Preparation method of high-strength tungsten alloy

Abstract

The invention discloses a preparation method of a high-strength tungsten alloy, and belongs to the technical field of powder metallurgy. In the method, an upper-layer solid solution element, a lower-layer solid solution element, solid lubricating powder and activated powder with a preset particle size ratio are selected to be uniformly mixed with tungsten powder through ball milling according to a target mass fraction ratio, and then vacuum pressing, vacuum low-temperature sintering, vacuum heat preservation treatment, spark plasma sintering, low-temperature annealing treatment and cross rolling are carried out to obtain the high-temperature-resistant tungsten powder. The target tungsten alloy is prepared, and the attributes of the target tungsten alloy are improved. In the preparation process of the target tungsten alloy, the defects of bubbles, loopholes, unevenness and the like of the target tungsten alloy due to the fact that oxygen and other impurity elements permeate into the target tungsten alloy are overcome through the vacuum environment, the short sintering time and tungsten carbide, and the strength of the target tungsten alloy is improved.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy, and in particular to a method for preparing a high-strength tungsten alloy. Background Art

[0002] High-density tungsten alloy has the advantages of high strength, high hardness and good plasticity and toughness, and is widely used. Domestic and foreign scholars have conducted research on powder modification, enhanced sintering, deformation strengthening and heat treatment processes to improve the performance of high-density tungsten alloy.

[0003] The Chinese patent application with publication number CN109338160A discloses a castable forgeable solid solution tungsten alloy and a preparation method thereof, wherein the method adds elements that are solid-dissolved with tungsten and grain boundary strengthening elements, and prepares the tungsten alloy by vacuum melting, forging, and aging treatment. The mass fraction ratio of various components in the tungsten alloy prepared by the above patent is set arbitrarily, and no reasonable mass fraction ratio control method is involved.

[0004] The Chinese patent application with publication number CN118006997A discloses a method for preparing a low-oxygen heterogeneous structure tungsten-based composite material, wherein W powder, Ti powder, TiB2 powder and WC cemented carbide balls are placed in a ball mill for ball milling, and then a two-step sintering method is used to prepare a W-Ti-TiB2 tungsten-based composite material with high hardness and low oxygen content. The two-step sintering method is used in the above patent to prepare the tungsten-based composite material, which takes a long time to prepare, resulting in a high oxygen content in contact with the tungsten-based composite material and many internal gaps.

[0005] The Chinese patent application with publication number CN103602868A discloses a method for preparing a high-density fine-grained W-TiC alloy material, wherein the method firstly uses a wet high-energy ball milling method to mix TiC powder and W powder uniformly, obtains a mixed powder after vacuum drying, and then performs spark plasma sintering on the mixed powder to obtain a sintered blank, and finally performs multi-fire die forging on the sintered blank to obtain a high-density fine-grained W-TiC alloy material. The multi-fire die forging time in the above-mentioned patent is long, and the surface of the W-TiC alloy material is oxidized, which reduces the strength of the W-TiC alloy.

[0006] The Chinese patent application with publication number CN116024448A discloses a method for preparing a high-density fine-grained tungsten alloy with a non-equiatomic high-entropy alloy binder phase, wherein the method firstly mixes tungsten powder with a high-entropy alloy binder phase powder and then performs low-energy ball milling to mix the powder to obtain a mixed powder, and then sequentially pre-presses and discharges plasma sintered the mixed powder to obtain a high-density fine-grained tungsten alloy with a non-equiatomic high-entropy alloy binder phase after cooling. The above patent obtains the mixed powder by low-energy ball milling, and there is a problem of agglomeration between the mixed powders. During the discharge plasma sintering process, the tungsten powder and the high-entropy alloy binder phase powder diffuse, and the friction increases, which is not conducive to the preparation of tungsten alloy. Therefore, the prior art needs to be further improved. Summary of the invention

[0007] In order to solve the defects of the above-mentioned prior art, the present invention proposes a method for preparing a high-strength tungsten alloy. The present invention selects an upper solid solution element, a lower solid solution element, a solid lubricating powder and an activated powder with a predetermined particle size ratio and uniformly mixes them with tungsten powder according to a target mass fraction ratio, and then prepares the target tungsten alloy through vacuum pressing, vacuum low-temperature sintering, vacuum insulation treatment, spark plasma sintering, low-temperature annealing treatment, and cross rolling to improve the properties of the target tungsten alloy.

[0008] The technical solution of the present invention is achieved in this way: A method for preparing a high-strength tungsten alloy comprises the following steps: Step 1: Select at least one upper layer solid solution element and one lower layer solid solution element from the solid solution element set, select a particle size of tungsten powder within the particle size range, and determine the particle sizes of the upper layer solid solution element and the lower layer solid solution element according to the particle size of the tungsten powder and the predetermined particle size ratio; Step 2: Establish a three-dimensional atomic model according to the particle size of tungsten powder, the particle size of the upper solid solution element and the lower solid solution element, and the pressing mold, and determine the target mass fraction ratio of tungsten powder, the upper solid solution element and the lower solid solution element according to the three-dimensional atomic model; Step 3: Set the ball milling parameters, put the tungsten powder with a predetermined particle size ratio, the upper layer solid solution element and the lower layer solid solution element into the ball milling tank according to the target mass fraction ratio, and prepare tungsten alloy powder; Step 4: Select at least one activation element from the activation set, add tungsten alloy powder, solid lubricant powder and activation powder into the pressing mold to mix, and select a target pressure within the first pressure range for vacuum pressing; Step 5: performing vacuum low-temperature sintering and vacuum heat preservation treatment on the tungsten alloy powder within the first temperature range to prepare a tungsten alloy embryo; Step 6: performing spark plasma sintering on the tungsten alloy embryo within the second temperature range, adding carbon powder for low temperature annealing, and preparing the tungsten alloy; Step 7: Perform microscopic scanning on the tungsten alloy to obtain the average length and average width of the voids in the tungsten alloy and establish a constitutive model of the tungsten alloy; Step 8: Determine the target transverse stress and the target longitudinal stress according to the constitutive model and the average length and the average width of the voids in the tungsten alloy, and cross-roll the tungsten alloy according to the target transverse stress and the target longitudinal stress to prepare the target tungsten alloy; Step 9: Measure the properties of the target tungsten alloy. If the properties of the target tungsten alloy are qualified, the process ends; otherwise, return to step 1.

[0009] In the present invention, in step 1, the solid solution element set includes all elements that can be dissolved with tungsten element, namely, solid solution elements, and the solid solution element set = {molybdenum, tantalum, niobium, rhenium, chromium, vanadium, vanadium, titanium, iron, nickel, cobalt}, and the solid solution elements whose mass ratio to tungsten atoms is greater than 0.9 are lower-layer solid solution elements, otherwise they are upper-layer solid solution elements.

[0010] In the present invention, in step 1, the particle size range is 1 nanometer to 10 nanometers, and the predetermined particle size ratio of the tungsten powder, the upper layer solid solution element and the lower layer solid solution element is .

[0011] In the present invention, in step 2, the mass fraction ratio of the upper solid solution element and the lower solid solution element is 1:1, and when min{V3} in the three-dimensional atomic model is min{V3}, the mass fraction ratio of tungsten powder, upper solid solution element and lower solid solution element is the target mass fraction ratio, wherein V3=V0-V1-V2, V0 is the volume of the pressing mold, V1 is the volume of the tungsten powder in the pressing mold, V2 is the sum of the volumes of the upper solid solution element and the lower solid solution element, and V3 is the volume of the voids in the pressing mold.

[0012] In the present invention, in step 4, the activation set = {lanthanum, cerium, nickel, copper, silver, cobalt, aluminum oxide, titanium dioxide, titanium carbide, tantalum carbide, hafnium carbide, titanium boride}, the solid lubricating powder is a powder that can reduce friction, the activation powder is a powder of an activation element, the particle size of the solid lubricating powder ≤ the particle size of the activation powder < the particle size of the tungsten alloy powder, the mass fraction of the tungsten alloy powder accounts for [90%, 95%], the mass fraction of the solid lubricating powder accounts for [1%, 2%], and the mass fraction of the activation powder accounts for [1%, 8%].

[0013] In the present invention, in step 5, the first temperature range is [800°C, 1000°C], the vacuum low-temperature sintering time is [100min, 160min], the vacuum insulation treatment time is [60min, 100min], and the vacuum insulation treatment temperature is [400°C, 800°C].

[0014] In the present invention, in step 6, the second temperature range is [1000°C, 1200°C], the spark plasma sintering time is [2min, 5min], the sintering pressure is [30MPa, 80MPa], the heating rate is [40°C / min, 100°C / min], the particle size of the activated powder < the particle size of the carbon powder ≤ the particle size of the tungsten alloy powder, the mass fraction of the carbon powder is [1%, 2%], the temperature of the low-temperature annealing treatment is [100°C, 500°C], and the time of the low-temperature annealing treatment is [60min, 240min].

[0015] In the present invention, in step 7, the constitutive model is , σ is the stress applied to the tungsten alloy, E is the elastic modulus of the tungsten alloy, ε1 is the plastic strain of the tungsten alloy, σ1 is the yield stress of the tungsten alloy, and n is the hardening index of the tungsten alloy.

[0016] In the present invention, in step 9, the properties of the target tungsten alloy include strength, hardness, and density.

[0017] The method and system for preparing the high-density tungsten alloy of the present invention have the following beneficial effects: the present invention sets a predetermined particle size ratio of tungsten powder, upper solid solution elements and lower solid solution elements, so that the upper solid solution elements and the lower solid solution elements are fully filled in the gaps between particles of tungsten powder, thereby enhancing the density of the target tungsten alloy. The target mass fraction ratio of tungsten powder, upper solid solution elements and lower solid solution elements is determined according to the three-dimensional atomic model, thereby improving the strength of the target tungsten alloy, which is beneficial to the later pressing of tungsten alloy powder and the preparation of the target tungsten alloy. The particle size of tungsten powder is reduced by ball milling operation, and the upper solid solution elements and the lower solid solution elements are fully mixed with tungsten powder by adding solid lubricating powder, thereby improving the fluidity of powder, reducing friction during pressing, promoting the diffusion of activated elements, upper solid solution elements and lower solid solution elements during sintering, and reducing the difficulty of preparing the target tungsten alloy. The target tungsten alloy is prepared by combining activation sintering, two-step sintering and spark plasma sintering, and the grain growth and porosity of the target tungsten alloy are better controlled, thereby optimizing the mechanical properties and physical properties of the material. Vacuum low-temperature sintering helps to remove volatile components, reduce the risk of bubbles or other defects during spark plasma sintering, and make the material more uniform, creating better conditions for spark plasma sintering, thereby improving the overall quality of the target tungsten alloy. Activated sintering reduces the energy consumption of vacuum low-temperature sintering and spark plasma sintering. Spark plasma sintering shortens the sintering time, reduces unnecessary oxidation reactions, and improves the density of the target tungsten alloy. By adding carbon powder to the tungsten alloy embryo for low-temperature annealing, the carbon powder forms dense tungsten carbide on the surface of the tungsten alloy embryo, improving hardness, wear resistance and corrosion resistance. By cross-rolling the tungsten alloy, the voids are reduced and the strength of the target tungsten alloy is increased. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The flowchart of the method for preparing the high-strength tungsten alloy of the present invention is as follows; Figure 2 A schematic diagram of a predetermined particle size ratio of the present invention; Figure 3 is a schematic diagram of a three-dimensional atomic model of the present invention; Figure 4 Schematic diagram of the microstructure of the tungsten alloy of the present invention. DETAILED DESCRIPTION

[0019] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0020] Due to the different weights of the upper and lower solid solution elements, when the upper and lower solid solution elements are ball-milled with tungsten powder, the upper and lower solid solution elements will occupy the gaps in the tungsten powder respectively, which is beneficial to the later sintering. During the vacuum low-temperature sintering period, the upper and lower solid solution elements respectively dissolve with tungsten elements, inhibiting the dissolution-precipitation process of tungsten elements, achieving the purpose of refining tungsten grains, and improving the strength, toughness and wear resistance of the tungsten alloy embryo. When the sintering temperature is between 1000℃ and 1200℃, the densification mechanism of spark plasma sintering is mainly particle sliding under the dominance of sintering pressure. When the sintering temperature is above 1200℃, based on creep theory, increasing the sintering pressure and increasing the sintering temperature will increase the stress factor and reduce the apparent activation energy. The corresponding densification mechanism may shift from dislocation climb to grain boundary diffusion, resulting in an increase in grain boundaries and a reduction in the strength and hardness of the target tungsten alloy. Tungsten carbide has good resistance to oxidation at room temperature and higher temperatures. In an environment above 500°C, the oxidation rate of tungsten carbide will increase, so the temperature of low-temperature annealing treatment is below 500°C. During the entire preparation process of the target tungsten alloy, the vacuum environment, short sintering time and tungsten carbide prevent impurity elements such as oxygen from penetrating into the interior of the target tungsten alloy, resulting in bubbles, holes, uneven defects in the target tungsten alloy, and improving the density of the target tungsten alloy. There is usually a positive correlation between the density and strength of tungsten alloys, and higher density helps to improve the strength of the target tungsten alloy. Embodiment 1

[0021] like Figures 1 to 4 As shown, the method for preparing the high-strength tungsten alloy of the present invention comprises the following steps.

[0022] Step 1: Select at least one upper solid-solution element and one lower solid-solution element from the solid-solution element set, select a tungsten powder particle size within the particle size range, and determine the particle sizes of the upper solid-solution element and the lower solid-solution element according to the particle size of the tungsten powder and the predetermined particle size ratio. The solid-solution element set contains all elements that can be solid-dissolved with tungsten, namely solid-solution elements, and the solid-solution element set = {molybdenum, tantalum, niobium, rhenium, chromium, vanadium, vanadium, titanium, iron, nickel, cobalt}. The solid-solution element whose mass ratio to tungsten atoms is greater than 0.9 is the lower solid-solution element, and vice versa. The lower solid-solution element can be rhenium or tantalum, and the upper solid-solution element can be molybdenum, niobium, chromium, vanadium, vanadium, titanium, iron, nickel, and cobalt. The particle size range is 1 nanometer to 10 nanometers. In order to fully fill the gaps between the particles of the tungsten powder with the upper solid-solution element and the lower solid-solution element, such as Figure 2 As shown, the big circle represents tungsten powder, the small circle represents the upper solid solution element and the lower solid solution element, and the predetermined particle size ratio R1:R2:R3 of the tungsten powder, the upper solid solution element and the lower solid solution element is set to .

[0023] Step 2: According to the particle size of tungsten powder, the particle size of upper and lower solid solution elements, and the pressing mold, a three-dimensional atomic model is established, and the target mass fraction ratio of tungsten powder, upper and lower solid solution elements is determined according to the three-dimensional atomic model. The mass fraction ratio of upper and lower solid solution elements is 1:1. Figure 3 As shown, the cuboid in the three-dimensional atomic model represents the pressing die, the large circle represents the tungsten powder, and the small circle represents the upper solid solution element and the lower solid solution element. When min{V3} in the three-dimensional atomic model, the mass fraction ratio of tungsten powder, upper solid solution element and lower solid solution element is the target mass fraction ratio, where V3=V0-V1-V2, V0 is the volume of the pressing die, V1 is the volume of tungsten powder in the pressing die, V2 is the sum of the volumes of the upper solid solution element and the lower solid solution element, and V3 is the volume of the voids in the pressing die. The smaller the volume of the voids in the pressing die, the higher the density of the tungsten alloy, which is more conducive to the later pressing of tungsten alloy powder and the preparation of tungsten alloy.

[0024] Step 3: Set the ball milling parameters, put the tungsten powder, upper solid solution elements and lower solid solution elements of the predetermined particle size ratio into the ball mill according to the target mass fraction ratio, and prepare the tungsten alloy powder. The particle size of the tungsten powder initially added during ball milling is not within the particle size range, but only forms a predetermined particle size ratio with the upper solid solution elements and the lower solid solution elements. By adjusting the ball milling parameters, the particle size of the tungsten powder is reduced after a long period of ball milling until the particle size of the tungsten powder is within the particle size range. The particle size of the tungsten powder is reduced by the ball milling operation, and the upper solid solution elements and the lower solid solution elements are fully mixed with the tungsten powder, which reduces the difficulty of preparing the tungsten alloy. The ball milling time is generally 12 to 48 hours. The larger the particle size of the tungsten powder, the longer the ball milling time.

[0025] Step 4: Select at least one activation element from the activation set, add tungsten alloy powder, solid lubricant powder and activation powder to the pressing mold for mixing, and select the target pressure within the first pressure range for vacuum pressing. Activation set = {lanthanum, cerium, nickel, copper, silver, cobalt, aluminum oxide, titanium dioxide, titanium carbide, tantalum carbide, hafnium carbide, titanium boride}, activation powder is the powder of the activation element, and the activation element significantly reduces the sintering temperature, promotes densification and improves material properties by changing the surface energy, interface structure and providing additional diffusion paths. Solid lubricant powder is a powder that can reduce friction, improve the fluidity of the powder, reduce friction during pressing, and promote the diffusion of activation elements, upper solid solution elements and lower solid solution elements during sintering. The particle size of solid lubricant powder ≤ the particle size of activation powder < the particle size of tungsten alloy powder, the mass fraction of tungsten alloy powder accounts for [90%, 95%], the mass fraction of solid lubricant powder accounts for [1%, 2%], and the mass fraction of activation powder accounts for [1%, 8%].

[0026] Step 5: The tungsten alloy powder is subjected to vacuum low-temperature sintering and vacuum heat preservation treatment within the first temperature range to prepare a tungsten alloy embryo. The first temperature range is [800°C, 1000°C], and the vacuum low-temperature sintering time is [100min, 160min]. The vacuum heat preservation treatment time is [60min, 100min], and the vacuum heat preservation treatment temperature is [400°C, 800°C]. During the vacuum low-temperature sintering period, the upper layer solid solution elements and the lower layer solid solution elements are respectively dissolved with the tungsten element, which inhibits the dissolution-precipitation process of the tungsten element, achieves the purpose of refining the tungsten grains, and improves the strength, toughness and wear resistance of the tungsten alloy embryo. After vacuum low-temperature sintering, vacuum heat preservation treatment is used to eliminate the temperature gradient caused by uneven heating speed, prevent deformation or cracks caused by local overheating of the tungsten alloy embryo, and provide sufficient time for atomic diffusion, so that the microstructural changes inside the tungsten alloy embryo can be fully carried out.

[0027] Step 6: Spark plasma sintering is performed on the tungsten alloy embryo within the second temperature range, and carbon powder is added for low temperature annealing to prepare tungsten alloy. The second temperature range is [1000℃, 1200℃], the spark plasma sintering time is [2min, 5min], the sintering pressure is [30MPa, 80MPa], and the heating rate is [40℃ / min, 100℃ / min]. Replacing the second step of the two-step sintering with spark plasma sintering shortens the sintering time and reduces unnecessary oxidation reactions. Through hot pressing and discharge effects, uniform pressure distribution is provided, and the contact and bonding between particles are enhanced. By equipping with an advanced control system, multiple parameters such as temperature, pressure, and current of spark plasma sintering can be monitored and adjusted in real time, which is beneficial to the preparation of tungsten alloy. The particle size of the activated powder < the particle size of the carbon powder ≤ the particle size of the tungsten alloy powder, and the mass fraction of the carbon powder is [1%, 2%]. The temperature of low temperature annealing treatment is [100℃, 500℃], and the time of low temperature annealing treatment is [60min, 240min]. In the process of low temperature annealing treatment, carbon powder is added to form dense tungsten carbide on the surface of tungsten alloy embryo, and oxygen is isolated at 500℃ to prevent the tungsten alloy embryo from being oxidized and causing the decrease of density and other properties. By defining the particle size of solid lubricating powder, activated powder, carbon powder, and tungsten alloy powder, the agglomeration problem between powders is solved, and the deficiency that activated powder is difficult to be evenly mixed into tungsten alloy powder is overcome, the lubrication and activation effects are guaranteed, and it is beneficial for carbon powder to form tungsten carbide on the surface of tungsten alloy embryo, and not penetrate the interior of tungsten alloy embryo, so as to improve hardness, wear resistance and corrosion resistance.

[0028] Step 7: Scan the tungsten alloy microscopically to obtain the average length and average width of the pores in the tungsten alloy and establish the constitutive model of the tungsten alloy. Figure 4 The microstructure of tungsten alloy shown in Figure 4 It can be seen that there are a lot of voids inside the tungsten alloy. The gray mass is the tungsten alloy and the black area is the void. By measuring the length and width of all the voids in the figure, the average length and average width are obtained. The constitutive model of tungsten alloy is , σ is the stress applied to the tungsten alloy, E is the elastic modulus of the tungsten alloy, ε1 is the plastic strain of the tungsten alloy, σ1 is the yield stress of the tungsten alloy, and n is the hardening index of the tungsten alloy. The elastic modulus of the tungsten alloy is measured by static tensile test, and the hardening index and yield stress of the tungsten alloy are measured by uniaxial tensile test and compression test, and then the specific function of the constitutive model is obtained.

[0029] Step 8: Determine the target transverse stress and target longitudinal stress according to the constitutive model, the average length and average width of the voids in the tungsten alloy, and cross-roll the tungsten alloy according to the target transverse stress and target longitudinal stress to prepare the target tungsten alloy. Cross-rolling the tungsten alloy can reduce voids and increase the density of the tungsten alloy. Substitute the average length and average width into the constitutive model to obtain the target transverse stress and target longitudinal stress, and cross-roll the tungsten alloy according to the target transverse stress and target longitudinal stress.

[0030] Step 9: Measure the properties of the target tungsten alloy. If the properties of the target tungsten alloy are qualified, then end, otherwise, return to step 1. The properties of the target tungsten alloy include strength, hardness, density, in addition to which, according to specific production requirements, the properties also include melting point, thermal expansion coefficient, etc.

[0031] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a high-strength tungsten alloy, characterized in that: The following steps are involved: Step 1: Select at least one upper layer solid solution element and one lower layer solid solution element from the solid solution element set, select a particle size of tungsten powder within the particle size range, and determine the particle sizes of the upper layer solid solution element and the lower layer solid solution element according to the particle size of the tungsten powder and the predetermined particle size ratio; Step 2: Establish a three-dimensional atomic model according to the particle size of tungsten powder, the particle size of the upper solid solution element and the lower solid solution element, and the pressing mold, and determine the target mass fraction ratio of tungsten powder, the upper solid solution element and the lower solid solution element according to the three-dimensional atomic model; Step 3: Set the ball milling parameters, put the tungsten powder with a predetermined particle size ratio, the upper layer solid solution element and the lower layer solid solution element into the ball milling tank according to the target mass fraction ratio, and prepare tungsten alloy powder; Step 4: Select at least one activation element from the activation set, add tungsten alloy powder, solid lubricant powder and activation powder into the pressing mold to mix, and select a target pressure within the first pressure range for vacuum pressing; Step 5: performing vacuum low-temperature sintering and vacuum heat preservation treatment on the tungsten alloy powder within the first temperature range to prepare a tungsten alloy embryo; Step 6: performing spark plasma sintering on the tungsten alloy embryo within the second temperature range, adding carbon powder for low temperature annealing, and preparing the tungsten alloy; Step 7: Perform microscopic scanning on the tungsten alloy to obtain the average length and average width of the voids in the tungsten alloy and establish a constitutive model of the tungsten alloy; Step 8: Determine the target transverse stress and the target longitudinal stress according to the constitutive model and the average length and the average width of the voids in the tungsten alloy, and cross-roll the tungsten alloy according to the target transverse stress and the target longitudinal stress to prepare the target tungsten alloy; Step 9: Measure the properties of the target tungsten alloy. If the properties of the target tungsten alloy are qualified, the process ends; otherwise, return to step 1.

2. The method for preparing the high-strength tungsten alloy according to claim 1, wherein: In step 1, the solid solution element set includes all elements that can be dissolved in tungsten, namely, solid solution elements, and the solid solution element set = {molybdenum, tantalum, niobium, rhenium, chromium, vanadium, vanadium, titanium, iron, nickel, cobalt}. The solid solution elements whose mass ratio to tungsten atoms is greater than 0.9 are lower-layer solid solution elements, otherwise they are upper-layer solid solution elements.

3. The method for preparing the high-strength tungsten alloy according to claim 1, characterized in that: In step 1, the particle size range is 1 nanometer to 10 nanometers, and the predetermined particle size ratio of the tungsten powder, the upper layer solid solution element and the lower layer solid solution element is .

4. The method for preparing the high-strength tungsten alloy according to claim 1, characterized in that: In step 2, the mass fraction ratio of the upper solid solution element and the lower solid solution element is 1:

1. When min{V3} in the three-dimensional atomic model is reached, the mass fraction ratio of the tungsten powder, the upper solid solution element and the lower solid solution element is the target mass fraction ratio, wherein V3=V0-V1-V2, V0 is the volume of the pressing mold, V1 is the volume of the tungsten powder in the pressing mold, V2 is the sum of the volumes of the upper solid solution element and the lower solid solution element, and V3 is the volume of the voids in the pressing mold.

5. The method for preparing the high-strength tungsten alloy according to claim 1, characterized in that: In step 4, the activation set = {lanthanum, cerium, nickel, copper, silver, cobalt, aluminum oxide, titanium dioxide, titanium carbide, tantalum carbide, hafnium carbide, titanium boride}, the solid lubricating powder is a powder that can reduce friction, the activation powder is a powder of an activation element, the particle size of the solid lubricating powder ≤ the particle size of the activation powder < the particle size of the tungsten alloy powder, the mass fraction of the tungsten alloy powder accounts for [90%, 95%], the mass fraction of the solid lubricating powder accounts for [1%, 2%], and the mass fraction of the activation powder accounts for [1%, 8%].

6. The method for preparing the high-strength tungsten alloy according to claim 1, characterized in that: In step 5, the first temperature range is [800°C, 1000°C], the vacuum low-temperature sintering time is [100min, 160min], the vacuum insulation treatment time is [60min, 100min], and the vacuum insulation treatment temperature is [400°C, 800°C].

7. The method for preparing the high-strength tungsten alloy according to claim 1, characterized in that: In step 6, the second temperature range is [1000°C, 1200°C], the spark plasma sintering time is [2min, 5min], the sintering pressure is [30MPa, 80MPa], the heating rate is [40°C / min, 100°C / min], the particle size of the activated powder < the particle size of the carbon powder ≤ the particle size of the tungsten alloy powder, the mass fraction of the carbon powder is [1%, 2%], the temperature of the low-temperature annealing treatment is [100°C, 500°C], and the time of the low-temperature annealing treatment is [60min, 240min].

8. The method for preparing the high-strength tungsten alloy according to claim 1, characterized in that: In step 7, the constitutive model is , σ is the stress applied to the tungsten alloy, E is the elastic modulus of the tungsten alloy, ε1 is the plastic strain of the tungsten alloy, σ1 is the yield stress of the tungsten alloy, and n is the hardening index of the tungsten alloy.

9. The method for preparing the high-strength tungsten alloy according to claim 1, characterized in that: In step 9, the properties of the target tungsten alloy include strength, hardness, and density.

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