A low-density refractory high-entropy alloy and its preparation method and application

Abstract

The present invention discloses a low-density refractory high-entropy alloy and a preparation method and application thereof. The atomic percentages of the low-density refractory high-entropy alloy are as follows: Al: 10.0-11.0 at%; Mo: 10.0-11.0 at%; Nb: 20.5-21.5 at%; Ti: 25.5-27.0 at%; V: 10.0-11.0 at%; Zr: 20.5-21.5 at%. Its density is 6.35-6.55 g / cm 3 . The alloy is prepared by a vacuum non-consumable arc furnace. The as-cast alloy has a BCC structure and its microstructure presents a dendritic morphology; after homogenization treatment and furnace cooling, the dendritic structure in the alloy disappears and a large number of precipitated phases appear, which is a BCC1 + BCC2 + AlZr2 multiphase structure; the melting point of the alloy is greater than 1400 °C, the yield strength at room temperature is higher than 1733 MPa, the compressive strength at room temperature is higher than 1781 MPa, the yield strength and compressive strength at 800 °C are respectively higher than 921 MPa and 987 MPa, and at 1000 °C they are respectively higher than 338 MPa and 448 MPa, and the average Vickers microhardness is as high as 458.

Description

Technical Field

[0001] The present invention belongs to the field of high-temperature alloys, and particularly relates to a low-density refractory high-entropy alloy, a preparation method and an application thereof. Background Art

[0002] With the continuous development of the aerospace industry, there is an urgent need for metal structural materials with excellent high-temperature mechanical properties. Nickel-based superalloys have advantages such as high-temperature strength, high-temperature oxidation resistance, heat-resistant corrosion resistance and high-temperature fatigue resistance, and have broad application prospects in the fields of aerospace and energy storage, such as jet engines and turbines; although great progress has been made in the control of the microstructure and composition and the improvement of the properties of nickel-based superalloys, and some applications have been achieved in the fields of aerospace and energy storage, etc., it is far from reaching the level of large-scale engineering applications. The main reasons are two aspects: one is that the density is relatively high (about 8.5 g / cm3); the other is that the use at higher working temperatures is limited by its solidus line and melting temperature. Compared with nickel-based superalloys, high-entropy alloys using high-melting-point refractory elements have excellent high-temperature mechanical properties and play a crucial role in the direction of high-temperature structural materials. However, high-entropy alloys contain 5 or more main metal elements, and the atomic ratio of each element is between 5% and 35%. It has four major effects that traditional alloys do not have: high-entropy effect, lattice distortion effect, slow diffusion effect, and "cocktail" effect. Reasonable element design can enable high-entropy alloys to possess properties superior to traditional alloys, such as hardness, high-temperature properties, etc. In recent years, high-entropy alloys have been studied a lot, and people have initially understood the partial influence of main elements on the physical and mechanical properties of alloys. High-entropy alloys based on refractory metal elements with very high melting points are called refractory high-entropy alloys. Refractory high-entropy alloys are mainly composed of high-melting-point elements as constituent elements, so they have a higher melting point and better high-temperature resistance. At the same time, the alloys also have the common effects of high-entropy alloys and can exhibit more excellent comprehensive properties at high temperatures. They are a kind of high-temperature alloys with broad development prospects. The emergence of refractory high-entropy alloys provides a new idea for the development of a new generation of high-temperature materials and is expected to meet the growing performance requirements at higher working temperatures. Summary of the Invention

[0003] The present invention discloses a low-density refractory high-entropy alloy, a preparation method and an application thereof to solve any of the above and potential problems in the prior art.

[0004] To achieve the above object, the technical solution provided by the present invention is: a low-density refractory high-entropy alloy, and the atomic percentages of the respective components of the low-density refractory high-entropy alloy are: Al: 10.0-11.0 at%; Mo: 10.0-11.0 at%; Nb: 20.5-21.5 at%; Ti: 25.5-27.0 at%; V: 10.0-11.0 at%; Zr: 20.4-21.5 at%.

[0005] Further, the low-density refractory high-entropy alloy has a multiphase structure of BCC1 + BCC2 + AlZr2, and the melting point of the alloy is not lower than 1400 °C; the density is 6.35-6.55 g / cm 3 .

[0006] Further, the atomic percentages of the respective components of the low-density refractory high-entropy alloy are: Al: 10.12 at%; Mo: 10.20 at%; Nb: 21.48 at%; Ti: 25.64 at%; V: 10.98 at%; Zr: 21.50 at%; the alloy density is 6.38 g / cm 3 .

[0007] Further, the atomic percentages of the respective components of the low-density refractory high-entropy alloy are: Al: 10.53 at%; Mo: 10.53 at%; Nb: 21.06 at%; Ti: 26.31 at%; V: 10.53 at%; Zr: 21.04 at%; the alloy density is 6.36 g / cm 3 .

[0008] Further, the atomic percentages of the respective components of the low-density refractory high-entropy alloy are: Al: 10.99 at%; Mo: 10.99 at%; Nb: 20.5 at%; Ti: 25..59 at%; V: 10.99 at%; Zr: 20.94 at%; the alloy density is 6.36 g / cm 3 .

[0009] Another object of the present invention is to provide a method for preparing the low-density refractory high-entropy alloy as described above, and the method specifically includes the following preparation steps:

[0010] S1) Raw material preparation: Take quantitative raw material blocks of Al, Mo, Nb, Ti, V, and Zr according to atomic percentages, and perform pretreatment;

[0011] S2) Melting preparation: The raw material blocks treated in S1) are melted multiple times by a vacuum melting process, and after homogenization heat treatment, a low-density refractory high-entropy alloy is obtained.

[0012] Further, the specific process of S1) is:

[0013] S1.1) Remove the impurities and scale on the surface of the raw material block, and then accurately weigh the required mass of the raw material.

[0014] S1.2) Subsequently, all the weighed raw materials are placed in absolute ethanol for ultrasonic oscillation cleaning to remove the surface impurities and then dried.

[0015] Furthermore, the specific process of S2) is as follows:

[0016] S2.1) Before melting, evacuate the vacuum to below 5×10 -3 Pa, and the current during melting is 380 A - 400 A; turn over the material every time a melting is completed, and melt at least 8 times repeatedly.

[0017] S2.2) Then carry out homogenization heat treatment, and the specific process is: 1190°C - 1210°C, 24 hours, furnace cooling.

[0018] Furthermore, the strain rate of the low-density refractory high-entropy alloy is 0.001 s -1 , its room-temperature yield strength is not less than 1733 MPa, and the compressive strength is not less than 1781 MPa; at 800°C, the yield strength is not less than 921 MPa, and the compressive strength is not less than 987 MPa; at 1000°C, the yield strength is not less than 338 MPa, and the compressive strength is not less than 448 MPa.

[0019] A low-density refractory high-entropy alloy prepared by the above method is applied in the field of medium- and high-temperature structural materials.

[0020] The beneficial effects of the present invention: Due to the adoption of the above technical solution, the low-density refractory high-entropy alloy of the present invention has a density of 6.35 - 6.55 g / cm 3 , and belongs to a low-density refractory high-entropy superalloy.

[0021] The alloy prepared by a vacuum non-consumable arc furnace has a BCC structure in the as-cast state, and the microstructure presents a dendritic morphology; after homogenization treatment at 1200°C for 24 hours and furnace cooling, the dendritic structure of the alloy disappears, and a large number of precipitated phases appear, forming a BCC1 + BCC2 + AlZr2 multiphase structure.

[0022] The melting point of this alloy is greater than 1400 °C, and it has high room-temperature compressive mechanical properties. Its as-cast room-temperature compressive yield strength can reach 1631 MPa, the compressive strength can reach 1798 MPa. At 800 °C, the yield strength and compressive strength reach 561 MPa and 608 MPa respectively, and at 1000 °C, they reach 144 MPa and 166 MPa respectively. The average Vickers microhardness is 474. After homogenization treatment at 1200 °C for 24 hours and furnace cooling, the room-temperature yield strength can reach 1733 MPa, the compressive strength reaches 1781 MPa. At 800 °C, the yield strength and compressive strength reach 921 MPa and 987 MPa respectively, and at 1000 °C, they reach 338 MPa and 448 MPa respectively. The average Vickers microhardness is 458. Description of the Drawings

[0023] Figure 1 It is the morphology diagram of the as-cast structure of the low-density refractory high-entropy alloy prepared by the preparation method of the present invention. (a) is 500x (b) is 10000x.

[0024] Figure 2 It is the schematic diagram of the XRD analysis result of the as-cast low-density refractory high-entropy alloy.

[0025] Figure 3 It is the schematic diagram of the DSC experimental test result of the low-density refractory high-entropy alloy.

[0026] Figure 4 It is the schematic diagram of the morphology of the low-density refractory high-entropy alloy after homogenization heat treatment for 24 hours and furnace cooling. (a) 100x (b) 200x (c) 500x (d) 1000x.

[0027] Figure 5 It is the schematic diagram of the XRD test result of the low-density refractory high-entropy alloy after homogenization.

[0028] Figure 6 It is the schematic diagram of the comparison of the stress-strain curves of the as-cast compression test of the low-density refractory high-entropy alloy; (a) is at room temperature (b) is at high temperatures of 800 °C and 1000 °C.

[0029] Figure 7 It is the schematic diagram of the comparison of the stress-strain curves of the compression test of the low-density refractory high-entropy alloy after homogenization heat treatment for 24 hours and furnace cooling; (a) is at room temperature (b) is at high temperatures of 800 °C and 1000 °C. Detailed Embodiments

[0030] The following further describes the technical solutions of the present invention in conjunction with specific embodiments and drawings.

[0031] The embodiments of the present invention provide the design, preparation and properties of a refractory high-entropy alloy, including the following processes:

[0032] Composition Design:

[0033] To obtain a refractory high-entropy alloy material with low density, first, low-density refractory alloying elements with relatively low density are selected, including titanium (ρ = 4.54 g / cm 3 ), vanadium (ρ = 6.11 g / cm 3 ), zirconium (ρ = 6.50 g / cm 3 ), niobium (ρ = 8.57 g / cm 3 ), and molybdenum (ρ = 10.22 g / cm 3 ). Secondly, to further reduce the alloy density, aluminum (ρ = 2.70 g / cm 3 ) is added. Finally, a detailed calculation and analysis of the thermodynamics and empirical criteria of the high-entropy alloy are carried out to judge the system stability of the alloy, the formation tendency of intermetallic compounds, the formation tendency of solid solution phases, etc.

[0034] To judge the stability of an alloy system, it can be calculated by formula (1). The smaller the value of the Gibbs free energy ΔG mix , the more stable the alloy system. When ΔH mix is the same, the larger ΔS mix , the smaller ΔG mix , and the more stable the system. When the value of ΔH mix is much higher than the entropy value required for the formation of intermetallic compounds, the tendency of the system to form a simple solid solution is stronger. When the absolute temperature T increases, ΔG mix decreases, and the system stability increases. When ΔH mix is positive, the larger its value, the more significant the repulsive interaction between elements; conversely, when ΔH mix is negative, the smaller its value, the greater the attractive interaction between elements, and the easier the formation of intermetallic compounds. The calculation formulas of ΔH mix and ΔS mix are shown in formulas (2) and (3).

[0035] ΔG mix = ΔH mix - TΔS mix (1)

[0036]

[0037]

[0038] where c i is the atomic ratio of elements, R (8.314 J·k -1 ·mol -1 ) is the gas constant, and Ω ij is the regular solution interaction parameter between the i-th and j-th elements.

[0039] Another criterion is the entropy effect criterion, as shown in Equation (4):

[0040]

[0041] Ω is the interaction parameter between elements. Defining Ω is to compare ΔH mix mixing and ΔS mix on the comprehensive influence of phase formation. When Ω > 1, it indicates that the driving force given by the mixing entropy is greater than the resistance caused by the mixing enthalpy, and the system is prone to form a simple solid solution; conversely, when Ω ≤ 1, the driving force is less than the resistance, and intermetallic compounds are likely to be generated in the system, which can also lead to composition segregation.

[0042] In addition, there is also the solid solution criterion, as shown in Equation (5);

[0043]

[0044] where δ is the atomic size difference, c i is the atomic ratio of elements, r i is the atomic radius of elements, and is the average atomic radius. A large number of experimental test results show that when Ω ≥ 1.1 and δ ≤ 6.6, the high-entropy alloy system tends to form a simple solid solution.

[0045] In addition, the valence electron concentration (VEC) can well describe the stability of BCC and FCC solid solutions, and its calculation formula is as shown in Equation (6):

[0046]

[0047] where c i is the atomic percentage of each element, and VEC i is the valence electron concentration of each element. With the help of VEC, the structure of the formed phase can be judged and predicted. A high VEC (>8.0) will tend to form an FCC phase, and conversely (<6.87) will tend to form a BCC phase, while intermediate values (i.e., between 8.0 and 6.87) will result in a mixture of FCC and BCC phases.

[0048] The electronegativity standard deviation Δχ is also an important criterion. The higher the entropy alloy that tends to form compounds, the generally larger its electronegativity standard deviation. The calculation formula of Δχ is as shown in Equation (7), where c i is the atomic percentage of each element; χ i is the Pauling electronegativity of element i, and is the arithmetic mean of electronegativity. When the Δχ of the alloy > 0.133, the TCP phase exists stably.

[0049]

[0050] On this basis, various alloying elements were reasonably added to design a low-density refractory high-entropy alloy with an atomic percentage of 10.53Al-10.53Mo-21.06Nb-26.31Ti-10.53V-21.04Zr. Table 1 shows the calculation results of the alloy thermodynamic parameter criteria. It can be seen that: this alloy is prone to form a BCC structure, has a solid solution strengthening effect, and has a tendency to form a solid solution + intermetallic compound, and there is likely to be a TCP phase.

[0051] Table 1 Calculation results of the thermodynamic parameters of the low-density refractory high-entropy alloy

[0052]

[0053] Example 1:

[0054] The atomic percentages of the various components of a low-density refractory high-entropy alloy are: Al: 10.53 at%; Mo: 10.53 at%; Nb: 21.06 at%; Ti: 26.31 at%; V: 10.53 at%; Zr: 21.04 at%. The following are the preparation steps of a new type of low-density refractory high-entropy alloy:

[0055] Raw material preparation: Calculate and take a certain amount of raw material blocks of Al, Mo, Nb, Ti, V, and Zr. Grind off the surface impurities and oxide scales generated by cutting on the raw material blocks with sandpaper. Then accurately weigh the required raw material quality on a balance. Subsequently, all the weighed raw materials are placed in absolute ethanol for ultrasonic oscillation cleaning to remove surface impurities and then dried;

[0056] Smelting preparation: Place the raw materials in a copper crucible of a small vacuum arc furnace to smelt and obtain a new type of refractory high-entropy alloy. The current requirement during smelting is 380A - 400A. The vacuum arc furnace needs to pump the vacuum degree to below 5×10 -3 Pa before smelting. Turn over each time after one smelting is completed, and smelt at least 8 times repeatedly to obtain the ingot of this alloy;

[0057] Table 2 shows the results of testing the density three times by the Archimedes method. It can be seen that the average density of the alloy is 6.36 g / cm 3 , belonging to a low-density refractory high-entropy alloy. Figure 1It is a backscattered electron image of the as-cast microstructure of a new refractory high-entropy alloy prepared by vacuum arc furnace melting. Obvious dendritic structures can be seen. Different contrasts reflect different element distributions. The dendrite trunks are enriched with metal elements with larger atomic numbers, while the interdendritic regions are enriched with elements with smaller atomic numbers. Table 3 shows the results of point analysis by EDS. It can be seen from this that Mo, Zr, Al, and Nb show segregation. The dendrite trunks are rich in Mo and Nb, and the interdendritic regions are rich in Al and Zr. While Ti and V are distributed basically evenly, and the overall composition analysis result is very close to the designed composition, indicating that there is no obvious volatilization of low-melting-point elements during the melting process. Figure 2 It is the XRD analysis result of the as-cast alloy. The results show that the V0.5 alloy has two BCC structure peaks, and no peaks other than BCC are observed.

[0058] Table 2 Alloy density test results

[0059]

[0060]

[0061] Table 3 Alloy EDS analysis results (at%)

[0062]

[0063] Figure 3 It is the DSC experimental test result of the low-density refractory high-entropy alloy. According to this result, it can be seen that the melting point of the alloy is higher than 1400 °C. The homogenization process of the alloy needs to comprehensively consider issues such as eliminating segregation, melting of low-melting-point regions, grain growth, and oxidation. The homogenization temperature cannot be set too high. Therefore, the homogenization temperature is set to 1190 °C - 1210 °C, the time is 24 hours, and it is cooled in the furnace. Figure 4 It is the microstructure morphology of the new refractory high-entropy alloy after homogenization heat treatment at 1190 °C - 1210 °C for 24 hours and cooled in the furnace. It can be seen that the dendritic morphology disappears, and many phases with contrasts significantly different from the matrix are generated. A large number of rod-shaped or needle-shaped and block-shaped or granular phases are distributed in the matrix in a continuous chain-like manner. Figure 5 It is the XRD analysis result of the homogenized alloy. It can be seen that the homogenized alloy contains peaks of BCC1 and BCC2 structures, as well as a large number of precipitated AlZr2 phases.

[0064] Table 4 shows the results of three Vickers hardness (HV0.5) tests at different positions of the low-density refractory high-entropy alloy in the as-cast state and after homogenization treatment at 1200 °C for 24 hours and cooled in the furnace. It can be found that the hardness value of the alloy is relatively high. The average HV0.5 of the as-cast state reaches more than 474, and it reaches 458 after homogenization.

[0065] Table 4 Alloy Vickers hardness HV0.5 test results

[0066]

[0067] The stress-strain curve of the as-cast alloy in the compression test is as Figure 6 shown, the strain rate is 0.001 s -1 . Its as-cast room-temperature compression yield strength can reach 1631 MPa, the compressive strength can reach 1798 MPa, and they reach 561 MPa and 608 MPa respectively at 800 °C, and 144 MPa and 166 MPa respectively at 1000 °C; after homogenization treatment at 1200 °C for 24 hours and furnace cooling, the stress-strain curve of the compression test is as Figure 7 shown, the strain rate is still 0.001 s -1 . Its room-temperature yield strength can reach 1733 MPa, the compressive strength reaches 1781 MPa, and they reach 921 MPa and 987 MPa respectively at 800 °C, and 338 MPa and 448 MPa respectively at 1000 °C. After homogenization treatment, the high-temperature yield strength of the alloy is significantly improved.

[0068] Example 2:

[0069] The atomic percentages of the components of a low-density refractory high-entropy alloy are: Al: 10.14 at%; Mo: 10.22 at%; Nb: 21.50 at%; Ti: 25.66 at%; V: 10.98 at%; Zr: 21.50 at%; the alloy density is 6.38 g / cm 3 .

[0070] Preparation steps of the low-density refractory high-entropy alloy:

[0071] Raw material preparation: Calculate and take a certain amount of raw material blocks of Al, Mo, Nb, Ti, V, and Zr. Grind off the surface impurities and oxide scales generated by cutting on the raw material blocks, and then accurately weigh the required raw material mass on a balance. Subsequently, all the weighed raw materials are placed in absolute ethanol for ultrasonic oscillation cleaning to remove surface impurities, and then dried;

[0072] Smelting preparation: Place the raw materials in a copper crucible of a small vacuum arc furnace for smelting to obtain a new type of refractory high-entropy alloy. The current requirement during smelting is 380 A - 400 A. Before smelting, the vacuum arc furnace needs to pump the vacuum degree to below 5×10 -3 Pa. Each time after smelting, it needs to be turned over, and smelting should be repeated at least 8 times to obtain the ingot of this alloy; the average density of the alloy is 6.38 g / cm 3 ,

[0073] Example 3:

[0074] The atomic percentages of the components of a low-density refractory high-entropy alloy are as follows: Al: 10.99 at%; Mo: 10.99 at%; Nb: 20.5 at%; Ti: 25.59 at%; V: 10.99 at%; Zr: 20.94 at%. Preparation steps of the low-density refractory high-entropy alloy:

[0075] Raw material preparation: Calculate and weigh a certain amount of raw material blocks of Al, Mo, Nb, Ti, V, and Zr. Use sandpaper to polish off the surface impurities and oxide scales generated by cutting on the raw material blocks. Then, accurately weigh the required mass of the raw materials on a balance. Subsequently, place all the weighed raw materials in absolute ethanol for ultrasonic oscillation cleaning to remove surface impurities, and conduct drying treatment;

[0076] Smelting preparation: Place the raw materials in a copper crucible of a small vacuum arc furnace for smelting to obtain a new refractory high-entropy alloy. The current requirement during smelting is 380 A - 400 A. Before smelting, the vacuum arc furnace needs to pump the vacuum degree to below 5×10 -3 Pa. Flip the material every time a smelting is completed, and smelt at least 8 times repeatedly to obtain the ingot of this alloy; The average density of the alloy is 6.36 g / cm 3 .

[0077] The above has introduced in detail a new low-density refractory high-entropy alloy provided by the embodiments of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; At the same time, for those of ordinary skill in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

[0078] As certain terms are used in the specification and claims to refer to particular components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in names as a way to distinguish components, but use the difference in functions of components as the criterion for distinction. As mentioned throughout the specification and claims, "comprising" and "including" are open-ended terms, so they should be interpreted as "including / including but not limited to". "Roughly" means 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 in the specification is the preferred implementation manner for implementing the present application, but the description is for the purpose of explaining the general principle of the present application and is not used to limit the scope of the present application. The protection scope of the present application shall be subject to what is defined by the appended claims.

[0079] It should also be noted that the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a commodity or system comprising a series of elements not only includes those elements but also other elements not expressly listed, or elements inherent to such commodity or system. Without further limitation, an element defined by the statement "comprising an..." does not exclude the presence of additional identical elements in the commodity or system comprising said element.

[0080] It should be understood that the term "and / or" used herein is merely a description of the relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. Additionally, the character " / " herein generally indicates that the associated objects before and after are in an "or" relationship.

[0081] The above description illustrates and describes several preferred embodiments of the present application. However, as mentioned above, it should be understood that the present application is not limited to the forms disclosed herein, should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be changed within the scope of the application concept described herein through the above teachings or the technology or knowledge in the relevant field. And any changes and modifications made by those skilled in the art without departing from the spirit and scope of the present application shall fall within the protection scope of the appended claims of the present application.

Claims

1. A low-density refractory high-entropy alloy, characterized in that: The atomic percentages of the respective components of the low-density refractory high-entropy alloy are as follows: Al: 10.0 - 11.0 at%; Mo: 10.0 - 11.0 at%; Nb: 20.5 - 21.5 at%; Ti: 25.5 - 27.0 at%; V: 10.0 - 11.0 at%; Zr: 20.4 - 21.5 at%. The low-density refractory high-entropy alloy has a multiphase structure of BCC1 + BCC2 + AlZr2, and the melting point of the alloy is not lower than 1400 °C; the density is 6.35 - 6.55 g / cm 3 .

2. The low-density refractory high-entropy alloy according to claim 1, characterized in that, The atomic percentages of the respective components of the low-density refractory high-entropy alloy are as follows: Al: 10.14 at%; Mo: 10.22 at%; Nb: 21.50 at%; Ti: 25.66 at%; V: 10.98 at%; Zr: 21.50 at%; the alloy density is 6.38 g / cm 3 .

3. The low-density refractory high-entropy alloy according to claim 1, wherein The atomic percentages of the respective components of the low-density refractory high-entropy alloy are as follows: Al: 10.53 at%; Mo: 10.53 at%; Nb: 21.06 at%; Ti: 26.31 at%; V: 10.53 at%; Zr: 21.04 at%; The alloy density is 6.37 g / cm 3 .

4. The low-density refractory high-entropy alloy according to claim 1, wherein The atomic percentages of the respective components of the low-density refractory high-entropy alloy are as follows: Al: 10.99 at%; Mo: 10.99 at%; Nb: 20.5 at%; Ti: 25.59 at%; V: 10.99 at%; Zr: 20.94 at%; the alloy density is 6.36 g / cm 3 .

5. A method for preparing a low-density refractory high-entropy alloy according to any one of claims 1-4, characterized in that: The method specifically includes the following preparation steps: S1) Raw material preparation: Quantitative raw material blocks of Al, Mo, Nb, Ti, V, and Zr are taken according to atomic percentages and pretreated; S2) Melting and preparation: The raw material blocks treated in S1) are melted multiple times by a vacuum melting process, and after homogenization heat treatment, a low-density refractory high-entropy alloy is obtained; The specific process is as follows: S2.1) Before smelting, evacuate the vacuum to below 5×10 -3 Pa, and the current during smelting is 380A - 400A; turn over the material each time a smelting is completed, and smelt at least 8 times repeatedly; S2.2) Then, homogenization heat treatment is carried out. The specific process is: the temperature is 1190 °C to 1210 °C, the time is 22 - 26 hours, and it is cooled with the furnace.

6. The method according to claim 5, characterized in that, The specific process of S1) is as follows: S1.1) Remove the surface impurities and scale of the raw material blocks, and then accurately weigh the required mass of the raw materials; S1.2) Then, all the weighed raw materials are placed in absolute ethanol for ultrasonic vibration cleaning to remove the surface impurities and then dried.

7. The method according to claim 5, wherein The strain rate of the low-density refractory high-entropy alloy is 0.001 s -1 , and its yield strength at room temperature is not less than 1733 MPa, and its compressive strength is not less than 1781 MPa; at 800 °C, the yield strength is not less than 921 MPa, and the compressive strength is not less than 987 MPa; at 1000 °C, the yield strength is not less than 338 MPa, and the compressive strength is not less than 448 MPa.

8. A low-density refractory high-entropy alloy prepared by the method according to any one of claims 5 - 7 is used in the field of high-temperature structural materials.

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