Tungsten-based alloy preparation method for reducing irradiation vacancy defect concentration

Abstract

The invention provides a tungsten-based alloy preparation method for reducing irradiation vacancy defect concentration, and belongs to the technical field of tungsten-based alloy design optimization. On the basis of the alloy composition for reducing the irradiation vacancy defect of the tungsten-based alloy according to the size of the'mixed dumbbell 'binding energy, the composition of the tungsten-based alloy designed according to the size of the'mixed dumbbell' binding energy is W-xRe-yCr, W powder, Re powder and Cr powder are mixed according to the mass and subjected to ball milling for a certain time, then a ternary alloy block is obtained through spark plasma sintering, and the tungsten-based alloy with the irradiation vacancy defect is obtained. The method comprises the following steps: firstly, carrying out hot rolling and annealing heat preservation treatment, and finally, carrying out Fe ion irradiation on the compact ternary alloy, so that the irradiated ternary alloy has a relatively obvious influence on reduction of irradiation vacancy defect concentration, and meanwhile, the ternary alloy shows a synergistic effect which is remarkably superior to that of binary alloys (such as W-Re and W-Cr) in the aspect of irradiation resistance.

Description

Technical Field

[0001] This invention belongs to the field of tungsten-based alloy design and optimization technology, specifically relating to a method for preparing tungsten-based alloys that reduces the concentration of irradiation vacancy defects. Background Technology

[0002] Tungsten (W) is considered an ideal material for the first wall of nuclear fusion reactors due to its high melting point, low coefficient of thermal expansion, high thermal conductivity (173 W / m·K), and low hydrogen (H) isotope retention rate, making it a core candidate material for international fusion devices such as ITER. However, when tungsten is bombarded by high-energy neutrons (14 Mev) in its service environment, it generates a large number of high-concentration point defects and void accumulation defects. These microscopic defects induced by radiation gradually accumulate and affect the further embrittlement, swelling, and even cracking of tungsten properties, greatly limiting its reliability and stability under dynamic thermal load environments. Therefore, it is crucial to design and develop a tungsten-based alloy with high radiation resistance and effectively reduce the concentration of radiation vacancy defects.

[0003] The most significant characteristic of tungsten materials during irradiation damage is the high concentration of interstitial atoms. According to relevant literature, X atoms in WX alloys can capture irradiation-induced W interstitial defects, forming a possible configuration: <110> The WX “hybrid dumbbell” structure is designed in the following direction. This hybrid dumbbell structure can reduce the concentration of vacancy defects to some extent. Therefore, considering the stability of this “hybrid dumbbell”, common WX alloying elements are screened and designed. Among the common alloying elements that can be selected, there are chromium (Cr), rhenium (Re), molybdenum (Mo), and tantalum (Ta). Among them, the binding energy of W interstitial atoms with Cr substitution atoms is the largest (3.02 eV), the binding energy with Re substitution atoms is 0.79 eV, the binding energy with Mo substitution atoms is 0.35 eV, and the binding energy with Ta substitution atoms is -0.72 eV. The sign of the binding energy indicates whether a “hybrid dumbbell” structure can be formed. The higher or lower the binding energy, the stronger the stability of the “hybrid dumbbell” structure. The stronger the binding energy, the better the effect of reducing vacancy defects after irradiation. Therefore, based on this inference, a W-Re-Cr ternary alloy is designed. Summary of the Invention

[0004] The purpose of this invention is to propose a method for preparing tungsten-based alloys that reduces the concentration of irradiation vacancy defects. The prepared W-Re-Cr ternary alloy exhibits a synergistic effect in radiation resistance that is significantly better than that of binary alloys (such as W-Re and W-Cr).

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing a tungsten-based alloy with reduced irradiation vacancy defect concentration includes the following steps:

[0007] (1) Powder metallurgy of W-xRe-yCr: The W-xRe-yCr ternary alloy was designed based on the strength of the mixed dumbbell bonding energy. The alloy powder was obtained by wet ball milling according to the mass ratio of tungsten (W) powder, rhenium (Re) powder and chromium (Cr) powder of 90~99.8:0.1~5:0.1~5.

[0008] (2) Sintering and forming process of W-xRe-yCr: A certain amount of ball-milled alloy powder is weighed and placed into a mold. The mold is then placed in a discharge plasma sintering furnace for pressure sintering to obtain an alloy block.

[0009] (3) Hot rolling treatment of W-xRe-yCr: The alloy block obtained by sintering is hot rolled at a certain temperature. For different passes, the deformation amount of each pass is reasonably allocated according to the total deformation amount, and finally W-xRe-yCr alloy is prepared.

[0010] (4) Annealing treatment of W-xRe-yCr: The W-xRe-yCr alloy obtained by hot rolling is annealed;

[0011] (5) Irradiation treatment of W-xRe-yCr: The W-xRe-yCr alloy obtained by annealing is polished to obtain an irradiated sample, and then subjected to irradiation treatment.

[0012] As a preferred embodiment of the present invention, in step (1), the ball milling time is 32-40 h, the ball milling speed is 300-500 rpm, and the ball-to-material ratio is 10-15:1. Alcohol is added as a process control agent during the wet ball milling process, and at least two different diameters of grinding balls are used. The particle size distribution of tungsten (W) powder, rhenium (Re) powder, and chromium (Cr) powder are all in the range of 1-10 µm, and the particle sizes of the three powders used are similar.

[0013] As a preferred technical solution of the present invention, in step (2), the alloy powder is loaded into a graphite mold for SPS discharge plasma furnace. The powder and the mold are separated by carbon paper and Ta foil. The powder is pre-pressed at 10 MPa. After pre-pressing, the powder is placed in the furnace. The pressure in the furnace is evacuated to a vacuum state and sintering begins. The current and initial pressure are set to ensure that the sintering process is as follows: the sample is heated from room temperature to 600 ℃ at 100 ℃ / min and the pressure is 15 MPa; then the temperature is increased from 600 ℃ to 1000 ℃ at 100 ℃ / min and held for 3 min, and the pressure is increased from 15 MPa to 40 MPa; then the temperature is increased from 1000 ℃ to 1500 ℃ at 100 ℃ / min and held for 5 min, and the pressure is increased from 40 MPa to 50 MPa; after successful sintering, the sample is allowed to cool in the furnace and then removed.

[0014] As a preferred technical solution of the present invention, in step (3), hot rolling is carried out in three processes at 1200 ℃, and the deformation amount is controlled to be 10%, 6% and 4% for each process.

[0015] As a preferred technical solution of the present invention, in step (4), the rolled alloy is annealed at a temperature of 900~1300 ℃ and a holding time of 30~120 min.

[0016] As a preferred technical solution of the present invention, in step (5), the sample is ground and polished to a mirror surface without obvious scratches in the order of grinding and polishing; then irradiation treatment is performed, and the irradiation process is 6.4 MeV Fe ions irradiated at 800 °C.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] 1. Complementarity and synergistic enhancement of defect trapping: Under irradiation, the binding energy between Cr and W interstitial atoms is the highest (3.02 eV), which can form a highly stable... <110> The "hybrid dumbbell" structure effectively traps irradiation defects and suppresses the aggregation of vacancy-type defects. While the binding energy of Re (0.79 eV) is lower than that of Cr, it is still positive, providing auxiliary defect-trapping capabilities. Simultaneously, it avoids the interference risks from elements with negative binding energy, such as Ta (e.g., the W-Ta system may exacerbate defect aggregation). Compared to binary alloys such as W-Cr and W-Re, the ternary alloy design enables the formation of a multi-level, multi-mechanism defect-trapping system based on binary alloys, significantly improving radiation resistance.

[0019] 2. Optimization of Mechanical Properties and Suppression of Brittleness: Pure W and W-Cr alloys are prone to embrittlement at high temperatures, while W-Re alloys are prone to forming brittle σ phases after irradiation, affecting the service life of the material. In this invention, the introduction of Re not only improves the high-temperature strength and creep resistance of the alloy, but also alleviates the embrittlement tendency of the W-Re system by suppressing the formation of σ phases. Cr further enhances the structural stability of the alloy. The synergistic effect of these three elements allows the W-Re-Cr alloy to maintain excellent radiation resistance while also possessing good high-temperature mechanical properties and toughness.

[0020] Therefore, this invention designs tungsten-based alloys by combining different energy levels. The design of the W-Re-Cr alloy fills the gaps in the existence of previous binary alloys and ensures the advantage of significantly reducing the concentration of irradiation vacancy defects. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the unit cell of a W-Re-Cr alloy after irradiation damage.

[0022] Figure 2The TEM results are for the W-5Re-1Cr sample after irradiation.

[0023] Figure 3 The TEM results are for the W-5Re sample after irradiation.

[0024] Figure 4 The TEM results are for the W-1Cr sample after irradiation.

[0025] Figure 5 The results are TEM images of a pure W sample after irradiation. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings.

[0027] In this embodiment of the invention, the void aggregation of W-Re-Cr ternary alloy and binary alloy WX (X=Re or Cr) and pure W under the same irradiation parameters and temperature was compared and characterized by TEM.

[0028] Example 1

[0029] Preparation of W-Re-Cr alloy:

[0030] (1) Tungsten (W) powder, rhenium (Re) powder, and chromium (Cr) powder with a particle size D90 of 10 µm were placed into a ball mill jar at a mass ratio of 94:5:1 and a ball-to-powder ratio of 10:1. At the same time, an appropriate amount of 99.9% pure alcohol was added to just submerge the balls and powder as a process control agent (PCA). Then, the ball mill jar was placed in a glove box and filled with argon gas to prevent oxidation of the powder during the ball milling process. Finally, it was placed in a high-energy planetary ball mill for ball milling at a speed of 400 rpm for a cycle of 32 h, with 30 min of forward and reverse rotation and a 20 min interval.

[0031] (2) Place the sample in a vacuum oven for drying, then sieve the powder (100 mesh). Take 25 g of the powder and place it in a Φ20 graphite mold. Separate the powder and the mold with carbon paper and Ta foil. First, pre-press it at 10 MPa. After pre-pressing, place it in the furnace. The pressure in the furnace is evacuated to a vacuum state and sintering begins. Set the current and initial pressure to ensure that the sintering process is as follows: the sample is heated from room temperature to 600 ℃ at 100 ℃ / min and the pressure is 15 MPa; then the temperature is increased from 600 ℃ to 1000 ℃ at 100 ℃ / min and held for 3 min, and the pressure is increased from 15 MPa to 40 MPa; then the temperature is increased from 1000 ℃ to 1500 ℃ at 100 ℃ / min and held for 5 min, and the pressure is increased from 40 MPa to 50 MPa; after successful sintering, wait for the furnace to cool and then take it out.

[0032] (3) After sintering, hot rolling is carried out in three processes at a high temperature of 1200 ℃, with each deformation amount being 10%, 6% and 4%; after hot rolling, the product is taken out and annealed at a temperature of 1000 ℃ for 60 min.

[0033] (4) The samples were wire-cut into squares measuring 5×5×1.2 mm. After repeated grinding and polishing with 120, 240, 320, 400, 500, 600, 800, 1000 and 1200 grit sandpaper, W-5Re-1Cr irradiated samples were obtained. The irradiation process involved 6.4 MeV of Fe ions at 800 °C. After irradiation, the samples were examined using TEM to observe point defects and void aggregation.

[0034] Example 2

[0035] Preparation of W-5Re alloy:

[0036] (1) Tungsten (W) powder and rhenium (Re) powder with a particle size D90 of 10 µm were placed in a ball mill jar at a mass ratio of 95:5 and a ball-to-powder ratio of 10:1. At the same time, an appropriate amount of 99.9% pure alcohol was added to just submerge the balls and powder as a process control agent (PCA). Then, the ball mill jar was placed in a glove box and filled with argon gas to prevent oxidation of the powder during the ball milling process. Finally, it was placed in a high-energy planetary ball mill for ball milling at a speed of 400 rpm for a cycle of 32 h, with 30 min of forward and reverse rotation and a 20 min interval.

[0037] (2) Place the sample in a vacuum oven for drying, then sieve the powder (100 mesh). Take 25 g of the powder and place it in a Φ20 graphite mold. Separate the powder and the mold with carbon paper and Ta foil. First, pre-press it at 10 MPa. After pre-pressing, place it in the furnace. The pressure in the furnace is evacuated to a vacuum state and sintering begins. Set the current and initial pressure to ensure that the sintering process is as follows: the sample is heated from room temperature to 600 ℃ at 100 ℃ / min and the pressure is 15 MPa; then the temperature is increased from 600 ℃ to 1000 ℃ at 100 ℃ / min and held for 3 min, and the pressure is increased from 15 MPa to 40 MPa; then the temperature is increased from 1000 ℃ to 1500 ℃ at 100 ℃ / min and held for 5 min, and the pressure is increased from 40 MPa to 50 MPa; after successful sintering, wait for the furnace to cool and then take it out.

[0038] (3) After sintering, hot rolling is carried out in three processes at a high temperature of 1200 ℃, with each deformation amount being 10%, 6% and 4%; after hot rolling, the product is taken out and annealed at a temperature of 1000 ℃ for 60 min.

[0039] (4) The samples were wire-cut into squares measuring 5×5×1.2 mm. After repeated grinding and polishing with 120, 240, 320, 400, 500, 600, 800, 1000 and 1200 grit sandpaper, W-5Re irradiated samples were obtained. The irradiation process involved irradiation with 6.4 MeV of Fe ions at 800 °C. After irradiation, the samples were examined using TEM to observe point defects and void aggregation.

[0040] Example 3

[0041] Preparation of W-1Cr alloy:

[0042] (1) Tungsten (W) powder and chromium (Cr) powder with a particle size D90 of 10 µm were placed into a ball mill jar at a mass ratio of 99:1, with the ball-to-powder ratio controlled at 10:1. At the same time, an appropriate amount of 99.9% pure alcohol was added to just submerge the balls and powder as a process control agent (PCA). Then, the ball mill jar was placed in a glove box and filled with argon gas to prevent oxidation of the powder during the ball milling process. Finally, it was placed in a high-energy planetary ball mill for ball milling at a speed of 400 rpm for a cycle of 32 h, with 30 min of forward and reverse rotation and a 20 min interval.

[0043] (2) Place the sample in a vacuum oven for drying, then sieve the powder (100 mesh). Take 25 g of the powder and place it in a Φ20 graphite mold. Separate the powder and the mold with carbon paper and Ta foil. First, pre-press it at 10 MPa. After pre-pressing, place it in the furnace. The pressure in the furnace is evacuated to a vacuum state and sintering begins. Set the current and initial pressure to ensure that the sintering process is as follows: the sample is heated from room temperature to 600 ℃ at 100 ℃ / min and the pressure is 15 MPa; then the temperature is increased from 600 ℃ to 1000 ℃ at 100 ℃ / min and held for 3 min, and the pressure is increased from 15 MPa to 40 MPa; then the temperature is increased from 1000 ℃ to 1500 ℃ at 100 ℃ / min and held for 5 min, and the pressure is increased from 40 MPa to 50 MPa; after successful sintering, wait for the furnace to cool and then take it out.

[0044] (3) After sintering, hot rolling is carried out in three processes at a high temperature of 1200 ℃, with each deformation amount being 10%, 6% and 4%; after hot rolling, the product is taken out and annealed at a temperature of 1000 ℃ for 60 min.

[0045] (4) The samples were wire-cut into squares measuring 5×5×1.2 mm. After repeated grinding and polishing with 120, 240, 320, 400, 500, 600, 800, 1000, and 1200 grit sandpaper, W-1Cr irradiated samples were obtained. The irradiation process involved 6.4 MeV of Fe ions at 800 °C. After irradiation, the samples were examined using TEM to observe point defects and void aggregation.

[0046] Example 4

[0047] Preparation of pure tungsten (W):

[0048] (1) Pure tungsten (W) powder with a particle size D90 of 10 µm was placed into a ball mill jar, with the ball-to-powder ratio controlled at 10:1. At the same time, an appropriate amount of 99.9% pure alcohol was added to just submerge the balls and powder as a process control agent (PCA). Then, the ball mill jar was placed in a glove box and filled with argon gas to prevent oxidation of the powder during the ball milling process. Finally, it was placed in a high-energy planetary ball mill for ball milling at a speed of 400 rpm for a cycle of 32 h, with 30 min of forward and reverse rotation and a 20 min interval.

[0049] (2) Place the sample in a vacuum oven for drying, then sieve the powder (100 mesh). Take 25 g of the powder and place it in a Φ20 graphite mold. Separate the powder and the mold with carbon paper and Ta foil. First, pre-press it at 10 MPa. After pre-pressing, place it in the furnace. The pressure in the furnace is evacuated to a vacuum state and sintering begins. Set the current and initial pressure to ensure that the sintering process is as follows: the sample is heated from room temperature to 600 ℃ at 100 ℃ / min and the pressure is 15 MPa; then the temperature is increased from 600 ℃ to 1000 ℃ at 100 ℃ / min and held for 3 min, and the pressure is increased from 15 MPa to 40 MPa; then the temperature is increased from 1000 ℃ to 1500 ℃ at 100 ℃ / min and held for 5 min, and the pressure is increased from 40 MPa to 50 MPa; after successful sintering, wait for the furnace to cool and then take it out.

[0050] (3) After sintering, hot rolling is carried out in three processes at a high temperature of 1200 ℃, with each deformation amount being 10%, 6% and 4%; after hot rolling, the product is taken out and annealed at a temperature of 1000 ℃ for 60 min.

[0051] (4) The samples were wire-cut into square samples with dimensions of 5×5×1.2 mm. After repeated grinding and polishing with 120, 240, 320, 400, 500, 600, 800, 1000 and 1200 grit sandpaper, pure W-irradiated samples were obtained. The irradiation process was irradiation with 6.4 MeV of Fe ions at 800 °C. After irradiation, the samples were observed for point defects and void aggregation using TEM.

[0052] Figure 1 This study demonstrates the microscopic mechanism by which Re and Cr atoms synergistically fill vacancies in W-Re-Cr ternary alloys during irradiation. Compared to the process in single binary alloys where only one alloying element forms a "mixed dumbbell" structure, the Re and Cr atoms in the ternary system can more effectively capture and stabilize irradiation-induced point defects through synergistic action, thereby kinetically accelerating the recombination and elimination of vacancies and further improving radiation resistance.

[0053] according to Figures 2 to 5 The transmission electron microscopy (TEM) analysis results, through a systematic comparison of the microstructures of W-Re-Cr ternary alloy, W-Re and W-Cr binary alloy and pure W under the same irradiation conditions, clearly show that the irradiation-induced vacancy defect concentration in the W-Re-Cr ternary alloy is significantly lower than that in other comparative systems, indicating that this ternary composition has the best effect in suppressing vacancy aggregation.

Claims

1. A method for preparing tungsten-based alloys with reduced irradiation vacancy defect concentration, characterized in that, Includes the following steps: (1) Powder metallurgy of W-xRe-yCr: W-xRe-yCr ternary alloy was designed based on the strength of the mixed dumbbell bonding energy. The alloy powder was obtained by wet ball milling according to the mass ratio of tungsten (W) powder, rhenium (Re) powder and chromium (Cr) powder of 90~99.8:0.1~5:0.1~5. (2) Sintering and forming process of W-xRe-yCr: A certain amount of ball-milled alloy powder is weighed and placed into a mold. The mold is then placed in a discharge plasma sintering furnace for pressure sintering to obtain an alloy block. (3) Hot rolling treatment of W-xRe-yCr: The alloy block obtained by sintering is hot rolled at a certain temperature. For different passes, the deformation amount of each pass is reasonably allocated according to the total deformation amount, and finally W-xRe-yCr alloy is prepared. (4) Annealing treatment of W-xRe-yCr: The W-xRe-yCr alloy obtained by hot rolling is annealed; (5) Irradiation treatment of W-xRe-yCr: The W-xRe-yCr alloy obtained by annealing is polished to obtain an irradiated sample, and then subjected to irradiation treatment.

2. The method for preparing tungsten-based alloys with reduced irradiation vacancy defect concentration as described in claim 1, characterized in that, In step (1), the ball milling time is 32~40 h, the ball milling speed is 300~500 rpm, and the ball-to-material ratio is 10~15:

1.

3. The method for preparing tungsten-based alloys with reduced irradiation vacancy defect concentration as described in claim 1, characterized in that, In step (1), alcohol is added as a process control agent in the wet ball milling process, and at least two different diameters of ball milling beads are added.

4. The method for preparing tungsten-based alloys with reduced irradiation vacancy defect concentration as described in claim 1, characterized in that, In step (1), the particle size distribution of tungsten (W) powder, rhenium (Re) powder and chromium (Cr) powder are all in the range of 1~10 µm, and the particle sizes of the three powders used are similar.

5. The method for preparing tungsten-based alloys with reduced irradiation vacancy defect concentration as described in claim 1, characterized in that, In step (2), the alloy powder is loaded into a graphite mold for the SPS discharge plasma furnace. The powder and the mold are separated by carbon paper and Ta foil. The powder is pre-pressed at 10 MPa. After pre-pressing, the powder is placed in the furnace. The furnace pressure is evacuated to a vacuum state and sintering begins. The current and initial pressure are set to ensure that the sintering process is as follows: the sample is heated from room temperature to 600 ℃ at 100 ℃ / min and the pressure is 15 MPa; then the temperature is increased from 600 ℃ to 1000 ℃ at 100 ℃ / min and held for 3 min, while the pressure increases from 15 MPa to 40 MPa; then the temperature is increased from 1000 ℃ to 1500 ℃ at 100 ℃ / min and held for 5 min, while the pressure increases from 40 MPa to 50 MPa. After successful sintering, the sample is allowed to cool in the furnace and then removed.

6. The method for preparing tungsten-based alloys with reduced irradiation vacancy defect concentration as described in claim 1, characterized in that, In step (3), the hot rolling process is carried out in three stages at 1200 ℃, and the deformation amount is controlled to be 10%, 6% and 4% for each stage.

7. The method for preparing tungsten-based alloys with reduced irradiation vacancy defect concentration as described in claim 1, characterized in that, In step (4), the rolled alloy is annealed at a temperature of 900~1300 ℃ and a holding time of 30~120 min.

8. The method for preparing tungsten-based alloys with reduced irradiation vacancy defect concentration as described in claim 1, characterized in that, In step (5), the sample is ground and polished to a mirror finish with no obvious scratches, following the order of grinding and polishing. Then, it is subjected to irradiation treatment, in which 6.4 MeV of Fe ions are irradiated at 800 °C.

9. A low-irradiation vacancy defect tungsten-based alloy prepared by the method according to any one of claims 1 to 8.

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