A complete process method for improving the thermal diffusivity of tungsten-rhenium alloy plates by rhenium segregation

Abstract

This invention discloses a complete process method for improving the thermal diffusivity of tungsten-rhenium alloy plates by rhenium segregation. The complete process method includes: mixing tungsten powder and rhenium powder of different particle sizes in a specific ratio to obtain a uniformly mixed powder; cold isostatically pressing and sintering the mixed powder to form a sintered blank; subjecting the sintered blank to hot rolling deformation treatment; and high-temperature annealing treatment. This invention, by strictly controlling the size of the added tungsten and rhenium powders, causes localized rhenium segregation in the sintered tungsten-rhenium alloy blank. After hot deformation, the rhenium segregates form anisotropic rhenium composition segregation, resulting in a higher thermal diffusivity of the tungsten-rhenium alloy in the RD direction. High-temperature annealing further improves the thermal diffusivity in all directions, yielding a tungsten-rhenium alloy plate with a high thermal diffusivity.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of high-thermal-conductivity profile preparation, and particularly relates to a full-process method for improving the thermal diffusion coefficient of tungsten-rhenium alloy plate through rhenium segregation. BACKGROUND

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

[0003] One of the most common methods to improve the mechanical properties of pure tungsten is to add solid solution elements for alloying. In order to overcome the disadvantages of low toughness and DBTT of pure tungsten, one or more elements that can dissolve in the alpha-W phase are added to tungsten to improve the mechanical properties of 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 alloy. As a material without 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 at room temperature can reach 26%, and within this solubility range, the mechanical properties gradually improve with the increase of Re solid solution content.

[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, the first wall material needs to withstand high thermal load, so the heat needs to be quickly conducted to the heat sink material behind the first wall material. Usually, the first wall material and the heat sink material are combined into a W / Cu system. In the whole heat transfer process, the thermal conductivity of the first wall material itself is also crucial. High thermal conductivity can quickly transfer heat to the outer layer to avoid large thermal load and enable the reactor to run well.

[0005] For tungsten-rhenium alloy used as the first wall material, how to improve the mechanical properties by adding rhenium while avoiding the reduction of thermal conductivity as much as possible is a problem that needs to be solved for the further development of fusion reactors. SUMMARY

[0006] The application discloses a full-process method for improving thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation.

[0007] To solve the above technical problems, the technical scheme of the application is as follows: a full-process method for improving thermal diffusion coefficient of tungsten-rhenium alloy plate by rhenium segregation, which specifically comprises the following steps:

[0008] S1) configuring tungsten powder and rhenium powder with different particle sizes according to a predetermined ratio and uniformly mixing the same by using a double-motion mixer to obtain uniformly dispersed tungsten-rhenium alloy powder;

[0009] S2) cold isostatic 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 rhenium-segregated tungsten-rhenium alloy blank;

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

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

[0012] Further, the tungsten powder in S1) has a Fisher particle size of 1-10 microns, and the rhenium powder has a Fisher particle size of 50-100 microns;

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

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

[0015] Further, the purity of the tungsten powder and the rhenium powder in S1) is greater than 99.99%.

[0016] Further, the density of the sintered tungsten-rhenium alloy blank in S2) under the hydrogen atmosphere is greater than 95%.

[0017] Further, the heating device used in the hot rolling process in S3) is a hydrogen furnace, the heating temperature is 1,550-1,700 DEG C, the holding time is 0.5-1 h, the holding time between each pass is 0.2-0.3 h, the thickness reduction percentage of each pass is 10-20%, and the deformation rate of the tungsten-rhenium alloy plate after hot rolling is greater than 60%.

[0018] Further, the annealing temperature in S4) is 1,000-2,000 DEG C, the annealing time is 1-100 h, and the furnace is cooled down.

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

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

[0021] A tungsten-rhenium alloy plate is prepared by the above full-process method.

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

[0023] 1. The present application uses tungsten powder and rhenium powder to mix powder, cold isostatic pressing to press green body, hydrogen furnace sintering tungsten-rhenium alloy blank, high-temperature annealing treatment, and completes the full-process preparation of high-thermal-conductivity tungsten-rhenium alloy plate. In the preparation process, fine tungsten powder and coarse rhenium powder are selected to mix powder in the powder mixing process, so that a tungsten-rhenium alloy blank containing rhenium segregation is obtained after sintering, and a rhenium-segregated anisotropic tungsten-rhenium alloy plate is obtained after further rolling, thereby improving the problem of thermal diffusion coefficient reduction caused by the addition of rhenium in the tungsten alloy.

[0024] 2. Compared with the traditional process, the present application adopts high-temperature annealing, reduces the internal defects of the rolled tungsten-rhenium alloy plate, enhances the order and periodicity of the internal lattice of the plate, and improves the thermal diffusion coefficient of the tungsten-rhenium alloy plate in each direction. When tungsten-based material is used as the first wall material of a fusion reactor, the strength of the heat conduction capacity is crucial to the service life of the material. In the case of fixed composition, it is difficult to improve the thermal diffusion coefficient. The present application creatively introduces rhenium segregation and annealing, which can finally improve the thermal diffusion coefficient of the plate by 3-8%, and significantly enhances the heat conduction capacity of the tungsten alloy. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a process route map of the full-process method for improving the thermal diffusion coefficient of the tungsten-rhenium alloy plate according to the present application.

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

[0027] Figure 3 It is a secondary electron and surface scan map of the high-thermal tungsten-rhenium alloy blank prepared in Example 1 of the present application before rolling.

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

[0029] Figure 5 It is a secondary electron and surface scan map of the tungsten-rhenium alloy blank prepared in Example 2 of the present application before rolling. Detailed Implementation

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

[0031] like Figure 1 As shown, this invention provides a complete process method for improving the thermal diffusivity of tungsten-rhenium alloy plates through rhenium segregation. The method includes the following steps:

[0032] Step 1: Fine tungsten powder and coarse rhenium powder are mixed according to a predetermined configuration and then uniformly mixed using a dual-motion method to obtain uniformly dispersed tungsten-rhenium alloy powder.

[0033] Step 2: The uniformly mixed tungsten-rhenium powder obtained in Step 1 is loaded into a rubber sleeve and cold isostatically pressed to obtain a green blank. The green blank is then placed in a hydrogen furnace for sintering to obtain a rhenium segregated tungsten-rhenium alloy blank.

[0034] Step 3: The tungsten-rhenium alloy billet containing rhenium segregation obtained in Step 2 is hot rolled to obtain a tungsten-rhenium alloy plate with rhenium segregation anisotropy.

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

[0036] The above-mentioned whole-process preparation method for improving the thermal diffusivity of tungsten-rhenium alloy plates by introducing rhenium segregation, wherein the tungsten powder and rhenium powder mentioned in step one have a mass purity of 99.99% or higher, the high purity can avoid the influence of impurity elements on the thermal diffusivity of tungsten alloy plates.

[0037] The above-described complete process for preparing tungsten-rhenium alloy plates with improved thermal diffusivity due to rhenium segregation involves using tungsten powder with a Fisher particle size between 1 μm and 10 μm and rhenium powder with a Fisher particle size between 50 μm and 100 μm in step one. The selection of these parameters facilitates obtaining a structure with rhenium segregation in the sintered blank, while also ensuring that a second phase is not generated in the sintered blank due to severe rhenium segregation. Furthermore, it considers the powder's pressing properties, which is beneficial for obtaining a high-density sintered blank.

[0038] The above-described complete preparation method for improving the thermal diffusivity of tungsten-rhenium alloy plates through rhenium segregation involves a tungsten-rhenium mixed powder in step one, where the mass percentage of rhenium powder is 0.1% to 10%, with the remainder being tungsten. The selection of these parameters avoids the reduction in interparticle distance caused by excessive rhenium addition during the entire pressing process, which would inhibit rhenium diffusion and the formation of a second phase, thus reducing processing performance.

[0039] The above-mentioned whole-process preparation method for improving the thermal diffusivity of tungsten-rhenium alloy plates by rhenium segregation requires that the tungsten powder and rhenium powder be mixed at more than 10,000 revolutions per minute using a dual-motion mixer in step one. The selection of the above parameters is conducive to the uniform mixing of tungsten powder and rhenium powder, avoiding the agglomeration of rhenium powder and tungsten powder due to uneven mixing, which would cause the formation of a second phase in the rhenium segregation region of the sintered blank, which is not conducive to subsequent hot working deformation.

[0040] The above-mentioned whole-process preparation method for improving the thermal diffusivity of tungsten-rhenium alloy plates by rhenium segregation, wherein the density of the tungsten-rhenium alloy billet sintered in a hydrogen atmosphere in step two is greater than 95%.

[0041] The above-described full-process preparation method for improving the thermal diffusivity of tungsten-rhenium alloy plates by rhenium segregation requires that the deformation rate of the tungsten-rhenium alloy plate after hot rolling in step three be greater than 60%. The hot rolling process uses a hydrogen furnace with a heating temperature of 1550℃~1700℃, a holding time of 0.5h~1h, and a holding time of 0.2h~0.3h between each rolling pass. The thickness reduction percentage for each rolling pass is 10%~20%. These parameter selections are beneficial for obtaining tungsten-rhenium alloy plates with rhenium segregation anisotropy, resulting in an anisotropic distribution of the thermal diffusivity of the tungsten-rhenium alloy, and an improvement in the thermal diffusivity along the RD direction.

[0042] The above-described complete preparation method for improving the thermal diffusivity of tungsten-rhenium alloy plates by reducing rhenium segregation involves an annealing temperature of 1000℃~2000℃ and an annealing time of 1h~100h, with furnace cooling. The annealing equipment must be a hydrogen furnace, a vacuum furnace, or an inert atmosphere furnace. These parameter selections help reduce the presence of defects in the tungsten-rhenium alloy plates, improve the order and periodicity of the internal crystal lattice, and prevent the rhenium segregation from weakening or disappearing during annealing due to rhenium diffusion, thereby further improving the thermal diffusivity of the tungsten-rhenium alloy plates.

[0043] Example 1

[0044] This embodiment includes the following steps:

[0045] Step 1: Prepare tungsten powder and rhenium powder with a purity of 99.99% and Fisher particle sizes of 3μm and 100μm respectively at a mass fraction of 98% and 2%. Use a dual-motion mixer to mix the tungsten powder and rhenium powder evenly. The mixer parameters are: speed 50 rpm and time 4h to obtain a uniformly dispersed tungsten-rhenium mixed powder.

[0046] Step 2: Press the tungsten-rhenium mixed powder obtained in Step 1 using a cold isostatic pressing device to obtain a green blank, and then sinter it in a hydrogen furnace to obtain a tungsten-rhenium alloy blank with a density greater than 95%.

[0047] Step 3: The tungsten-rhenium alloy billet obtained in Step 2 is rolled using a hot rolling mill. The heating equipment used is a hydrogen furnace, the heating temperature is 1650℃, the holding time is 0.5h, and the holding time between each rolling pass is 0.25h. The thickness reduction percentage of each rolling pass is 15%, and finally a tungsten-rhenium alloy plate with a deformation of more than 60% is obtained.

[0048] Step 4: The tungsten-rhenium alloy plate obtained in Step 3 is subjected to high-temperature annealing treatment using heating equipment. The annealing temperature is 1500℃ and the time is 1 hour. The heating equipment used is a hydrogen furnace. Finally, recrystallized tungsten-rhenium alloy plate is obtained.

[0049] Figure 3 and Figure 4 The scanning electron microscope (SEM) images and compositional distribution of rhenium segregation in the sintered billet and rolled rhenium alloy plate prepared in this embodiment are shown below. 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 and is not anisotropic. After rolling, the plate exhibits anisotropic rhenium segregation.

[0050] Table 1 shows the thermal diffusivity 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 diffusivity in the RD direction, and the thermal diffusivity is further improved after annealing.

[0051] Table 1. Thermal diffusivity of the high thermal conductivity tungsten-rhenium alloy sheet prepared in this embodiment under 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 purity of 99.99% and Fisher particle sizes of 3μm and 70μm respectively at a mass fraction of 98% and 2%. Use a dual-motion mixer to mix the tungsten powder and rhenium powder evenly. The mixer parameters are: speed 50rpm, time 4h, to obtain a uniformly dispersed tungsten-rhenium mixed powder.

[0056] Step 2: Press the tungsten-rhenium mixed powder obtained in Step 1 using a cold isostatic pressing device to obtain a green blank, and then sinter it in a hydrogen furnace to obtain a tungsten-rhenium alloy blank with a density greater than 95%.

[0057] Step 3: The tungsten-rhenium alloy billet obtained in Step 2 is rolled using a hot rolling mill. The heating equipment used is a hydrogen furnace, the heating temperature is 1650℃, the holding time is 0.5h, and the holding time between each rolling pass is 0.25h. The thickness reduction percentage of each rolling pass is 15%, and finally a tungsten-rhenium alloy plate with a deformation of more than 60% is obtained.

[0058] Step 4: The tungsten-rhenium alloy plate obtained in Step 3 is subjected to high-temperature annealing treatment using heating equipment. The annealing temperature is 1500℃ and the time is 1 hour. The heating equipment used is a hydrogen furnace. Finally, recrystallized tungsten-rhenium alloy plate is obtained.

[0059] Figure 5 The images shown are secondary electron and surface scans of the tungsten-rhenium alloy billet prepared in this embodiment before rolling. Figure 5 As can be seen, as the rhenium powder particles become finer, the rhenium segregation region in the sintered billet decreases, and the anisotropy of rhenium segregation formed after subsequent rolling weakens.

[0060] Table 2 shows the thermal diffusivity 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 diffusivity in the RD direction. After annealing, the thermal diffusivity is further improved, but compared with Example 1, the thermal diffusivity in the RD direction is reduced.

[0061] Table 2 shows the thermal diffusivity of the high thermal conductivity tungsten-rhenium alloy plates prepared in this embodiment under different directions after sintering, rolling, and annealing.

[0062]

[0063] The above provides a detailed description of the entire process of improving the thermal diffusivity of tungsten-rhenium alloy plates through rhenium segregation, as provided in the embodiments of this application. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and its core ideas; furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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 full-process method for introducing rhenium segregation to improve the thermal diffusion coefficient of tungsten-rhenium alloy plate material, characterized in that, The whole-process method specifically comprises the following steps: S1) configuring tungsten powder and rhenium powder of different particle sizes according to a predetermined ratio, and uniformly mixing using a double-motion mixer to obtain uniformly dispersed tungsten-rhenium alloy powder; The tungsten powder has a Fisher particle size of 1-10 μm, and the rhenium powder has a Fisher particle size of 50-100 μm; The mass ratio of the rhenium powder in the tungsten-rhenium mixed powder is 0.1-10%, and the balance is tungsten; The double-motion mixer has a rotation number of not less than 10,000; The purity of the tungsten powder and the rhenium powder is not less than 99.99%; S2) cold isostatic 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 rhenium-partially-aggregated tungsten-rhenium alloy blank; The sintered tungsten-rhenium alloy blank has a density of greater than 95% under a hydrogen atmosphere; S3) hot rolling the rhenium-partially-aggregated tungsten-rhenium alloy blank obtained in S2) to obtain a tungsten-rhenium alloy plate having rhenium-partially-aggregated anisotropy; The hot rolling process uses a heating device which is a hydrogen furnace, the heating temperature is 1,550-1,700 °C, the holding time is 0.5-1 h, and the holding time between each pass is 0.2-0.3 h, the thickness reduction percentage of each pass is 10-20%, and the deformation rate of the tungsten-rhenium alloy plate after hot rolling is greater than 60%; S4) annealing the tungsten-rhenium alloy plate having rhenium-partially-aggregated anisotropy obtained in S3) in a high-temperature furnace to obtain a tungsten-rhenium alloy plate having a high thermal diffusion coefficient; The annealing temperature is 1,000-2,000 °C, the annealing time is 1-100 h, and the cooling is furnace cooling.

2. The full flow process of claim 1, wherein, The annealing device is a hydrogen furnace, a vacuum furnace or an inert gas atmosphere furnace.

3. The full flow process of claim 1, wherein, 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 3-10%.

4. A sheet of tungsten-rhenium alloy, characterized by, The tungsten-rhenium alloy plate is obtained by the whole-process method according to any one of claims 1-3.

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