A method for preparing tungsten-rhenium-potassium alloy plates and its application

Abstract

This invention belongs to the field of powder metallurgy technology and discloses a tungsten-rhenium-potassium alloy plate, its preparation method, and its application. The preparation method includes the following steps: spray drying to produce powder, cold isostatic pressing, low-temperature pre-sintering, hot pressing sintering, rolling, and heat treatment, thereby obtaining the tungsten-rhenium-potassium alloy plate. This invention improves the uniformity of rhenium and potassium distribution in the tungsten matrix by preparing fine and uniform tungsten-rhenium-potassium alloy powder through spray drying. By combining low-temperature pre-sintering for deoxidation and hot pressing for densification sintering, a blank with a density ≥95% is prepared, solving the problem of cracking during rolling and improving the yield of the plate. The potassium bubbles inside the prepared tungsten-rhenium-potassium alloy plate exhibit nanoscale characteristics and are uniformly distributed, meeting the requirements for use as a plasma-facing first wall material in fusion reactors.

Description

Technical Field

[0001] This invention relates to the field of powder metallurgy technology, specifically to a method for preparing tungsten-rhenium-potassium alloy plates and their applications. Background Technology

[0002] The plasma-facing first wall material in a nuclear fusion reactor operates under extremely complex and harsh environments, including high-flux plasma bombardment and fast neutron irradiation, making it a core and critical material for fusion reactors. Tungsten, with its high melting point, high thermal conductivity, high sputtering threshold, low tritium retention, and low corrosion rate, is considered one of the best candidates for plasma-facing materials in fusion reactors. However, tungsten still has some drawbacks, such as a high ductile-brittle transition temperature, low recrystallization temperature, and irradiation-induced hardening, which greatly limits its engineering applications in fusion reactors. To address these issues, researchers have employed various improvement methods, such as dispersion strengthening (introducing carbides, nitrides, potassium bubbles, etc.), solid solution strengthening (adding rhenium, hafnium, tantalum, etc.), and structural optimization (hot rolling, hot forging, etc.). Among these, tungsten-rhenium-potassium alloy plates are considered the best choice for the plasma-facing first wall material in fusion reactors. Through the "rhenium effect," the recrystallization temperature of tungsten alloys is increased, plasticity is significantly improved, and machinability is enhanced. Furthermore, the potassium bubbles formed by trace potassium doping act as pinning agents for tungsten grain growth, improving both low-temperature toughness and high-temperature strength. Therefore, tungsten-rhenium-potassium plates for fusion reactors have become a research hotspot both domestically and internationally.

[0003] To leverage the advantages of tungsten-rhenium-potassium alloys (TRO-rhenium-potassium alloys), such as high thermal conductivity, high strength and toughness, and high recrystallization temperature, large deformation processing is required to obtain TRO-rhenium-potassium plates. However, TRO-rhenium-potassium alloys are difficult to deform; the introduction of potassium bubbles reduces the density of the TRO-rhenium-potassium plate blank, making processing and deformation difficult. Furthermore, the introduction of rhenium causes severe hardening of the plate during processing, and the alloy's microstructure and properties are highly sensitive to deformation process parameters. Currently, there are relatively few reports on TRO-rhenium-potassium alloy plate preparation technologies. Traditional powder metallurgy rolling processes for tungsten plates easily lead to deformation and cracking of TRO-rhenium-potassium alloy plates. Therefore, there is an urgent need to develop a preparation process that can solve the problems of difficult processing and easy cracking of TRO-rhenium-potassium alloy plates to meet the engineering requirements for their use in fusion reactors. Summary of the Invention

[0004] This invention discloses a method for preparing tungsten-rhenium-potassium alloy plates and their applications, in order to solve any of the above-mentioned and other potential problems in the prior art.

[0005] To achieve the above-mentioned technical objectives, the present invention provides the following technical solution: a tungsten-rhenium-potassium alloy plate, wherein the mass percentage of each component of the tungsten-rhenium-potassium alloy plate is: tungsten 95-99%, rhenium 1-5% and potassium 0.005%-0.01%.

[0006] This invention provides a method for preparing a tungsten-rhenium-potassium alloy plate, the method comprising the following steps:

[0007] S1) According to the design ratio, weigh out the corresponding mass of ammonium metatungstate, ammonium rhenium, aluminum nitrate and potassium silicate, stir and dissolve them completely, spray dry to prepare precursor powder, and then reduce with hydrogen to obtain doped tungsten rhenium alloy powder.

[0008] S2) The doped tungsten-rhenium alloy powder prepared in S1) is loaded into a rubber sleeve and subjected to cold isostatic pressing to produce a green blank of doped tungsten-rhenium alloy plate.

[0009] S3) The green body pressed in S2) is pre-fired at low temperature in a hydrogen atmosphere to remove the oxygen element impurity in the green body;

[0010] S4) The pre-fired green blank of S3) is hot-pressed and sintered in an argon atmosphere to obtain a tungsten rhenium potassium alloy plate blank.

[0011] S5) The tungsten-rhenium-potassium alloy billet obtained by hot pressing and sintering in S4) is subjected to large deformation rolling and annealing to obtain tungsten-rhenium-potassium alloy plate.

[0012] Furthermore, the specific process in S1) is as follows:

[0013] S1.1) Weigh out the appropriate amounts of ammonium metatungstate, ammonium rhenium, aluminum nitrate and potassium silicate and place them in a stirred tank containing deionized water. Heat and stir in an oil bath to obtain a clear solution.

[0014] S1.2) The clarified solution is fed into a spray drying device for spray drying to prepare the precursor powder;

[0015] S1.3) The precursor powder is spread evenly on a tungsten boat for hydrogen reduction, and after cooling in the furnace, tungsten-rhenium alloy powder is obtained.

[0016] Furthermore, in step S1.2), the inlet air temperature is 180-200℃, and the feed rate is 3-5L / h;

[0017] The hydrogen reduction parameters in S1.3) are as follows: first, keep the temperature at 300-500℃ for 1-3 hours, then raise the temperature to 900-1000℃ and keep it at 4-6 hours, and maintain the hydrogen flow rate at 3-5L / min.

[0018] Furthermore, the cold isostatic pressure parameters in S2) are: cold isostatic pressure 180-220MPa, and pressure holding time 10-15min.

[0019] Furthermore, the low-temperature pre-sintering parameters in S3) are: sintering temperature 1000-1500℃, holding time 4-6h, and flowing hydrogen sintering atmosphere.

[0020] Furthermore, the hot pressing sintering parameters in S4) are: sintering temperature 1700-2000℃; holding time 1-2h; sintering pressure 30-50MPa.

[0021] Furthermore, in step S5), the rolling process requires heating the tungsten-rhenium-potassium alloy plate billet at 1400-1500℃ for 0.5-1h and then immediately taking it out for rolling, with the total deformation of the billet controlled at 70-80%. The annealing temperature is 900-1100℃, and the annealing time is 0.5-2h.

[0022] In another aspect, the present invention provides a tungsten-rhenium-potassium alloy plate prepared by the above method, which has no microcracks inside the plate, no cracks or deformation at the edges, and a yield of over 90%.

[0023] The beneficial effects of the present invention are as follows: due to the adoption of the above technical solution, the preparation method of the present invention uses spray drying to prepare tungsten rhenium potassium precursor powder. This method can improve the uniformity of the distribution of rhenium and potassium elements in the tungsten matrix, and the prepared tungsten rhenium potassium alloy powder is fine, uniform and has high sintering activity.

[0024] By combining low-temperature pre-sintering for deoxidation with hot-pressing densification sintering, the density of tungsten-rhenium-potassium alloy billets can be effectively improved, reaching over 95%. Furthermore, hot-pressing sintering yields billets with fine and uniform grain sizes, further improving the machinability of tungsten-rhenium-potassium alloy sheets. Cracking during rolling is significantly reduced, edge cracks are eliminated, and the yield is significantly increased, thus improving the production efficiency of tungsten-rhenium-potassium alloy sheets.

[0025] The potassium bubbles inside the tungsten-rhenium-potassium alloy plate prepared by the method of this invention are nanoscale and uniformly distributed. The synergistic effect of this uniformly distributed nanoscale potassium bubble and the rhenium effect enables the tungsten-rhenium-potassium alloy to exhibit superior high-temperature strength, high-temperature stability, and thermal shock resistance compared to pure tungsten and tungsten-rhenium alloys.

[0026] In summary, the tungsten-rhenium-potassium alloy plate and its preparation method proposed in this invention solve a series of problems in the preparation process of tungsten-rhenium-potassium alloy plates, while improving the yield and obtaining tungsten-rhenium-potassium alloy plates with excellent performance, thus meeting the requirements of plasma-oriented first wall materials for fusion reactors. Attached Figure Description

[0027] Figure 1 This is a flowchart illustrating a method for preparing a tungsten-rhenium-potassium alloy plate.

[0028] Figure 2 This is a cross-sectional SEM image of the tungsten-rhenium-potassium alloy plate prepared in Example 1 of the present invention.

[0029] Figure 3This is a cross-sectional SEM image of the tungsten-rhenium-potassium alloy plate prepared in Example 2 of the present invention. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] Example 1

[0032] (1) Spray drying powder production

[0033] According to the mass percentages of each component of the tungsten-rhenium-potassium alloy plate (97% tungsten, 3% rhenium, and 0.01% potassium), the corresponding masses of ammonium metatungstate, ammonium rheniumate, aluminum nitrate, and potassium silicate were weighed and placed in a stirred tank containing deionized water. The mixture was heated and stirred in an oil bath until completely dissolved, then spray-dried to obtain precursor powder. The inlet air temperature for spray drying was 200℃, and the feed rate was 4L / h. The powder was then spread evenly on a tungsten boat for hydrogen reduction. The hydrogen reduction parameters were: first, holding at 400℃ for 2 hours, then raising the temperature to 1000℃ and holding for 6 hours, maintaining a hydrogen flow rate of 5L / min. After furnace cooling, the doped tungsten-rhenium alloy powder was obtained.

[0034] (2) Cold isostatic pressing

[0035] The alloy powder from step (1) is loaded into a special rubber sleeve for cold isostatic pressing. The cold isostatic pressing parameters are: pressing pressure 200MPa, holding time 15min; and a green sheet is obtained.

[0036] (3) Low-temperature pre-sintering

[0037] The pressed green body from step (2) is placed in a sintering furnace and pre-fired at low temperature in a flowing hydrogen atmosphere to remove the impurity oxygen element in the green body. The sintering temperature is 1500℃ and the holding time is 4h.

[0038] (4) Hot pressing and sintering

[0039] The pre-fired green blank in step (3) was hot-pressed and sintered in an argon atmosphere to obtain a tungsten rhenium potassium alloy plate blank with a density of over 95%. The hot-pressing sintering temperature was 1900℃, the holding time was 1h, and the sintering pressure was 30MPa.

[0040] (5) Rolling and heat treatment

[0041] The tungsten-rhenium-potassium alloy plate blank obtained by hot pressing and sintering in step (4) is rolled. The blank is heated at 1450℃ for 1 hour and then immediately taken out for rolling. The total deformation of the blank is controlled at 75%. After annealing at 1100℃ for 1 hour, the tungsten-rhenium-potassium alloy plate is obtained. Figure 2The internal microstructure of the plate shown clearly reveals uniformly distributed nanoscale potassium bubbles, which play a crucial role in improving the performance of the tungsten-rhenium-potassium alloy plate. Figure 1 As shown.

[0042] Example 2

[0043] (1) Spray drying powder production

[0044] According to the mass percentages of each component of the tungsten-rhenium-potassium alloy plate (99% tungsten, 1% rhenium, and 0.005% potassium), the corresponding masses of ammonium metatungstate, ammonium rheniumate, aluminum nitrate, and potassium silicate were weighed and placed in a stirred tank containing deionized water. The mixture was heated and stirred in an oil bath until completely dissolved, then spray-dried to obtain precursor powder. The inlet air temperature for spray drying was 180℃, and the feed rate was 5L / h. The powder was then spread evenly on a tungsten boat for hydrogen reduction. The hydrogen reduction parameters were: first, holding at 350℃ for 3 hours, then raising the temperature to 950℃ and holding for 4 hours, maintaining a hydrogen flow rate of 4L / min. After furnace cooling, the doped tungsten-rhenium alloy powder was obtained.

[0045] (2) Cold isostatic pressing

[0046] The alloy powder from step (1) is loaded into a special rubber sleeve for cold isostatic pressing. The cold isostatic pressing parameters are: pressing pressure 220MPa, holding time 10min; and a green sheet is obtained.

[0047] (3) Low-temperature pre-sintering

[0048] The pressed green body from step (2) is placed in a sintering furnace and pre-fired at low temperature in a flowing hydrogen atmosphere to remove the impurity oxygen element in the green body. The sintering temperature is 1400℃ and the holding time is 4h.

[0049] (4) Hot pressing and sintering

[0050] The pre-fired green blank in step (3) was hot-pressed and sintered in an argon atmosphere to obtain a tungsten rhenium potassium alloy plate blank with a density of over 95%. The hot-pressing sintering temperature was 2000℃, the holding time was 2h, and the sintering pressure was 50MPa.

[0051] (5) Rolling and heat treatment

[0052] The tungsten-rhenium-potassium alloy plate blank obtained by hot pressing and sintering in step (4) is rolled. The blank is heated at 1400℃ for 0.5h and then immediately taken out for rolling. The total deformation of the blank is controlled at 80%. After annealing at 1000℃ for 2h, the tungsten-rhenium-potassium alloy plate is obtained. Figure 3 The internal microstructure of the plate shown clearly reveals uniformly distributed nanoscale potassium bubbles, which play an important role in improving the performance of the tungsten-rhenium-potassium alloy plate.

[0053] The preparation method of tungsten-rhenium-potassium alloy plate and its application provided in the embodiments of this application have been described in detail above. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​this application; at the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​this application. Therefore, the content of this specification should not be construed as a limitation of this application.

[0054] Certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This specification and claims do not distinguish components based on differences in name, but rather on differences in function. The terms "comprising" and "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising / including but not limited to". "Approximately" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect within a certain margin of error. The following descriptions in the specification are preferred embodiments for carrying out this application; however, these descriptions are for the purpose of illustrating the general principles of this application and are not intended to limit the scope of this application. The scope of protection of this application shall be determined by the appended claims.

[0055] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the product or system that includes said element.

[0056] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0057] The foregoing description illustrates and describes several preferred embodiments of this application. However, as previously stated, it should be understood that this application is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the application concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of this application should be within the protection scope of the appended claims.

Claims

1. A method for preparing a tungsten-rhenium-potassium alloy plate, characterized in that, The preparation method specifically includes the following steps: S1) According to the design ratio of tungsten-rhenium-potassium alloy plate, weigh out the corresponding mass of ammonium metatungstate, ammonium rhenium, aluminum nitrate and potassium silicate, completely dissolve and stir, and spray dry to prepare precursor powder, and then obtain doped tungsten-rhenium alloy powder by hydrogen reduction. The design composition of the tungsten-rhenium-potassium alloy plate is: tungsten 95-99 wt%, rhenium 1-5 wt%, and potassium 0.005%-0.01 wt%. S2) The doped tungsten-rhenium alloy powder prepared in S1) is loaded into a rubber sleeve and subjected to cold isostatic pressing to produce a green blank of doped tungsten-rhenium alloy plate. The cold isostatic pressing parameters are: cold isostatic pressing pressure 180-220MPa, holding time 10-15min; S3) The green body pressed in S2) is pre-fired at low temperature in a hydrogen atmosphere to remove the oxygen element impurity in the green body; The low-temperature pre-sintering parameters are: sintering temperature 1000-1500℃, holding time 4-6h, and flowing hydrogen sintering atmosphere. S4) The pre-fired green billet of S3) is hot-pressed and sintered in an argon atmosphere to obtain a tungsten-rhenium-potassium alloy plate blank; The hot pressing sintering parameters are: sintering temperature 1700-2000℃; holding time 1-2h; sintering pressure 30-50MPa. S5) The tungsten-rhenium-potassium alloy billet obtained by hot pressing and sintering in S4) is subjected to deformation rolling and annealing to obtain tungsten-rhenium-potassium alloy sheet. The rolling process requires heating the tungsten-rhenium-potassium alloy plate billet at 1400-1500℃ for 0.5-1 hour and then immediately taking it out for rolling. The total deformation of the billet should be controlled at 70-80%. The annealing temperature is 900-1100℃, and the annealing time is 0.5-2h; The potassium bubbles inside the prepared tungsten-rhenium-potassium alloy plate are nanoscale and uniformly distributed. The synergistic effect of these uniformly distributed nanoscale potassium bubbles and the rhenium effect enables the tungsten-rhenium-potassium alloy to exhibit excellent high-temperature strength, high-temperature stability and thermal shock resistance at high temperatures.

2. The method according to claim 1, characterized in that, The inlet air temperature for spray drying in S1) is 180-200℃, and the feed rate is 3-5L / h; The hydrogen reduction parameters are as follows: first, maintain the temperature at 300-500℃ for 1-3 hours, then raise the temperature to 900-1000℃ and maintain it for 4-6 hours, with the hydrogen flow rate maintained at 3-5 L / min.

3. The preparation method according to claim 1, characterized in that, The yield of tungsten-rhenium-potassium alloy plates prepared by the method is not less than 90%.

4. The application of a tungsten-rhenium-potassium alloy plate prepared by any one of claims 1-3 in the field of fusion reactor engineering.

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