High-specific-gravity tungsten-refractory high-entropy alloy composite material and preparation method thereof

Abstract

The invention relates to the technical field of high-specific-gravity tungsten alloy materials, in particular to a high-specific-gravity tungsten-refractory high-entropy alloy composite material and a preparation method thereof. The specific preparation method comprises the following steps that an iron-nickel phase serves as a binding phase, tungsten powder and refractory high-entropy alloy powder serve as a reinforcing phase, after the tungsten powder, the refractory high-entropy alloy powder, iron powder and nickel powder are subjected to ball milling and mixing, spark plasma sintering is conducted at the temperature of 1100-1300 DEG C, and the iron-nickel phase and the reinforcing phase are formed in the sintering process; and the high-specific-gravity tungsten-refractory high-entropy alloy composite material is prepared. According to the preparation method, a spark plasma sintering process is used, and multiple high-specific-gravity tungsten-refractory high-entropy alloy composite materials with different components, different structures and mechanical properties are prepared by changing the components and sintering process parameters of the multi-principal-element tungsten alloy; the problem that the head of an armor-piercing shell core material prepared from an existing high-specific-gravity tungsten alloy material is prone to passivation in the penetration process is solved.

Description

Technical Field

[0001] The invention relates to the technical field of high-density tungsten alloy materials, and in particular to a high-density tungsten-refractory high-entropy alloy composite material and a preparation method thereof. Background Art

[0002] At present, tungsten alloy has good properties such as high strength, high density, good corrosion resistance and oxidation resistance, and is widely used in the fields of aviation, aerospace, military industry and electronic industry. In particular, high-density tungsten alloy can be used as the core material of armor-piercing projectiles in the military field.

[0003] High-density tungsten alloys are mainly based on tungsten as the matrix, and a small amount of nickel, iron, cobalt and other elements are added to the tungsten matrix to form a high-density two-phase alloy. For example, a high-density tungsten alloy material currently under study is mainly prepared by liquid phase sintering of reduced tungsten powder, nickel powder, iron powder and reduced cobalt powder. However, when the obtained high-density tungsten alloy material is used to prepare the core material of armor-piercing projectiles, since the high-density tungsten alloy material is adiabatic shear-insensitive material, thermoplastic softening occurs first during high-speed penetration, and the core head forms a mushroom head shape, and then an adiabatic shear band appears, resulting in a large penetration resistance, and the tungsten alloy is easily passivated during the penetration process, thereby greatly reducing its armor-piercing performance. Summary of the invention

[0004] In order to solve the problem that the head of the armor-piercing projectile core material prepared from the existing high-density tungsten alloy material is easily passivated during the penetration process, the purpose of the present invention is to provide a high-density tungsten-refractory high-entropy alloy composite material and a preparation method thereof.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows.

[0006] The first aspect of the present invention provides a method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material, comprising the following steps:

[0007] With iron powder and nickel powder as a binder phase, with tungsten powder and refractory high entropy alloy powder as a reinforcement phase, tungsten powder, refractory high entropy alloy powder, iron powder and nickel powder are mixed by ball milling, and then spark plasma sintering is performed at 1100° C. to 1300° C. to prepare a high-density tungsten-refractory high entropy alloy composite material; in terms of volume fraction, the high-density tungsten-refractory high entropy alloy composite material is prepared from the following raw materials:

[0008] Tungsten powder 62% to 85%, refractory high entropy alloy powder 10% to 25%, mixed powder of iron powder and nickel powder 5% to 20%, totaling 100%.

[0009] The present invention mainly adjusts the ratio of the refractory high entropy alloy reinforcement phase and the iron-nickel bonding phase, combines the spark plasma sintering process, forms the iron-nickel phase and the reinforcement phase during the sintering process, and prepares a high-density tungsten-refractory high entropy alloy composite material with good performance. The present invention improves the density of the high-density tungsten-refractory high entropy alloy composite material while improving the compressive strength and compression strain, so that the actual density of the composite material exceeds 15g / cm 3 , the density is over 98%, the compressive strength is close to 2.5Gpa, and the compressive strain is over 25%.

[0010] Preferably, the refractory high entropy alloy powder is composed of at least four elements of W, Mo, Ta, Nb, Hf, Zr, Ti, V, Fe, and Ni.

[0011] Preferably, the refractory high entropy alloy powder is obtained by mixing powders of at least four elements of W, Mo, Ta, Nb, Hf, Zr, Ti, V, Fe, and Ni in an equimolar ratio, arc melting into alloy button ingots, hydrogenating and crushing the alloy button ingots, and then plasma spheroidizing.

[0012] Preferably, the high specific gravity tungsten-refractory high entropy alloy composite material is prepared from the following raw materials, measured by volume fraction:

[0013] Tungsten powder 62% to 65%, refractory high entropy alloy powder 15% to 20%, mixed powder of iron powder and nickel powder 15% to 20%, totaling 100%.

[0014] The present invention can help improve the density of the high-density tungsten-refractory high-entropy alloy composite material by adjusting the proportion of each raw material, especially adjusting the mixed powder of iron powder and nickel powder within the range of 15% to 20%.

[0015] Preferably, the ratio of balls to materials in the ball milling is 3 to 10: 1. The ratio of balls to materials in the ball milling can be adjusted according to actual mixing conditions.

[0016] Preferably, the speed of the ball milling is 200 r / min to 300 r / min, and the time of the ball milling is 8 h to 16 h. The speed and time of the ball milling can be adjusted according to the actual mixing conditions.

[0017] Preferably, the sintering pressure of the spark plasma sintering is 5 MPa to 40 MPa.

[0018] Preferably, the sintering procedure of the spark plasma sintering is: under vacuum conditions, heating to 1000°C at a heating rate of 100°C / min, heating to 1100°C-1300°C at a heating rate of 50°C / min, and then keeping at 1100°C-1300°C for 5min-10min.

[0019] Preferably, the sintering temperature of the spark plasma sintering is 1200°C to 1250°C.

[0020] The present invention helps to study the influence of sintering temperature on the organization, mechanical properties and sintering density of spark plasma sintering samples by adjusting the sintering temperature of spark plasma sintering. A high sintering temperature will increase the density of the sintered sample and improve the mechanical properties of the material, but an excessively high sintering temperature will cause the sample to overflow during the sintering process. Similarly, a low sintering temperature will cause the interstitial phase to not be completely melted during the sintering process, thereby increasing the number of pores in the sintered sample, reducing the density of the sample, and further affecting the organization and mechanical properties of the sintered sample.

[0021] The second aspect of the present invention provides a high specific gravity tungsten-refractory high entropy alloy composite material, which is prepared by the preparation method described in the first aspect.

[0022] The present invention uses a spark plasma sintering process to prepare a variety of high-density tungsten-refractory high-entropy alloy composite materials with different compositions, structures and mechanical properties by changing the composition of multiple main component tungsten alloys and sintering process parameters.

[0023] Preferably, the high-density tungsten-refractory high-entropy alloy composite material has a density of 96.8% to 99.3%, a compressive strength of 2501 MPa to 3050 MPa, and a compressive strain of 27% to 37%.

[0024] Beneficial effects of the present invention:

[0025] 1. The present invention uses a spark plasma sintering process to prepare a variety of high-density tungsten-refractory high-entropy alloy composite materials with different compositions, structures and mechanical properties by changing the composition of multiple main tungsten alloys and sintering process parameters.

[0026] 2. The high-density tungsten-refractory high-entropy alloy composite material prepared by the present invention has excellent mechanical properties, and its actual measured density exceeds 15g / cm 3 The lowest density can reach more than 97%, and the highest density can reach more than 99%. The highest compressive strength exceeds 3Gpa, and the highest compression strain can reach more than 35%.

[0027] 3. The preparation process of the present invention is easy to operate, the material sintering time is short, the molding effect is good, the material density is high, and it is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is a macroscopic picture of the high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 1.

[0029] Figure 2This is the microstructure morphology of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 1.

[0030] Figure 3 This is the compressive stress-strain curve of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 1.

[0031] Figure 4 This is the microstructure morphology of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 2.

[0032] Figure 5 This is the microstructure morphology of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 3.

[0033] Figure 6 This is the compressive stress-strain curve of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 3.

[0034] Figure 7 This is the microstructure morphology of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 4. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0036] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making any creative work shall fall within the scope of protection of the present invention.

[0037] A high-density tungsten alloy material currently under study is mainly prepared by liquid phase sintering of reduced tungsten powder, nickel powder, iron powder and reduced cobalt powder. However, when the obtained high-density tungsten alloy material is used to prepare the core material of armor-piercing projectiles, since the high-density tungsten alloy material is adiabatic shear-insensitive material, it first undergoes thermoplastic softening during high-speed penetration, and the core head forms a mushroom head shape, and then an adiabatic shear band appears, resulting in greater penetration resistance, and the tungsten alloy is easily passivated during the penetration process, thus greatly reducing its armor-piercing performance.

[0038] As a multi-principal alloy, refractory high-entropy alloy breaks through the design concept of single principal element of traditional alloys, and embodies excellent properties different from traditional alloys, especially in extreme environments such as high temperature, high pressure, and high strain rate. The emergence of high-entropy alloys breaks the design concept of single principal element composition of traditional alloys based on mixing enthalpy. Multi-principal high-entropy alloys have the characteristics of high entropy value, severe lattice distortion, and hysteresis diffusion, which can promote the formation of simple solid solutions, thereby obtaining simple solid solution phases such as BCC, FCC or HCP with excellent performance, or multi-phase structures, with excellent comprehensive properties including high strength, high hardness, good plasticity, wear resistance and corrosion resistance, and because of its self-sharpening and energy release characteristics, it has broad application prospects in the military field.

[0039] Based on this, in order to solve the problem that the head of the armor-piercing projectile core material prepared from the existing high-density tungsten alloy material is easily passivated during the penetration process, the present invention aims to compound a refractory high-entropy alloy with a high-density tungsten alloy, and utilize the properties of the refractory high-entropy alloy to improve the problem that the high-density tungsten alloy is easily passivated during the penetration process.

[0040] Spark Plasma Sintering, or SPS for short, is an advanced material processing technology mainly used in the field of powder metallurgy. It combines the advantages of traditional hot pressing sintering and discharge machining technology, and can quickly and efficiently sinter metal or ceramic powders directly into dense solid materials. In the SPS process, the powder material is loaded into a mold made of a conductive material, such as graphite. Two electrodes in contact with the mold apply pressure to the powder and pass a high-voltage pulse current in a short time. When the current passes through the powder, it will generate resistance heating between the particles, resulting in local high temperature, which will cause the particles to bond and eventually form a dense solid material. Since the heating is concentrated at the contact point of the particles, the heating efficiency is very high. Spark plasma sintering has a series of advantages, such as fast heating speed, short sintering time, controllable organizational structure, energy saving and environmental protection. The advantages of spark plasma sintering technology can make up for the shortcomings of traditional powder metallurgy sintering technology, and it is an effective way to further improve and improve the performance of tungsten alloys.

[0041] The technical solution of the present invention is further described below through specific embodiments.

[0042] In the following examples, the methods described are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0043] Tungsten powder, specification: 15-53μm / 1-3μm, Beijing Yanbang New Material Technology Co., Ltd.

[0044] Iron powder, specification: <10μm, Beijing Yanbang New Material Technology Co., Ltd.

[0045] Nickel powder, specification: <10μm, Beijing Yanbang New Material Technology Co., Ltd.

[0046] WMoTaNb alloy powder, WMoTaNbTi alloy powder, WMoTaNbV alloy powder, specification: 15μm~53μm, Beijing Yanbang New Material Technology Co., Ltd.

[0047] The WMoTaNb alloy powder is prepared by mixing W, Mo, Ta and Nb in equal molar ratios, arc melting into WMoTaNb alloy button ingots, hydrogenation crushing of the WMoTaNb alloy button ingots, and plasma spheroidization to obtain the WMoTaNb alloy powder.

[0048] The WMoTaNbTi alloy powder is prepared by mixing W, Mo, Ta, Nb and Ti in equal molar ratios, arc melting into WMoTaNbTi alloy button ingots, hydrogenation crushing of the WMoTaNbTi alloy button ingots, and plasma spheroidization to obtain the WMoTaNbTi alloy powder.

[0049] The WMoTaNbV alloy powder is prepared by mixing W, Mo, Ta, Nb and V in equal molar ratios, arc melting into WMoTaNbV alloy button ingots, hydrogenation crushing of the WMoTaNbV alloy button ingots, and plasma spheroidization to obtain the WMoTaNbV alloy powder.

[0050] In the following embodiments, the mass ratio of iron powder to nickel powder is 1:2, and the volume ratio of iron powder to nickel powder is about 1:1.77. The volume ratio and volume fraction here are the volumes calculated after the components are fully densified.

[0051] Example 1

[0052] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0053] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, using tungsten powder with a particle size of 15μm to 53μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNb alloy powder with a particle size of 15μm to 53μm.

[0054] According to the volume fraction of tungsten powder of 62%, the volume fraction of iron powder and nickel powder of 18%, and the volume fraction of WMoTaNb alloy powder of 20%, totaling 100%, the weight of each raw material was determined, and each raw material was weighed. The purity of each raw material used was ≥99.9%.

[0055] Pour the weighed raw materials into a 500 mL nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the ball-to-material ratio of 3:1 according to the total weight of the raw materials. Fix the nylon ball milling jar to the planetary ball mill and ball mill at a speed of 300 r / min for 8 hours. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain the mixed powder for sintering.

[0056] Step 2, sintering: Use a graphite mold with a diameter of 42 mm as the sintering mold, spray a high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 80g of mixed powder for sintering into the graphite mold; wrap the contact surface between the mixed powder for sintering and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0057] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 30 MPa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1200℃ with a heating rate of 50℃ / min, and kept at 1200℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0058] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 1 was used as sample 1, and photographed, the microstructure morphology was observed, and the compressive stress-strain curve was tested.

[0059] The photo of the high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 1 is shown in Figure 1 The diameter of sample 1 is measured to be 42 mm. The density of sample 1 is measured by Archimedes drainage method to be 16.04 g / cm 3 , the theoretical density is 16.2g / cm 3 , the density of sample 1 is calculated to be 99%.

[0060] The microstructure of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 1 is as follows: Figure 2 As shown. Figure 2 It can be seen that in the microstructure of sample 1, the white particles are tungsten particles, the spherical particles are WMoTaNb alloy powder, and the gray phase is FeNi phase.

[0061] The compressive stress-strain curve of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 1 is as follows: Figure 3 As shown. Two samples 1 are tested separately and the test results are averaged. Figure 3 It can be seen that Sample 1 has a compressive strength of 2501 MPa and a compressive strain of 27%.

[0062] Example 2

[0063] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0064] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, using tungsten powder with a particle size of 15μm to 53μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNbTi alloy powder with a particle size of 15μm to 53μm.

[0065] According to the volume fraction of tungsten powder of 62%, the volume fraction of iron powder and nickel powder of 18%, and the volume fraction of WMoTaNbTi alloy powder of 20%, totaling 100%, the weight of each raw material was determined, and each raw material was weighed. The purity of each raw material used was ≥99.9%.

[0066] Pour the weighed raw materials into a 500 mL nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the ball-to-material ratio of 4:1 according to the total weight of the raw materials. Fix the nylon ball milling jar to the planetary ball mill and mill at a speed of 250 r / min for 10 hours. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain the mixed powder for sintering.

[0067] Step 2, sintering: Use a graphite mold with a diameter of 30 mm as the sintering mold, spray a high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 55g of mixed powder for sintering into the graphite mold; wrap the contact surface between the mixed powder for sintering and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0068] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 30 MPa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1200℃ with a heating rate of 50℃ / min, and kept at 1200℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0069] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 2 was used as sample 2, and photographed and its microstructure was observed.

[0070] The microstructure of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering in Example 2 is as follows: Figure 4 As shown. The diameter of sample 2 is measured to be 30 mm. The density of sample 2 is measured to be 98.5% according to the Archimedean drainage method. In the microstructure of sample 2, the white particles are tungsten particles, the spherical particles are WMoTaNbTi alloy powder, and the gray phase is FeNi phase.

[0071] Example 3

[0072] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0073] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, using tungsten powder with a particle size of 1μm to 3μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNbV alloy powder with a particle size of 15μm to 53μm.

[0074] According to the volume fraction of tungsten powder of 62%, the volume fraction of iron powder and nickel powder of 18%, and the volume fraction of WMoTaNbV alloy powder of 20%, totaling 100%, the weight of each raw material was determined, and each raw material was weighed. The purity of each raw material used was ≥99.9%.

[0075] Pour the weighed raw materials into a 500 mL nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the total weight of the raw materials at a ball-to-material ratio of 4:1. Fix the nylon ball milling jar to a planetary ball mill and mill at a speed of 200 r / min for 16 hours. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain a mixed powder for sintering.

[0076] Step 2, sintering: Use a graphite mold with a diameter of 30 mm as the sintering mold, spray a high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 55g of mixed sintering powder into the graphite mold; wrap the contact surface between the mixed sintering powder and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0077] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 5 MPa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1250℃ with a heating rate of 50℃ / min, and kept at 1250℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0078] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 3 was used as Sample 3, and photographed, the microstructure morphology was observed, and the compressive stress-strain curve was tested.

[0079] The microstructure of the high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 3 is as follows: Figure 5 As shown. The diameter of sample 3 is measured to be 30 mm. The density of sample 3 is measured by Archimedes drainage method to be 97.9%. Figure 5It can be seen that in the microstructure of sample 3, the white particles are tungsten particles, the spherical particles are WMoTaNbV alloy powder, and the gray phase is FeNi phase.

[0080] The compressive stress-strain curve of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering is as follows: Figure 6 As shown. Figure 6 It can be seen that Sample 3 has a compressive strength of 3050 MPa and a compressive strain of 37%.

[0081] Example 4

[0082] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0083] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, using tungsten powder with a particle size of 15μm to 53μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNbTi alloy powder with a particle size of 15μm to 53μm.

[0084] According to the mass fraction volume of tungsten powder of 70%, the mass fraction volume of iron powder and nickel powder of 10%, and the volume fraction of WMoTaNbTi alloy powder of 20%, totaling 100%, the weight of each raw material was determined, and each raw material was weighed. The purity of each raw material used was ≥99.9%.

[0085] Pour the weighed raw materials into a 500 mL nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the ball-to-material ratio of 4:1 according to the total weight of the raw materials. Fix the nylon ball milling jar to the planetary ball mill and mill at a speed of 250 r / min for 10 hours. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain the mixed powder for sintering.

[0086] Step 2, sintering: Use a graphite mold with a diameter of 30 mm as the sintering mold, spray high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 55g of mixed powder for sintering into the graphite mold; wrap the contact surface between the mixed powder for sintering and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0087] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 40Mpa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1200℃ with a heating rate of 50℃ / min, and kept at 1200℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0088] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 4 was used as sample 4, and photographed and its microstructure was observed.

[0089] The diameter of sample 4 was measured to be 30 mm, and the density of sample 4 was measured by the Archimedes drainage method to be only 87%.

[0090] The microstructure of the high-density tungsten-refractory high-entropy alloy composite material prepared by sintering is as follows: Figure 7 As shown. Figure 7 It can be seen that the surface of sample 4 has many holes, resulting in low density. By comparing sample 2 of Example 2, it can be found that, under the condition that other conditions remain constant, reducing the content of FeNi can reduce the density of the high-density tungsten-refractory high-entropy alloy composite material.

[0091] Example 5

[0092] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0093] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, using tungsten powder with a particle size of 15μm to 53μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNb alloy powder with a particle size of 15μm to 53μm.

[0094] According to the volume fraction of tungsten powder 72%, iron powder and nickel powder 18%, WMoTaNb alloy powder 10%, totaling 100%, the weight of each raw material was determined, and each raw material was weighed. The purity of each raw material used was ≥99.9%.

[0095] Pour the weighed raw materials into a 500ml nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the total weight of the raw materials and the ball-to-material ratio of 3:1. Fix the nylon ball milling jar to the planetary ball mill and mill at a speed of 250r / min for 10h. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain the mixed powder for sintering.

[0096] Step 2, sintering: Use a graphite mold with a diameter of 42 mm as the sintering mold, spray high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 80g of mixed powder for sintering into the graphite mold; wrap the contact surface between the mixed powder for sintering and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0097] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 30 MPa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1200℃ with a heating rate of 50℃ / min, and kept at 1200℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0098] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 5 was used as Sample 5, and the diameter of Sample 5 was measured to be 42 mm. The density of Sample 5 was measured by the Archimedean drainage method to be 96.8%.

[0099] Example 6

[0100] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0101] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, using tungsten powder with a particle size of 15μm to 53μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNb alloy powder with a particle size of 15μm to 53μm.

[0102] According to the volume fraction of tungsten powder 85%, iron powder and nickel powder 5%, WMoTaNb alloy powder 10%, totaling 100%, the weight of each raw material was determined, and each raw material was weighed. The purity of each raw material used was ≥99.9%.

[0103] Pour the weighed raw materials into a 500ml nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the total weight of the raw materials and the ball-to-material ratio of 3:1. Fix the nylon ball milling jar to the planetary ball mill and mill at a speed of 250r / min for 10h. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain the mixed powder for sintering.

[0104] Step 2, sintering: Use a graphite mold with a diameter of 42 mm as the sintering mold, spray high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 80g of mixed powder for sintering into the graphite mold; wrap the contact surface between the mixed powder for sintering and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0105] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 30 MPa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1250℃ with a heating rate of 50℃ / min, and kept at 1250℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0106] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 6 is used as Sample 6, and the diameter of Sample 6 is measured to be 42 mm. The density of Sample 6 is measured by the Archimedean drainage method to be 72%.

[0107] Example 7

[0108] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0109] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, using tungsten powder with a particle size of 15μm to 53μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNb alloy powder with a particle size of 15μm to 53μm.

[0110] According to the volume fraction of tungsten powder 65%, iron powder and nickel powder 20%, WMoTaNb alloy powder 15%, totaling 100%, the weight of each raw material was determined, and each raw material was weighed. The purity of each raw material used was ≥99.9%.

[0111] Pour the weighed raw materials into a 500ml nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the total weight of the raw materials and the ball-to-material ratio of 3:1. Fix the nylon ball milling jar to the planetary ball mill and mill at a speed of 250r / min for 10h. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain the mixed powder for sintering.

[0112] Step 2, sintering: Use a graphite mold with a diameter of 42 mm as the sintering mold, spray high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 80g of mixed powder for sintering into the graphite mold; wrap the contact surface between the mixed powder for sintering and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0113] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 30 MPa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1100℃ with a heating rate of 50℃ / min, and kept at 1100℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0114] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 7 was used as Sample 7, and the diameter of Sample 7 was measured to be 42 mm. The density of Sample 7 was measured by the Archimedean drainage method to be 99.3%.

[0115] Example 8

[0116] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0117] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, using tungsten powder with a particle size of 15μm to 53μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNb alloy powder with a particle size of 15μm to 53μm.

[0118] According to the volume fraction of tungsten powder 65%, iron powder and nickel powder 10%, WMoTaNb alloy powder 25%, totaling 100%, after determining the weight of each raw material, each raw material was weighed, and the purity of each raw material used was ≥99.9%.

[0119] Pour the weighed raw materials into a 500ml nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the total weight of the raw materials and the ball-to-material ratio of 3:1. Fix the nylon ball milling jar to the planetary ball mill and mill at a speed of 250r / min for 10h. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain the mixed powder for sintering.

[0120] Step 2, sintering: Use a graphite mold with a diameter of 42 mm as the sintering mold, spray high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 80g of mixed powder for sintering into the graphite mold; wrap the contact surface between the mixed powder for sintering and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0121] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 30 MPa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1300℃ with a heating rate of 50℃ / min, and kept at 1300℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0122] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering in Example 8 was used as Sample 8, and the diameter of Sample 8 was measured to be 42 mm. The density of Sample 8 was measured by the Archimedean drainage method to be 88.1%.

[0123] Example 9

[0124] A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material comprises the following steps:

[0125] Step 1, prepare mixed powder for sintering: first design the composition of high specific gravity tungsten-refractory high entropy alloy composite material, use tungsten powder with a particle size of 15μm to 53μm, iron powder with a particle size of less than 10μm, nickel powder with a particle size of less than 10μm and WMoTaNbV alloy powder with a particle size of 15μm to 53μm.

[0126] According to the volume fraction of tungsten powder of 62%, the volume fraction of iron powder and nickel powder of 18%, and the volume fraction of WMoTaNbV alloy powder of 20%, totaling 100%, the weight of each raw material was determined, and each raw material was weighed. The purity of each raw material used was ≥99.9%.

[0127] Pour the weighed raw materials into a 500 mL nylon ball milling jar, and add the corresponding weight of zirconia ball milling beads according to the total weight of the raw materials at a ball-to-material ratio of 4:1. Fix the nylon ball milling jar to a planetary ball mill and mill at a speed of 200 r / min for 16 hours. After the ball milling is completed, use a sieve to sieve out the ball-milled mixed powder to obtain a mixed powder for sintering.

[0128] Step 2, sintering: Use a graphite mold with a diameter of 30 mm as the sintering mold, spray a high-temperature boron nitride release agent on the pressure head and inner wall of the sintering mold. Pour 55g of mixed sintering powder into the graphite mold; wrap the contact surface between the mixed sintering powder and the graphite mold with carbon paper, and wrap the outside of the graphite mold with carbon felt to improve the thermal insulation effect of the graphite mold.

[0129] The graphite mold containing the mixed powder for sintering was placed in a spark plasma sintering furnace, and then vacuumed for 15 minutes, applied a pressure of 5 MPa, and set the sintering program: 0℃~1000℃ with a heating rate of 100℃ / min, 1000℃~1250℃ with a heating rate of 50℃ / min, and kept at 1250℃ for 10 minutes before sintering. After sintering, the furnace was cooled, the furnace door was opened to take samples, and demolding was performed to obtain a high-density tungsten-refractory high-entropy alloy composite material.

[0130] The high specific gravity tungsten-refractory high entropy alloy composite material prepared by sintering Example 9 is used as Sample 9. The diameter of Sample 9 is measured to be 30 mm. The density of Sample 9 is measured to be 97.5% according to the Archimedes drainage method. Sample 9 is measured to have a compressive strength of 2845 MPa and a compressive strain of 24.1%.

[0131] The high specific gravity tungsten-refractory high entropy alloy composite materials prepared by sintering Examples 1 to 9 are respectively used as Sample 1, Sample 2, Sample 3, Sample 4, Sample 5, Sample 6, Sample 7, Sample 8 and Sample 9; the amount of raw materials used to prepare Samples 1 to 9 is compared in Table 1. The particle size comparison of the raw materials used to prepare Samples 1 to 9 is shown in Table 2.

[0132] Table 1 Comparison of the amount of raw materials used in preparing samples 1 to 9

[0133]

[0134]

[0135] Table 2 Comparison of particle sizes of raw materials used to prepare samples 1 to 8

[0136] Example Tungsten powder Iron powder and nickel powder Refractory high entropy alloy powder Sample Example 1 15μm~53μm <10μm 15μm~53μm Sample 1 Example 2 15μm~53μm <10μm 15μm~53μm Sample 2 Example 3 1μm~3μm <10μm 15μm~53μm Sample 3 Example 4 15μm~53μm <10μm 15μm~53μm Sample 4 Example 5 15μm~53μm <10μm 15μm~53μm Sample 5 Example 6 15μm~53μm <10μm 15μm~53μm Sample 6 Example 7 15μm~53μm <10μm 15μm~53μm Sample 7 Example 8 15μm~53μm <10μm 15μm~53μm Sample 8 Example 9 15μm~53μm <10μm 15μm~53μm Sample 9

[0137] Note: The refractory high entropy alloy powder of Sample 1 and Samples 5 to 8 is WMoTaNb alloy powder; the refractory high entropy alloy powder of Sample 2 and Sample 4 is WMoTaNbTi alloy powder; the refractory high entropy alloy powder of Sample 3 and Sample 9 is WMoTaNbV alloy powder.

[0138] Density calculation and mechanical property test were performed on samples 1 to 9, and the results are shown in Table 3.

[0139] Table 3 Density and mechanical properties test results of samples 1 to 8

[0140] Sample diameter Density Compressive strength Compression strain Sample 1 42mm 99％ 2501MPa 27％ Sample 2 30mm 98.5％ 2931MPa 21％ Sample 3 30mm 97.9％ 3050MPa 37％ Sample 4 30mm 87％ 2447MPa 12％ Sample 5 42mm 96.8％ 2200MPa 22％ Sample 6 42mm 72％ 1822MPa 9％ Sample 7 42mm 99.3％ 2213MPa 31％ Sample 8 42mm 88.1％ 2203MPa 13％ Sample 9 30mm 97.5％ 2845MPa 24.1％

[0141] -Note: “-” means not tested.

[0142] From the analysis of Tables 1 to 3, it can be seen that with the decrease of the content of iron powder and nickel powder, the density of the sample is significantly reduced. When the volume fraction of iron powder and nickel powder is 15% to 20%, the density of the sample is above 96%; when the volume fraction of iron powder and nickel powder is 10%, the density of the sample is 87% to 88.1%; when the volume fraction of iron powder and nickel powder is less than 10%, the density of the sample is 72%. It can be seen that the content of iron powder and nickel powder can affect the density of the prepared sample.

[0143] The refractory high entropy alloy powder, as a reinforcing phase of the composite material, will directly affect the strength of the sample. By comparing Example 1 with Example 5, it can be seen that under the same conditions, as the WMoTaNb content increases, the compressive strength of the sample increases and the compressive strain decreases.

[0144] From the comparison between Example 1 and Example 9, it can be seen that, under the same conditions, as the particle size of tungsten powder decreases, the compressive strength and compressive strain increase. It can be seen that the particle size of tungsten powder can affect the mechanical properties of the prepared sample.

[0145] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a high specific gravity tungsten-refractory high entropy alloy composite material, characterized in that: The following steps are involved: Using iron powder and nickel powder as a binder phase, and tungsten powder and refractory high entropy alloy powder as a reinforcement phase, tungsten powder, refractory high entropy alloy powder, iron powder and nickel powder are mixed by ball milling, and then spark plasma sintering is performed at 1100°C to 1300°C to prepare a high-density tungsten-refractory high entropy alloy composite material; The high specific gravity tungsten-refractory high entropy alloy composite material is prepared from the following raw materials by volume fraction: Tungsten powder 62% to 85%, refractory high entropy alloy powder 10% to 25%, mixed powder of iron powder and nickel powder 5% to 20%, totaling 100%.

2. The method for preparing the high-density tungsten-refractory high-entropy alloy composite material according to claim 1, characterized in that: The refractory high entropy alloy powder is composed of at least four elements of W, Mo, Ta, Nb, Hf, Zr, Ti, V, Fe and Ni.

3. The method for preparing the high-density tungsten-refractory high-entropy alloy composite material according to claim 2, characterized in that: The refractory high entropy alloy powder is obtained by mixing powders of at least four elements of W, Mo, Ta, Nb, Hf, Zr, Ti, V, Fe and Ni in an equal molar ratio, arc melting into alloy button ingots, hydrogenating and crushing the alloy button ingots, and then plasma spheroidizing them.

4. The method for preparing the high-density tungsten-refractory high-entropy alloy composite material according to claim 1, characterized in that: The high specific gravity tungsten-refractory high entropy alloy composite material is prepared from the following raw materials by volume fraction: Tungsten powder 62% to 65%, refractory high entropy alloy powder 15% to 20%, mixed powder of iron powder and nickel powder 15% to 20%, totaling 100%.

5. The method for preparing the high-density tungsten-refractory high-entropy alloy composite material according to claim 1, characterized in that: The ball-to-material ratio of the ball milling mixture is 3 to 10:

1.

6. The method for preparing the high-density tungsten-refractory high-entropy alloy composite material according to claim 1, characterized in that: The rotation speed of the ball milling mixing is 200 r / min to 300 r / min, and the time of the ball milling mixing is 8 h to 16 h.

7. The method for preparing the high-density tungsten-refractory high-entropy alloy composite material according to claim 1, characterized in that: The sintering pressure of the spark plasma sintering is 5MPa to 40MPa.

8. The method for preparing the high-density tungsten-refractory high-entropy alloy composite material according to claim 1, characterized in that: The sintering procedure of the spark plasma sintering is: under vacuum conditions, heating to 1000°C at a heating rate of 100°C / min, heating to 1100°C-1300°C at a heating rate of 50°C / min, and then keeping at 1100°C-1300°C for 5min-10min.

9. A high specific gravity tungsten-refractory high entropy alloy composite material, characterized in that: The preparation method is described in any one of claims 1 to 8.

10. The high-density tungsten-refractory high-entropy alloy composite material according to claim 9, characterized in that: The high-density tungsten-refractory high-entropy alloy composite material has a density of 96.8% to 99.3%, a compressive strength of 2501 MPa to 3050 MPa, and a compressive strain of 27% to 37%.

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