Soft Cu phase and Y2O3 hard particle coupled toughened high-thermal-conductivity tungsten material and preparation method thereof

Abstract

The invention provides a soft Cu phase and Y2O3 hard particle coupled toughened high-thermal-conductivity tungsten material and a preparation method, and belongs to the technical field of powder metallurgy engineering. The preparation method comprises the following steps: firstly, preparing a CuY precursor alloy through an electric arc melting technology, atomizing the CuY precursor alloy to prepare powder, taking the powder and industrial pure tungsten powder as raw materials, and proportioning by taking nominal components of a target tungsten alloy sintered body as a reference; then, carrying out high-energy ball milling on the composite powder to obtain uniformly mixed composite powder; and finally, the composite powder is subjected to hot pressed sintering, and the bulk tungsten-based composite material with the soft Cu phase separated out at the grain boundary and the Y2O3 hard particles evenly and dispersedly distributed is obtained. According to the method, the tungsten-based composite material strengthened and toughened by coupling the grain boundary Cu soft phase and the Y2O3 dispersed hard particles can be obtained, the low-temperature plastic deformation capacity of the product can be remarkably improved through introduction of the soft Cu phase, the heat conduction performance is improved, and a new thought is provided for developing a high-strength and high-conductivity tungsten material with high heat conductivity and excellent mechanical performance.

Description

Technical Field

[0001] The invention belongs to the technical field of powder metallurgy engineering, and relates to a high thermal conductivity tungsten material which is strengthened and toughened by coupling a soft Cu phase with Y2O3 hard particles, and a preparation method thereof. Background Art

[0002] Tungsten-based materials with high melting points can still maintain high strength at 1500°C. At the same time, they have good thermal conductivity, high sputtering threshold and low tritium retention. They are widely used in aerospace, national defense, nuclear fusion devices and other fields.

[0003] Pure tungsten has a ductile-brittle transition temperature of approximately 200-400°C, making it a brittle material at room temperature. The recrystallization temperature of processed pure tungsten is approximately 1200-1300°C. In high-heat-load service environments, the surface temperature can reach as high as 2000°C, causing recrystallization and deterioration of strength and ductility. Tungsten-based composites, including WK ​​alloys, carbides, and oxide-dispersion-strengthened tungsten, can significantly increase the recrystallization temperature but do not improve the material's room-temperature ductility. Y2O3, with its excellent thermal and chemical stability, is a key strengthening phase in dispersion-strengthened tungsten materials. Lian Youyun and others from the Southwest Institute of Nuclear Physics obtained a W-Y2O3 alloy with a density of 99.3% through hydrogen sintering and high-energy forging processes, and its room temperature tensile strength was only 480 MPa; they further obtained a W-Y2O3 rod with a diameter of 12 mm through a four-pass rotary forging process, and the room temperature tensile strength could be increased to 1.25 GPa (Tan Yang, Lian Youyun, Feng Fan, et al. Effect of deuterium plasma pre-irradiation on the thermal shock resistance of W-Y2O3 alloy [J]. Nuclear Fusion and Plasma Physics, 2019, 39(2): 151-157.). Ma Zongqing et al. from Tianjin University obtained a 2.3 mm thick bulk W-Y2O3 alloy by wet chemical method combined with hydrogen sintering and hot rolling. The tensile strength of the material can reach 1.17 GPa at 150°C (Li L, Dong Z, Ma Z, et al. Ultrahigh strength and toughness in W-Y2O3 alloy with bimodal and lamellar structures[J]. Materials Research Letters, 2023, 11(6): 439-445.). Existing experiments have shown that Y2O3 hard particles can effectively improve the strength and hardness of tungsten materials, but are not conducive to improving the room temperature and low temperature plasticity of the material. During the tensile process, stress concentration is easily generated at the junction of Y2O3 hard particles and tungsten matrix, inducing cracks and causing brittle intergranular fracture. It is particularly important to point out that the presence of Y2O3 oxide particles with poor thermal conductivity will seriously affect the thermal conductivity of the material (Lv Y, FanY, Zhao S, et al. The microstructure evolution, damage behavior and failure analysis of fine-grained W-Y2O3 composites under high transient thermal shock[J]. International Journal of Refractory Metals and Hard Materials, 2022, 107: 105905-1-12.).

[0004] Tungsten heavy alloys are multiphase composites with a tungsten matrix (typically ≥80 wt.%) and a metal with a lower melting point than tungsten (such as Ni-Fe, Ni-Co, and Ni-Cu) distributed as a secondary phase at the grain boundaries. This multiphase structure typically maintains the unique properties of the tungsten matrix while effectively improving the tungsten material's plastic deformation at room temperature or low temperatures (corresponding to the ductile-brittle transition temperature from room temperature to pure tungsten). These materials are typically produced by liquid-phase sintering. The sintering process easily induces the dissolution and precipitation of tungsten particles, resulting in a coarsening of the matrix grain size (20-60 μm) and a deterioration in the material's strength (German R.M., Sintered tungsten heavy alloys: Review of microstructure, strength, densification, and distortion [J], International Journal of Refractory Metals and Hard Materials, 2022, 108:105940-1-12.).

[0005] The present invention uses a special Cu-Y alloy as a precursor and successfully introduces a soft Cu phase with high electrical and thermal conductivity into a W-Y2O3 oxide particle dispersion-strengthened tungsten material, achieving complementary performance advantages between W-Y2O3 and tungsten heavy alloy materials, and obtaining a high thermal conductivity W-Y2O3 material that is synergistically strengthened and toughened by the soft Cu phase at the grain boundaries and the dispersed Y2O3 hard particles. This can significantly improve the low-temperature plastic deformation ability and thermal conductivity of existing W-Y2O3 materials: a composite powder of tungsten and Cu-Y alloy is prepared by high-energy ball milling. During the subsequent sintering process, the Y element absorbs free oxygen in the tungsten powder to form Y2O3 particles in situ at the grain boundaries and within the grains, achieving a uniform dispersion distribution of the oxide; while the Cu element is segregated and precipitated at the grain boundaries through diffusion. Compared to single oxide dispersion-strengthened tungsten alloys, the coupled strengthening of pure Cu and Y2O3 dispersed particles at the grain boundaries offers the following performance breakthroughs: While ensuring microstructure refinement, increased material density, and strength, the presence of soft Cu at the grain boundaries enhances the overall thermal conductivity of the material, suppresses intergranular cracking, and improves the material's low-temperature plasticity. This represents a new class of tungsten-based materials that combines high thermal conductivity with a well-balanced combination of strength and plasticity. Summary of the Invention

[0006] In order to overcome the problems of room temperature brittleness and insufficient thermal conductivity commonly found in existing oxide dispersion-strengthened tungsten materials, the present invention provides a high thermal conductivity tungsten material having improved thermal conductivity and low-temperature plasticity by a soft Cu phase at the grain boundaries and synergistically strengthened with dispersed Y2O3 hard particles, and a preparation method thereof. The present invention can solve the following problems existing in the current W-Y2O3 dispersion-strengthened tungsten materials: (1) a large decrease in the thermal conductivity of the material (generally more than 20% lower than that of pure tungsten at room temperature, see the aforementioned literature); (2) grain boundary brittleness caused by impurity elements such as oxygen in the matrix tungsten; (3) intergranular cracking that is prone to occur at the junction of W / Y2O3 hard particles; and (4) low density of the sintered material due to the initial compaction density.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for preparing a high-thermal conductivity tungsten material that is reinforced by coupling a soft Cu phase with Y2O3 hard particles. The method first prepares a CuY precursor alloy through arc melting technology, atomizes the precursor alloy into a powder, and uses it as a raw material together with industrial pure tungsten powder, with the ingredients being formulated based on the nominal composition of the target tungsten alloy sintered body. The precursor alloy is then subjected to high-energy ball milling in an anhydrous ethanol medium environment to obtain a uniformly mixed composite powder. Finally, the composite powder is hot-pressed and sintered to obtain a bulk tungsten-based composite material with a soft Cu phase precipitated at the grain boundaries and Y2O3 hard particles uniformly and dispersed. The method specifically includes the following steps:

[0009] The first step is to prepare Cu x Y 100-x Alloy powder;

[0010] Step 1.1, using industrial pure Cu and Y metal as raw materials, prepare a mixture with an atomic percentage composition of Cu x Y 100-x A precursor alloy (x=80~60, atomic percentage) is melted into an alloy ingot with uniform composition using a common non-consumable vacuum arc melting furnace, and the mass loss rate of the precursor alloy before and after melting does not exceed 0.5%.

[0011] Step 1.2: crush the alloy ingot and put it into the gas atomization powder making device for atomization powder making: melt it completely by medium frequency induction heating, spray it out by atomization technology, and cool it to obtain spherical particle powder with a particle size of 3~40μm. After screening, it is used for standby. x Y 100-x In the atomization powder making process, the atomizing gas is industrial pure argon, the spray pressure is 3-10 MPa, and the guide rod nozzle aperture of the gas atomization powder making device is 1-2 mm.

[0012] Step 2: Preparation of W+Cu x Y 100-x Composite powder;

[0013] Step 2.1, commercially available industrial pure tungsten powder (median particle size 4.2 μm) was selected as the matrix material, and the Cu obtained in step 1.2 was used as the matrix material. x Y 100-x Alloy powder is used as an additive, weighed and prepared to obtain a mixture, the composition formula of the mixture is W+(0.8~1.5wt.%)Cu x Y 100-x The corresponding nominal composition of the target alloy is W-(0.42~1.11wt.%)Cu-(0.21~0.72wt.%)Y, where Cu is the source of pure Cu soft phase in the target material, while Y provides a component for the in-situ formation of Y2O3 hard particles in the target material.

[0014] In step 2.2, the mixture from step 2.1 is placed in a ball mill along with grinding balls (ball-to-material ratio 5:1-10:1). High-energy ball milling is performed in anhydrous ethanol at a speed of 400-500 rpm for 20-30 hours. After milling, the powder is removed and vacuum-dried to obtain a composite powder with a median particle size of 0.5-2.0 μm. Step 3: Preparation of a W-Cu-Y sintered body.

[0015] Step 3.1: Place the composite powder obtained in the second step into a vacuum hot pressing sintering furnace for hot pressing and sintering to produce a W-(0.42~1.11wt.%)Cu-(0.21~0.72wt.%)Y bulk material, that is, a high thermal conductivity tungsten material. During the hot pressing sintering process of step 3.1, the blank preload pressure is 30MPa, and the vacuum degree during sintering is 3×10 -2 Pa, the hot pressing sintering process mainly goes through two stages: the sintering temperature of the first stage is 1400-1500℃, and the holding time is 60min; the sintering temperature of the second stage is 1700-1800℃, and the holding time is 2-4h. The pressure in both stages is 60MPa.

[0016] In step 3.2, after the hot-pressing sintering process is completed, the sintered body is cooled to room temperature in the furnace and removed for observation of density, phase composition, microstructure, and performance. The results indicate that the present invention produces a high-density, high-thermal-conductivity tungsten material synergistically strengthened and toughened by the soft Cu phase at the grain boundaries and the dispersed hard Y2O3 particles. Its density is over 99.0%; the room temperature thermal conductivity of the invented material is greater than 150W / m·K (pure tungsten is about 172W / m·K, and the existing room temperature thermal conductivity value of W-Y2O3 is generally more than 20% lower than that of pure tungsten, see the aforementioned literature), and its thermal conductivity value becomes closer to that of pure tungsten as the temperature increases, and is basically the same as pure tungsten above 500°C; the room temperature tensile fracture strength of the invented tungsten-based composite material is greater than 1000MPa, and the tensile strength and elongation at 200°C reach 850MPa and more than 7.0% respectively, which is significantly better than pure tungsten material under the same conditions (it has no tensile plastic deformation ability when the temperature is below 300°C, and its tensile fracture strength at room temperature and 200°C is 511MPa and 673MPa respectively).

[0017] A high thermal conductivity tungsten material with a soft Cu phase and Y2O3 hard particles coupled and toughened, wherein the high thermal conductivity tungsten material is based on W+Cu x Y 100-x The composite powder is obtained by ordinary hot pressing and sintering, while W+Cu x Y 100-x The composite powder is made of industrial pure W powder and Cu-rich Cu x Y 100-x Precursor alloy powders are mixed in specific proportions and then subjected to high-energy ball milling. This high-strength, high-toughness, and high-thermal conductivity tungsten material is characterized by the following microstructures: Cu concentrates at the tungsten grain boundaries, precipitating and existing as pure Cu soft-phase particles; Y absorbs free oxygen in the tungsten powder to form Y2O3 particles, which are dispersed within the tungsten matrix and at the grain boundaries.

[0018] Furthermore, the high thermal conductivity tungsten material can be further manipulated through subsequent plastic processing (such as hot rolling and high-energy forging) to further control the morphology and distribution of pure Cu and Y2O3 in the high thermal conductivity tungsten material, optimizing the coupled strengthening and toughening effect. This provides a new method for powder metallurgy to manufacture high thermal conductivity tungsten materials with an excellent balance of strength and plasticity.

[0019] The beneficial effects of the present invention are:

[0020] (1) The present invention is based on special Cu x Y 100-x Precursor alloy, prepared W+Cu x Y 100-x Composite powder; based on this, soft Cu particles were successfully introduced into W-Y2O3 material using conventional hot pressing sintering technology to obtain a tungsten-based composite material that is strengthened and toughened by coupling the soft Cu phase at the grain boundary and the dispersed hard particles of Y2O3.

[0021] (2) The introduction of the soft Cu phase not only significantly improves the low-temperature plastic deformation ability of the high-strength W-Y2O3 material; but also, due to the excellent electrical and thermal conductivity of Cu, the introduction of the soft Cu phase also significantly improves the thermal conductivity of the high-strength W-Y2O3 material.

[0022] (3) Special Cu involved in the present invention x Y 100-x The precursor alloy liquefies during sintering and reacts with impurities in the tungsten matrix. The Y element absorbs free oxygen from the tungsten powder, forming oxides in situ at grain boundaries and within the grains. This achieves uniform oxide distribution and has multiple effects, including dispersion strengthening, grain refinement, and grain boundary purification. Meanwhile, the Cu element precipitates at the tungsten grain boundaries as a pure Cu phase. With its high thermal conductivity and ductility, it enhances grain boundary bonding strength, improves the material's mechanical properties and transient thermal shock resistance, and ensures the high thermal conductivity of the tungsten-based composite material. This provides new insights into the development of high-strength, high-conductivity tungsten materials with both high thermal conductivity and excellent mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the synchrotron radiation X-ray diffraction spectrum of the W-0.70wt.%Cu-0.40wt.%Y sintered material obtained in Example 1.

[0024] Figure 2 This is the microstructure of the W-0.70wt.%Cu-0.40wt.%Y sintered body obtained in Example 1 (backscattered electron image).

[0025] Figure 3 %Cu-0.40wt.%Y sintered material obtained in Example 1 under uniaxial tension at 200°C (the dotted line is the engineering stress-strain curve of pure tungsten under the same conditions for reference and comparison).

[0026] Figure 4 This is a comparison curve of the thermal conductivity values ​​of the W-0.70wt.%Cu-0.40wt.%Y sintered body obtained in Example 1 and the reference pure tungsten at different temperatures. DETAILED DESCRIPTION

[0027] The specific preparation process and effects of the present invention are further described below through five examples.

[0028] Example 1 (W-0.70wt.%Cu-0.40wt.%Y material)

[0029] (1) The first step is to prepare Cu 71 Y 29 Alloy powder;

[0030] Step 1.1, using industrial pure Cu (purity>99.99%) and Y metal (purity>99.9%) as raw materials, prepare Cu 71 Y 29 The alloy was placed in a water-cooled copper crucible in a non-consumable vacuum arc melting furnace and vacuumed to 6×10 - 3 Pa, and filled with 0.01MPa of industrial pure Ar gas for non-consumable arc melting, the working current of the melting is 300A; the alloy is turned upside down and repeatedly melted 4 times to obtain a uniform composition of Cu 71 Y 29 For alloy ingots, the mass loss of the alloy before and after smelting is about 0.3%.

[0031] Step 1.2, Cu 71 Y 29 The alloy ingot is crushed and placed in a graphite crucible for atomization and powdering: Cu 71 Y 29 The alloy is completely melted and sprayed out for cooling using atomization technology. The atomizing gas spray pressure is 5 MPa and the nozzle aperture of the guide rod is 2 mm. Spherical powder material with a particle size of 10~25 μm is obtained and sieved for later use.

[0032] (2) The second step is to prepare W+Cu 71 Y 29 Composite powder;

[0033] In step 2.1, industrial pure tungsten powder (particle size 4.2 μm) was used to mix with Cu powder (particle size 18-23 μm) obtained in step 1.2. 71 Y 29 Powder (sieved with 600~800 mesh) is used as raw material, weighed and prepared into W+1.1wt.%Cu 71 Y 29 A composite powder (corresponding to the target alloy with a nominal composition of W, 0.70 wt.% Cu, and 0.40 wt.% Y) was prepared. The powders were mixed and loaded into a ball mill along with grinding balls (a ball-to-material ratio of 5:1). High-energy ball milling was performed in anhydrous ethanol for 25 hours at a speed of 450 rpm. The milled powder was removed and dried in a vacuum drying oven to obtain a composite powder with a median particle size of 2.0 μm.

[0034] (3) The third step is to prepare a W-0.70wt.%Cu-0.40wt.%Y sintered body by vacuum hot pressing;

[0035] Step 3.1: Pour about 500 g of the composite powder obtained in step 2 into a graphite mold, place it in a vacuum hot pressing sintering furnace, and evacuate to 3×10 -2Pa, while simultaneously applying a preload of 30 MPa. The temperature was then raised to 1450°C at a rate of 10°C / min and held for 60 minutes. The temperature was then further raised to 1800°C and held for 3 hours. The applied pressure during both holding stages was 60 MPa. After sintering, the sample was cooled to room temperature in the furnace and removed for experimental observation.

[0036] The density of the W-0.70wt.%Cu-0.40wt.%Y sintered body was measured by drainage method to be 99.2%. The synchrotron radiation X-ray diffraction spectrum (SR-XRD) of the sintered body sample is shown in the attached figure. Figure 1 As shown in the figure, the strong diffraction peaks are all from the body-centered cubic tungsten matrix (corresponding to the standard diffraction spectrum of PDF#97-015-1760), and the remaining low-intensity diffraction peaks can be respectively calibrated by the face-centered cubic pure Cu phase (PDF#04-001-2764) and the face-centered cubic Y2O3 phase (PDF#97-015-1760), indicating that the main phase of the matrix of the obtained sintered material is body-centered cubic tungsten, which is accompanied by a certain amount of pure Cu and Y2O3 precipitated phase. The microstructure characteristics of the sintered sample are shown in the attached figure. Figure 2 As shown in the figure, it can be seen that there are nearly round particles of varying sizes dispersed in the grain boundaries and inside the grains, with a size ranging from 0.2 to 3 μm. Combining the composition analysis and SR-XRD test results, it can be seen that it corresponds to Y2O3 (see Appendix Figure 2 Similarly, it was confirmed that the larger particles appearing at the grain boundaries were pure Cu phases with a size of 2-3 μm, as shown in the attached figure. Figure 2 The above results show that the technology of the present invention has successfully prepared a bulk tungsten-based composite material with soft Cu phase precipitated at the grain boundary and Y2O3 hard particles uniformly and dispersedly distributed.

[0037] Further performance test results show that the room temperature uniaxial tensile strength of the new tungsten-based material obtained by the present invention is 1120 MPa, and it has excellent low-temperature plasticity and thermal conductivity. Figure 3 The following example shows the tensile engineering stress-strain curve of a W-0.70wt.%Cu-0.40wt.%Y sintered sample at 200°C, and also shows the experimental data of a pure tungsten reference sample under the same experimental conditions. The results show that the uniaxial tensile strength and elongation of the sintered sample at 200°C reach 900MPa and 8.3% respectively, while pure tungsten undergoes brittle fracture at 200°C when the loading stress reaches 673MPa. Figure 4A temperature-dependent thermal conductivity curve for a W-0.70wt.%Cu-0.40wt.%Y sintered sample is presented. Its room-temperature thermal conductivity is slightly lower than that of pure tungsten, at 164 W / m·K (under the same conditions, the room-temperature thermal conductivity of a single W-0.4wt.%Y material without Cu precipitation is only 120 W / m·K). As the temperature increases, the thermal conductivity of this material approaches that of pure tungsten, reaching values ​​essentially identical to those of pure tungsten above 500°C.

[0038] Example 2 (W-0.42wt.%Cu-0.38wt.%Y material) (1) The first step is to prepare Cu 60 Y 40 Alloy powder;

[0039] Step 1.1, using industrial pure Cu (purity>99.99%) and Y metal (purity>99.9%) as raw materials, prepare Cu 60 Y 40 The alloy was placed in a water-cooled copper crucible in a non-consumable vacuum arc melting furnace and vacuumed to 6×10 - 3 Pa, and filled with 0.01MPa of industrial pure Ar gas for non-consumable arc melting, the working current of the melting is 300A; the alloy is turned upside down and repeatedly melted 4 times to obtain a uniform composition of Cu 60 Y 40 For alloy ingots, the alloy mass loss before and after smelting is about 0.5%.

[0040] Step 1.2, Cu 60 Y 40 The alloy ingot is crushed and placed in a graphite crucible, and the Cu 60 Y 40 The alloy is completely melted and sprayed out using atomization technology. The atomizing gas spray pressure is 3 MPa and the guide rod nozzle aperture is 1.5 mm. Spherical powder with a particle size of 5~30 μm is obtained and sieved for later use.

[0041] (2) The second step is to prepare W+Cu 60 Y 40 Composite powder;

[0042] In step 2.1, industrial pure tungsten powder (particle size 4.2 μm) was mixed with Cu powder (particle size 13-23 μm) obtained in step 1.2. 60 Y 40 Powder is used as raw material, weighed and prepared into W+0.8wt.%Cu 60 Y 40The composite powder (corresponding to the target alloy with a nominal composition of W-0.42wt.%Cu-0.38wt.%Y) was loaded into a ball mill together with grinding balls at a ball-to-material ratio of 7:1 and subjected to high-energy ball milling in anhydrous ethanol medium for 20 hours at a speed of 500 rpm. The W+Cu composite powder with a median particle size of 2.0 μm was obtained. 60 Y 40 Composite powder.

[0043] (3) The third step is to prepare a W-0.42wt.%Cu-0.38wt.%Y sintered body by vacuum hot pressing;

[0044] Step 3.1: Place 500 g of the composite powder obtained in step 2.1 into a graphite mold, place it in a vacuum hot pressing sintering furnace, preload it with 30 MPa, and evacuate it to 3×10 -2 The sample was then heated to 1400°C and held for 60 minutes. The temperature was then raised to 1800°C and held for 2 hours. The applied pressure during the sintering process was 60 MPa. Finally, the sample was cooled to room temperature and removed for experimental observation.

[0045] The density of the W-0.42wt.%Cu-0.38wt.%Y sintered body measured by the drainage method was 99.0%. SR-XRD and scanning electron microscopy analysis results showed that the matrix of the sintered body was body-centered cubic tungsten, with pure Cu phase and Y2O3 particles generated on the matrix. The Y2O3 particles were dispersed and evenly distributed within the crystals and grain boundaries of the matrix tungsten grains, with a size between 0.2-2μm; the pure Cu phase particles were slightly larger, at 1-2μm, and precipitated only at the grain boundaries of the tungsten grains. The results of mechanical and thermal conductivity tests showed that the room temperature uniaxial tensile fracture strength of the W-0.42wt.%Cu-0.38wt.%Y sample was 1200MPa, and its uniaxial tensile strength and elongation at 200°C were 950MPa and 7.0%, respectively; the room temperature thermal conductivity value was 156W / m·K; and the trend of its thermal conductivity value with temperature was similar to that of the material in Example 1.

[0046] Example 3 (W-0.59wt.%Cu-0.21wt.%Y material)

[0047] (1) The first step is to prepare Cu 80 Y 20 Alloy powder;

[0048] Step 1.1, using industrial pure Cu (purity>99.99%) and Y metal (purity>99.9%) as raw materials, prepare Cu 80 Y 20 The alloy was placed in a water-cooled copper crucible in a vacuum arc furnace and evacuated to 6×10 -3Pa, filled with 0.01MPa pure Ar gas protection for non-consumable arc melting, the melting current is 300A; flip upside down and repeatedly melt 4 times to obtain Cu with uniform composition 80 Y 20 For alloy ingots, the alloy mass loss before and after smelting is about 0.3%.

[0049] Step 1.2, Cu 80 Y 20 After the alloy ingot is crushed, it is placed in a graphite crucible and completely melted by medium-frequency induction heating. It is then sprayed out and powdered using atomization technology. The atomizing gas spray pressure is 10 MPa, and the nozzle aperture of the guide rod is 1 mm. Spherical powder with a particle size of 3-30 μm is obtained and sieved for later use.

[0050] (2) The second step is to prepare W+Cu 80 Y 20 Composite powder;

[0051] In step 2.1, industrial pure tungsten powder (particle size 4.2 μm) was used to mix with Cu powder (particle size 6.5-18 μm) obtained in step 1.2. 80 Y 20 Powder is used as raw material, weighed and prepared into W+0.8wt.%Cu 80 Y 20 The composite powder (corresponding to the target alloy with a nominal composition of W-0.59wt.%Cu-0.21wt.%Y) was packed with grinding balls at a ball-to-material ratio of 10:1 and milled in anhydrous ethanol at a high speed of 500rpm for 30h. The W+Cu composite powder with a median particle size of 0.5μm was obtained. 80 Y 20 Composite powder.

[0052] (3) The third step is to prepare a W-0.59wt.%Cu-0.21wt.%Y sintered body by vacuum hot pressing;

[0053] Step 3.1: Place 500 g of the composite powder obtained in step 2.1 into a graphite mold, place it in a vacuum hot pressing sintering furnace, preload it with 30 MPa, and evacuate it to 3×10 -2 The sample was then heated to 1500°C and held for 60 minutes. The temperature was then raised to 1700°C and held for 4 hours. The applied pressure during the sintering process was 60 MPa. Finally, the sample was cooled to room temperature and removed for experimental observation.

[0054] The W-0.42wt.%Cu-0.38wt.%Y sintered compact, measured by the water displacement method, had a density of 99.3%. SR-XRD and scanning electron microscopy analysis revealed a body-centered cubic tungsten matrix, with pure Cu phases and Y2O3 particles of 0.5-1.5μm in size formed on the tungsten grains. The Y2O3 particles were dispersed and evenly distributed within the matrix grains and at their grain boundaries, while pure Cu phase particles were found only at the tungsten grain boundaries. Mechanical and thermal conductivity testing revealed that the W-0.42wt.%Cu-0.38wt.%Y sample exhibited a room-temperature uniaxial tensile strength of 1030MPa, a uniaxial tensile strength of 850MPa, and an elongation of 9.8% at 200°C. The room-temperature thermal conductivity was 170W / m·K, and the temperature-dependent thermal conductivity trend was similar to that of the material in Example 1.

[0055] Example 4 (W-0.78wt.%Cu-0.72wt.%Y material)

[0056] (1) The first step is to prepare Cu 60 Y 40 Alloy powder;

[0057] Step 1.1, using industrial pure Cu with purity >99.99% and Y metal with purity >99.9% as raw materials, prepare Cu 60 Y 40 The alloy was placed in a water-cooled copper crucible in a non-consumable vacuum arc furnace and evacuated to 6×10 -3 Pa, filled with 0.01MPa industrial pure Ar gas protection, non-consumable arc melting, melting working current is 300A; repeated melting 4 times, obtain uniform composition of Cu 60 Y 40 Alloy ingot, the sample mass loss before and after smelting is about 0.5%.

[0058] Step 1.2, Cu 60 Y 40 The alloy ingot is crushed and placed in a graphite crucible, which is fully melted by medium-frequency induction heating. The powder is made by atomization technology with an atomizing gas spray pressure of 7 MPa and a guide rod nozzle aperture of 2 mm. Spherical powder with a particle size of 10-40 μm is obtained and sieved for later use.

[0059] (2) The second step is to prepare W+Cu 60 Y 40 Composite powder;

[0060] In step 2.1, industrial pure tungsten powder (particle size 4.2 μm) and Cu 2+ powder (particle size 10-18 μm) obtained in step 1.2 were used. 60 Y 40Powder is used as raw material, weighed and prepared into W+1.5wt.%Cu 60 Y 40 The composite powder (corresponding to the target alloy with nominal composition of W-0.78wt.%Cu-0.72wt.%Y) was loaded into a ball mill together with grinding balls (ball-to-material ratio 8:1) and ball milled in anhydrous ethanol medium for 25 hours at a speed of 400 rpm. The W+Cu composite powder with a median particle size of 1.8μm was obtained. 60 Y 40 Composite powder.

[0061] (3) The third step is to prepare a W-0.78wt.%Cu-0.72wt.%Y sintered body by vacuum hot pressing;

[0062] Step 3.1: Place 500 g of the composite powder obtained in step 2.1 into a graphite mold in a vacuum hot pressing sintering furnace, preload it with 30 MPa, and evacuate it to 3×10 -2 The sample was then heated to 1400°C and held for 60 minutes. The temperature was then raised to 1800°C and held for 2.5 hours. The applied pressure during the sintering process was 60 MPa. Finally, the sample was cooled to room temperature and removed for experimental observation.

[0063] The density of the W-0.78wt.%Cu-0.72wt.%Y sintered body measured by the drainage method was 99.3%. SR-XRD and scanning electron microscopy analysis results showed that the matrix of the sintered body was body-centered cubic tungsten, on which pure Cu and Y2O3 phases were generated. The Y2O3 particles were dispersed and evenly distributed within the crystals and grain boundaries of the matrix tungsten grains, with a size between 0.5-2μm; pure Cu phase particles were only visible at the grain boundaries of the tungsten grains, with a size of around 1.5μm. The results of mechanical and thermal conductivity tests showed that the room temperature uniaxial tensile fracture strength of the W-0.42wt.%Cu-0.38wt.%Y sample was 1290MPa, and its uniaxial tensile strength and elongation at 200°C were 970MPa and 9.2%, respectively; the room temperature thermal conductivity value was 150W / m·K; and the trend of its thermal conductivity value changing with temperature was similar to that of the material in Example 1.

[0064] Example 5 (W-1.11wt.%Cu-0.39wt.%Y material)

[0065] (1) The first step is to prepare Cu 80 Y 20 Alloy powder;

[0066] Step 1.1, using industrial pure Cu (purity>99.99%) and Y metal (purity>99.9%) as raw materials, prepare Cu 80 Y 20 The alloy was placed in a water-cooled copper crucible in a vacuum arc furnace and evacuated to 6×10-3 Pa, filled with 0.01MPa pure Ar gas protection for non-consumable arc melting, the melting current is 300A; repeated melting 4 times to obtain uniform composition of Cu 80 Y 20 For alloy ingots, the alloy mass loss before and after smelting is about 0.3%.

[0067] Step 1.2, Cu 80 Y 20 After the alloy ingot is crushed, it is placed in a graphite crucible and completely melted by medium-frequency induction heating. The alloy is then powdered using liquid atomization technology. The atomizing gas spray pressure is 9 MPa, and the nozzle aperture of the guide rod is 2 mm. Spherical powder with a particle size of 8 to 35 μm is obtained and sieved for later use.

[0068] (2) The second step is to prepare W+Cu 80 Y 20 Composite powder;

[0069] In step 2.1, industrial pure tungsten powder (particle size 4.2 μm) was used to mix with Cu powder (particle size 18-25 μm) obtained in step 1.2. 80 Y 20 Powder is used as raw material, weighed and prepared into W+1.5wt.%Cu 80 Y 20 The composite powder (corresponding to the target alloy with a nominal composition of W-1.11wt.%Cu-0.39wt.%Y) was packed with grinding balls at a ball-to-material ratio of 8:1 and milled in anhydrous ethanol at a high speed of 450rpm for 25h. The W+Cu composite powder with a median particle size of 2.0μm was obtained. 80 Y 20 Composite powder.

[0070] (3) The third step is to prepare a W-1.11wt.%Cu-0.39wt.%Y sintered body by vacuum hot pressing;

[0071] Step 3.1: Place 500 g of the composite powder obtained in step 2.1 into a graphite mold, place it in a vacuum hot pressing sintering furnace, preload it with 30 MPa, and evacuate it to 3×10 -2 The sample was then heated to 1500°C and held for 60 minutes. The temperature was then raised to 1800°C and held for 3 hours. The applied pressure during the sintering process was 60 MPa. Finally, the sample was cooled to room temperature and removed for experimental observation.

[0072] The density of the W-1.11wt.%Cu-0.39wt.%Y sintered body, measured by the water displacement method, was 99.5%. SR-XRD and scanning electron microscopy analysis revealed that the sintered body matrix was body-centered cubic tungsten, with pure Cu phases approximately 1-2μm in size and Y2O3 particles 0.8-1.5μm in size associated with the tungsten grains. The Y2O3 particles were dispersed and evenly distributed within the matrix grains and at the grain boundaries, while pure Cu phase particles were only present at the tungsten grain boundaries. Mechanical and thermal conductivity testing revealed that the W-1.11wt.%Cu-0.39wt.%Y sample had a room temperature uniaxial tensile strength of 1050MPa, and its uniaxial tensile strength and elongation at 200°C reached 860MPa and 10.1%, respectively. The room temperature thermal conductivity was 168W / m·K, and the temperature-dependent thermal conductivity trend was similar to that of the material in Example 1.

[0073] The above-mentioned embodiment results show that: the present invention is based on the special W+Cu x Y 100-x The composite powder is prepared through conventional vacuum hot pressing sintering technology to produce a W-Y2O3 composite material with uniform structure, high density and pure Cu phase precipitation at the grain boundary. That is, the Cu element is distributed at the tungsten grain boundary in the form of pure Cu phase. After the Y element absorbs the free oxygen in the raw material powder, it forms oxides in situ at the grain boundary and within the grain, realizing the uniform and dispersed distribution of Y2O3 oxide in the matrix tungsten particles. Finally, a high thermal conductivity tungsten-based material is obtained which is strengthened and toughened by the coupling of the soft Cu phase at the grain boundary and the dispersed Y2O3 hard particles.

[0074] The above-described embodiments merely express the implementation methods of the present invention, but should not be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high thermal conductivity tungsten material by coupling and toughening a soft Cu phase with Y2O3 hard particles, characterized in that: The preparation method comprises the following steps: firstly, preparing a CuY precursor alloy by arc melting technology, atomizing and pulverizing the alloy and using it together with industrial pure tungsten powder as raw materials, and preparing the ingredients based on the nominal composition of the target tungsten alloy sintered body; then, placing the alloy in an anhydrous ethanol medium environment and performing high-energy ball milling to obtain a uniformly mixed composite powder; and finally, hot pressing and sintering the composite powder to obtain a tungsten-based composite material in which a soft Cu phase precipitates at the grain boundaries and Y2O3 hard particles are uniformly and dispersedly distributed, thereby obtaining a high thermal conductivity tungsten material.

2. The method for preparing a high thermal conductivity tungsten material having a soft Cu phase coupled with Y2O3 hard particles and toughened according to claim 1, characterized in that: The preparation method specifically comprises the following steps: The first step is to prepare Cu x Y 100-x Alloy powder; Step 1.1, using industrial pure Cu and Y metal as raw materials, prepare a mixture with an atomic percentage composition of Cu x Y 100-x A precursor alloy of , wherein x = 80~60, is melted into an alloy ingot with uniform composition; Step 1.2: crush the alloy ingot and put it into the gas atomization powder making device for atomization powder making to obtain Cu x Y 100-x Alloy powder; Step 2: Preparation of W+Cu x Y 100-x Composite powder; Step 2.1, select industrial pure tungsten powder as the matrix material, and mix the Cu x Y 100-x Alloy powder is used as an additive to prepare a mixture. The general formula of the mixture is W+(0.8~1.5wt.%)Cu x Y 100-x The corresponding nominal composition of the target alloy is W-(0.42~1.11wt.%)Cu-(0.21~0.72wt.%)Y, where Cu is the source of pure Cu soft phase in the target material, and Y provides the component for the in-situ formation of Y2O3 hard particles in the target material; Step 2.2: The mixture in step 2.1 is placed in a ball mill together with the grinding balls. After high-energy ball milling in anhydrous ethanol, the powder is taken out and vacuum dried to obtain W+Cu x Y 100-x Composite powder; The third step is to prepare a W-Cu-Y sintered body; Step 3.1, the W+Cu x Y 100-x The composite powder was placed in a vacuum hot pressing sintering furnace for hot pressing and sintering to produce W-(0.42~1.11wt.%)Cu-(0.21~0.72wt.%)Y bulk materials; Step 3.2: After the hot pressing sintering process is completed, the sintered body is cooled to room temperature in the furnace to obtain a high thermal conductivity tungsten material.

3. The method for preparing a high thermal conductivity tungsten material having a soft Cu phase coupled with Y2O3 hard particles and strengthened by toughening according to claim 2, characterized in that: In the step 1.1, a uniform alloy ingot is melted in a common non-consumable vacuum arc melting furnace, and the mass loss rate of the precursor alloy before and after melting does not exceed 0.5%.

4. The method for preparing a high thermal conductivity tungsten material having a soft Cu phase coupled with Y2O3 hard particles and strengthened by toughening according to claim 2, characterized in that: In step 1.2, the alloy ingot is completely melted by medium frequency induction heating, and is sprayed and cooled by atomization technology to obtain spherical particle powder with a particle size of 3 to 40 μm. After screening, Cu x Y 100-x Alloy powder; in the atomization powder making process, the atomizing gas is industrial pure argon, the spray pressure is 3~10MPa, and the aperture of the guide rod nozzle of the gas atomization powder making device is 1~2mm.

5. The method for preparing a high thermal conductivity tungsten material having a soft Cu phase coupled with Y2O3 hard particles and strengthened by toughening according to claim 2, characterized in that: In the step 2.2, the ball-to-material ratio of the high-energy ball milling is 5:1-10:1; the ball milling speed is 400-500 rpm, and the ball milling time is 20-30 h.

6. The method for preparing a high thermal conductivity tungsten material having a soft Cu phase coupled with Y2O3 hard particles and strengthened by toughening according to claim 2, characterized in that: In step 2.2, W+Cu x Y 100-x The median particle size of the composite powder is 0.5~2.0μm.

7. The method for preparing a high thermal conductivity tungsten material having a soft Cu phase coupled with Y2O3 hard particles and strengthened by toughening according to claim 2, characterized in that: During the hot pressing sintering process of step 3.1, the blank preload pressure is 30 MPa, and the vacuum degree during sintering is 3×10 -2 Pa, the hot pressing sintering process mainly goes through two stages: the sintering temperature of the first stage is 1400-1500℃, and the holding time is 60min; the sintering temperature of the second stage is 1700-1800℃, and the holding time is 2-4h. The pressure in both stages is 60MPa.

8. A high thermal conductivity tungsten material with a soft Cu phase coupled with Y2O3 hard particles for toughening, characterized in that: The high thermal conductivity tungsten material is prepared by the preparation method described in any one of claims 1 to 7, and its organizational characteristics are: the Cu element is segregated at the tungsten grain boundaries, precipitated and exists in the form of pure Cu soft phase particles; the Y element absorbs free oxygen in the tungsten powder to form Y2O3 particles, which are dispersed in the crystals and grain boundaries of the tungsten matrix.

9. The high thermal conductivity tungsten material according to claim 8, characterized in that: The high thermal conductivity tungsten material has a density of over 99.0%, a room temperature thermal conductivity greater than 150 W / m·K, a room temperature tensile strength greater than 1000 MPa, and a tensile strength and elongation of over 850 MPa and 7.0% at 200°C, respectively.

10. The high thermal conductivity tungsten material according to claim 8, characterized in that: The high thermal conductivity tungsten material can also be used to control the morphology and distribution of pure Cu and Y2O3 in the high thermal conductivity tungsten material through subsequent plastic processing to optimize the coupling strengthening and toughening effect.

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