A tungsten-based composite material with high pseudo-plasticity and a preparation method thereof

Abstract

The present application provides a tungsten-based composite material with high pseudo-plasticity and a preparation method thereof. The matrix of the composite material is a tungsten (W) matrix with added aluminum nitride (AlN) particles, and the toughening body is short tungsten fiber (W f ) without plating on the surface, wherein the short fiber W f is added in an amount of 10% to 50% (vol.%), and the AlN particles are added in an amount of 2.0% to 15.0% (wt.%). The short fiber W f is ball-mixed with raw material powder in a certain proportion, and then sintered by using a spark plasma sintering technology, with a sintering temperature of 1500 to 2000 ℃, a sintering pressure of 50 to 80 MPa, and a holding time of 1 to 5 min. The short fiber W f toughened tungsten-based composite material disclosed in the present application has a weak combination between the fiber and the matrix under the premise of dense sintering, and the comprehensive performance of the "strong / weak alternating combination interface" between the fiber and the matrix is weak combination, so that the composite material has excellent pseudo-plasticity characteristics and high strength and toughness.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy for preparing high-performance tungsten-based composite materials, specifically to a short-fiber W-type composite material with excellent pseudoplasticity and high density. f Toughened W-based composite materials and their preparation methods. Background Technology

[0002] Magnetic confinement tokamak devices are among the most promising for achieving controlled nuclear fusion. The plasma-facing materials in these devices must withstand high thermal loads, intense beam particle impacts, and neutron irradiation, making their service environment extremely harsh. Tungsten, with its high melting point, low coefficient of thermal expansion, low sputtering corrosion rate, and low deuterium-tritium retention rate, is considered a candidate material for future plasma-facing applications. However, tungsten is brittle and prone to cracking under thermal stress induced by high thermal loads.

[0003] Fiber toughening is currently the main approach to solving the brittleness problem of tungsten materials for plasma applications. This involves introducing tungsten fiber toughening agents (W0) into the tungsten matrix (W). f Preparation of tungsten fiber-toughened tungsten matrix composites (W f / W composite materials) achieve energy dissipation mechanisms such as crack deflection, crack bridging, fiber debonding, and fiber pull-out, thereby improving the strength and toughness of the composite material. Compared with alloying, particle strengthening, and fine-grain strengthening processes, fiber toughening processes do not suffer from thermal load degradation or neutron irradiation degradation in strengthening tungsten materials. Commonly used tungsten fiber toughening materials include long tungsten fibers, tungsten fiber webs, three-dimensional tungsten wire braids, and short tungsten fibers. However, long fibers W f / W Composite Materials and Fiber Webs W f The mechanical properties of both tungsten / tungsten composite materials exhibit anisotropy. The mechanical properties perpendicular to the direction of the long tungsten fibers or tungsten fiber web are relatively low, and the preparation processes for both materials are quite complex, requiring the artificial laying of long tungsten fibers or tungsten fiber webs, which makes it difficult to guarantee the stability of product quality. Fiber braided W f While / W composite materials can improve the strength and toughness of tungsten materials in three dimensions, they require the pre-fabrication of a three-dimensional tungsten wire braid, making the process relatively complex. Short fiber W, prepared using short tungsten fibers as the toughening agent... f / W composite materials have advantages such as isotropic mechanical properties, simple preparation process, and high product quality stability, and have now become W f The main direction of development for the application of / W composite materials.

[0004] short fiber W fOne of the key concerns regarding W / W composite materials is their "pseudoplasticity." "Pseudoplasticity" specifically refers to the "sawtooth" pattern in the rising phase of the load-displacement curve during external force loading, meaning that the material can recover and rise again after a slight decrease in load. Short fiber W / W composites exhibit excellent "pseudoplasticity." f / W composites typically exhibit high strength and toughness. Obtaining short-fiber W with "pseudoplasticity" is a key objective. f / W composite materials are mainly produced through two approaches:

[0005] (1) Pre-coating short fiber W using surface coating technology f A ceramic coating is prepared on the surface, and then short fiber W is prepared using it as a toughening agent. f / W composite materials. The essence of this method relies on the presence of a ceramic compound layer between the fiber and the matrix to achieve a weak bond between them. The fiber / matrix interface structure with relatively weak bonding strength facilitates energy dissipation mechanisms such as crack deflection, crack bridging, fiber debonding, and fiber pull-out, thereby achieving the "pseudo-plasticity" of the composite material and improving its strength and toughness. Luo Guangnan, Zhao Sixiang, and others have prepared short fiber W coated with ZrO2, La2O3, Y2O3, etc., using physical vapor deposition, chemical vapor deposition, or sol-gel methods. f And using it as a toughening agent, short fiber W was prepared. f / W composite material, short fiber W was found f The presence of a surface coating is beneficial for the composite material to exert an energy dissipation mechanism [A tungsten-based plasma-oriented material and its preparation method, Publication No.: CN 102560292 A]. Y. Mao et al. prepared Y2O3-coated short fibers W using magnetron sputtering. f And using it as a toughening agent, short fiber W was prepared. f The / W composite material exhibits significant "pseudoplastic" characteristics, with a room temperature fracture toughness of 38.86 MPa·m. 1 / 2 The room temperature fracture energy density reaches 2.7 KJ / m³. 2 However, the pure W material prepared under the same process parameters did not exhibit "pseudo-plasticity" characteristics, and its room temperature fracture toughness was only 5.48 MPa·m. 1 / 2 The room temperature fracture energy density is only 0.11 kJ / m³. 2 . [Y.Mao,JWCoenen,J.Riesch,S.Sistla,J. J.Reiser,A.Terra,C.Chen,Y.Wu,L.Raumann,T. H. Gietl, R. Neu, C. Linsmeier, C. Broeckmann, Fracture behavior of random distributed short tungsten fiber-reinforced tungsten composites, Nucl. Fusion. 59(2019) 86034]. However, short fiber W f The preparation cost of the surface coating is high and the process is very complex, using short fiber W for coating. f Preparation of short fiber W for toughening f While / W composite materials can achieve good "pseudoplasticity" and toughness, they are only suitable for small-batch preparation and are not conducive to large-scale industrial production. In addition, the vapor pressure of the coating material (such as oxides) is relatively high, and the integrity of the coating is easily damaged under the action of sintering temperature and pressure, affecting the "pseudoplasticity" and mechanical properties of the composite material [Y.Mao, JWCoenen, J.Riesch, S.Sistla, J. B. Jasper, A. Terra, T. H. Gietl, M. Bram, J. Gonzalez-Julian, C. Linsmeier, C. Broeckmann, Development and characterization of powder metallurgically produced discontinuous tungsten fiber reinforced tungsten composites, Phys. Scr. 2017 (2017) 14005. Therefore, through short fiber W f The method of achieving "pseudoplasticity" in composite materials by pre-coating the surface has significant limitations.

[0006] (2) By reducing the sintering process parameters, using uncoated short fiber W f To prepare porous, low-density short fibers W for toughening f / W composite material. A lower overall degree of sintering densification in the composite material indicates shorter fiber W... f The fiber and matrix were not densely sintered (some areas were densely sintered, while others were porous). The essence of this method is to utilize this non-dense sintering state to achieve a weak bond between the fiber and the matrix, thereby leveraging the energy dissipation mechanism of fiber toughening to achieve "pseudo-plasticity" in the composite material and improve its strength and toughness. Wu Yucheng, Zhu Huijuan, and others used uncoated short fiber W... f Short fiber W was prepared for toughening. f / W composite material, optimizing the strength and toughness of the composite material by controlling the porosity (equivalent to controlling the density) and pore distribution [a method for preparing large-size tungsten fiber-reinforced tungsten W f / W composite material method, publication number: CN 113953510 A]. Y.Mao et al. used uncoated short fiber W f To act as a toughening agent, short fiber W was prepared at relatively low sintering temperatures (1400℃ or 1550℃). f / W composite materials, with a density of 75.4%–87.0%, indicate that porous, low-density short fiber W f / W composites exhibit significant "pseudoplasticity," while pure W materials prepared under the same processing parameters do not. The composite material prepared at a sintering temperature of 1550℃ achieves a room-temperature fracture toughness of 30 MPa·m. 1 / 2 The room temperature fracture toughness of pure W material prepared under the same process parameters is only 5 MPa·m. 1 / 2 [Y.Mao, J.Coenen, S.Sistla, C. Liu, A. Terra, X. Tan, J. Riesch, T. Hoeschen, Y. Wu, C. Broeckmann, C. Linsmeier, Design of tungstenfiber-reinforced tungsten composites with porous matrix,Mater.Sci.Eng.A.817(2021)141361][Y.Mao,JWCoenen,S.Sistla,X.Tan,J.Riesch,L.Raumann,D.Schwalenberg,T. C. Chen, Y. Wu, C. Broeckmann, C. Linsmeier, Development of tungsten fiber-reinforced tungsten with a porous matrix, Phys. Scr. 2020 (2020) 14030. [Using uncoated short fiber W...] f To prepare porous, low-density short fibers W for toughening f / W composites achieve "pseudoplasticity" while avoiding the complex process of pre-preparing a coating on the fiber surface. However, low-density short fiber W f / W composite materials contain numerous pores. During thermal conduction, the thermal conductivity at the pore locations is extremely poor. Therefore, porous, low-density short fiber W f / W composite materials have low thermal conductivity. As tungsten materials used in plasma applications, they need to possess both high strength and toughness to prevent cracking and failure under significant thermal stress, and excellent thermal conductivity to ensure rapid heat dissipation and prevent melting or recrystallization embrittlement of the plasma-facing side due to excessively high temperatures. Furthermore, low-density short-fiber W... f / W composite materials also have poor airtightness and hydrogen barrier properties, which is not conducive to their long-term service as plasma-oriented materials.

[0007] In summary, existing methods for obtaining short fibers W with "pseudo-plasticity" f The existing methods for using W / W composite materials have significant limitations. These composites suffer from difficulties in fiber coating preparation, unstable microstructure and properties, or low density, failing to meet future application requirements for plasma materials. Therefore, it is necessary to develop a W / W composite material with uncoated short fibers. f Short fiber W, which acts as a toughening agent, possesses excellent pseudoplasticity and high density. f Toughened W-based composite materials are of great significance. Summary of the Invention

[0008] This invention aims to provide a method for using uncoated short fibers W f W is a toughening agent with excellent pseudoplasticity and high density short fiber. f Toughened W-based composite materials and their preparation methods. Towards short-fiber W... f AlN particles are added to the W matrix of the / W composite material, and the sintering process parameters are adjusted to achieve densification during sintering. By adjusting the particle size and amount of AlN particles in the matrix, the overall performance of the "strong / weak alternating bonding interface" between the fiber and the matrix is ​​controlled (making its overall performance exhibit weak bonding), thus achieving "pseudoplasticity" while ensuring high density of the composite material.

[0009] The tungsten-based composite material with high pseudoplasticity proposed in this invention has a tungsten (W) matrix with added aluminum nitride (AlN) particles as the matrix and a toughening agent of short tungsten fibers (W) without surface coating as the toughening agent. f ), of which short fibers W f The addition amount is 10% to 50% by volume, the addition amount of AlN particles in the matrix is ​​2.0% to 15.0% by mass, and the addition amount of activating sintering elements in the matrix is ​​0% to 1.0% by mass.

[0010] Furthermore, the activating sintering elements in the matrix include iron powder, nickel powder, cobalt powder, aluminum powder, and palladium powder, with an addition amount of 0.1% to 1.0% by mass.

[0011] The preparation method of the above-mentioned tungsten-based composite material with high pseudoplasticity includes the following steps:

[0012] Step (1) Treat short fibers W with anhydrous ethanol or acetone f Ultrasonic cleaning is performed, followed by vacuum drying. Short fiber W is prepared in a certain proportion. f W powder, AlN powder and activated sintering element powder, including short fiber W f The addition amount is 10% to 50% by volume, and the addition amount of AlN particles is 2.0% to 15.0% by mass. The above raw materials are mixed evenly using a ball milling process to obtain a mixed powder.

[0013] Step (2) The mixed powder is densified by sintering. The mixed powder is sintered by spark plasma sintering process. The sintering temperature is 1500-2000℃, the sintering pressure is 50-80MPa, and the holding time is 1-5min to obtain tungsten-based composite material.

[0014] Furthermore, in step (1), short fiber W f It is a potassium-doped tungsten fiber with a diameter of 50–250 μm and a length of 1–4 mm. The potassium content is 50–80 ppm, the W powder particle size is 500 nm–10 μm, the AlN powder particle size is 20 nm–20 μm, and the activation sintering element powder particle size is 1–5 μm.

[0015] Furthermore, in step (1), when the raw materials are ball-milled and mixed, the ball mill jar and grinding balls are made of cemented carbide. First, W powder, AlN powder and activated sintering element powder are placed in the ball mill jar in a certain proportion, with a ball-to-material ratio of 5:1 to 10:1. The ball milling time is 5 to 30 hours, and the rotation speed is 200 to 400 r / min. Then, short fiber W is added... f Place the materials in a ball mill jar at a ratio of 1:4 to 2:1, mill for 0.5 to 1 hour, and rotate at a speed of 50 to 150 r / min.

[0016] Furthermore, in step (1), high-purity Ar is introduced into the ball mill jar as a protective atmosphere during raw material mixing, and in step (2), high-purity Ar is used as a protective atmosphere throughout the spark plasma sintering process.

[0017] Further, in step (2), the discharge plasma sintering process is heated to the target temperature at a heating rate of 50-100℃ / min, and the sintering pressure is simultaneously applied to the target pressure during the heating process. The heat preservation process and the pressure preservation process are carried out simultaneously, and then the furnace is cooled while the pressure is unloaded.

[0018] Furthermore, if the equipment used for sintering cannot meet the temperature requirements, and the sintering temperature is below 1800℃, activation sintering elements can be added to the tungsten matrix, including but not limited to iron powder (Fe), nickel powder (Ni), cobalt powder (Co), aluminum powder (Al), palladium powder (Pd), etc. The amount of activation sintering element powder added is 0.1% to 1.0% by mass. The activation sintering process is used to reduce the temperature required for densification of tungsten-based composite materials.

[0019] The tungsten-based composite material of this invention, which exhibits high pseudoplasticity, is suitable for the field of high-performance tungsten-based structural materials, and is particularly suitable for the field of plasma-oriented materials for nuclear fusion.

[0020] It should be noted that some activating sintering elements, such as Ni, Co, and Pd, are subject to radiation transmutation. Under neutron irradiation, these elements can produce radioactive elements with long half-lives, and therefore their use is prohibited in the field of nuclear fusion-oriented plasma materials. Accordingly, Fe can be selected as an activating sintering element in this field. If there are no restrictions on the elements used in the application of the material, other activating sintering elements can be selected.

[0021] The advantages of this invention are:

[0022] 1. This invention uses uncoated short fibers W f Short fiber W with excellent "pseudoplasticity" and high density was prepared for the toughening agent. f Toughened W-based composite materials. For the first time, under the premise of dense sintering of the composite material, the bonding strength between the fiber and the matrix was controlled by adding AlN particles to the W matrix. f / W matrix and "W" f / AlN particles" alternately combine at the interface, where "W f The bonding strength at the " / W matrix" position is relatively strong, and the "W" position has a strong bonding strength. f The weak bonding strength of the AlN particles results in a weak overall bond at the fiber-matrix alternating strong / weak bonding interface, leading to energy dissipation mechanisms such as crack deflection, crack bridging, fiber debonding, and fiber pull-out. This method is simple, low-cost, and suitable for mass industrial production. The resulting composite material exhibits high density, excellent pseudoplasticity, and high strength and toughness.

[0023] 2. The tungsten-based composite material of this invention with high pseudoplasticity has a dense sintered AlN particle / W composite matrix. AlN particles are dispersed within the grain boundaries and grains of the W matrix, refining the matrix grains and pinning grain boundaries and dislocations. Dislocations accumulate at grain boundaries and second-phase particles, requiring significant external force to overcome obstacles for dislocation movement. Simultaneously, the tortuous grain boundaries created by the fine grains increase crack propagation paths, hindering crack growth. Therefore, the strength and toughness of the W matrix are improved, further enhancing the strength and toughness of the composite material. Furthermore, AlN particles possess high thermal conductivity (higher than pure W), and the dispersed AlN particles within the W matrix act as rapid channels for heat conduction in the composite material, their high thermal conductivity compensating for the interfacial thermal resistance introduced by the addition of second-phase particles. Therefore, the addition of AlN particles within the W matrix simultaneously improves the strength, toughness, and thermal conductivity of the composite material. Attached Figure Description

[0024] Figure 1 This is a schematic diagram showing the fiber positions of the composite materials prepared in Examples 1-3.

[0025] Figure 2 This is a SEM image showing the microstructure of the composite material prepared in Example 1, showing the fiber locations.

[0026] Figure 3 The load-displacement curves show the fracture toughness of the composite material prepared in Example 1.

[0027] Figure 4 The load-displacement curves show the fracture toughness of the composite material prepared in Example 2.

[0028] Figure 5 The load-displacement curves show the fracture toughness of the composite material prepared in Example 3.

[0029] Figure 6 This is a schematic diagram showing the fiber positions of the composite materials prepared in Comparative Examples 1-3.

[0030] Figure 7 SEM image of the microstructure of the composite material prepared in Comparative Example 1, showing the fiber locations.

[0031] Figure 8 The load-displacement curves show the fracture toughness of the composite material prepared in Comparative Example 1.

[0032] Figure 9 The load-displacement curves show the fracture toughness of the composite material prepared in Comparative Example 2.

[0033] Figure 10 The load-displacement curves show the fracture toughness of the composite material prepared in Comparative Example 3. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited thereto. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention.

[0035] Example 1

[0036] This embodiment describes a tungsten-based composite material with high pseudoplasticity and its preparation method.

[0037] The composite material involved has a composition of 30% W. f / W+4%AlN, i.e., uncoated short fiber W f The volume fraction is 30%, and the mass fraction of AlN particles in the W matrix is ​​4%; the short fibers involved are W f It has a diameter of 100μm, a length of 2mm, a potassium content of 70ppm, a W powder particle size of 6μm, and an AlN powder particle size of 3μm.

[0038] The preparation method in this embodiment specifically includes the following steps:

[0039] Step (1) Treat short fibers W with anhydrous ethanol f Ultrasonic cleaning and vacuum drying were performed. W powder, AlN powder, and short-fiber W were then mixed. f The powders were ball-milled in a specific ratio, using a cemented carbide jar and grinding balls. High-purity Ar was used as a protective atmosphere in the jar. First, W powder and AlN powder were placed in the jar at a ball-to-powder ratio of 8:1. The milling time was 6 hours, and the rotation speed was 200 r / min. Then, short-fiber W... f The mixture is placed in a ball mill jar at a ball-to-material ratio of 1:2, milled for 0.5 hours at a speed of 60 r / min to obtain a mixed powder.

[0040] Step (2) involves sintering the mixed powder using spark plasma sintering at a temperature of 1900℃ and a pressure of 70MPa. The holding and pressure holding times are 5 minutes. The temperature is increased to the target temperature at a rate of 80℃ / min, and the sintering pressure is simultaneously increased to the target pressure during the heating process. The holding and pressure holding processes are carried out simultaneously, followed by furnace cooling while the pressure is unloaded. High-purity Ar is used as the protective atmosphere throughout the sintering process to obtain short fiber W. f Toughened W-based composite material. A structural schematic diagram showing the fiber locations in the composite material is shown below. Figure 1 As shown, the actual microstructure diagram is as follows: Figure 2 As shown, the density is 99.5%, the room temperature thermal conductivity is 150.6 W / (m·K), and the room temperature fracture toughness is 9.52 MPa·m. 1 / 2 The corresponding load-displacement curves are as follows: Figure 3 As shown, it exhibits obvious "pseudoplastic" characteristics.

[0041] Example 2

[0042] This embodiment describes a tungsten-based composite material with high pseudoplasticity and its preparation method.

[0043] The composite material involved has a composition of 10% W. f / W-0.45%Fe+8%AlN, i.e., uncoated short fiber W f The volume fraction is 10%, the mass fraction of Fe, the activation sintering element in the W matrix is ​​0.45%, and the mass fraction of AlN particles is 8%; the short fibers involved are W f The particle size is 150 μm in diameter, 2.5 mm in length, and contains 60 ppm potassium. The particle size of W powder is 3 μm, Fe powder is 1 μm, and AlN powder is 500 nm.

[0044] The preparation method in this embodiment specifically includes the following steps:

[0045] Step (1) Treat short fibers W with anhydrous ethanol f Ultrasonic cleaning and vacuum drying were performed. W powder, Fe powder, AlN powder, and short fiber W were then mixed. f The materials used in the ball milling process were cemented carbide, including the mill jar and grinding balls. High-purity Ar was used as a protective atmosphere in the mill jar. First, W powder, Fe powder, and AlN powder were placed in the mill jar at a ratio of 8:1 (ball to powder), and milled for 10 hours at a speed of 250 r / min. Then, short-fiber W... f The materials are placed in a ball mill jar at a ball-to-material ratio of 1:1, and the ball milling time is 1 hour and the rotation speed is 70 r / min to obtain a mixed powder.

[0046] Step (2) involves sintering the mixed powder using spark plasma sintering at a temperature of 1600℃ and a pressure of 60MPa. The holding and pressure holding times are 3 minutes. The temperature is increased to the target temperature at a rate of 100℃ / min, and the sintering pressure is simultaneously increased to the target pressure during the heating process. The holding and pressure holding processes are carried out simultaneously, followed by furnace cooling while the pressure is unloaded. High-purity Ar is used as the protective atmosphere throughout the sintering process to obtain short fiber W. f Toughened W-based composite material. A structural schematic diagram showing the fiber locations in the composite material is shown below. Figure 1 As shown, the density is 99.8%, the room temperature thermal conductivity is 90.4 W / (m·K), and the room temperature fracture toughness is 6.78 MPa·m. 1 / 2 The corresponding load-displacement curves are as follows: Figure 4 As shown, it exhibits obvious "pseudoplastic" characteristics.

[0047] Example 3

[0048] This embodiment describes a tungsten-based composite material with high pseudoplasticity and its preparation method.

[0049] The composite material involved has a composition of 20% W. f / W-0.25%Fe+10%AlN, i.e., uncoated short fiber W f The volume fraction is 20%, the mass fraction of Fe, the activation sintering element in the W matrix is ​​0.25%, and the mass fraction of AlN particles is 10%; the short fibers involved are W f The particle size is 250 μm in diameter, 2 mm in length, and 65 ppm in potassium. The particle size of W powder is 1 μm, the particle size of Fe powder is 1 μm, and the particle size of AlN powder is 100 nm.

[0050] The preparation method in this embodiment specifically includes the following steps:

[0051] Step (1) Treat short fibers W with anhydrous ethanol f Ultrasonic cleaning and vacuum drying were performed. W powder, Fe powder, AlN powder, and short fiber W were then mixed. f The powders were ball-milled in a specific ratio, using a cemented carbide jar and grinding balls. High-purity Ar was used as a protective atmosphere in the jar. First, W powder, Fe powder, and AlN powder were placed in the jar at a ball-to-powder ratio of 10:1. The milling time was 15 hours, and the rotation speed was 250 r / min. Then, short-fiber W... f The mixture is placed in a ball mill jar at a ball-to-material ratio of 1:2, milled for 1 hour at a speed of 60 r / min to obtain a mixed powder.

[0052] Step (2) involves sintering the mixed powder using spark plasma sintering at a temperature of 1600℃ and a pressure of 50MPa. The holding and pressure holding times are 1 min, with the temperature increased at a rate of 100℃ / min to the target temperature. The sintering pressure is simultaneously increased to the target pressure during the heating process. The holding and pressure holding processes are carried out simultaneously, followed by furnace cooling while the pressure is unloaded. High-purity Ar is used as the protective atmosphere throughout the sintering process to obtain short fiber W. f Toughened W-based composite material. A structural schematic diagram showing the fiber locations in the composite material is shown below. Figure 1 As shown, the density is 99.7%, the room temperature thermal conductivity is 104.7 W / (m·K), and the room temperature fracture toughness is 7.91 MPa·m. 1 / 2 The corresponding load-displacement curves are as follows: Figure 5 As shown, it exhibits obvious "pseudoplastic" characteristics.

[0053] Comparative Example 1

[0054] The implementation procedure is the same as in Example 1. The only difference between Comparative Example 1 and Example 1 is that the W matrix of the composite material involved in Comparative Example 1 does not contain AlN particles, and only contains 30% W.f / W composite material, i.e., uncoated short fiber W f The volume fraction is 30%. A structural schematic diagram of the fiber location in the resulting composite material is shown below. Figure 6 As shown, the actual microstructure diagram is as follows: Figure 7 As shown, the density is 99.7%, the room temperature thermal conductivity is 119.3 W / (m·K), and the room temperature fracture toughness is 7.81 MPa·m. 1 / 2 The corresponding load-displacement curves are as follows: Figure 8 As shown, it does not exhibit "pseudoplasticity".

[0055] Comparative Example 2

[0056] The implementation procedure is the same as in Example 2. The only difference between Comparative Example 2 and Example 2 is that the W matrix of the composite material involved in Comparative Example 2 does not contain AlN particles, and only contains 10% W. f / W-0.45%Fe composite material, i.e., uncoated short fiber W f The volume fraction is 10%, and the mass fraction of Fe, the activation sintering element in the W matrix, is 0.45%. A schematic diagram of the fiber location in the resulting composite material is shown below. Figure 6 As shown, the density is 99.9%, the room temperature thermal conductivity is 75.2 W / (m·K), and the room temperature fracture toughness is 4.59 MPa·m. 1 / 2 The corresponding load-displacement curves are as follows: Figure 9 As shown, it does not exhibit "pseudoplasticity".

[0057] Comparative Example 3

[0058] The implementation procedure is the same as in Example 3. The only difference between Comparative Example 3 and Example 3 is that the W matrix of the composite material involved in Comparative Example 3 does not contain AlN particles, and only contains 20% W. f / W-0.25%Fe composite material, i.e., uncoated short fiber W f The volume fraction is 20%, and the mass fraction of Fe, the activation sintering element in the W matrix, is 0.25%. A schematic diagram of the fiber location in the resulting composite material is shown below. Figure 6 As shown, the density is 99.8%, the room temperature thermal conductivity is 86.9 W / (m·K), and the room temperature fracture toughness is 5.14 MPa·m. 1 / 2 The corresponding load-displacement curves are as follows: Figure 10 As shown, it does not exhibit "pseudoplasticity".

Claims

1. A method for producing a tungsten-based composite material having high pseudo plasticity, characterized by, The method comprises the following steps: Step (1) Apply anhydrous ethanol or acetone to short fibers W f Ultrasonic cleaning is performed, followed by vacuum drying, and short fiber W is prepared in a certain proportion. f W powder, AlN powder and activated sintering element powder, including short fiber W f The addition amount is 10%~50% by volume, the AlN particle addition amount is 2.0%~15.0% by mass, and the addition amount of activation sintering element in the matrix is ​​0~1.0% by mass. The above raw materials are mixed evenly by ball milling to obtain mixed powder. The short fibers W f The potassium-doped tungsten fiber has a diameter of 50-250 μm, a length of 1-4 mm, and a potassium element content of 50-80 ppm; the W powder has a particle size of 500 nm-10 μm; and the AlN powder has a particle size of 20 nm-20 μm. Step (2) The mixed powder is densified and sintered, the mixed powder is sintered by using a spark plasma sintering process, the sintering temperature is 1500-2000 o C, the sintering pressure is 50-80 MPa, the holding and pressure maintaining time is 1-5 min, and the tungsten-based composite material is obtained.

2. The method of producing a tungsten-based composite material having high pseudoplasticity according to claim 1, characterized by, In step (1), the activated sintering element powder has a particle size of 1-5 μm.

3. The method of producing a tungsten-based composite material having high pseudo plasticity according to claim 1, characterized by, In step (1), when the raw materials are ball-mixed, the ball-milling tank and the grinding ball are made of hard alloy. The W powder, the AlN powder and the activated sintering element powder are placed in the ball-milling tank in proportion, the ball-to-material ratio is 5:1-10:1, the ball-milling time is 5-30 h, and the rotating speed is 200-400 r / min. Then the short fiber W f The short fiber W is placed in the ball-milling tank in proportion, the ball-to-material ratio is 1:4-2:1, the ball-milling time is 0.5-1 h, and the rotating speed is 50-150 r / min.

4. The method of producing a tungsten-based composite material having high pseudo plasticity according to claim 1, characterized by, In step (1), high-purity Ar is filled into the ball mill tank as a protective atmosphere during the mixing of raw materials, and in step (2), high-purity Ar is used as a protective atmosphere during the whole process of the spark plasma sintering.

5. The method of producing a tungsten-based composite material having high pseudo plasticity according to claim 1, characterized by, In step (2), the sintering process is performed at a temperature increasing rate of 50-100 o C / min to the target temperature, the sintering pressure is loaded to the target pressure synchronously with the temperature increasing process, the holding process is performed synchronously with the pressure holding process, and then the furnace is cooled down while the pressure is unloaded.

6. The method of producing a tungsten-based composite material having high pseudo plasticity according to claim 1, characterized by, sintering temperature is lower than 1800 o When the W base is sintered at C, activated sintering element powder, including iron powder, nickel powder, cobalt powder, aluminum powder, and palladium powder, is added to the W base, and the activated sintering element powder is added in an amount of 0.1-1.0% by mass.

7. A tungsten-based composite material having high pseudo plasticity, characterized in that, The tungsten-based composite material prepared by the method of any one of claims 1-6, wherein the matrix is a tungsten (W) matrix added with aluminum nitride (AlN) particles, and the toughening body is a short fiber W f .

8. The tungsten-based composite material with high pseudoplasticity according to claim 7, characterized in that, The activated sintering elements in the matrix include iron powder, nickel powder, cobalt powder, aluminum powder and palladium powder, and the addition amount is 0.1-1.0% by mass percentage.

9. The tungsten-based composite material with high pseudo-plasticity according to claim 7 or 8 is used for high-performance tungsten-based structural materials and is suitable for nuclear fusion facing plasma materials.

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