Full-process method for improving thermal diffusion coefficient of tungsten-rhenium alloy plate through rhenium segregation

Abstract

The invention discloses a whole-process method for improving the thermal diffusion coefficient of a tungsten-rhenium alloy plate through rhenium segregation. The whole-process method comprises the following steps: preparing tungsten powder and rhenium powder with different particle sizes in proportion to obtain uniformly mixed powder of the tungsten powder and the rhenium powder; carrying out cold isostatic pressing on the mixed powder and sintering to prepare a sintered blank; carrying out heating rolling deformation treatment on the sintered blank; and performing high-temperature annealing treatment. According to the method, local segregation of rhenium is formed in a tungsten-rhenium alloy sintered blank by strictly controlling the sizes of the added tungsten powder and rhenium powder, after thermal deformation, rhenium segregation blocks can form anisotropic rhenium component segregation, the tungsten-rhenium alloy shows a higher thermal diffusion coefficient in the RD direction, and after high-temperature annealing, the tungsten-rhenium alloy has a higher thermal diffusion coefficient in the RD direction. The thermal diffusion coefficient in each direction can be further improved, and the tungsten-rhenium alloy plate with the high thermal diffusion coefficient is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of high thermal conductivity profile preparation, and specifically relates to a full-process method for improving the thermal diffusion coefficient of a tungsten-rhenium alloy plate by rhenium segregation. Background Art

[0002] Nuclear energy, with its advantages of cleanliness, safety and abundant reserves, is bound to become the most ideal energy source for human energy supply in the future. In the field of nuclear energy, due to the extremely complex and harsh environment in the reactor, such as the bombardment of high-flux plasma and fast neutron irradiation, extremely high requirements are placed on the high-temperature mechanical properties and radiation resistance of plasma-facing materials. Metal tungsten is regarded as one of the best candidate materials for nuclear plasma-facing materials due to its high melting point (3430℃), high thermal conductivity (173W / m / k), high sputtering threshold, low tritium retention and low corrosion rate. However, pure tungsten materials have disadvantages such as low-temperature brittleness, recrystallization brittleness, and radiation embrittlement, which lead to poor thermal shock resistance, easy fracture and notch, etc. Therefore, the above properties need to be further improved to meet the processing and service requirements of nuclear plasma-facing materials.

[0003] Adding solid solution elements to pure tungsten for alloying is one of the most commonly used methods to improve the mechanical properties of pure tungsten. In order to overcome the low toughness and DBTT shortcomings of pure tungsten, one or more elements that can dissolve in the α-W phase are added to tungsten to improve the mechanical properties of the tungsten alloy. Since the first report in 1995 that the addition of Re can improve the toughness of tungsten, a large number of studies have been devoted to further exploring the mechanical properties of W-Re alloys. As a material without a ductile-brittle transition temperature, the addition of Re to W can also reduce the ductile-brittle transition temperature. In the W-Re binary system, the solubility of Re in W can reach 26% at room temperature. Within this solubility range, as the amount of Re solid solution increases, its mechanical properties gradually improve.

[0004] The addition of rhenium can improve the mechanical properties of tungsten alloy, but the addition of rhenium also reduces the thermal conductivity of tungsten alloy. In a fusion reactor, in addition to excellent mechanical properties, the first wall material also needs to withstand high heat loads, so the heat needs to be quickly transferred to the heat sink material on the back of the first wall material. Usually, the first wall material and the heat sink material are combined into a W / Cu system. In the entire heat transfer process, the thermal conductivity of the first wall material itself is also crucial. High thermal conductivity can transfer heat to the outer layer in time, avoid the occurrence of large heat loads, and enable the reactor as a whole to operate well.

[0005] For the tungsten-rhenium alloy used as the first wall material, how to improve the mechanical properties while avoiding the decrease in thermal conductivity as much as possible by adding rhenium is an issue that needs to be urgently addressed for further development in fusion reactors. Summary of the invention

[0006] The invention discloses a full-process method for improving the thermal diffusion coefficient of a tungsten-rhenium alloy plate by rhenium segregation, so as to solve any of the above and other potential problems in the prior art.

[0007] In order to solve the above technical problems, the technical solution of the present invention is: a full-process method for improving the thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation, and the full-process method specifically includes the following steps:

[0008] S1) tungsten powder and rhenium powder of different particle sizes are configured according to a predetermined ratio, and are evenly mixed using a double-motion mixer to obtain a uniformly dispersed tungsten-rhenium alloy powder;

[0009] S2) cold isostatically pressing the uniformly mixed tungsten-rhenium powder obtained in S1) to obtain a green body, and then sintering the green body in a hydrogen furnace to obtain a tungsten-rhenium alloy blank with rhenium segregation;

[0010] S3) hot rolling the rhenium segregated tungsten-rhenium alloy billet obtained in S2) to obtain a tungsten-rhenium alloy plate having rhenium segregation anisotropy;

[0011] S4) placing the tungsten-rhenium alloy plate with rhenium segregation anisotropy obtained in S3) in a high-temperature furnace for annealing to obtain a tungsten-rhenium alloy plate with a high thermal diffusion coefficient.

[0012] Furthermore, the tungsten powder in S1) has a Fischer-Tropsch particle size of 1 μm to 10 μm, and the rhenium powder has a Fischer-Tropsch particle size of 50 μm to 100 μm;

[0013] The mass proportion of rhenium powder in the tungsten-rhenium mixed powder is 0.1% to 10%, and the balance is tungsten;

[0014] The double-motion mixer has a rotation frequency of not less than 10,000 revolutions.

[0015] Furthermore, the purity of the tungsten powder and the rhenium powder in S1) is above 99.99%.

[0016] Furthermore, the density of the tungsten-rhenium alloy billet sintered in a hydrogen atmosphere in S2) is greater than 95%.

[0017] Furthermore, the hot rolling process in S3) uses a hydrogen furnace as the heating equipment, the heating temperature is 1550°C to 1700°C, the insulation time is 0.5h to 1h, and the insulation time between each rolling pass is 0.2h to 0.3h, and the thickness reduction percentage of each rolling pass is 10% to 20%; and the deformation rate of the tungsten-rhenium alloy plate after hot rolling is greater than 60%.

[0018] Furthermore, the annealing temperature in S4) is 1000° C. to 2000° C., the annealing time is 1 h to 100 h, and the furnace is cooled.

[0019] Furthermore, the annealing equipment is a hydrogen furnace, a vacuum furnace or an inert atmosphere furnace.

[0020] Furthermore, the tungsten-rhenium alloy plate has different thermal diffusion coefficients in different directions, and has high thermal diffusion coefficients in TD and RD directions. Compared with the plate prepared by the conventional preparation method, the thermal diffusion coefficient can be increased by 3% to 10%.

[0021] A tungsten-rhenium alloy plate is obtained by processing the tungsten-rhenium alloy plate using the above-mentioned full-process method.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. The present invention uses tungsten powder and rhenium powder mixed powder, cold isostatic pressing green body, hydrogen furnace sintering tungsten rhenium alloy billet, high temperature annealing treatment, to complete the full process preparation of high thermal conductivity tungsten rhenium alloy plate, in the preparation process by selecting fine tungsten powder and coarse rhenium powder to mix powder in the powder mixing process, so that after sintering, a tungsten rhenium alloy billet containing rhenium segregation is obtained, and after further rolling, a tungsten rhenium alloy plate with anisotropic rhenium segregation can be obtained, thereby improving the problem of decreased thermal diffusion coefficient caused by rhenium addition in tungsten alloy.

[0024] 2. Compared with the traditional process, the present invention adopts high temperature annealing to reduce the defects inside the rolled tungsten-rhenium alloy plate, enhance the orderliness and periodicity of the lattice inside the plate, and improve the thermal diffusion coefficient of the tungsten-rhenium alloy plate in all directions. When tungsten-based materials are used as the first wall material of fusion reactors, the strength of thermal conductivity is crucial to the service life of the material. Under the condition of fixed composition, it is difficult to achieve the improvement of thermal diffusion coefficient. The present invention creatively introduces rhenium segregation and annealing, which can eventually increase the thermal diffusion coefficient of the plate by 3% to 8%, significantly enhancing the thermal conductivity of tungsten alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention provides a process roadmap for a full-process method for improving the thermal diffusion coefficient of a tungsten-rhenium alloy plate by rhenium segregation.

[0026] Figure 2 This is a physical picture of the high thermal conductivity tungsten-rhenium alloy hot-rolled plate prepared in Example 1 of the present invention.

[0027] Figure 3 Secondary electron and surface scan images of the high-temperature tungsten-rhenium alloy billet prepared in Example 1 of the present invention before rolling.

[0028] Figure 4 This is the backscattered electron and composition diagram in the TD direction of the high thermal conductivity tungsten-rhenium alloy hot-rolled plate prepared in Example 1 of the present invention.

[0029] Figure 5 Secondary electron and surface scan images of the tungsten-rhenium alloy billet prepared in Example 2 of the present invention before rolling. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments.

[0031] like Figure 1 As shown, the present invention provides a full-process method for improving the thermal diffusion coefficient of a tungsten-rhenium alloy plate by rhenium segregation, and the method comprises the following steps:

[0032] Step 1: fine-grained tungsten powder and coarse-grained rhenium powder are uniformly mixed according to a predetermined configuration using double motion to obtain uniformly dispersed tungsten-rhenium alloy powder;

[0033] Step 2: Put the uniformly mixed tungsten-rhenium powder obtained in step 1 into a rubber sleeve for cold isostatic pressing to obtain a green body, and then place the green body in a hydrogen furnace for sintering to obtain a tungsten-rhenium alloy blank with rhenium segregation;

[0034] Step 3, hot rolling the tungsten-rhenium alloy billet containing rhenium segregation obtained in step 2 to obtain a tungsten-rhenium alloy plate having rhenium segregation anisotropy;

[0035] Step 4: placing the tungsten-rhenium alloy plate with rhenium segregation anisotropy obtained in step 3 in a high-temperature furnace for annealing to obtain a tungsten-rhenium alloy plate with a high thermal diffusion coefficient.

[0036] In the above-mentioned full-process preparation method for introducing rhenium segregation to improve the thermal diffusion coefficient of tungsten-rhenium alloy plate, the mass purity of the tungsten powder and rhenium powder in step 1 is both above 99.99%. The high purity can avoid the influence of impurity elements on the thermal diffusion coefficient of the tungsten alloy plate.

[0037] In the above-mentioned full-process preparation method for improving the thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation, the tungsten powder used in step 1 has a particle size between 1 μm and 10 μm, and the rhenium powder has a particle size between 50 μm and 100 μm. The selection of the above parameters is conducive to obtaining a structure with rhenium segregation in the sintered blank, while also ensuring that the second phase will not be generated in the sintered blank due to severe rhenium segregation, and also taking into account the pressing performance of the powder, which is conducive to obtaining a high-density sintered blank.

[0038] In the above-mentioned full-process preparation method for improving the thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation, the mass proportion of rhenium powder in the tungsten-rhenium mixed powder described in step 1 is 0.1% to 10%, and the balance is tungsten. The above parameters are selected to avoid the reduction of the distance between rhenium particles in the entire pressed green body due to the addition of a large amount of rhenium, thereby inhibiting the diffusion of rhenium to form a second phase and reducing the processing performance.

[0039] In the above-mentioned full-process preparation method for improving the thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation, the tungsten powder and rhenium powder in step 1 need to be mixed for more than 10,000 revolutions using a double-motion mixer. The selection of the above-mentioned parameters is conducive to the uniform mixing of tungsten powder and rhenium powder, avoiding the segregation of rhenium powder and tungsten powder due to uneven mixing, which causes the rhenium segregation area in the sintered blank to produce a second phase, which is not conducive to subsequent hot working deformation.

[0040] In the above-mentioned full-process preparation method for improving the thermal diffusion coefficient of a tungsten-rhenium alloy plate by rhenium segregation, the density of the tungsten-rhenium alloy billet sintered in a hydrogen atmosphere in step 2 is greater than 95%.

[0041] In the above-mentioned full-process preparation method for improving the thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation, the deformation rate of the tungsten-rhenium alloy plate after hot rolling described in step 3 needs to be greater than 60%; the heating equipment used in the hot rolling process is a hydrogen furnace, the heating temperature is 1550℃~1700℃, the insulation time is 0.5h~1h, and the insulation time between each rolling pass is 0.2h~0.3h, and the thickness reduction percentage of each rolling pass is 10%~20%. The above-mentioned parameter selection is conducive to obtaining a tungsten-rhenium alloy plate with rhenium segregation anisotropy, so that the thermal diffusion coefficient of the tungsten-rhenium alloy presents anisotropic distribution, and the thermal diffusion coefficient is improved in the RD direction.

[0042] In the above-mentioned full-process preparation method for improving the thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation, the annealing temperature in step 4 is 1000℃~2000℃, the annealing time is 1h~100h, and the furnace is cooled; the annealing equipment needs to be a hydrogen furnace, a vacuum furnace and an inert atmosphere furnace. The above-mentioned parameter selection is conducive to reducing the existence of defects in the tungsten-rhenium alloy plate, improving the orderliness and periodicity of the internal lattice of the tungsten-rhenium alloy plate, and at the same time, the generated rhenium segregation will not be weakened and disappear due to the diffusion of rhenium during the annealing process, which can further improve the thermal diffusion coefficient of the tungsten-rhenium alloy plate.

[0043] Example 1

[0044] This embodiment includes the following steps:

[0045] Step 1: Prepare tungsten powder and rhenium powder with a mass purity of 99.99% and a Fisher particle size of 3 μm and 100 μm respectively according to a mass fraction of 98% and 2%, and use a double-motion mixer to mix the tungsten powder and rhenium powder. The mixer parameters are: speed 50 rpm, time 4 hours, to obtain a uniformly dispersed tungsten-rhenium mixed powder;

[0046] Step 2: Using cold isostatic pressing equipment to press the tungsten-rhenium mixed powder obtained in step 1 to obtain a green billet, and then sintering it in a hydrogen furnace to obtain a tungsten-rhenium alloy billet with a density greater than 95%;

[0047] Step 3: hot rolling mill is used to roll the tungsten-rhenium alloy billet obtained in step 2. The heating equipment used is a hydrogen furnace. The heating temperature is 1650° C., the holding time is 0.5 h, and the holding time between each rolling pass is 0.25 h. The thickness reduction percentage of each rolling pass is 15%, and finally a tungsten-rhenium alloy sheet with a deformation greater than 60% is obtained;

[0048] Step 4: Use a heating device to perform high-temperature annealing on the tungsten-rhenium alloy plate obtained in step 3. The annealing temperature is 1500° C. and the time is 1 hour. The heating device used is a hydrogen furnace, and finally a recrystallized tungsten-rhenium alloy plate is obtained.

[0049] Figure 3 and Figure 4 The rhenium segregation scanning electron graph and composition distribution of the sintered billet and rolled high thermal conductivity tungsten-rhenium alloy sheet prepared in this embodiment are shown in FIG. Figure 3 and Figure 4 It can be seen that the rhenium segregation of the tungsten-rhenium alloy plate is spherically distributed in the sintered billet without anisotropy. After rolling, the plate exhibits anisotropic rhenium segregation.

[0050] Table 1 shows the thermal diffusion coefficients of the high thermal conductivity tungsten-rhenium alloy plate prepared in this embodiment in different directions after sintering, rolling and annealing. It can be seen that the sample exhibits the highest thermal diffusion coefficient in the RD direction, and the thermal diffusion coefficient is further improved after annealing.

[0051] Table 1 Thermal diffusivity of the high thermal conductivity tungsten-rhenium alloy sheet prepared in this example in different directions after sintering, rolling and annealing

[0052]

[0053] Example 2

[0054] This embodiment includes the following steps:

[0055] Step 1: Prepare tungsten powder and rhenium powder with a mass purity of 99.99% and a Fisher particle size of 3 μm and 70 μm respectively according to a mass fraction of 98% and 2%, and mix the tungsten powder and rhenium powder using a double-motion mixer. The mixer parameters are: speed 50 rpm, time 4 hours, to obtain a uniformly dispersed tungsten-rhenium mixed powder;

[0056] Step 2: Using cold isostatic pressing equipment to press the tungsten-rhenium mixed powder obtained in step 1 to obtain a green billet, and then sintering it in a hydrogen furnace to obtain a tungsten-rhenium alloy billet with a density greater than 95%;

[0057] Step 3: hot rolling mill is used to roll the tungsten-rhenium alloy billet obtained in step 2. The heating equipment used is a hydrogen furnace. The heating temperature is 1650° C., the holding time is 0.5 h, and the holding time between each rolling pass is 0.25 h. The thickness reduction percentage of each rolling pass is 15%, and finally a tungsten-rhenium alloy sheet with a deformation greater than 60% is obtained;

[0058] Step 4: Use a heating device to perform high-temperature annealing on the tungsten-rhenium alloy plate obtained in step 3. The annealing temperature is 1500° C. and the time is 1 hour. The heating device used is a hydrogen furnace, and finally a recrystallized tungsten-rhenium alloy plate is obtained.

[0059] Figure 5 The secondary electron and surface scan images of the tungsten-rhenium alloy billet prepared in this embodiment before rolling. Figure 5 It can be seen that as the rhenium powder particles become finer, the rhenium segregation area in the sintered billet becomes smaller, and the anisotropy of the rhenium segregation formed after subsequent rolling weakens.

[0060] Table 2 shows the thermal diffusion coefficients of the high thermal conductivity tungsten-rhenium alloy plate prepared in this embodiment in different directions after sintering, rolling and annealing. It can be seen that the sample exhibits the highest thermal diffusion coefficient in the RD direction, and the thermal diffusion coefficient is further improved after annealing, but the thermal diffusion coefficient in the RD direction is reduced compared with Example 1.

[0061] Table 2 Thermal diffusion coefficients of the high thermal conductivity tungsten-rhenium alloy plate prepared in this embodiment in different directions after sintering, rolling and annealing.

[0062]

[0063] The above is a detailed introduction to the full-process method for improving the thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation provided in the embodiment of the present application. The description of the above embodiment is only used to help understand the method and its core idea of ​​the present application; at the same time, for those skilled in the art, according to the idea of ​​the present application, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

[0064] For example, certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different nouns to refer to the same component. This specification and claims do not use differences in names as a way to distinguish components, but use differences in the functions of components as the criteria for distinction. As mentioned throughout the specification and claims, "including" and "comprising" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Approximately" means that within an acceptable error range, those skilled in the art can solve the technical problem within a certain error range and basically achieve the technical effect. The subsequent description of the specification is a preferred embodiment of the present application, but the description is for the purpose of illustrating the general principles of the present application, and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the definition of the attached claims.

[0065] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a product or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such a product or system. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the product or system including the elements.

[0066] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0067] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art do not deviate from the spirit and scope of the present application, and should be within the scope of protection of the claims attached to the present application.

Claims

1. A full-process method for improving the thermal diffusion coefficient of tungsten-rhenium alloy sheet by rhenium segregation, characterized in that: The full process method specifically includes the following steps: S1) tungsten powder and rhenium powder of different particle sizes are configured according to a predetermined ratio, and are evenly mixed using a double-motion mixer to obtain a uniformly dispersed tungsten-rhenium alloy powder; S2) cold isostatically pressing the uniformly mixed tungsten-rhenium powder obtained in S1) to obtain a green body, and then sintering the green body in a hydrogen furnace to obtain a tungsten-rhenium alloy blank with rhenium segregation; S3) hot rolling the rhenium segregated tungsten-rhenium alloy billet obtained in S2) to obtain a tungsten-rhenium alloy plate having rhenium segregation anisotropy; S4) placing the tungsten-rhenium alloy plate with rhenium segregation anisotropy obtained in S3) in a high-temperature furnace for annealing to obtain a tungsten-rhenium alloy plate with a high thermal diffusion coefficient.

2. The full process method according to claim 1, characterized in that: The tungsten powder in S1) has a particle size of 1 μm to 10 μm, and the rhenium powder has a particle size of 50 μm to 100 μm; The mass proportion of rhenium powder in the tungsten-rhenium mixed powder is 0.1% to 10%, and the balance is tungsten; The double-motion mixer has a rotation frequency of not less than 10,000 revolutions.

3. The full process method according to claim 1, characterized in that: The purity of the tungsten powder and the rhenium powder in S1) is above 99.99%.

4. The full process method according to claim 1, characterized in that: The density of the tungsten-rhenium alloy billet sintered in a hydrogen atmosphere in S2) is greater than 95%.

5. The full process method according to claim 1, characterized in that: The hot rolling process in S3) uses a hydrogen furnace as the heating equipment, the heating temperature is 1550°C to 1700°C, the insulation time is 0.5h to 1h, and the insulation time between each rolling pass is 0.2h to 0.3h, and the thickness reduction percentage of each rolling pass is 10% to 20%; and the deformation rate of the tungsten-rhenium alloy plate after hot rolling is greater than 60%.

6. The full process method according to claim 1, characterized in that: The annealing temperature in S4) is 1000° C. to 2000° C., the annealing time is 1 h to 100 h, and the furnace is cooled.

7. The process method according to claim 1, characterized in that: The annealing equipment is a hydrogen furnace, a vacuum furnace or an inert atmosphere furnace.

8. The full process method according to claim 1, characterized in that: The tungsten-rhenium alloy plate has different thermal diffusion coefficients in different directions, and the thermal diffusion coefficients in the TD and RD directions can be increased by 3% to 10%.

9. A tungsten-rhenium alloy plate, characterized in that: The tungsten-rhenium alloy plate is obtained by processing using the full-process method described in any one of claims 1 to 8.

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