum carbide in the matrix form a metallurgical bond through cobalt liquid phase diffusion, promoting atomic diffusion between molybdenum carbide and the hard phase, forming a W-Mo-C-Co solid solution transition layer, improving the bonding strength between the matrix and the hard phase, and reducing the risk of spalling of the hard phase.

[0018] 4. Co and Ni in the binder phase enter the MoC lattice through substitutional diffusion, forming a Co / Ni doped MoC solid solution, enhancing the interfacial metallurgical bond. Cr forms a diffusion barrier, while improving the bonding strength between molybdenum carbide particles and the matrix, ensuring the stability of the binder components in the matrix.

[0019] 5. After the water glass decomposes, uniform micropores with a size not greater than 1 micron are formed on the surface of the nano tungsten carbide shell. When the hard phase combines with the matrix, the binder phase in the matrix infiltrates into the pores through capillary action, forming a "metal pinning" structure. After cooling, a "mechanical interlocking interface" is formed, which is beneficial to improving the bonding strength between the hard phase and the matrix.

[0020] The following further describes the technical solution of this invention in detail through examples. Detailed implementation manners

[0021] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. In case of inconsistency, the meaning described in this specification or the meaning derived from the content recorded in this specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0022] The following will give a detailed description of the implementation manners of the present invention.

[0023] A rare earth modified tungsten carbide alloy includes a hard phase and a matrix. The mass percentage of the hard phase is 80wt.% - 90wt.%, and the mass percentage of the matrix is 10wt.% - 20wt.%. The hard phase is uniformly distributed in the matrix. The hard phase includes a rare earth modified tungsten carbide core, and the outside of the rare earth modified tungsten carbide core is coated with a nano tungsten carbide shell. The mass percentage of the rare earth modified tungsten carbide core in the hard phase is 85wt.% - 95wt.%, and the mass percentage of the nano tungsten carbide shell in the hard phase is 5wt.% - 15wt.%.

[0024] The rare earth modified tungsten carbide core is spherical, and the particle size of the rare earth modified tungsten carbide core is 20μm - 30μm.

[0025] The rare earth modified tungsten carbide core includes the following components by mass percentage: tungsten carbide particles with a particle size of 150nm - 200nm are 15wt.% - 20wt.%, tungsten carbide particles with a particle size of 1.0μm - 1.5μm are 50wt.% - 70wt.%, tungsten carbide particles with a particle size of 3μm - 5μm are 10wt.% - 20wt.%, rare earth oxide is 0.1wt.% - 0.5wt.%, and cobalt powder with a particle size of 1.0μm - 1.5μm is 8wt.% - 10wt.%.

[0026] The particle size of the rare earth oxide is 0.5μm - 1.0μm, and the rare earth oxide is one of cerium oxide and yttrium oxide.

[0027] The particle size of the nano tungsten carbide in the nano tungsten carbide shell is 0.2μm - 0.4μm. The nano tungsten carbide shell includes 90wt.% - 95wt.% nano tungsten carbide, 5wt.% - 10wt.% cobalt, and 1wt.% - 2wt.% sodium silicate.

[0028] In this invention, the rare-earth modified tungsten carbide core is micron-sized and is composed of tungsten carbide particles with different particle sizes mixed together. Different tungsten carbide particles form a multi-level grain distribution, and initial strengthening is achieved through the "mechanism of grain boundary hindering dislocation movement". The external nano-tungsten carbide shell further enhances the surface hardness through the nano effect. The nano-sized grain size significantly increases the grain boundary density, greatly shortening the dislocation slip path, and higher stress is required to initiate plastic deformation, further improving the surface hardness of the hard phase.

[0029] There is a difference in the coefficient of thermal expansion between the nano-tungsten carbide shell and the micron-sized core. The surface effect of nano WC makes its coefficient of thermal expansion slightly higher than that of micron WC. During the cooling process, compressive stress is generated in the shell and tensile stress is generated in the core, forming a residual stress gradient. When the alloy bears an external load, the compressive stress at the interface can offset part of the tensile stress, delaying crack initiation. The high-toughness cobalt phase in the nano shell acts as a "toughness buffer layer" and can absorb the energy of crack propagation, thereby enhancing the impact toughness of the alloy.

[0030] Rare-earth oxides are adsorbed on the WC grain boundaries during the sintering process, reducing the grain boundary energy, inhibiting abnormal grain growth, and at the same time reducing the precipitation of brittle phases at the grain boundaries, enhancing the grain boundary bonding force, and further improving the fracture toughness. In addition, rare-earth oxides are adsorbed on the surfaces of nano-tungsten carbide and micron-tungsten carbide, reducing the surface energy difference between tungsten carbide particles with different particle sizes, reducing the agglomeration tendency caused by the surface energy gradient, and promoting the uniform dispersion of particles of different scales. During the sintering process, rare-earth oxides react with copper sulfate aqueous solution to form a low-melting-point phase, forming a temporary liquid phase, filling the gaps between nano / micron particles, and enhancing the metallurgical bonding between particles through liquid-phase diffusion. The rare-earth oxides on the surface of the core chemically react with the cobalt phase in the nano-tungsten carbide shell during the coating process, forming a rare-earth-cobalt composite interface layer, improving the bonding strength between the nano-tungsten carbide shell and the rare-earth modified tungsten carbide core, and promoting the uniform coating of the nano-tungsten carbide shell on the rare-earth modified tungsten carbide core.

[0031] Excessive rare-earth oxides segregate at the interface to form a "pinning effect". When a crack propagates from the shell to the core, rare-earth oxides can act as a second phase, hindering the linear propagation of the crack, forcing the crack to deflect or branch, consuming more energy, and thus improving the toughness and wear resistance of the tungsten carbide alloy.

[0032] In the hard phase, the outer-layer nano WC has high hardness and preferentially bears abrasive wear; the inner-layer nano / micron composite tungsten carbide core provides support to avoid overall crushing. When the shell wears to a certain extent, the multi-level grain structure of the core continues to play a wear-resistant role, forming a continuous wear-resistant gradient. The micron / nano composite structure of the tungsten carbide core has very good toughness, and the nano-structured shell has a high surface hardness, thus forming a rare-earth modified tungsten carbide hard phase with hard outer and tough inner, which is beneficial to improving the hardness, toughness and wear resistance of the tungsten carbide alloy.

[0033] The matrix comprises tungsten carbide at 80 wt.% - 85 wt.%, molybdenum carbide at 3 wt.% - 5 wt.%, a binder at 10 wt.% - 15 wt.% and an additive at 3 wt.% - 5 wt.%; the particle size of tungsten carbide in the matrix is 2 μm - 3 μm, the particle size of molybdenum carbide is 3 μm - 5 μm, the binder comprises four elements of Fe, Co, Ni, Cr with a molar ratio of 1:1:1:1, and the additive is a mixture of one or more of titanium, tantalum, and niobium.

[0034] Molybdenum carbide has very high hardness. As a hard second phase, molybdenum carbide is uniformly distributed in the tungsten carbide and binder phase of the matrix. Through the dispersion strengthening mechanism, it hinders the movement of dislocations, improving the toughness and hardness of the matrix. The thermal expansion coefficient of molybdenum carbide is between that of tungsten carbide and the binder phase, which can reduce the mismatch of interfacial thermal stress and reduce the generation of microcracks during the cooling process. Molybdenum carbide and tungsten carbide form a dual hard phase system in the matrix, alternately bearing cutting, reducing the wear damage of a single phase, and being beneficial to improving the wear resistance of the tungsten carbide alloy.

[0035] The cobalt on the surface of the core-shell structured hard phase and molybdenum carbide in the matrix form a metallurgical bond through the liquid-phase diffusion of cobalt, promoting the atomic diffusion between molybdenum carbide and the hard phase, forming a W-Mo-C-Co solid solution transition layer, improving the bonding strength between the matrix and the hard phase, and reducing the risk of spalling of the hard phase.

[0036] The binder formed by the four elements of Fe, Co, Ni, Cr is beneficial to improving the wettability between molybdenum carbide and the binder phase, and improving the bonding strength between molybdenum carbide particles and the matrix. The atomic radii of Co and Ni in the binder phase are close to the atomic radius of Mo in the MoC lattice. Through substitutional diffusion, they enter the MoC lattice, forming a Co / Ni-doped MoC solid solution, enhancing the interfacial metallurgical bond. The electron affinity of Cr and Mo is similar. Cr is adsorbed on the interface through electrostatic interaction, forming a Cr-Mo atomic chain at the interface, forming a diffusion barrier, inhibiting the depletion of the binder phase caused by the excessive diffusion of Co and Ni into the interior of MoC, and while improving the bonding strength between molybdenum carbide particles and the matrix, ensuring the stability of the binder components of the matrix.

[0037] A preparation method of a rare-earth modified tungsten carbide alloy comprises the following steps: S1. Prepare a rare-earth modified tungsten carbide core.

[0038] It comprises the following steps: S11. Weigh tungsten carbide particles with a particle size of 150 nm - 200 nm, tungsten carbide particles with a particle size of 1.0 μm - 1.5 μm, tungsten carbide particles with a particle size of 3 μm - 5 μm, and cobalt powder according to the mass ratio, and carry out ball milling and mixing to obtain a tungsten carbide mixed powder. Zirconium balls are used for ball milling, the ball-to-material ratio is 6:1, the ball milling speed is 300 r / min - 400 r / min, and the ball milling time is 12 h - 24 h.

[0039] S12. Weigh rare earth oxides according to the mass ratio, and add the rare earth oxides and the tungsten carbide mixed powder into an aqueous copper sulfate solution with a mass concentration of 15% - 20%, and stir evenly to obtain a mixed solution.

[0040] S13. Feed the mixed solution into an atomizing nozzle for atomization, and the atomized droplets are sprayed into a reaction furnace at a temperature of 1200 °C - 1300 °C for reaction. After the reactants are rinsed and dried, a rare earth-modified tungsten carbide core is obtained.

[0041] S2. Coat a nano tungsten carbide shell on the outside of the rare earth-modified tungsten carbide core to obtain a hard phase.

[0042] It includes the following steps: S21. Add nano tungsten carbide according to the mass ratio, mix the rare earth-modified tungsten carbide core and nano tungsten carbide, add water glass, and carry out ball milling and mixing in an alcohol medium with a ball-to-material ratio of 5:1 - 8:1. The ball milling speed is 300 r / min - 400 r / min, and the ball milling time is 12 h - 24 h to obtain a composite powder.

[0043] Water glass acts as a dispersant in the ball milling stage. By electrostatic repulsion, it prevents the aggregation of nano tungsten carbide, which is beneficial to improving the uniformity of the dispersion between nano tungsten carbide and the rare earth-modified tungsten carbide core.

[0044] S22. Put the composite powder into a heating furnace for pre-sintering. The pre-sintering temperature is 300 °C - 500 °C, and the pre-sintering time is 1 h - 2 h.

[0045] The heating rate of pre-sintering is not greater than 5 °C / min. At a lower heating rate, it is beneficial to the volatilization of alcohol, and sodium silicate decomposes at 300 °C - 500 °C, releasing carbon dioxide gas, forming uniform micropores with a size not greater than 1 μm on the surface of the nano-tungsten carbide shell. When the hard phase combines with the matrix, the binder phase in the matrix infiltrates into the voids through capillary action, forming a "metal pinning" structure. After cooling, a "mechanical interlock interface" is formed, which is beneficial to improving the bonding strength between the hard phase and the matrix. Moreover, it increases the actual contact area between the hard phase and the matrix, which is also beneficial to improving the bonding strength between the hard phase and the matrix. The porosity of the nano-tungsten carbide shell is below 5%. Co and Ni in the binder phase react with nano-tungsten carbide to form a solid solution strengthening layer, which seals the micropores on the nano-tungsten carbide shell.

[0046] S23: Heat the heating furnace to 1200 °C - 1300 °C and keep it warm for 1 h - 2 h; then heat the heating furnace to 1400 °C - 1500 °C, apply a pressure of 5 - 10 MPa, and keep it warm for 1 h - 2 h to obtain a sintered body. The entire sintering process is carried out under the protection of an inert gas.

[0047] S24: Crush the sintered body, ball mill it, and screen it to obtain hard phase particles with a particle size of 25 μm - 35 μm.

[0048] S3: Prepare the matrix raw materials, add the hard phase to the matrix raw materials, mix them evenly, press them into shape and sinter them to obtain a rare earth modified tungsten carbide alloy blank.

[0049] It includes the following steps: S31: Weigh Fe, Co, Ni, and Cr powders according to the component ratio, and mix them evenly by ball milling to obtain a binder powder. The ball-to-material ratio of ball milling is 10:1, the ball milling speed is 300 r / min - 400 r / min, and the ball milling time is 40 h - 50 h.

[0050] S32: Mix and ball mill the binder powder, tungsten carbide, molybdenum carbide, titanium, tantalum, and niobium powders to obtain the matrix raw materials. The ball-to-material ratio of ball milling is 6:1, the ball milling speed is 300 r / min - 400 r / min, and the ball milling time is 12 h - 24 h. After ball milling, dry the matrix raw materials, and the drying conditions are drying in a vacuum drying oven at 60 °C for 12 h - 24 h.

[0051] S33. Add the hard phase to the matrix raw material, ball mill the mixture until uniform, and then press into shape. The ball-to-material ratio during ball milling is 6:1, the ball milling speed is 300-400 rpm, and the ball milling time is 12-24 hours. Sinter the mixture in a spark plasma sintering furnace, and after cooling, obtain a rare earth-modified tungsten carbide alloy blank. Sintering is carried out under inert gas protection at a sintering temperature of 1300-1400°C, a sintering time of 20-30 minutes, and a sintering pressure of 20-40 MPa.

[0052] Pressure sintering is performed during the sintering process, so that the molten binder phase can be fully squeezed and infiltrated into the micropores on the surface of the hard phase. At the same time, the nanocarbide particles undergo plastic deformation to seal the pores of the shell, thereby improving the density of the hard phase and the bonding strength with the matrix.

[0053] S4. Heat-treating the hard tungsten carbide alloy blank to obtain a hard tungsten carbide alloy at a temperature of 1200°C to 1300°C for 4 to 6 hours. The heat treatment causes titanium carbide, niobium carbide, and tantalum carbide to precipitate from the tungsten carbide alloy matrix, thereby improving the hardness, wear resistance, and heat resistance of the tungsten carbide alloy matrix.

[0054] Example 1 A rare earth-modified tungsten carbide alloy comprises a hard phase and a matrix. The hard phase comprises 82% by weight of the matrix and 18% by weight of the matrix. The hard phase is evenly distributed within the matrix. The hard phase comprises a rare earth-modified tungsten carbide core, which is coated with a nano-tungsten carbide shell. The rare earth-modified tungsten carbide core accounts for 90% by weight of the hard phase, while the nano-tungsten carbide shell accounts for 10% by weight of the hard phase.

[0055] The rare earth modified tungsten carbide core includes the following components in mass percentage: 16wt.% of tungsten carbide particles with a particle size of 150nm-200nm, 63.9wt.% of tungsten carbide particles with a particle size of 1.0μm-1.5μm, 12wt.% of tungsten carbide particles with a particle size of 3μm-5μm, 0.1wt.% of rare earth oxide, and 8wt.% of cobalt powder with a particle size of 1.0μm-1.5μm.

[0056] The particle size of the rare earth oxide is 0.5 μm-1.0 μm, and the rare earth oxide is cerium oxide.

[0057] The particle size of the nano-tungsten carbide in the nano-tungsten carbide shell is 0.2 μm-0.4 μm, and the nano-tungsten carbide shell comprises 93 wt.% of nano-tungsten carbide, 6 wt.% of cobalt and 1 wt.% of water glass.

[0058] The matrix comprises 82 wt.% tungsten carbide, 3 wt.% molybdenum carbide, 12 wt.% binder and 3 wt.% additive; the particle size of tungsten carbide in the matrix is 2 μm - 3 μm, the particle size of molybdenum carbide is 3 μm - 5 μm, the binder comprises four elements of Fe, Co, Ni, and Cr with a molar ratio of 1:1:1:1, and the additive is titanium.

[0059] A preparation method of a rare earth modified tungsten carbide alloy comprises the following steps: S1. Prepare a rare earth modified tungsten carbide core.

[0060] It comprises the following steps: S11. Weigh tungsten carbide particles with a particle size of 150 nm - 200 nm, tungsten carbide particles with a particle size of 1.0 μm - 1.5 μm, tungsten carbide particles with a particle size of 3 μm - 5 μm and cobalt powder according to the mass ratio, and carry out ball milling and mixing to obtain a tungsten carbide mixed powder. Zirconia balls are used for ball milling, the ball-to-powder ratio is 6:1, the ball milling speed is 300 r / min, and the ball milling time is 20 h.

[0061] S12. Weigh rare earth oxides according to the mass ratio, add the rare earth oxides and the tungsten carbide mixed powder into an aqueous copper sulfate solution with a mass concentration of 20%, and stir evenly to obtain a mixed solution.

[0062] S13. Feed the mixed solution into an atomizing nozzle for atomization, and spray the atomized droplets into a reaction furnace at a temperature of 1200 °C for reaction. After washing and drying the reactants, a rare earth modified tungsten carbide core is obtained.

[0063] S2. Coat a nano tungsten carbide shell on the outside of the rare earth modified tungsten carbide core to obtain a hard phase.

[0064] It comprises the following steps: S21. Add nano tungsten carbide according to the mass ratio, mix the rare earth modified tungsten carbide core and nano tungsten carbide, add sodium silicate, and carry out ball milling and mixing in an alcohol medium with a ball-to-powder ratio of 6:1. The ball milling speed is 300 r / min, and the ball milling time is 20 h to obtain a composite powder.

[0065] S22. Put the composite powder into a heating furnace for presintering, the presintering temperature is 400 °C, and the presintering time is 2 h.

[0066] S23. Raise the temperature of the heating furnace to 1200 °C and hold for 1 h; then raise the temperature of the heating furnace to 1500 °C, apply a pressure of 8 MPa, and hold for 2 h to obtain a sintered body. The whole sintering process is carried out under the protection of inert gas.

[0067] S24. Crush the sintered body, then carry out ball milling and sieving to obtain hard phase particles with a particle size of 25 μm - 35 μm.

[0068] S3. Prepare a matrix raw material, add the hard phase into the matrix raw material and mix them evenly, press and form them, and then sinter them to obtain a rare earth modified tungsten carbide alloy blank.

[0069] The following steps are involved: S31. Weigh Fe, Co, Ni, and Cr powders according to the composition ratio and mix them uniformly by ball milling to obtain a binder powder. The ball-to-material ratio of the ball milling is 10:1, the ball milling speed is 400 r / min, and the ball milling time is 50 h.

[0070] S32. Mix binder powder, tungsten carbide, molybdenum carbide, titanium, tantalum, and niobium powders and ball mill to obtain a matrix material. The ball-to-material ratio during ball milling is 6:1, the milling speed is 300 r / min, and the milling time is 20 hours. After ball milling, the matrix material is dried in a vacuum drying oven at 60°C for 12 hours.

[0071] S33. Add the hard phase to the matrix raw material, ball mill the mixture until uniform, and then press into shape. The ball-to-material ratio during ball milling is 6:1, the milling speed is 300 rpm, and the milling time is 20 hours. Sinter the mixture in a spark plasma sintering furnace, and after cooling, a rare earth-modified tungsten carbide alloy blank is obtained. Sintering is performed under inert gas protection at a sintering temperature of 1300°C, a sintering time of 20 minutes, and a sintering pressure of 25 MPa.

[0072] S4. Heat-treating the hard tungsten carbide alloy blank to obtain a hard tungsten carbide alloy. The heat-treating temperature is 1200° C. and the heat-treating time is 4 hours.

[0073] Example 2 A rare earth-modified tungsten carbide alloy comprises a hard phase and a matrix. The hard phase comprises 84% by weight of the hard phase and 16% by weight of the matrix. The hard phase is evenly distributed within the matrix. The hard phase comprises a rare earth-modified tungsten carbide core, which is coated with a nano-tungsten carbide shell. The rare earth-modified tungsten carbide core accounts for 90% by weight of the hard phase, while the nano-tungsten carbide shell accounts for 10% by weight of the hard phase.

[0074] The rare earth modified tungsten carbide core includes the following components in mass percentage: 18wt.% of tungsten carbide particles with a particle size of 150nm-200nm, 57.6wt.% of tungsten carbide particles with a particle size of 1.0μm-1.5μm, 15wt.% of tungsten carbide particles with a particle size of 3μm-5μm, 0.4wt.% of rare earth oxide, and 9wt.% of cobalt powder with a particle size of 1.0μm-1.5μm.

[0075] The particle size of the rare earth oxide is 0.5 μm-1.0 μm, and the rare earth oxide is cerium oxide.

[0076] The particle size of tungsten carbide nanoparticles in the tungsten carbide nanoparticle shell is 0.2 μm - 0.4 μm. The tungsten carbide nanoparticle shell comprises 90 wt.% tungsten carbide nanoparticles, 8 wt.% cobalt, and 2 wt.% water glass.

[0077] The substrate comprises 80 wt.% tungsten carbide, 4 wt.% molybdenum carbide, 13 wt.% binder, and 3 wt.% additive; the particle size of tungsten carbide in the substrate is 2 μm - 3 μm, the particle size of molybdenum carbide is 3 μm - 5 μm, the binder comprises four elements of Fe, Co, Ni, and Cr with a molar ratio of 1:1:1:1, and the additive is titanium.

[0078] A preparation method of a rare earth modified tungsten carbide alloy comprises the following steps: S1. Prepare a rare earth modified tungsten carbide core.

[0079] It comprises the following steps: S11. Weigh tungsten carbide particles with a particle size of 150 nm - 200 nm, tungsten carbide particles with a particle size of 1.0 μm - 1.5 μm, tungsten carbide particles with a particle size of 3 μm - 5 μm, and cobalt powder according to the mass ratio, and perform ball milling and mixing to obtain a tungsten carbide mixed powder. The ball milling uses zirconia balls, the ball-to-material ratio is 6:1, the ball milling speed is 300 r / min, and the ball milling time is 20 h.

[0080] S12. Weigh rare earth oxides according to the mass ratio, add the rare earth oxides and the tungsten carbide mixed powder into a copper sulfate aqueous solution with a mass concentration of 20%, and stir evenly to obtain a mixed solution.

[0081] S13. Feed the mixed solution into an atomizing nozzle for atomization, spray the atomized droplets into a reaction furnace at a temperature of 1300 °C for reaction, and after washing and drying the reactants, obtain a rare earth modified tungsten carbide core.

[0082] S2. Coat a tungsten carbide nanoparticle shell on the outside of the rare earth modified tungsten carbide core to obtain a hard phase.

[0083] It comprises the following steps: S21. Add tungsten carbide nanoparticles according to the mass ratio, mix the rare earth modified tungsten carbide core and tungsten carbide nanoparticles, add water glass, and perform ball milling and mixing in an alcohol medium with a ball-to-material ratio of 6:1, a ball milling speed of 300 r / min, and a ball milling time of 20 h to obtain a composite powder.

[0084] S22. Put the composite powder into a heating furnace for presintering, the presintering temperature is 500 °C, and the presintering time is 2 h.

[0085] S23. Heat the furnace to 1300 °C and hold for 2 h; then heat the furnace to 1500 °C, apply a pressure of 10 MPa, and hold for 2 h to obtain a sintered body. The entire sintering process is carried out under the protection of an inert gas.

[0086] S24. Crush the sintered body, ball mill it, and screen it to obtain hard phase particles with a particle size of 25 μm - 35 μm.

[0087] S3. Prepare the matrix raw materials, add the hard phase to the matrix raw materials, mix them evenly, press and sinter them to obtain a rare earth modified tungsten carbide alloy blank.

[0088] It includes the following steps: S31. Weigh Fe, Co, Ni, and Cr powders according to the component ratio, and mix them evenly by ball milling to obtain the binder powder. The ball-to-material ratio of ball milling is 10:1, the ball milling speed is 400 r / min, and the ball milling time is 50 h.

[0089] S32. Mix and ball mill the binder powder, tungsten carbide, molybdenum carbide, titanium, tantalum, and niobium powders to obtain the matrix raw materials. The ball-to-material ratio of ball milling is 6:1, the ball milling speed is 300 r / min, and the ball milling time is 20 h. After ball milling, dry the matrix raw materials. The drying conditions are drying in a vacuum drying oven at 60 °C for 24 h.

[0090] S33. Add the hard phase to the matrix raw materials, ball mill and mix them evenly, and then press and form. The ball-to-material ratio of ball milling is 6:1, the ball milling speed is 300 r / min, and the ball milling time is 20 h. Sinter in a spark plasma sintering furnace, and after cooling, obtain a rare earth modified tungsten carbide alloy blank. The sintering is carried out under the protection of an inert gas. The sintering temperature is 1400 °C, the sintering time is 30 min, and the sintering pressure is 30 MPa.

[0091] S4. Heat-treat the hard tungsten carbide alloy blank to obtain a hard tungsten carbide alloy. The heat treatment temperature is 1200 °C, and the heat treatment time is 5 h.

[0092] Example 3 A rare earth modified tungsten carbide alloy, including a hard phase and a matrix. The mass percentage of the hard phase is 89 wt.%, and the mass percentage of the matrix is 11 wt.%. The hard phase is evenly distributed in the matrix. The hard phase includes a rare earth modified tungsten carbide core, and the outside of the rare earth modified tungsten carbide core is coated with a nano tungsten carbide shell. The mass percentage of the rare earth modified tungsten carbide core in the hard phase is 94 wt.%, and the mass percentage of the nano tungsten carbide shell in the hard phase is 6 wt.%.

[0093] The rare-earth modified tungsten carbide core comprises components in the following mass percentages: tungsten carbide particles with a particle size of 150 nm - 200 nm are 15 wt.%, tungsten carbide particles with a particle size of 1.0 μm - 1.5 μm are 61.8 wt.%, tungsten carbide particles with a particle size of 3 μm - 5 μm are 15 wt.%, rare-earth oxide is 0.2 wt.%, and cobalt powder with a particle size of 1.0 μm - 1.5 μm is 8 wt.%.

[0094] The particle size of the rare-earth oxide is 0.5 μm - 1.0 μm, and the rare-earth oxide is yttrium oxide.

[0095] In the nano tungsten carbide shell, the particle size of the nano tungsten carbide is 0.2 μm - 0.4 μm. The nano tungsten carbide shell comprises 92 wt.% nano tungsten carbide, 6 wt.% cobalt, and 2 wt.% sodium silicate.

[0096] The matrix comprises 82 wt.% tungsten carbide, 3 wt.% molybdenum carbide, 10 wt.% binder, and 5 wt.% additive; the particle size of tungsten carbide in the matrix is 2 μm - 3 μm, the particle size of molybdenum carbide is 3 μm - 5 μm, the binder comprises four elements of Fe, Co, Ni, and Cr with a molar ratio of 1:1:1:1, and the additive is titanium.

[0097] A preparation method of the rare-earth modified tungsten carbide alloy comprises the following steps: S1. Prepare the rare-earth modified tungsten carbide core.

[0098] It comprises the following steps: S11. Weigh tungsten carbide particles with a particle size of 150 nm - 200 nm, tungsten carbide particles with a particle size of 1.0 μm - 1.5 μm, tungsten carbide particles with a particle size of 3 μm - 5 μm, and cobalt powder according to the mass ratio, and perform ball milling and mixing to obtain a tungsten carbide mixed powder. Zirconia balls are used for ball milling, the ball-to-powder ratio is 6:1, the ball milling speed is 300 r / min, and the ball milling time is 20 h.

[0099] S12. Weigh the rare-earth oxide according to the mass ratio, and add the rare-earth oxide and the tungsten carbide mixed powder into a 15% copper sulfate aqueous solution, and stir evenly to obtain a mixed solution.

[0100] S13. Feed the mixed solution into an atomizing nozzle for atomization, and spray the atomized droplets into a reaction furnace at a temperature of 1300 °C for reaction. After washing and drying the reactants, the rare-earth modified tungsten carbide core is obtained.

[0101] S2. Coat a nano tungsten carbide shell on the outside of the rare-earth modified tungsten carbide core to obtain a hard phase.

[0102] It comprises the following steps: S21. Add tungsten carbide nanometer according to the mass ratio, mix the rare earth modified tungsten carbide core with tungsten carbide nanometer, add water glass, and carry out ball milling and mixing in an alcohol medium at a ball-to-material ratio of 6:1. The ball milling speed is 300 r / min, and the ball milling time is 20 h to obtain composite powder.

[0103] S22. Put the composite powder into a heating furnace for presintering. The presintering temperature is 300 °C, and the presintering time is 2 h.

[0104] S23. Heat up the heating furnace to 1300 °C and keep it warm for 2 h; then heat up the heating furnace to 1500 °C, apply a pressure of 10 MPa, and keep it warm for 2 h to obtain a sintered body. The whole sintering process is carried out under the protection of inert gas.

[0105] S24. Crush the sintered body, carry out ball milling and sieving to obtain hard phase particles with a particle size of 25 μm - 35 μm.

[0106] S3. Prepare the matrix raw materials, add the hard phase to the matrix raw materials and mix evenly, press and mold, and then sinter to obtain a rare earth modified tungsten carbide alloy blank.

[0107] It includes the following steps: S31. Weigh Fe, Co, Ni, and Cr powders according to the component ratio, and carry out ball milling and mixing evenly to obtain binder powder. The ball-to-material ratio of ball milling is 10:1, the ball milling speed is 400 r / min, and the ball milling time is 50 h.

[0108] S32. Mix and ball mill the binder powder, tungsten carbide, molybdenum carbide, titanium, tantalum, and niobium powders to obtain matrix raw materials. The ball-to-material ratio of ball milling is 6:1, the ball milling speed is 300 r / min, and the ball milling time is 20 h. After ball milling, dry the matrix raw materials. The drying conditions are drying in a vacuum drying oven at 60 °C for 24 h.

[0109] S33. Add the hard phase to the matrix raw materials, ball mill and mix evenly, and then press and mold. The ball-to-material ratio of ball milling is 6:1, the ball milling speed is 300 r / min, and the ball milling time is 20 h. Sinter in a spark plasma sintering furnace, and after cooling, obtain a rare earth modified tungsten carbide alloy blank. The sintering is carried out under the protection of inert gas. The sintering temperature is 1400 °C, the sintering time is 30 min, and the sintering pressure is 30 MPa.

[0110] S4. Carry out heat treatment on the hard tungsten carbide alloy blank to obtain a hard tungsten carbide alloy. The heat treatment temperature is 1200 °C, and the heat treatment time is 5 h.

[0111] Comparative Example 1 The difference between this comparative example and Example 2 is that in this comparative example, the hard phase only includes a rare earth modified tungsten carbide core, and the outside of the core is not coated with a nano tungsten carbide shell.

[0112] In the preparation method, the preparation process of the nano tungsten carbide shell is omitted.

[0113] Comparative Example 2 The difference between this comparative example and Example 2 is that in this comparative example, the rare earth modified tungsten carbide core only includes tungsten carbide particles with a particle size of 3 μm - 5 μm.

[0114] Comparative Example 3 The difference between this comparative example and Example 2 is that in this comparative example, the rare earth modified tungsten carbide core only includes tungsten carbide particles with a particle size of 150 nm - 200 nm.

[0115] Comparative Example 4 The difference between this comparative example and Example 2 is that in this comparative example, the nano tungsten carbide shell does not contain water glass, and the mass percentage of cobalt is 10 wt.%.

[0116] Comparative Example 5 The difference between this comparative example and Example 2 is that in this comparative example, the matrix does not contain molybdenum carbide, and the mass percentage of tungsten carbide in the matrix is 84 wt.%.

[0117] The Rockwell hardness, fracture toughness, transverse rupture strength, and wear amount of the tungsten carbide alloys prepared in Examples 1 - 3 and Comparative Examples 1 - 5 were detected. The fracture toughness was carried out according to the hard alloy fracture toughness standard ISO28079 - 2009, the hardness was carried out according to GBT3849.1 - 2015 Hard alloy Rockwell hardness (A scale) Part 1: Test method, and the transverse rupture strength was carried out according to GBT3851 - 2015 Determination method for transverse rupture strength of hard alloys. The wear amount calculation was carried out according to Q / 62071126 - 8F0524 - 2014 "Determination method for abrasive wear of hard alloys". The properties of the tungsten carbide alloys prepared in Examples 1 - 3 and Comparative Examples 1 - 5 are shown in Table 1.

[0118] Table 1 Properties of tungsten carbide alloys prepared in Examples 1 - 3 and Comparative Examples 1 - 5 ;

[0119] As can be seen from Table 1, wrapping a nano tungsten carbide shell outside the rare earth modified tungsten carbide core in the tungsten carbide alloy can effectively improve the hardness, fracture toughness, flexural strength and wear resistance of the tungsten carbide alloy; the rare earth modified tungsten carbide core with a micro-nano composite structure, adding molybdenum carbide to the matrix, and adding a proportion of water to the nano tungsten carbide shell are all beneficial to improving the hardness, fracture toughness and flexural strength of the tungsten carbide alloy, and the wear volume is relatively small, which is beneficial to improving the wear resistance of the tungsten carbide alloy.

[0120] Therefore, adopting the rare earth modified tungsten carbide alloy and its preparation method described in the present invention can solve the problems of poor hardness and wear resistance of the existing tungsten carbide alloy, and is beneficial to improving the toughness of the tungsten carbide alloy.

[0121] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that: they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A rare earth modified tungsten carbide alloy, characterized in that: It includes a hard phase and a matrix, the mass percentage of the hard phase is 80wt.%-90wt.%, the mass percentage of the matrix is 10wt.%-20wt.%, and the hard phase is evenly distributed in the matrix; the hard phase includes a rare earth modified tungsten carbide core, the outside of the rare earth modified tungsten carbide core is covered with a nano tungsten carbide shell, the mass percentage of the rare earth modified tungsten carbide core in the hard phase is 85wt.%-95wt.%, and the mass percentage of the nano tungsten carbide shell in the hard phase is 5wt.%-15wt.%.

2. A rare earth modified tungsten carbide alloy according to claim 1, characterized in that: The rare earth modified tungsten carbide core is spherical, and the particle size of the rare earth modified tungsten carbide core is 20 μm-30 μm.

3. A rare earth modified tungsten carbide alloy according to claim 2, characterized in that: The rare earth modified tungsten carbide core includes the following components in mass percentage: 15wt.%-20wt.% of tungsten carbide particles with a particle size of 150nm-200nm, 50wt.%-70wt.% of tungsten carbide particles with a particle size of 1.0μm-1.5μm, 10wt.%-20wt.% of tungsten carbide particles with a particle size of 3μm-5μm, 0.1wt.%-0.5wt.% of rare earth oxide, and 8wt.%-10wt.% of cobalt powder with a particle size of 1.0μm-1.5μm.

4. A rare earth modified tungsten carbide alloy according to claim 3, characterized in that: The particle size of the rare earth oxide is 0.5 μm-1.0 μm, and the rare earth oxide is one of cerium oxide and yttrium oxide.

5. The rare earth modified tungsten carbide alloy according to claim 4, characterized in that: The particle size of the nano-tungsten carbide in the nano-tungsten carbide shell is 0.2 μm-0.4 μm, and the nano-tungsten carbide shell comprises 90 wt.%-95 wt.% of nano-tungsten carbide, 5 wt.%-10 wt.% of cobalt and 1 wt.%-2 wt.% of water glass.

6. The rare earth modified tungsten carbide alloy according to claim 1, characterized in that: The matrix includes 80wt.%-85wt.% of tungsten carbide, 3wt.%-5wt.% of molybdenum carbide, 10wt.%-15wt.% of a binder and 3wt.%-5wt.% of an additive in percentage by mass; the particle size of tungsten carbide in the matrix is 2μm-3μm, the particle size of molybdenum carbide is 3μm-5μm, the binder includes four elements of Fe, Co, Ni and Cr in a molar ratio of 1:1:1:1, and the additive is one or a mixture of several of titanium, tantalum and niobium.

7. The method for preparing a rare earth modified tungsten carbide alloy according to claim 6, characterized in that: The following steps are involved: S1. preparing a rare earth modified tungsten carbide core; S2, coating the outer surface of the rare earth modified tungsten carbide core with a nano-tungsten carbide shell to obtain a hard phase; S3, preparing a matrix raw material, adding the hard phase to the matrix raw material and mixing them evenly, pressing and then sintering to obtain a rare earth modified tungsten carbide alloy blank; S4. Heat-treating the hard tungsten carbide alloy blank to obtain hard tungsten carbide alloy, wherein the heat-treating temperature is 1200° C.-1300° C., and the heat-treating time is 4 hours-6 hours.

8. The method for preparing a rare earth modified tungsten carbide alloy according to claim 7, characterized in that: Said S1 comprises the following steps: S11, weighing tungsten carbide particles with a particle size of 150 nm to 200 nm, tungsten carbide particles with a particle size of 1.0 μm to 1.5 μm, tungsten carbide particles with a particle size of 3 μm to 5 μm, and cobalt powder according to a mass ratio, ball-milling and mixing to obtain a tungsten carbide mixed powder; S12, weighing rare earth oxide according to the mass ratio, adding the rare earth oxide and tungsten carbide mixed powder to a copper sulfate aqueous solution with a mass concentration of 15%-20%, stirring evenly to obtain a mixed solution; S13, sending the mixed liquid into an atomizing nozzle for atomization, spraying the atomized liquid droplets into a reactor with a temperature of 1200° C.-1300° C. for reaction, washing and drying the reactants to obtain a rare earth modified tungsten carbide core.

9. The method for preparing a rare earth modified tungsten carbide alloy according to claim 8, wherein: The S2 comprises the following steps: S21. Add nano-tungsten carbide according to the mass ratio, mix the rare earth modified tungsten carbide core and the nano-tungsten carbide, add water glass, and ball mill the mixture in an alcohol medium at a ball-to-material ratio of 5:1-8:1 at a ball milling speed of 300 rpm to 400 rpm for 12 h to 24 h to obtain a composite powder; S22, placing the composite powder into a heating furnace for pre-sintering at a temperature of 300° C. to 500° C. for a time of 1 h to 2 h; S23, heating the heating furnace to 1200-1300° C. and keeping the temperature for 1-2 hours; then heating the heating furnace to 1400-1500° C., applying a pressure of 5 MPa-10 MPa, and keeping the temperature for 1-2 hours to obtain a sintered body; S24, crushing the sintered body, ball milling, and sieving to obtain hard phase particles.

10. The method for preparing a rare earth modified tungsten carbide alloy according to claim 9, characterized in that: The S3 includes the following steps: S31, weighing Fe, Co, Ni, and Cr powders according to the component ratio, and mixing them uniformly by ball milling to obtain a binder powder; S32, mixing and ball-milling the binder powder, tungsten carbide, molybdenum carbide, titanium, tantalum, and niobium powder to obtain a matrix raw material; S33. Add the hard phase to the matrix raw material, mix evenly by ball milling, press into shape, sinter in a spark plasma sintering furnace, and obtain a rare earth modified tungsten carbide alloy blank after cooling; the sintering temperature is 1300°C-1400°C, the sintering time is 20min-30min, and the sintering pressure is 20MPa-40MPa.