A method for preparing high-entropy alloys using niobium-tantalum waste

Abstract

This application belongs to the field of alloy materials and discloses a method for preparing high-entropy alloys using niobium-tantalum waste. The invention utilizes valuable niobium- and tantalum-containing waste generated from electron beam melting of niobium and tantalum, and through a series of processing steps, prepares a refractory high-entropy alloy, NbMoTaVSiAl. This invention not only achieves the reuse of waste materials but also successfully develops silicon-reinforced tungsten-molybdenum-tantalum-niobium high-entropy alloy materials. This material is suitable for high-temperature applications such as first-stage turbine guide vanes, nuclear fusion reactors, and high-speed aircraft.

Description

Technical Field

[0001] This application relates to the field of alloy materials technology, specifically to a method for preparing high-entropy alloys using niobium-tantalum waste. Background Technology

[0002] In the process of preparing metallic niobium and tantalum using aluminothermic reduction combined with vacuum electron beam purification, niobium- and tantalum-containing waste is generated. Some researchers have attempted to recover niobium and tantalum from the alloy waste. However, existing recycling technologies are not suitable for processing this waste, mainly because in addition to niobium and tantalum, the waste also contains a large amount of low-melting-point element aluminum and other impurities, especially silicon, which contains 0.3% or higher, making it difficult to recover pure metallic niobium and tantalum.

[0003] Therefore, how to treat and effectively utilize this waste is a topic worthy of research. Summary of the Invention

[0004] Objective of the Invention: To address the shortcomings of existing technologies, this application proposes a method for preparing high-entropy alloys using niobium-tantalum waste. This invention ingeniously utilizes alloy waste that is difficult to purify and recycle to obtain a high-entropy alloy containing niobium and tantalum.

[0005] Technical solution: The high-entropy alloy to be prepared by this invention comprises: tungsten, molybdenum, tantalum, niobium, aluminum, and silicon. The proportions of the elements are: W: 32-34%, Mo: 16-18%, Ta: 32-34%, Nb: 16-18%, Al: 0.5-1%, and Si: 0.2-1.0%.

[0006] The niobium- and tantalum-containing waste materials mentioned in this invention are waste materials generated during the vacuum electron beam purification process for preparing metallic niobium and metallic tantalum, wherein the silicon content is greater than 0.3%.

[0007] The method for preparing high-entropy alloys using niobium-tantalum waste provided by this invention includes the following steps:

[0008] Niobium- and tantalum-containing waste materials are crushed into 0-3mm particles, mixed evenly, and subjected to chemical composition analysis. The analyzed elements include niobium / tantalum, aluminum, and silicon. Refractory metal oxides such as tantalum pentoxide, niobium pentoxide, tungsten oxide, and molybdenum trioxide are baked to remove moisture at 150-200℃ for 30-120 minutes. The baked tantalum pentoxide, niobium pentoxide, tungsten oxide, molybdenum trioxide, along with the niobium and tantalum waste materials, aluminum powder, calcium fluoride, and sodium chlorate, are weighed and mixed in a mixer for 10-20 minutes to ensure thorough mixing. The mixed raw materials are transferred to a pre-prepared alumina crucible and placed in a vacuum thermal reduction furnace. An oxidation-reduction reaction is initiated, and the reaction product is cooled in the furnace for 8-16 hours. The crucible is removed, and the resulting high-entropy alloy and slag are separated. The surface of the high-entropy alloy ingot is polished clean to obtain a tungsten-molybdenum-tantalum-niobium high-entropy alloy ingot.

[0009] Furthermore, a preferred embodiment of the present invention includes the following steps:

[0010] Step 1: The niobium / tantalum-containing waste is subjected to multi-stage crushing and screening to sizes of 0-1mm, 0-3mm, and 0-5mm respectively. The crushed material is then mixed in a mixer for 10-30 minutes. The mixed material is placed in a hopper, and six samples are taken from different locations using a sampler for Nb / Ta and Al main element analysis.

[0011] If the sample test result deviation is less than 1% (the deviation is defined as the difference between the maximum and minimum content), proceed to step 2; if the test result deviation is greater than 1%, further crush the mixture to 0-1mm and 0-3mm respectively, and repeat the above mixing and testing steps.

[0012] If the deviation of the test result is less than 1%, proceed to step 2; if the deviation of the test result is greater than 1%, further crush the mixture to 0-1mm, and repeat the above mixing and testing steps until the deviation of the test result is less than 1%.

[0013] Niobium-containing waste is processed according to the method described above until the deviation of the test results is less than 1%; after processing, the final content of niobium-containing waste is calculated as: niobium ω1; aluminum ω2; silicon ω3;

[0014] The tantalum-containing waste is processed according to the steps described above until the deviation of the test results is less than 1%. After the tantalum-containing waste is processed, the final content obtained by the test is: tantalum ω4; aluminum ω5; silicon ω6.

[0015] Step 2: Bake the refractory metal oxides niobium pentoxide, tantalum pentoxide, tungsten oxide, and molybdenum trioxide to remove moisture. The baking temperature is 150-200℃, and the baking time is 30-120 minutes. Weigh the baked tantalum pentoxide, niobium pentoxide, tungsten oxide, and molybdenum trioxide, along with the niobium and tantalum waste from Step 1, aluminum powder, calcium fluoride, and sodium chlorate, and mix them in a mixer for 10-20 minutes to ensure thorough and uniform mixing of the raw materials.

[0016] Step 3: Transfer the mixed raw materials into a pre-prepared alumina crucible, place it in a vacuum thermal reduction furnace, evacuate to less than 50 Pa, introduce argon gas at 20-60 kPa, and ignite to initiate a redox reaction. Cool the reaction product in the furnace for 8-16 hours, remove the crucible, separate the obtained high-entropy alloy from the slag, and polish the surface of the high-entropy alloy ingot to obtain a tungsten-molybdenum-tantalum-niobium high-entropy alloy ingot.

[0017] For this invention, the ratio of the amount of niobium and tantalum waste added to the amount of raw materials is very important in order to effectively utilize niobium and tantalum waste.

[0018] Specifically, the addition of niobium and tantalum must meet the following conditions:

[0019] 16%≤(M- Nb-1 *ω1+M- Nb-2 *69.9%) / M≤18% (I)

[0020] 16%≤(M- Ta-1 *ω4+M- Ta-2 *81.9%) / M≤18% (II)

[0021] In formulas (I) and (II), the weight percentages are as follows:

[0022] M- Nb-1 ω1 represents the number of parts of niobium waste added; ω1 represents the niobium content of the niobium-containing waste after treatment; M- Nb-2 This refers to the proportion of niobium pentoxide added;

[0023] M- Ta-1 ω4 represents the number of parts added to the tantalum-niobium waste; ω4 represents the tantalum content after treatment of the tantalum-containing waste; M- Ta-2 The number of parts of tantalum pentoxide added;

[0024] M represents the total number of parts of the target high-entropy alloy.

[0025] Specifically, the addition of sodium chlorate must meet the following conditions:

[0026] 2800<(△H1*M -Nb-2 +△H2*M -Ta-2+△H3*M*33% / 73.91%+△H4*M*17% / 66.67%+△H5*M -氯酸钠 ) / M 原料 <3200 (III)

[0027] In formula (III), by mass parts:

[0028] M -氯酸钠 This refers to the number of parts of sodium chlorate added;

[0029] M 原料 The total amount of raw materials added includes niobium pentoxide, tantalum pentoxide, tungsten trioxide, molybdenum trioxide, aluminum powder, sodium chlorate, calcium fluoride, niobium waste, and tantalum waste.

[0030] △H1 is the heat of reaction between niobium pentoxide and aluminum, with a value of 3371.71 kJ / kg;

[0031] △H2 is the heat of reaction between tantalum pentoxide and aluminum, with a value of 1696.54 kJ / kg;

[0032] △H3 is the heat of reaction between tungsten trioxide and aluminum, with a value of 3618.97 kJ / kg;

[0033] △H4 is the heat of reaction between molybdenum trioxide and aluminum, with a value of 6472.92 kJ / kg;

[0034] △H5 is the heat of reaction between sodium chlorate and aluminum, with a value of 16334.4 kJ / kg.

[0035] Specifically, the addition of tungsten trioxide and molybdenum trioxide must meet the following conditions.

[0036] 32% <M- W / 73.91% / M<34% (IV)

[0037] 16% <M- Mo / 66.67% / M<18% (V)

[0038] In formulas (IV) and (V), by mass parts,

[0039] M- W M- represents the number of parts of tungsten trioxide added. Mo The number of parts of molybdenum trioxide added.

[0040] Specifically, the addition of aluminum powder must meet the following conditions:

[0041] M- Al粉 +M- Nb-1 *ω2+M- Ta-1 *ω5=k1*M- Nb-2 +k2*M-Ta-2 +k3*M- W +k4*M- Mo +k5*M -氯酸钠 (VI)

[0042] In formula (VI), by mass parts,

[0043] M- Al粉 The number of parts of aluminum powder added;

[0044] k1 is the aluminum powder consumption coefficient for niobium oxide, with a value of 0.3886;

[0045] k2 is the aluminum powder consumption coefficient for tantalum oxide, with a value of 0.2036;

[0046] k3 is the aluminum powder consumption coefficient for tungsten oxide, with a value of 0.38;

[0047] k4 is the aluminum powder consumption coefficient for molybdenum oxide, with a value of 0.23;

[0048] The coefficient for consuming aluminum powder with sodium chlorate K5 is 0.507.

[0049] ω2 represents the aluminum content after processing niobium-containing waste;

[0050] ω5 represents the tantalum content after the tantalum-containing waste has been processed.

[0051] Specifically, the addition of calcium fluoride must meet the following conditions:

[0052] M -Al总 *3% <M- 氟化钙 <M -Al总 *8% (VII)

[0053] In formula (VII), by mass parts,

[0054] M- 氟化钙 The number of parts of calcium fluoride added.

[0055] Specifically, the control of silicon content must meet the following conditions:

[0056] 0.2% < (M- Nb-1 *ω 3+ M- Ta-1 *ω 6+ M- 硅 ) / M<1.0% (VII)

[0057] In equation (VII),

[0058] ω2 represents the silicon content after processing niobium-containing waste;

[0059] ω5 represents the silicon content after processing tantalum-containing waste;

[0060] M- 硅 This refers to the amount of silicon introduced from other raw materials.

[0061] Beneficial Effects: This invention uses niobium / tantalum-containing waste generated from electron beam melting of niobium and tantalum as raw materials, cleverly utilizing its useful elements to prepare high-entropy alloys. In particular, the utilization of silicon is significant. Adding appropriate silicon elements to high-entropy alloys can form in-situ silicide ceramic phases with metallic elements, increasing the wear resistance and high-temperature oxidation resistance of the high-entropy alloys, improving the material's strength, and transforming harmful silicon elements in pure metals into beneficial silicide reinforcing phases in high-entropy alloys.

[0062] This invention transforms niobium-tantalum waste with high silicon content into a high-entropy alloy material with high strength and good high-temperature performance. This not only realizes the reuse of waste materials, but also successfully develops silicon-reinforced tungsten-molybdenum-tantalum-niobium high-entropy alloy material. This material is suitable for high-temperature fields such as first-stage turbine guide vanes, nuclear fusion reactors, and high-speed aircraft. Attached Figure Description

[0063] Figure 1 Metallographic photograph of the high-entropy alloy produced from niobium scrap #1 in Example 3.

[0064] Figure 2 Metallographic photograph of the high-entropy alloy produced from niobium scrap #2 in Example 3.

[0065] Figure 3 Metallographic photograph of the high-entropy alloy produced from niobium scrap #3 in Example 4. Detailed Implementation

[0066] The technical solution of this application will be described in detail below through embodiments, but the scope of protection of this application is not limited to the embodiments described. Unless otherwise specified, the percentage content mentioned in this application is generally a mass content.

[0067] Example 1

[0068] Niobium scrap was crushed to 0-3mm, and samples were taken for analysis. The contents of niobium and aluminum were found to be 21.34% and 77.90%, respectively.

[0069] The composition of the high-entropy alloy containing the four refractory metals W, Mo, Ta, and Nb is designed as follows: W 33%, Mo 16.5%, Ta 33%, Nb 16.5%. The designed exothermic reaction of the aluminothermic reduction reaction is -3020 kJ / kg. The reaction formula is calculated using chemical equations. The formula is: WO3 33.29 kg, MoO3 19.80 kg, Ta2O5 33.24 kg, Nb2O5 11.25 kg, niobium scrap 25.00 kg, calcium fluoride 0.8 kg, sodium chlorate 4.1 kg, and aluminum powder 9.71 kg. The weighed raw materials are loaded into a mixer and mixed for 20 minutes. The mixed raw materials are placed in an alumina crucible, and then the crucible is placed in a vacuum thermal reduction furnace. The vacuum is evacuated to below 50 Pa, and then argon gas is introduced to 20 kPa. The reaction is ignited, and after the reaction, it is cooled for 12 hours under argon protection. The reaction product is then removed, and the slag and alloy are separated. The alloy surface is shot blasted and polished to obtain a high-entropy alloy ingot.

[0070] A sample of the high-entropy alloy was analyzed, and its chemical composition is shown in the table below:

[0071] Table 1 Chemical composition of high-entropy alloy produced using niobium scrap #1

[0072] element W Mo Ta Nb Al Si O N content% 32.38 16.09 32.08 17.74 0.87 0.59 0.204 0.015

[0073] Example 2

[0074] The tantalum scrap was crushed to 0-3mm, and samples were taken for analysis. The contents of tantalum and aluminum were found to be Ta: 19.98% and Al: 78.78%, respectively.

[0075] The composition of the high-entropy alloy containing the four refractory metals W, Mo, Ta, and Nb is designed as follows: W 32.5%, Mo 17%, Ta 32.5%, Nb 17%. The designed exothermic reaction of the aluminothermic reduction is -3020 kJ / kg. The reaction formula is calculated using chemical equations. The formula is: WO3 20.49 kg, MoO3 12.75 kg, Ta2O5 16.18 kg, Nb2O5 12.16 kg, tantalum scrap 15.00 kg, calcium fluoride 0.74 kg, sodium chlorate 2.12 kg, and aluminum powder 6.8 kg. The weighed raw materials are loaded into a mixer and mixed for 20 minutes. The mixed raw materials are placed in an alumina crucible, and then the crucible is placed in a vacuum thermal reduction furnace. The vacuum is evacuated to below 50 Pa, and then argon gas is introduced to 20 kPa. The reaction is ignited, and after the reaction, it is cooled for 12 hours under argon protection. The reaction product is then removed, and the slag and alloy are separated. The alloy surface is shot blasted and polished to obtain a high-entropy alloy ingot.

[0076] A sample of the high-entropy alloy was analyzed, and its chemical composition is shown in the table below:

[0077] Table 2 Chemical composition of high-entropy alloys produced using tantalum scrap

[0078] element W Mo Ta Nb Al Si O N content% 32.09 16.09 30.07 18.74 1.26 0.61 0.35 0.087

[0079] The chemical composition of this high-entropy alloy deviated somewhat from the design, possibly because the scrap test values ​​could not represent the true content. Therefore, the scrap treatment and testing methods were adjusted.

[0080] Example 3

[0081] Two types of niobium waste were crushed to 0-3 mm and 0-5 mm respectively, and labeled as niobium waste #1 and niobium waste #2. The crushed niobium waste was mixed evenly for 15 minutes. Six samples were taken from different parts of the sampler for Nb / Ta and Al main element analysis. The analysis results are as follows:

[0082] Table 3 Sampling and analysis results of niobium waste

[0083]

[0084] The table above shows that niobium scrap #1, after processing, meets the requirements for niobium and aluminum with a deviation of less than 1%, while niobium scrap #2, after crushing, has a deviation greater than 1%. These two types of niobium scrap will be used to produce high-entropy alloys.

[0085] The refractory metal oxides such as tantalum pentoxide, niobium pentoxide, tungsten oxide, and molybdenum trioxide are baked to remove moisture. The baking temperature is 150-200℃ and the baking time is 30-120 minutes.

[0086] The composition of the high-entropy alloy containing the four refractory metals W, Mo, Ta, and Nb is designed as follows: W 32.3%, Mo 17.2%, Ta 32.3%, and Nb 17.2%. The designed exothermic reaction of the aluminothermic reduction reaction is -3016 kJ / kg. Based on the average niobium and aluminum content of niobium scrap #1 (ω1 = 27.96%, ω2 = 70.01%), the reaction formula is calculated using chemical equations. The formula is: WO3 40.73 kg, MoO3 25.80 kg, Ta2O5 39.44 kg, Nb2O5 10.61 kg, niobium scrap #1 35.00 kg, calcium fluoride 1.00 kg, sodium chlorate 5.70 kg, and aluminum powder 9.71 kg. The weighed raw materials are loaded into a mixer and mixed for 20 minutes. The mixed raw materials were placed in an alumina crucible, which was then placed in a vacuum thermal reduction furnace. The furnace was evacuated to below 50 Pa, and argon gas was introduced to 20 kPa. The reaction was then ignited. After the reaction, the furnace was cooled for 14 hours under argon protection. The reaction product was then removed, and the slag and alloy were separated. The alloy surface was shot-blasted and polished to obtain a high-entropy alloy ingot.

[0087] A sample of the high-entropy alloy was analyzed, and its chemical composition is shown in the table below:

[0088] Table 4 Chemical composition of high-entropy alloys produced using niobium scrap #1

[0089] element W Mo Ta Nb Al Si O N content% 32.38 17.01 32.08 17.04 0.87 0.32 0.104 0.015

[0090] Metallographic images of high-entropy alloys produced from niobium scrap #1, such as... Figure 1 As shown.

[0091] The designed exothermic reaction of the aluminothermic reduction reaction is -3016 kJ / kg. Using niobium scrap #2 to produce the high-entropy alloy, the reaction formula was calculated using chemical equations based on the average niobium and aluminum content of niobium scrap #2 (ω1 = 32.55%, ω2 = 66.09%): WO3 40.73 kg, MoO3 25.8 kg, Ta2O5 39.44 kg, Nb2O5 10.64 g, niobium scrap #2 30.00 kg, calcium fluoride 1.00 kg, sodium chlorate 5.40 kg, and aluminum powder 14.52 kg. The weighed raw materials were loaded into a mixer and mixed for 20 minutes. The mixed raw materials were then placed in an alumina crucible, which was then placed in a vacuum thermal reduction furnace. The furnace was evacuated to below 50 Pa, and then argon gas was introduced to 20 kPa. The reaction was ignited, and after the reaction, the furnace was cooled for 14 hours under argon protection. The reaction product was then removed, and the slag and alloy were separated. The alloy surface was shot-blasted and polished to obtain a high-entropy alloy ingot. Samples of this high-entropy alloy ingot were analyzed, and its chemical composition is shown below:

[0092] Table 5 Chemical composition of high-entropy alloys produced using niobium scrap #2

[0093] element W Mo Ta Nb Al Si O N content% 32.68 18.41 31.08 15.04 1.87 0.39 0.135 0.018

[0094] Metallographic images of high-entropy alloys produced from niobium scrap #2, such as... Figure 2 As shown.

[0095] The composition shows that the obtained high-entropy alloy deviates from the design value and the aluminum content exceeds the standard. This is because the aluminum and niobium segregation in the niobium scrap is relatively large, and the average value and the actual value are somewhat different.

[0096] Example 4

[0097] The tantalum scrap #3 was crushed to 0-3mm and mixed in a mixer for 20 minutes. The mixed material was placed in a hopper, and six samples were taken from different locations using a sampler for Nb / Ta and Al main element analysis. The test results of the six samples are shown in the table below:

[0098] Table 6. Sampling and Analysis Results of Tantalum Waste

[0099]

[0100] The refractory metal oxides such as tantalum pentoxide, niobium pentoxide, tungsten oxide, and molybdenum trioxide are baked to remove moisture. The baking temperature is 150-200℃ and the baking time is 30-120 minutes.

[0101] The composition of the high-entropy alloy containing the four refractory metals W, Mo, Ta, and Nb is designed as follows: W 33.0%, Mo 16.5%, Ta 33.0%, Nb 16.5%. The designed exothermic reaction of the aluminothermic reduction reaction is -3020 kJ / kg. Based on the average tantalum and aluminum content of tantalum scrap #3 (ω4 = 25.46%, ω5 = 73.40%), the reaction formula is calculated using chemical equations. The formula is: WO3 41.61 kg, MoO3 24.75 kg, Ta2O5 30.97 kg, Nb2O5 23.60 kg, tantalum scrap 30.00 kg, calcium fluoride 1.00 kg, sodium chlorate 4.5 kg, and aluminum powder 15.34 kg.

[0102] The weighed raw materials were placed into a mixer and mixed for 15 minutes. The mixed materials were then placed in an alumina crucible, which was then placed in a vacuum thermal reduction furnace. The furnace was evacuated to below 50 Pa, and then argon gas was introduced to 30 kPa. The reaction was initiated and cooled for 10 hours under argon protection. The reaction product was then removed, and the slag and alloy were separated. The alloy surface was shot-blasted and polished to obtain a high-entropy alloy ingot. A sample of this high-entropy alloy was analyzed, and its chemical composition is shown below:

[0103] Table 7 Chemical composition of high-entropy alloy produced using tantalum scrap #3

[0104] element W Mo Ta Nb Al Si O N content% 33.10 16.01 32.87 16.38 0.95 0.48 0.150 0.0084

[0105] Metallographic images of the high-entropy alloy produced from tantalum scrap #3, such as... Figure 3 As shown.

[0106] Example 5

[0107] Niobium scrap was crushed to 0-5 mm, and six samples were taken to measure its average content: Nb: 27.96%, Al: 71.45%, Si: 0.48%. The deviations between the maximum and minimum Nb and Al contents in the six samples were 2.21% and 1.76%, respectively.

[0108] The composition of the high-entropy alloy containing the four refractory metal elements W, Mo, Ta, and Nb is designed as follows: W 33.0%, Mo 16.5%, Ta 33.0%, and Nb 16.5%.

[0109] The designed exothermic reaction of the aluminothermic reduction reaction is -3020 kJ / kg. The reaction formula is obtained through calculation using chemical equations.

[0110] Accurately weigh the following oxide powders according to the formula: WO3 33.29 kg, MoO3 19.80 kg, Ta2O5 32.24 kg, Nb2O5 8.88 kg, niobium waste 25.00 kg, calcium fluoride 0.81 kg, sodium chlorate 4.38 kg, and aluminum powder 9.65 kg. Place the weighed raw materials into a mixer and mix for 20 minutes. Place the mixed raw materials into an alumina crucible, then place the crucible into a vacuum thermal reduction furnace. Evacuate to below 50 Pa, then purge with argon gas to 25 kPa, ignite the reaction, and cool under argon protection for 12 hours. Remove the reaction product and separate the slag and alloy. After shot blasting and polishing, obtain a high-entropy alloy ingot. Samples of this high-entropy alloy are analyzed, and the chemical composition is shown below:

[0111] Table 8 Chemical Composition of High Entropy Alloys

[0112] element W Mo Ta Nb Al Si O N content% 31.88 16.01 31.33 18.34 0.37 0.55 0.304 0.025

[0113] The results show that the composition deviates significantly from the design values, especially the niobium content, which exceeds the preset range for high-entropy alloys. This is because the niobium waste after crushing has significant segregation, and the average test value does not represent its true content, thus leading to the deviation in the composition of the high-entropy alloy.

[0114] Example 6

[0115] Niobium scrap #5 was crushed to 0-3mm, and six samples were taken. The average values ​​were: Nb: 28.36%, Al: 71.45%, Si: 0.48%. The deviations between the maximum and minimum Nb and Al contents in the six samples were 1.25% and 1.06%, respectively. Since the deviations were still greater than 1, the scrap was further crushed to 0-1mm, and six samples were taken again. The average values ​​were: Nb: 28.66%, Al: 71.05%, Si: 0.56%. The deviations between the maximum and minimum Nb and Al contents in the six samples were 0.39% and 0.47%, respectively.

[0116] The composition of the high-entropy alloy containing the four refractory metal elements W, Mo, Ta, and Nb is designed as follows: W 33.0%, Mo 16.5%, Ta 33.0%, and Nb 16.5%.

[0117] The designed exothermic reaction of the aluminothermic reduction reaction is -3020 kJ / kg. The reaction formula is obtained through calculation using chemical equations.

[0118] Accurately weigh the following oxide powders according to the formula: WO3 33.29 kg, MoO3 19.80 kg, Ta2O5 32.24 kg, Nb2O5 8.88 kg, niobium waste 25.00 kg, calcium fluoride 0.81 kg, sodium chlorate 4.38 kg, and aluminum powder 9.65 kg. Place the weighed raw materials into a mixer and mix for 20 minutes. Place the mixed raw materials into an alumina crucible, then place the crucible into a vacuum thermal reduction furnace. Evacuate to below 50 Pa, then purge with argon gas to 25 kPa, ignite the reaction, and cool under argon protection for 12 hours. Remove the reaction product and separate the slag and alloy. After shot blasting and polishing, obtain a high-entropy alloy ingot. Samples of this high-entropy alloy are analyzed, and the chemical composition is shown below:

[0119] Table 9 Chemical Composition of High Entropy Alloys

[0120] element W Mo Ta Nb Al Si O N content% 32.56 16.98 32.98 16.71 0.67 0.45 0.163 0.015

[0121] The results show that the composition is basically consistent with the design values, which also indicates that the niobium waste after crushing meets the usage requirements.

[0122] Example 7

[0123] The tantalum scrap was crushed to 0-3 mm, and six samples were taken. The average values ​​of the six samples were: Ta: 25.46%, Al: 73.40%. The deviation between the maximum and minimum values ​​of Ta and Al content in the six samples was less than 1%.

[0124] Niobium scrap was crushed to 0-3 mm, and six samples were taken. The average values ​​of the six samples were: Nb: 30.12%, Al: 68.94%. The deviations between the maximum and minimum Nb and Al contents in the six samples were all less than 1%.

[0125] The composition of the high-entropy alloy containing the four refractory metal elements W, Mo, Ta, and Nb is designed as follows: W 32.5%, Mo 17.0%, Ta 32.5%, and Nb 17.0%.

[0126] The designed exothermic reaction of the aluminothermic reduction reaction is -3020 kJ / kg. The reaction formula is obtained through calculation using chemical equations.

[0127] Accurately weigh the following oxide powders according to the formula: WO3 32.78 kg, MoO3 20.40 kg, Ta2O5 27.08 kg, Nb2O5 12.99 kg, tantalum scrap 15.00 kg, niobium scrap 15.00 kg, calcium fluoride 1.00 kg, sodium chlorate 0.20 kg, and aluminum powder 4.35 kg. Place the weighed raw materials into a mixer and mix for 20 minutes. Place the mixed raw materials into an alumina crucible, then place the crucible into a vacuum thermal reduction furnace. Evacuate to below 50 Pa, then purge with argon to 25 kPa, ignite the reaction, and cool under argon protection for 10 hours. Remove the reaction product and separate the slag and alloy. After shot blasting and polishing, a high-entropy alloy ingot is obtained. Samples of this high-entropy alloy are analyzed, and the chemical composition is shown below:

[0128] Table 10 Chemical Composition of High Entropy Alloys

[0129] element W Mo Ta Nb Al Si O N content% 32.30 16.60 32.01 16.81 0.75 0.89 0.120 0.012

[0130] The above description is merely a preferred embodiment of this application and is not intended to limit this application.

Claims

1. A method for preparing high-entropy alloy using niobium-tantalum waste material, characterized by, The niobium-containing and tantalum-containing waste materials are crushed into 0-5mm particles, mixed uniformly, and subjected to chemical composition analysis, mainly analyzing niobium / tantalum, aluminum, and silicon. The tantalum pentoxide, niobium pentoxide, tungsten oxide, and molybdenum trioxide are roasted to remove moisture, with a roasting temperature of 150-200℃ and a roasting time of 30-120min. The roasted tantalum pentoxide, niobium pentoxide, tungsten oxide, and molybdenum trioxide, as well as the treated niobium and tantalum waste materials, aluminum powder, calcium fluoride, and sodium chlorate are weighed and mixed in a mixer for 10-20 minutes to ensure uniform mixing of the raw materials. The mixed raw materials are then transferred into a pre-prepared aluminum oxide crucible and placed in a vacuum hot reduction furnace for oxidation-reduction reaction. The reaction product is cooled in the furnace for 8-16 hours, and the high-entropy alloy ingot is separated from the slag. The high-entropy alloy ingot is polished to obtain a tungsten-molybdenum-tantalum-niobium high-entropy alloy ingot. The addition of niobium and tantalum must satisfy the following conditions: 16% < (M- Nb-1 * ω1+ M- Nb-2 * 69.9%) / M < 18% (I) 16% < (M Ta-1 * ω4+ M- Ta-2 * 81.9%) / M < 18% (II) In formula (I) and formula (II), the mass fraction is: M- Nb-1 Fraction added for niobium waste; ω1 is the niobium content after treatment of the niobium-containing waste; M- Nb-2 Fraction added for niobium pentoxide; M- Ta-1 the fraction of tantalum niobium waste added; ω4 is the tantalum content after processing of the tantalum-containing waste; M- Ta-2 the fraction of tantalum pentoxide added; M is the total fraction of the target high-entropy alloy; The addition of sodium chlorate must satisfy the following conditions: 2800 < (ΔH1*M- Nb-2 + ΔH2*M- Ta-2 + ΔH3*M*33% / 73.91% + ΔH4*M*17% / 66.67% + ΔH5* M- 氯酸钠 ) / M 原料 <3200 (III) In formula (III), the mass fraction is: M- 氯酸钠 Parts added for sodium chlorate; M 原料 For the total raw material added, including niobium pentoxide, tantalum pentoxide, tungsten trioxide, molybdenum trioxide, aluminum powder, sodium chlorate, calcium fluoride, niobium waste, tantalum waste; △H1 is the heat of reaction of niobium pentoxide and aluminum, with a value of 3371.71kJ / kg; △H2 is the heat of reaction of tantalum pentoxide and aluminum, with a value of 1696.54kJ / kg; △H3 is the heat of reaction of tungsten trioxide and aluminum, with a value of 3618.97kJ / kg; △H4 is the heat of reaction of molybdenum trioxide and aluminum, with a value of 6472.92kJ / kg; △H5 is the heat of reaction of sodium chlorate and aluminum, with a value of 16334.4kJ / kg; The addition of tungsten trioxide and molybdenum trioxide must satisfy the following conditions: 32% M- W 73.91% M <34% (IV) 16% < M- Mo 66.67% < M < 18% (V) In formula (IV) and formula (V), the mass fraction is: M- W the number of parts of tungsten trioxide added; M- Mo the number of parts of molybdenum trioxide added; The addition of aluminum powder must satisfy the following conditions: M- Al粉 +M- Nb-1 *ω2+M- Ta-1 *ω5= k1*M- Nb-2 + k2* M- Ta-2 + k3* M- W + k4* M- Mo + k5* M- 氯酸钠 (VI) In formula (VI), the mass fraction is: M- Al粉 Parts added for aluminum powder; k1 is the aluminum consumption coefficient of niobium oxide, with a value of 0.3886; k2 is the aluminum consumption coefficient of tantalum oxide, with a value of 0.2036; k3 is the aluminum consumption coefficient of tungsten oxide, with a value of 0.38; k4 is the aluminum consumption coefficient of molybdenum oxide, with a value of 0.23; k5 is the aluminum consumption coefficient of sodium chlorate, with a value of 0.507; ω2 is the aluminum content of the treated niobium-containing waste material; ω5 is the aluminum content of the treated tantalum-containing waste material; The addition of calcium fluoride must satisfy the following conditions: M- Al总 *3%< M- 氟化钙 <M- Al总 *8% (VII) In formula (VII), the mass fraction is: M- 氟化钙 Parts added for calcium fluoride; M- Al总 is the total fraction of aluminum in the reaction feed; The control of silicon content must satisfy the following conditions: 0.2% < (M- Nb-1 *ω3+ M- Ta-1 *ω6+ M- 硅 ) / M < 1.0% (VII) In formula (VII), ω3 is the silicon content of the treated niobium-containing waste material; ω6 is the silicon content of the treated tantalum-containing waste material; M- 硅 amount of silicon in other raw materials. 2.The method for preparing high-entropy alloy using Nb-Ta waste according to claim 1, wherein, The method includes the following steps: Step 1: The niobium / tantalum-containing waste materials are subjected to multi-stage crushing and sieving, with the particle sizes being 0-1mm, 0-3mm, and 0-5mm. The crushed materials are mixed in a mixer for 10-30 minutes, and then placed in a material barrel. Six samples are taken from different parts for analysis of Nb / Ta and Al main elements. If the sample detection result deviation is less than 1%, the subsequent step 2 is entered; if the detection result deviation is greater than 1%, the above mixture is further crushed to 0-1mm, 0-3mm, and the above mixing and detection steps are repeated; If the detection result deviation is less than 1%, the subsequent step 2 is entered; if the detection result deviation is greater than 1%, the above mixture is further crushed to 0-1mm, and the above mixing and detection steps are repeated; until the detection result deviation is less than 1%; Step 2: Roast niobium pentoxide, tantalum pentoxide, tungsten oxide and molybdenum trioxide to remove moisture, the roasting temperature is 150-200℃, the roasting time is 30-120min, weigh the roasted tantalum pentoxide, niobium pentoxide, tungsten oxide, molybdenum trioxide, and the niobium and tantalum waste treated in step 1, aluminum powder, calcium fluoride and sodium chlorate, mix them in a mixer for 10-20 minutes to make the raw materials fully mixed and uniform; Step 3: Put the mixed raw materials into a pre-prepared alumina crucible and place it in a vacuum hot reduction furnace, vacuumize to less than 50Pa, fill with argon 20-60kPa, ignite to occur redox reaction, cool the reaction product in the furnace for 8-16 hours, take out the crucible, separate the high-entropy alloy and slag, polish the surface of the high-entropy alloy ingot to get a clean tungsten molybdenum tantalum niobium high-entropy alloy ingot. 3.The method for preparing high-entropy alloy using Nb-Ta waste according to claim 1, wherein, The high-entropy alloy has the following element proportions: W: 32-34%, Mo: 16-18%, Ta: 32-34%, Nb: 16-18%, Al: 0.5-1%, Si: 0.2-1.0%. 4.The method for preparing high-entropy alloy using Nb-Ta waste according to claim 2, characterized in that, The niobium-containing waste is treated according to the step 1 until the detection result deviation is less than 1%; the final detection result of the treated niobium-containing waste is: niobium ω1, aluminum ω2, silicon ω3. The tantalum-containing waste is treated according to the step 1 until the detection result deviation is less than 1%; the final detection result of the treated tantalum-containing waste is: tantalum ω4, aluminum ω5, silicon ω6.

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