Two-stage annealing heat treatment method for improving mechanical property of AlCrFeNiV series high-entropy alloy

Abstract

The invention belongs to the technical field of metal materials, and particularly relates to a two-stage annealing heat treatment method for improving the mechanical property of an AlCrFeNiV-series high-entropy alloy, which comprises the following steps: carrying out solution treatment on the as-cast AlCrFeNiV-series high-entropy alloy in a protective environment, and cooling to room temperature; then carrying out cold rolling treatment; finally, carrying out two-stage annealing treatment, and cooling to room temperature; in the two-stage annealing treatment, the temperature of the first-stage annealing is higher than that of the second-stage annealing. Compared with the prior art, the method solves the problems that in the prior art, the grain structure of the alloy cannot be effectively optimized through single-stage annealing treatment, and the precipitated phase and grain characteristics formed at the single temperature are limited in the aspect of improving the alloy strength. According to the scheme, by reasonably adjusting the heat treatment process, the AlCrFeNiV series high-entropy alloy is in a complete recrystallization state, and meanwhile two precipitation strengthening phases are separated out, so that the composite strengthening effect of precipitation strengthening and fine grain strengthening is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal materials, and in particular relates to a double-stage annealing heat treatment method for improving the mechanical properties of an AlCrFeNiV-based high-entropy alloy. Background Art

[0002] High entropy alloys are considered to be one of the three major breakthroughs in alloying theory in recent decades. Due to the unique alloy design concept and the significant high mixed entropy effect, it can simultaneously possess high strength, high hardness, good corrosion resistance and wear resistance, greatly increasing its application value in various fields. Among the various types of high entropy alloys, face-centered cubic lattice (FCC) structure high entropy alloys exhibit excellent room temperature fracture toughness and plastic deformation ability due to their unique crystal structure. For example, the typical Cantor alloy (FeCoCrNiMn) exhibits excellent ductility at room temperature, and its fracture elongation can reach 56%.

[0003] FCC high-entropy alloys (HEAs) exhibit low yield strength and tensile strength at room temperature, which, to a certain extent, limits their application range. Therefore, improving the strength of FCC HEAs while maintaining their ductility has been a research hotspot in the materials field in recent years. Previous studies have shown that both precipitation strengthening and grain refinement are effective methods for improving the strength of FCC HEAs, with annealing being essential for promoting the formation of precipitation phases and grain refinement within FCC HEAs.

[0004] In the prior art, CN115491529A discloses a method for regulating the precipitation phase to improve the mechanical properties of AlCrFeNiV high entropy alloys. The chemical formula of the AlCrFeNiV high entropy alloy for regulating the precipitation phase is Al 0.4 Cr 0.7 Fe x Ni2V 0.2 , x is selected from 0.5, 1, or 2. The method comprises: weighing elemental metals aluminum, chromium, iron, nickel, and vanadium, heating them under argon protection until they melt to obtain an alloy ingot; further heating and remelting them under argon protection, casting them into a cast high-entropy alloy; after ultrasonication, placing them in a vacuum environment or an argon protection environment, heating them for solution treatment, cold rolling them, and annealing them. However, traditional single-stage annealing treatments, which primarily aim to regulate the precipitation strengthening phase, are not effective in optimizing the alloy's grain structure. Furthermore, the precipitation phases and grain characteristics formed at a single temperature have limitations in improving alloy strength. Summary of the Invention

[0005] The purpose of the present invention is to address at least one of the above-mentioned problems by providing a two-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV-based high-entropy alloys. This method addresses the problems in the prior art where single-stage annealing cannot effectively optimize the alloy's grain structure, and the precipitation phases and grain characteristics formed at a single temperature have limitations in improving alloy strength. By rationally adjusting the heat treatment process, the AlCrFeNiV-based high-entropy alloy is kept in a fully recrystallized state while simultaneously precipitating two precipitation-strengthening phases: a nanoscale coherent L12 phase and an incoherent BCC phase. This achieves a combined strengthening effect of precipitation strengthening and grain refinement.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A two-stage annealing heat treatment method for improving the mechanical properties of an AlCrFeNiV high entropy alloy comprises the following steps:

[0008] The cast AlCrFeNiV high entropy alloy is placed in a protective environment for solution treatment and cooled to room temperature;

[0009] Then cold rolling is carried out;

[0010] Finally, a double-stage annealing treatment is performed and the mixture is cooled to room temperature;

[0011] In the two-stage annealing treatment, the temperature of the first stage annealing is higher than the temperature of the second stage annealing; wherein the first stage annealing is used to achieve complete recrystallization of the grains, and the second stage annealing is used to promote the stable precipitation of the second phase in the alloy.

[0012] Preferably, the cast AlCrFeNiV high entropy alloy is prepared by the following steps:

[0013] Metal raw materials are weighed according to the composition ratio of the AlCrFeNiV series high entropy alloy, mixed and heated to melt under a protective atmosphere to obtain an alloy ingot; heated and remelted several times under a protective atmosphere, and cast to obtain a cast AlCrFeNiV series high entropy alloy.

[0014] Preferably, the purity of the metal element in the metal element raw material is greater than or equal to 99.9%.

[0015] Preferably, the protective atmosphere is argon atmosphere.

[0016] Preferably, the heating and remelting is performed at least 5 times.

[0017] Preferably, the protective environment is a vacuum environment or an argon protective environment.

[0018] Preferably, the temperature of the solution treatment is 1200° C. and the time is 24 hours.

[0019] Preferably, the total deformation of the cold rolling process is 75-85%.

[0020] More preferably, the total deformation of the cold rolling treatment is 80%, which is beneficial to the recrystallization and precipitation during the alloy annealing process and prevents cracks caused by excessive rolling.

[0021] Preferably, in the double-stage annealing treatment:

[0022] The first stage annealing temperature is 1000℃ and the time is 20min;

[0023] The second stage annealing temperature is 600-800°C and the time is 6-96h.

[0024] Preferably, the AlCrFeNiV high entropy alloy is Al 0.4 Cr 0.7 FeNi2V 0.2 High entropy alloys;

[0025] The protective environment is a vacuum environment or an argon protective environment;

[0026] The temperature of the solution treatment is 1200°C and the time is 24 hours;

[0027] The total deformation of the cold rolling process is 75-85%;

[0028] In the double-stage annealing process:

[0029] The first stage annealing temperature is 1000℃ and the time is 20min;

[0030] The second stage annealing temperature is 600℃ and the time is 48h;

[0031] The double-stage annealing treatment enables the alloy to reach a fully recrystallized state, forming an ultrafine grain structure with an average grain size of less than 1 μm, and synergistically precipitates a coherent L12 nanoscale strengthening phase and an incoherent BCC hard phase in the ultrafine grain matrix, forming a multi-scale composite precipitation strengthening system.

[0032] The working principle of the present invention is:

[0033] The first-stage annealing treatment mainly achieves complete recrystallization of grains through dynamic regulation of grain boundary migration and dislocation slip activity. During the recrystallization process, the residual strain caused by rolling is relieved, the grains change from fibrous to equiaxed, and the grain size distribution becomes uniform.

[0034] The second-stage annealing treatment primarily promotes the stable precipitation of secondary phases in the alloy, primarily manifesting as the formation of ordered L12 and BCC precipitates within a tough FCC matrix. The BCC phase, a hard and brittle phase incoherent with the matrix, significantly increases the alloy's hardness. The L12 phase, coherent with the matrix, enhances the alloy's strength without sacrificing ductility.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] The present invention provides a two-stage annealing heat treatment method for improving the mechanical properties of an AlCrFeNiV-based high-entropy alloy. By rationally adjusting the heat treatment process, the present invention achieves a combined strengthening effect of grain refinement and precipitation strengthening, significantly improving the overall mechanical properties of the alloy.

[0037] The present invention primarily employs a two-stage annealing process, with high-temperature annealing followed by low-temperature annealing. The first stage annealing primarily achieves complete recrystallization of the grains through dynamic regulation of grain boundary migration and dislocation slip activity. During the recrystallization process, the residual strain caused by rolling is relieved, the grains transform from fibrous to equiaxed, and the grain size distribution becomes uniform. The second stage annealing primarily promotes the stable precipitation of the secondary phase in the alloy, primarily manifested as the precipitation of ordered L12 and BCC precipitates on a tough FCC matrix. The BCC phase is a hard and brittle phase that is incoherent with the matrix, and its presence significantly increases the hardness of the alloy. The L12 phase is coherent with the matrix, enabling the alloy to achieve increased strength without sacrificing plasticity. By implementing a two-stage annealing process, the present invention first promotes the alloy to a fully recrystallized state, forming an ultrafine-grained microstructure with an average grain size of less than 1 μm. Secondly, a coherent L12 nanoscale strengthening phase and an incoherent BCC hard phase are synergistically precipitated in the ultrafine-grained matrix, forming a multi-scale composite precipitation strengthening system.

[0038] This treatment method overcomes the limitations of conventional single-stage annealing. By regulating the synergistic effect of grain size and precipitation, the alloy achieves a combined strengthening effect of both grain refinement and precipitation strengthening. Ultimately, this method significantly improves the alloy's overall mechanical properties, successfully achieving a high-entropy alloy with a synergistic combination of high strength and high ductility. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Al prepared in Examples 1 to 3 and Comparative Example 1 0.4 Cr 0.7 FeNi2V 0.2 X-ray diffraction (XRD) pattern of high-entropy alloy.

[0040] Figure 2 Al prepared in Examples 1-3 and Comparative Example 2 0.4 Cr 0.7FeNi2V 0.2 Inverse pole figure (ad) and grain size distribution diagram (eh) of high-entropy alloy.

[0041] Figure 3 Al prepared in Examples 1 to 3 0.4 Cr 0.7 FeNi2V 0.2 BCC phase distribution diagram of high entropy alloy.

[0042] Figure 4 Al prepared in Example 2-Example 3 0.4 Cr 0.7 FeNi2V 0.2 Concentration profile of 60% Ni and 15% Al in a high-entropy alloy.

[0043] Figure 5 Al prepared in Examples 1 to 3 and Comparative Example 1 0.4 Cr 0.7 FeNi2V 0.2 Tensile curve of high entropy alloy.

[0044] Figure 6 Al prepared in Examples 1 to 3 and Comparative Example 1 0.4 Cr 0.7 FeNi2V 0.2 Microhardness diagram of high entropy alloys. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] In the following description, unless otherwise specified, the reagents used are commercially available products in the art, the methods used are well known in the art, and matters not mentioned are prior art.

[0047] A two-stage annealing heat treatment method for improving the mechanical properties of an AlCrFeNiV-based high-entropy alloy comprises the following steps:

[0048] Step 1: weighing metal raw materials of aluminum, chromium, iron, nickel, and vanadium according to the chemical formula, heating the metal raw materials until they are melted under argon protection to obtain an alloy ingot; further heating and remelting the metal ingot under argon protection several times, and casting the metal ingot into a cast high-entropy alloy;

[0049] Step 2: placing the cast high entropy alloy in a vacuum environment or an argon protection environment for solution treatment, followed by air cooling to room temperature; then cold rolling; and finally double-stage annealing, followed by air cooling to room temperature.

[0050] in,

[0051] AlCrFeNiV high entropy alloys are Al 0.4 Cr 0.7 FeNi2V 0.2 High entropy alloys,

[0052] The purity of the metal raw materials aluminum, chromium, iron, nickel and vanadium is greater than 99.9%.

[0053] The number of remelting is at least 5 times,

[0054] The solution treatment temperature is 1200℃ and the time is 24h.

[0055] The total deformation of the cold rolling process is 75-85% (preferably 80%), which is conducive to recrystallization and precipitation during the alloy annealing process and prevents cracks caused by excessive rolling.

[0056] In the double-stage annealing treatment, the first stage annealing temperature is 1000° C., the time is 20 minutes, and the second stage annealing temperature is 600-800° C., the time is 6-96 hours (preferably 600° C., 48 hours).

[0057] The present invention designs a two-stage heat treatment process for AlCrFeNiV high-entropy alloys. The precipitation phase and grain characteristics formed by this process have a significant effect on improving the strength of the alloy. The present invention will be further described in detail below with reference to the following examples, comparative examples and accompanying drawings.

[0058] Comparative Example 1

[0059] In this comparative example, Al 0.4 Cr 0.7 FeNi2V 0.2 The heat treatment steps of high entropy alloys are as follows:

[0060] (1) Solution treatment: After the as-cast high-entropy alloy ingot is ultrasonically cleaned with acetone to remove surface contaminants, it is vacuum-sealed in a quartz tube and filled with argon gas with a purity of ≥99.99% for protection. The ingot is kept at 1200°C for 2 h and then air-cooled to obtain a solid solution high-entropy alloy.

[0061] (2) Rolling treatment: The solid solution high entropy alloy is subjected to room temperature rolling deformation, using multiple rolling passes with a total deformation of 80% to obtain a rolled high entropy alloy;

[0062] (3) Single-stage annealing treatment: The rolled high-entropy alloy is kept at 1000°C for 20 min and air-cooled.

[0063] The XRD patterns of the obtained alloys are shown in Figure 1 As shown in Figure 2, there is no precipitation of other phases in the alloy except the FCC matrix. Figure 5The static tensile mechanical properties test results show that the room temperature (25 ° C) tensile yield strength of the alloy is 563MPa, the tensile strength is 1004MPa, and the elongation at break is 40%. The microhardness test of the prepared alloy is as follows Figure 6 As shown, the results show that the alloy hardness reaches 306HV.

[0064] Example 1

[0065] In this embodiment, Al 0.4 Cr 0.7 FeNi2V 0.2 The heat treatment steps of high entropy alloys are as follows:

[0066] (1) Solution treatment: After the as-cast high-entropy alloy ingot is ultrasonically cleaned with acetone to remove surface contaminants, it is vacuum-sealed in a quartz tube and filled with argon gas with a purity of ≥99.99% for protection. The ingot is kept at 1200°C for 2 h and then air-cooled to obtain a solid solution high-entropy alloy.

[0067] (2) Rolling treatment: The solid solution high entropy alloy is subjected to room temperature rolling deformation, using multiple rolling passes with a total deformation of 80% to obtain a rolled high entropy alloy;

[0068] (3) First stage annealing treatment: the rolled high entropy alloy is kept at 1000°C for 20 min and air-cooled.

[0069] (4) Second stage annealing treatment: the alloy obtained in step (3) is kept at 600°C for 6 hours and air-cooled.

[0070] The XRD patterns of the obtained alloys are shown in Figure 1 As shown in Figure 2, the alloy consists of FCC matrix and BCC precipitation phase. The obtained alloy was characterized by electron backscatter diffraction (EBSD) experiment ( Figure 2 a. Figure 2 e and Figure 3 a) It was confirmed to be in a completely recrystallized state, forming an ultrafine grain structure with an average grain size of 0.71μm, and containing a certain amount of BCC phase precipitation. The static tensile mechanical properties of the obtained alloy were tested, and the results showed that ( Figure 5 ), its room temperature (25 ℃) tensile yield strength is 637MPa, tensile strength is 896MPa, and elongation at break is 40%. The prepared alloy was subjected to microhardness test, and the test results are as follows Figure 6 As shown in the results, the hardness of the alloy reaches 404HV, which is 32% higher than that of Comparative Example 1. The reason for this is the precipitation of the BCC hard and brittle phase.

[0071] Example 2

[0072] In this embodiment, Al 0.4Cr 0.7 FeNi2V 0.2 The heat treatment steps of high entropy alloys are as follows:

[0073] (1) Solution treatment: After the as-cast high-entropy alloy ingot is ultrasonically cleaned with acetone to remove surface contaminants, it is vacuum-sealed in a quartz tube and filled with argon gas with a purity of ≥99.99% for protection. The ingot is kept at 1200°C for 2 h and then air-cooled to obtain a solid solution high-entropy alloy.

[0074] (2) Rolling treatment: The solid solution high entropy alloy is subjected to room temperature rolling deformation, using multiple rolling passes with a total deformation of 80% to obtain a rolled high entropy alloy;

[0075] (3) First stage annealing treatment: the rolled high entropy alloy is kept at 1000°C for 20 min and air-cooled.

[0076] (4) Second stage annealing treatment: the alloy obtained in step (3) is kept at 600°C for 48 hours and air-cooled.

[0077] The XRD patterns of the obtained alloys are shown in Figure 1 As shown in Figure 2, the alloy consists of FCC matrix and BCC and L12 precipitation phases. The obtained alloy was characterized by electron backscatter diffraction (EBSD) experiment ( Figure 2 b. Figure 2 f and Figure 3 b) It was confirmed that the alloy was in a completely recrystallized state, forming an ultrafine grain structure with an average grain size of 0.59 μm. In addition, there was obvious BCC phase precipitation. Due to the small size of the L12 phase, EBSD could not be observed, so atom probe tomography (APT) was used for detection. The APT results of the obtained alloy are shown in Figure 2. Figure 4 As shown in the figure, there is L12 phase rich in Ni and Al elements in the alloy. The static tensile mechanical properties of the obtained alloy were tested, and the results showed that ( Figure 5 ), its room temperature (25 ℃) tensile yield strength is 1020MPa, tensile strength is 1514MPa, and elongation at break is 23%. The prepared alloy was subjected to microhardness test, and the test results are as follows Figure 6 As shown, the results show that the alloy hardness reaches 493HV.

[0078] Compared to Example 1, both strength and hardness are significantly improved, attributed to the precipitation of the L12 phase. Calculated average equivalent radius of the L12 phase is 1.374 nm. The resulting alloy exhibits an ultrafine grain structure accompanied by the combined precipitation of BCC and L12 phases, resulting in a combined strengthening effect of both grain refinement and precipitation strengthening.

[0079] Example 3

[0080] In this embodiment, Al 0.4 Cr 0.7 FeNi2V 0.2 The heat treatment steps of high entropy alloys are as follows:

[0081] (1) Solution treatment: After the as-cast high-entropy alloy ingot is ultrasonically cleaned with acetone to remove surface contaminants, it is vacuum-sealed in a quartz tube and filled with argon gas with a purity of ≥99.99% for protection. The ingot is kept at 1200°C for 2 h and then air-cooled to obtain a solid solution high-entropy alloy.

[0082] (2) Rolling treatment: The solid solution high entropy alloy is subjected to room temperature rolling deformation, using multiple rolling passes with a total deformation of 80% to obtain a rolled high entropy alloy;

[0083] (3) First stage annealing treatment: the rolled high entropy alloy is kept at 1000°C for 20 min and air-cooled.

[0084] (4) Second stage annealing treatment: the alloy obtained in step (3) is kept at 600°C for 96 hours and air-cooled.

[0085] The XRD patterns of the obtained alloys are shown in Figure 1 As shown in Figure 2, the alloy consists of FCC matrix and BCC and L12 precipitation phases. The obtained alloy was characterized by electron backscatter diffraction (EBSD) experiment ( Figure 2 c. Figure 2 g and Figure 3 c) It was confirmed that the alloy was in a completely recrystallized state with an average grain size of 10.20 μm. In addition, only a small amount of BCC phase was precipitated. The results of the atomic probe tomography (APT) test of the obtained alloy are as follows: Figure 4 As shown in the figure, there is L12 phase rich in Ni and Al elements in the alloy. The static tensile mechanical properties test results of the obtained alloy ( Figure 5 ) shows that its room temperature (25 ° C) tensile yield strength is 705MPa, tensile strength is 1138MPa, and elongation at break is 34%. The prepared alloy was subjected to microhardness testing, and the test results are as follows Figure 6 As shown, the results show that the alloy hardness reaches 410HV.

[0086] Compared with Example 2, the strength and hardness of the alloy are reduced, which is not only due to the increase in the alloy grain size, but also due to the coarsening of the L12 precipitation phase.

[0087] Table 1 Average equivalent radius (R) of L12 phase in Examples 2-3 p ) and number density (N v )

[0088]

[0089] The maximum separation envelope method (MSEM) was used to calculate the average equivalent radius (R p ) and number density (N v The results are shown in Table 1. The average equivalent radius of the L12 phase increased from 1.374 nm to 2.055 nm, and the number density increased from 6.563×10 16 Reduced to 3.009×10 16 It can be seen that the coarsening of precipitates is accompanied by a decrease in their number density.

[0090] Comparative Example 2

[0091] In this comparative example, Al 0.4 Cr 0.7 FeNi2V 0.2 The heat treatment steps of high entropy alloys are as follows:

[0092] (1) Solution treatment: After the as-cast high-entropy alloy ingot is ultrasonically cleaned with acetone to remove surface contaminants, it is vacuum-sealed in a quartz tube and filled with argon gas with a purity of ≥99.99% for protection. The ingot is kept at 1200°C for 2 h and then air-cooled to obtain a solid solution high-entropy alloy.

[0093] (2) Rolling treatment: The solid solution high entropy alloy is subjected to room temperature rolling deformation, using multiple rolling passes with a total deformation of 80% to obtain a rolled high entropy alloy;

[0094] (3) Single-stage annealing treatment: The rolled high-entropy alloy is kept at 600°C for 6 hours and then air-cooled.

[0095] The obtained alloy was characterized by electron backscatter diffraction (EBSD) experiment ( Figure 2 d and Figure 2 h) It was confirmed that the alloy still maintained the long strip-shaped grains formed after the cold rolling treatment and did not reach a completely recrystallized state, resulting in an average grain size of 1.67 μm.

[0096] In summary, the present invention provides a two-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloys. The present invention achieves a composite strengthening effect of fine grain strengthening and precipitation strengthening by reasonably adjusting the heat treatment process, thereby significantly improving the comprehensive mechanical properties of the alloy. The present invention mainly adopts a two-stage annealing treatment, first high-temperature annealing and then low-temperature annealing. The first-stage annealing treatment mainly realizes the complete recrystallization of the grains through the dynamic regulation of grain boundary migration and dislocation slip activity. During the recrystallization process, the residual strain caused by rolling is relieved, the grains are changed from fibrous to equiaxed, and the grain size distribution becomes uniform (such as Figure 2The second stage annealing treatment mainly promotes the stable precipitation of the second phase in the alloy, which is mainly manifested as the precipitation of ordered L12 and BCC precipitates on the tough FCC matrix. Among them, the BCC phase is a hard and brittle phase that is not coherent with the matrix. Its existence significantly increases the hardness of the alloy (such as Figure 5 ), L12 phase is coherent with the matrix, which can improve the strength of the alloy without losing plasticity. The present invention implements a two-stage annealing process, firstly to promote the alloy to reach a complete recrystallization state, forming an ultra-fine grain structure with an average grain size of less than 1μm (such as Figure 2 ); secondly, a coherent L12 nanoscale strengthening phase and an incoherent BCC hard phase synergistically precipitate within the ultrafine-grained matrix, forming a multi-scale composite precipitation strengthening system. This treatment method overcomes the process limitations of traditional single-stage annealing. By regulating the synergistic mechanism of grain size and precipitation phase, the alloy simultaneously achieves a composite strengthening effect of grain refinement and precipitation strengthening. Ultimately, this method significantly improves the alloy's overall mechanical properties, successfully producing a high-entropy alloy with a synergistic combination of high strength and high ductility.

[0097] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A two-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloys, characterized in that: The steps include: The cast AlCrFeNiV high entropy alloy is placed in a protective environment for solution treatment and cooled to room temperature; Then cold rolling is carried out; Finally, a double-stage annealing treatment is performed and the mixture is cooled to room temperature; In the two-stage annealing treatment, the temperature of the first stage annealing is higher than the temperature of the second stage annealing; wherein the first stage annealing is used to achieve complete recrystallization of the grains, and the second stage annealing is used to promote the stable precipitation of the second phase in the alloy.

2. A two-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 1, characterized in that: The cast AlCrFeNiV high entropy alloy is prepared by the following steps: Metal raw materials are weighed according to the composition ratio of the AlCrFeNiV series high entropy alloy, mixed and heated to melt under a protective atmosphere to obtain an alloy ingot; heated and remelted several times under a protective atmosphere, and cast to obtain a cast AlCrFeNiV series high entropy alloy.

3. A two-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 2, characterized in that: The purity of the metal element in the metal element raw material is greater than or equal to 99.9%.

4. A two-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 2, characterized in that: The protective atmosphere is argon atmosphere.

5. A two-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 2, characterized in that: The heating and remelting are performed at least 5 times.

6. A two-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 1, characterized in that: The protective environment is a vacuum environment or an argon protective environment.

7. The double-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 1, characterized in that: The temperature of the solution treatment is 1200° C. and the time is 24 hours.

8. The double-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 1, characterized in that: The total deformation of the cold rolling process is 75-85%.

9. The double-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 1, characterized in that: In the double-stage annealing process: The first stage annealing temperature is 1000℃ and the time is 20min; The second stage annealing temperature is 600-800°C and the time is 6-96h.

10. The double-stage annealing heat treatment method for improving the mechanical properties of AlCrFeNiV high entropy alloy according to claim 1, characterized in that: The AlCrFeNiV high entropy alloy is Al 0.4 Cr 0.7 FeNi2V 0.2 High entropy alloys; The protective environment is a vacuum environment or an argon protective environment; The temperature of the solution treatment is 1200°C and the time is 24 hours; The total deformation of the cold rolling process is 75-85%; In the double-stage annealing process: The first stage annealing temperature is 1000℃ and the time is 20min; The second stage annealing temperature is 600℃ and the time is 48h; The double-stage annealing treatment enables the alloy to reach a fully recrystallized state, forming an ultrafine grain structure with an average grain size of less than 1 μm, and synergistically precipitates a coherent L12 nanoscale strengthening phase and an incoherent BCC hard phase in the ultrafine grain matrix, forming a multi-scale composite precipitation strengthening system.

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