A tungsten-potassium alloy and its preparation method and application

Abstract

The present invention belongs to the field of material technology, and specifically relates to a tungsten-potassium alloy and its preparation method and application. The preparation method of the tungsten-potassium alloy provided by the present invention comprises the following steps: 1) mixing tungsten oxide with K2SiO3, KCl and Al(NO3)3, and then drying and reducing to obtain doped tungsten powder; 2) pressing and sintering the doped tungsten powder in step 1) to obtain a tungsten-potassium alloy block; 3) heating the tungsten alloy block in step 2) under a protective atmosphere, hot rolling at 1400-1650°C, with a total rolling deformation of 40-70%, and annealing to obtain the tungsten-potassium alloy. The present invention accurately controls the hot rolling temperature and the hot rolling deformation, so that the obtained tungsten-potassium alloy has a strong {001} surface texture, which effectively improves the radiation resistance of the tungsten-potassium alloy.

Description

Technical Field

[0001] The present invention belongs to the field of material technology, and in particular relates to a tungsten-potassium alloy and a preparation method and application thereof. Background Art

[0002] The plasma-facing wall materials in nuclear fusion reactors need to serve under extremely harsh conditions such as high temperature, high heat load shock, and high-energy particle bombardment, and are the key to the development of fusion energy. Metal tungsten (W) is considered to be one of the most promising plasma-facing materials (PFMs) in future fusion reactors due to its high melting point (3410℃), excellent high-temperature strength, high elastic modulus, good thermal conductivity, low expansion coefficient, and low tritium retention rate. However, the low-temperature brittleness of W (i.e., relatively high ductile-brittle transition temperature DBTT), recrystallization brittleness, irradiation brittleness, and unsatisfactory irradiation performance have seriously restricted the engineering application of W in the field of nuclear energy.

[0003] In order to alleviate the above problems, researchers have been committed to developing advanced W-based alloys through mechanical processing methods such as mechanical alloying, hot forging or hot rolling. On the one hand, the fine grains caused by the second phase doping increase the grain boundary area, thereby reducing the average impurity concentration at the grain boundary, and then reducing the DBTT of the material; on the other hand, the nano second phase particles can delay the movement of dislocations and grain boundaries due to the pinning effect, thereby improving the mechanical properties of the material. Compared with pure tungsten, there are potassium bubbles of tens of nanometers in the tungsten potassium alloy matrix, so it has better high temperature stability, plasticity and toughness, and radiation resistance. Tungsten potassium is also becoming one of the important candidates for plasma-oriented materials.

[0004] Related literature research shows that pure tungsten with low-index crystal planes such as {001} plane texture has better radiation resistance. Therefore, regulating the texture of tungsten potassium alloy to have a strong {001} plane texture can theoretically further improve its radiation resistance. Tungsten potassium alloy was first used in the filaments of incandescent lamps, and is also called "doped tungsten wire", "anti-droop tungsten wire", "tungsten aluminum wire", etc. Because tungsten potassium alloy was mainly used in filament form in the early days, the texture research of tungsten potassium alloy mainly focuses on the filament texture, and there is almost no research on the control of surface texture. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defects in the prior art such as the lack of research on the strong {001} surface texture of tungsten potassium alloy and the need to further improve the radiation resistance of tungsten potassium alloy, thereby providing a tungsten potassium alloy and its preparation method and application.

[0006] The present invention provides a method for preparing a tungsten-potassium alloy, comprising the following steps:

[0007] 1) Tungsten oxide and K 2 SiO3 , KCl and Al(NO 3 ) 3 Mixing, then drying and reducing to obtain doped tungsten powder;

[0008] 2) pressing and sintering the tungsten powder doped in step 1) to obtain a tungsten-potassium alloy block;

[0009] 3) The tungsten alloy block in step 2) is heated in a protective atmosphere, hot rolled at 1400-1650° C., with a total rolling deformation of 40-70%, and annealed to obtain the tungsten potassium alloy.

[0010] Preferably, in step 3), the hot rolling temperature is 1450-1650° C., and the total hot rolling deformation is 55-65%.

[0011] Preferably, in step 1) K 2 SiO 3 The total mass percentage of tungsten oxide is 0.2-0.4%; the present invention does not limit the solution concentration and mixing method in step 1), and the optional solution and solid can be evenly infiltrated, with an appropriate degree of wetness, neither liquid exposed nor dry powder.

[0012] The total mass percentage of KCl in tungsten oxide is 0.4-0.7%;

[0013] The Al(NO 3 ) 3 The total mass percentage of tungsten oxides is 0.05-0.15%.

[0014] Preferably, in step 1), K 2 SiO 3 , KCl and Al(NO 3 ) 3 Mixed with tungsten oxide in the form of a solution;

[0015] And / or, the tungsten oxide is selected from at least one of yellow tungsten and blue tungsten.

[0016] Preferably, the drying temperature in step 1) is 80-90° C. and the drying time is 8-10 h;

[0017] and / or, the reduction step is performed in a hydrogen environment;

[0018] And / or, the reduction includes primary reduction and secondary reduction;

[0019] And / or, the primary reduction temperature is 500-650° C., and the reduction time is 1-2 h;

[0020] And / or, the secondary reduction temperature is 700-850° C., and the reduction time is 6-7 hours.

[0021] Preferably, the pressing pressure in step 2) is 100-250 MPa, and the pressing time is 30-40 min;

[0022] And / or, the sintering temperature is 2300-2800°C, the sintering time is 5-8h, and the sintering atmosphere is hydrogen;

[0023] And / or, the step 2) further comprises a pre-sintering step before sintering; the pre-sintering of the present invention is to improve the strength and conductivity of the green compact.

[0024] And / or, the pre-sintering temperature is 1150-1200° C., the pre-sintering time is 30-40 min, and the pre-sintering atmosphere is hydrogen.

[0025] Optionally, the compact in step 2) is pressed to a compact density of 9.5-10.5 g / cm 3 The present invention does not limit the equipment for pressing green sheets, and a cold press or a cold isostatic press can be selected.

[0026] Preferably, the heating temperature in step 3) is 1650-1700° C., and the holding time is 1-2 h;

[0027] And / or, the protective atmosphere is hydrogen;

[0028] And / or, the hot rolling is performed in 2-15 passes;

[0029] And / or, in step 3), the annealing temperature is 800-1200° C., and the annealing time is 1-2 h.

[0030] The present invention also provides a tungsten-potassium alloy prepared by the method described above, wherein the {001} plane texture of the tungsten-potassium alloy accounts for 14.22-26.89% of the total volume of the alloy.

[0031] Preferably, the components include W content not less than 99.95%, K content of 10-400ppm, and the rest are impurities, and the average size of potassium bubbles formed by K is less than 400nm;

[0032] Preferably, the average size of potassium bubbles is 80-200 nm.

[0033] The present invention also provides a tungsten-potassium alloy prepared by the method described above or the application of the tungsten-potassium alloy described above in the field of nuclear energy engineering.

[0034] The technical solution of the present invention has the following advantages:

[0035] (1) The preparation method of the tungsten-potassium alloy provided by the present invention comprises the following steps: 1) reacting tungsten oxide with K 2 SiO 3 , KCl and Al(NO 3 ) 3 Mix, then dry and reduce to obtain doped tungsten powder; 2) press and sinter the doped tungsten powder in step 1) to obtain a tungsten potassium alloy block; 3) heat the tungsten alloy block in step 2) under a protective atmosphere, hot roll at 1400-1650°C, with a total rolling deformation of 40-70%, and anneal to obtain the tungsten potassium alloy. The present invention can utilize the principle of dynamic recrystallization inducing the transformation of high-index surface texture to low-index surface texture by accurately controlling the hot rolling temperature and the total rolling deformation, and the obtained tungsten potassium alloy has a strong {001} surface texture; potassium bubble strong and tough tungsten alloy, i.e., tungsten potassium alloy, is used as the basic material for regulating low-index surface texture, and potassium bubbles in the matrix can also promote dynamic recrystallization, further promote the formation of {001} surface texture, and effectively improve the radiation resistance of tungsten potassium alloy.

[0036] (2) The preparation method of the tungsten potassium alloy provided by the present invention has a hot rolling temperature of 1450-1650°C and a total hot rolling deformation of 55-65%. The present invention further limits the hot rolling temperature and the hot rolling deformation, and the dynamic recrystallization-induced low-index surface texture transformation is more accurate, and the proportion of the {001} surface texture of the obtained tungsten potassium alloy is higher, and the radiation resistance is stronger.

[0037] (3) The preparation method of the tungsten potassium alloy provided by the present invention, the obtained strong {001} surface texture tungsten potassium alloy is a gas potassium bubble tough tungsten alloy with excellent toughness matching performance. The dispersed phase is a gas potassium bubble at high temperature, which has good deformability and can annihilate some dislocations, which can effectively improve the plastic toughness of the tungsten material. At the same time, the existence of the dispersed phase can improve the strength of the tungsten material through the Orowan effect, achieving the effect of toughness better than ordinary pure tungsten; at the same time, because the potassium bubble is mainly distributed at the grain boundary, it can hinder the lateral movement of the grain boundary, induce the interlocking grain structure with dovetail overlap, and improve the high temperature stability and high temperature creep performance of the tungsten potassium alloy. Finally, there is an interface between the potassium bubble and the tungsten matrix, which can be used as an irradiation defect capture site to further improve the radiation resistance of the tungsten potassium alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1Metallographic photograph of the tungsten-potassium alloy of Example 2 of the present invention;

[0040] Figure 2 The size and distribution of K bubbles in the tungsten potassium alloy of Example 2 of the present invention;

[0041] Figure 3 The inverse pole figure of the tungsten-potassium alloy texture type of Example 2 of the present invention. DETAILED DESCRIPTION

[0042] The following examples are provided for a better understanding of the present invention, but are not intended to limit the best mode of implementation, nor to limit the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with other prior arts shall fall within the protection scope of the present invention.

[0043] If no specific experimental steps or conditions are specified in the examples, the conventional experimental steps or conditions described in the literature in the field can be used. If no manufacturer is specified for the reagents or instruments used, they are all conventional reagent products that can be obtained commercially.

[0044] Example 1

[0045] This embodiment provides a method for preparing a tungsten-potassium alloy, comprising the following steps:

[0046] 1) Weigh 25kg of blue tungsten and K 2 SiO 3 、KCl、Al(NO 3 ) 3 Mixed in the form of an aqueous solution, wherein K 2 SiO 3 、KCl、Al(NO 3 ) 3 The mass percentage of the blue tungsten is 0.3%, 0.6% and 0.1% respectively, and then it is stirred and dried in a stirring pot, the drying temperature is 80℃, the drying time is 10h, and the dried mixed material is strictly reduced in two steps, the first reduction temperature is 600℃, the reduction time is 2h, and the second reduction temperature is 800℃, the reduction time is 6h, and the doped tungsten powder is obtained;

[0047] 2) The tungsten powder doped in step 1) was used to prepare a tungsten potassium alloy compact by a cold isostatic press at a pressure of 200 MPa for 30 min, followed by pre-sintering at 1200 °C for 30 min with a protective gas of H 2 Then the medium frequency induction sintering furnace was used for high temperature sintering. The sintering temperature was 2750℃ and the sintering time was 7h. The protective gas during the whole process was H 2 , and obtain a tungsten alloy block;

[0048] 3) The tungsten alloy block in step 2) is heated under a hydrogen protective atmosphere at a heating temperature of 1700°C and a holding time of 2h; then the tungsten alloy block is hot rolled using a double-roll reversible rolling mill, with a starting rolling temperature of 1650°C, a final rolling temperature of 1400°C, 6 hot rolling passes, and a total rolling deformation of 70%; finally, annealing is performed at an annealing temperature of 1200°C and an annealing time of 2h to obtain the tungsten potassium alloy.

[0049] After testing, the obtained tungsten potassium alloy has a composition of 99.96% W, 108ppm K, and the rest are impurities, with an average K bubble size of 149nm.

[0050] Example 2

[0051] This embodiment provides a method for preparing a tungsten-potassium alloy, comprising the following steps:

[0052] 1) Weigh 25kg of blue tungsten and K 2 SiO 3 、KCl、Al(NO 3 ) 3 Mixed in the form of an aqueous solution, wherein K 2 SiO 3 、KCl、Al(NO 3 ) 3 The mass percentage of the blue tungsten is 0.3%, 0.6% and 0.1% respectively, and then it is stirred and dried in a stirring pot, the drying temperature is 80℃, the drying time is 10h, and the dried mixed material is strictly reduced in two steps, the first reduction temperature is 600℃, the reduction time is 2h, and the second reduction temperature is 800℃, the reduction time is 6h, and the doped tungsten powder is obtained;

[0053] 2) The tungsten powder doped in step 1) was used to prepare a tungsten potassium alloy compact by a cold isostatic press at a pressure of 200 MPa for 30 min, followed by pre-sintering at 1200 °C for 30 min with a protective gas of H 2 Then the medium frequency induction sintering furnace was used for high temperature sintering. The sintering temperature was 2650℃ and the sintering time was 6h. The protective gas during the whole process was H 2 , and obtain a tungsten alloy block;

[0054] 3) The tungsten alloy block in step 2) is heated under a hydrogen protective atmosphere at a heating temperature of 1700°C and a holding time of 2h; then the tungsten alloy block is hot rolled using a double-roll reversible rolling mill, with a starting rolling temperature of 1650°C, a final rolling temperature of 1450°C, 4 hot rolling passes, and a total rolling deformation of 55%; finally, annealing is performed at an annealing temperature of 1200°C and an annealing time of 2h to obtain the tungsten potassium alloy.

[0055] After testing, the obtained tungsten-potassium alloy has a composition of 99.97% W, 99 ppm K, and the rest are impurities, with an average K bubble size of 101 nm.

[0056] The tungsten potassium alloy obtained by electron microscope was obtained. Figure 1 and Figure 2 ,in Figure 1 The equiaxed grains shown indicate the presence of dynamic recrystallization during hot rolling. Figure 2 The K-bubble distribution and their size are shown. Figure 3 It is the inverse pole figure of the texture type of tungsten potassium alloy. Its texture type is mainly {001} / / (RD-TD), that is, the texture of {001} / / rolled surface. The volume fraction of {001} / / rolled surface texture reaches 26.89%. RD, TD and ND are abbreviations for rolling direction, transverse direction and normal direction, respectively.

[0057] Example 3

[0058] This embodiment provides a method for preparing a tungsten-potassium alloy, comprising the following steps:

[0059] 1) Weigh 25kg of blue tungsten and K 2 SiO 3 、KCl、Al(NO 3 ) 3 Mixed in the form of an aqueous solution, wherein K 2 SiO 3 、KCl、Al(NO 3 ) 3 The mass percentage of the blue tungsten is 0.3%, 0.6% and 0.1% respectively, and then it is stirred and dried in a stirring pot, the drying temperature is 80℃, the drying time is 10h, and the dried mixed material is strictly reduced in two steps, the first reduction temperature is 600℃, the reduction time is 2h, and the second reduction temperature is 800℃, the reduction time is 6h, and the doped tungsten powder is obtained;

[0060] 2) The tungsten powder doped in step 1) was used to prepare a tungsten potassium alloy compact by a cold isostatic press at a pressure of 200 MPa for 30 min, followed by pre-sintering at 1200 °C for 30 min with a protective gas of H 2 Then the medium frequency induction sintering furnace was used for high temperature sintering. The sintering temperature was 2550℃ and the sintering time was 5h. The protective gas during the whole process was H 2 , and obtain a tungsten alloy block;

[0061] 3) The tungsten alloy block in step 2) is heated under a hydrogen protective atmosphere at a heating temperature of 1700°C and a holding time of 2h; then the tungsten alloy block is hot rolled using a double-roll reversible rolling mill, with a starting rolling temperature of 1650°C, a final rolling temperature of 1500°C, two hot rolling passes, and a total rolling deformation of 40%; finally, annealing is performed at an annealing temperature of 1200°C and an annealing time of 2h to obtain the tungsten potassium alloy.

[0062] After testing, the obtained tungsten-potassium alloy has a composition of 99.97% W, 102ppm K, and the rest are impurities, with an average K bubble size of 87nm.

[0063] Comparative Example 1

[0064] This comparative example provides a method for preparing a tungsten-potassium alloy, comprising the following steps:

[0065] 1) Weigh 25kg of blue tungsten and K 2 SiO 3 、KCl、Al(NO 3 ) 3 Mixed in the form of an aqueous solution, wherein K 2 SiO 3 、KCl、Al(NO 3 ) 3 The mass percentage of the blue tungsten is 0.3%, 0.6% and 0.1% respectively, and then it is stirred and dried in a stirring pot, the drying temperature is 80℃, the drying time is 10h, and the dried mixed material is strictly reduced in two steps, the first reduction temperature is 600℃, the reduction time is 2h, and the second reduction temperature is 800℃, the reduction time is 6h, and the doped tungsten powder is obtained;

[0066] 2) The tungsten powder doped in step 1) was used to prepare a tungsten potassium alloy compact by a cold isostatic press at a pressure of 200 MPa for 30 min, followed by pre-sintering at 1200 °C for 30 min with a protective gas of H 2 Then the medium frequency induction sintering furnace was used for high temperature sintering. The sintering temperature was 2750℃ and the sintering time was 7h. The protective gas during the whole process was H 2 , and obtain a tungsten alloy block;

[0067] 3) The tungsten alloy block in step 2) is heated under a hydrogen protective atmosphere at a heating temperature of 1700°C and a holding time of 2h; then the tungsten alloy block is hot rolled using a double-roll reversible rolling mill, with a starting rolling temperature of 1650°C, a final rolling temperature of 1350°C, 6 hot rolling passes, and a total rolling deformation of 82%; finally, annealing is performed at an annealing temperature of 1200°C and an annealing time of 2h to obtain the tungsten potassium alloy.

[0068] After testing, the obtained tungsten-potassium alloy has a composition of 99.95% W, 115 ppm K, and the rest are impurities, wherein the average size of K bubbles is 76 nm.

[0069] Comparative Example 2

[0070] This comparative example provides a method for preparing a tungsten-potassium alloy, comprising the following steps:

[0071] 1) Weigh 25kg of blue tungsten and K 2 SiO 3 、KCl、Al(NO 3 ) 3 Mixed in the form of an aqueous solution, wherein K 2 SiO 3 、KCl、Al(NO 3 ) 3 The mass percentage of the blue tungsten is 0.3%, 0.6% and 0.1% respectively, and then it is stirred and dried in a stirring pot, the drying temperature is 80℃, the drying time is 10h, and the dried mixed material is strictly reduced in two steps, the first reduction temperature is 600℃, the reduction time is 2h, and the second reduction temperature is 800℃, the reduction time is 6h, and the doped tungsten powder is obtained;

[0072] 2) The tungsten powder doped in step 1) was used to prepare a tungsten potassium alloy compact by a cold isostatic press at a pressure of 200 MPa for 30 min, followed by pre-sintering at 1200 °C for 30 min with a protective gas of H 2 Then the medium frequency induction sintering furnace was used for high temperature sintering. The sintering temperature was 2750℃ and the sintering time was 7h. The protective gas during the whole process was H 2 , and obtain a tungsten alloy block;

[0073] 3) The tungsten alloy block in step 2) is heated under a hydrogen protective atmosphere at a heating temperature of 1700°C and a holding time of 2h; then the tungsten alloy block is hot rolled using a double-roll reversible rolling mill, with a starting rolling temperature of 1650°C, a final rolling temperature of 1550°C, 6 hot rolling passes, and a total rolling deformation of 35%; finally, annealing is performed at an annealing temperature of 1200°C and an annealing time of 2h to obtain the tungsten potassium alloy.

[0074] After testing, the obtained tungsten-potassium alloy has a composition of 99.98% W, 90 ppm K, and the rest are impurities, with an average K bubble size of 68 nm.

[0075] Test Case

[0076] The volume fraction of the {001} plane texture of the samples prepared in Examples 1-3 and Comparative Examples 1-2 in the total volume of the alloy was measured by X-ray diffraction, and the measurement results are shown in Table 1. It can be seen from the results in the table that the present invention can effectively increase the volume fraction of the {001} plane texture of the tungsten potassium alloy.

[0077] Table 1

[0078]

[0079] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a tungsten-potassium alloy, characterized in that: The following steps are involved: 1) Mix tungsten oxide with K2SiO3, KCl and Al(NO3)3, then dry and reduce to obtain doped tungsten powder; 2) pressing and sintering the tungsten powder doped in step 1) to obtain a tungsten-potassium alloy block; 3) heating the tungsten alloy block in step 2) under a protective atmosphere, hot rolling at 1400-1650° C., with a total rolling deformation of 40-70%, and annealing to obtain the tungsten potassium alloy; The {001} surface texture of the tungsten potassium alloy accounts for 14.22-26.89% of the total volume of the alloy.

2. The method for preparing tungsten-potassium alloy according to claim 1, characterized in that: In step 3), the hot rolling temperature is 1450-1650° C., and the total hot rolling deformation is 55-65%.

3. The method for preparing tungsten-potassium alloy according to claim 1 or 2, characterized in that: In step 1), the total mass percentage of K2SiO3 in tungsten oxide is 0.2-0.4%; The total mass percentage of KCl in tungsten oxide is 0.4-0.7%; The total mass percentage of Al(NO3)3 in tungsten oxide is 0.05-0.15%.

4. The method for preparing tungsten-potassium alloy according to claim 1 or 2, characterized in that: In step 1), K2SiO3, KCl and Al(NO3)3 are mixed with tungsten oxide in the form of a solution; And / or, the tungsten oxide is selected from at least one of yellow tungsten and blue tungsten.

5. The method for preparing tungsten-potassium alloy according to claim 1 or 2, characterized in that: The drying temperature in step 1) is 80-90°C; the drying time is 8-10h; and / or, the reduction step is performed in a hydrogen environment; And / or, the reduction includes primary reduction and secondary reduction, the primary reduction temperature is 500-650° C., the reduction time is 1-2 h, and the secondary reduction temperature is 700-850° C., the reduction time is 6-7 h.

6. The method for preparing tungsten-potassium alloy according to claim 1 or 2, characterized in that: Step 2) The pressing pressure is 100-250 MPa and the pressing time is 30-40 min; and / or, the sintering temperature is 2300-2800° C., the sintering time is 5-8 hours, and the sintering atmosphere is hydrogen; And / or, the step 2) further comprises a pre-sintering step before sintering, the pre-sintering temperature is 1150-1200° C., the pre-sintering time is 30-40 min, and the pre-sintering atmosphere is hydrogen.

7. The method for preparing tungsten-potassium alloy according to claim 1 or 2, characterized in that: In step 3), the heating temperature is 1650-1700°C and the holding time is 1-2h; And / or, the protective atmosphere is hydrogen; And / or, the hot rolling is performed in 2-15 passes; And / or, in step 3), the annealing temperature is 800-1200° C. and the annealing time is 1-2 h.

8. A tungsten-potassium alloy prepared by the method according to any one of claims 1 to 7, characterized in that: The {001} surface texture of the tungsten potassium alloy accounts for 14.22-26.89% of the total volume of the alloy; The tungsten-potassium alloy comprises, by weight percentage, a W content of not less than 99.95%, a K content of 10-400 ppm, and the remainder being impurities; the average size of potassium bubbles formed by the K is less than 400 nm.

9. The tungsten-potassium alloy according to claim 8, characterized in that: The average size of potassium vesicles is 80-200nm.

10. Use of a tungsten-potassium alloy prepared by the method described in any one of claims 1 to 7 or a tungsten-potassium alloy described in claim 8 or 9 in the field of nuclear energy engineering.

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