CoCrFeNi series high-entropy alloy and preparation method thereof

Abstract

The invention belongs to the technical field of high-entropy alloys, and particularly relates to a CoCrFeNi series high-entropy alloy and a preparation method thereof. The chemical component expression of the alloy is (CoCrFeNi) 100-x-yNbxAly, x is the atomic percentage of Nb, y is the atomic percentage of Al, and x + y = 11-13; the high-entropy alloy at least comprises an FCC phase and a Laves phase. The preparation method comprises the steps that metal raw materials are weighed and subjected to impurity removal pretreatment; an oxygen absorption carrier is placed in the central crucible, and materials are sequentially placed in the main smelting crucible from bottom to top according to the melting points of all elements of the alloy in the raw materials from low to high; vacuumizing and inflating to establish an initial protective atmosphere, repeating vacuumizing and inflating for at least three times, and constructing a micro-negative-pressure protective atmosphere smelting environment; and preparing the CoCrFeNi series high-entropy alloy by a vacuum arc melting method. According to the method, the CoCrFeNi series high-entropy alloy with specific doping elements and doping proportions is screened out, and the requirement for cooperation of high strength and high plasticity is met.

Description

Technical Field

[0001] The present invention belongs to the technical field of high entropy alloys, and in particular relates to a CoCrFeNi-based high entropy alloy and a preparation method thereof. Background Art

[0002] High-entropy alloys (HEAs) are an emerging class of materials that transcend traditional alloy design concepts. Their core characteristic lies in their composition of five or more primary elements in equiatomic or near-equiatomic ratios. This unique multicomponent design triggers four core effects that distinguish them from traditional alloys: the high-entropy effect; the lattice distortion effect; the slow diffusion effect; and the "cocktail" effect. These effects contribute to HEAs' generally excellent strength-ductility balance, superior corrosion resistance, and good high-temperature stability. This outstanding combination of properties makes them highly attractive for applications in aerospace, nuclear power equipment, biomedical materials, and various extreme environments.

[0003] Among the many high-entropy alloy systems, CoCrFeNi alloys with a face-centered cubic crystal structure have become a representative system due to their excellent room-temperature plasticity (e.g., elongation at break is typically >50%), excellent low-temperature toughness, and significant work hardening ability. However, the yield strength of CoCrFeNi alloys with a single FCC phase is low, making it difficult to meet the requirements of engineering structural materials for the synergy between high strength and high plasticity. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a CoCrFeNi-based high entropy alloy and a preparation method thereof, aiming to solve at least one technical problem among the background technologies.

[0005] The present invention is achieved in that:

[0006] The first aspect of the present invention provides a CoCrFeNi series high entropy alloy, the chemical composition of which is expressed as (CoCrFeNi) 100-x-y Nb x Al y , wherein x is the atomic percentage of Nb, y is the atomic percentage of Al, and x+y=11 to 13;

[0007] The high entropy alloy includes at least an FCC phase and a Laves phase.

[0008] Preferably, the (CoCrFeNi) 100-x-y Nb x Al y In the example, x+y=12.

[0009] Preferably, the (CoCrFeNi) 100-x-y Nb x Al yIn the equation ( ), x=2~8, y=4~10.

[0010] Preferably, the (CoCrFeNi) 100-x-y Nb x Al y , x=2, y=10; a three-phase eutectic structure of FCC phase, BCC phase and Laves phase is formed in the high entropy alloy.

[0011] Preferably, the (CoCrFeNi) 100-x-y Nb x Al y , x=8, y=4, and a two-phase coherent structure of FCC phase and Laves phase is formed in the high entropy alloy.

[0012] A second aspect of the present invention provides a method for preparing the above-mentioned CoCrFeNi-based high entropy alloy, which comprises the following steps:

[0013] Weigh Al, Co, Cr, Fe, Ni, and Nb metal raw materials according to the preset atomic percentage requirements and perform impurity removal pretreatment;

[0014] A high entropy alloy oxygen absorbing carrier is placed in the central crucible of the vacuum melting equipment, and the raw materials are placed in the main melting crucible in order from low to high melting points and from bottom to top according to the melting points of the alloy elements in the raw materials. The main melting crucibles are arranged around the central crucible;

[0015] Evacuate the vacuum melting equipment and inflate it to create an initial protective atmosphere. Repeat the vacuuming and inflation process at least three times to create a slightly negative pressure protective atmosphere melting environment.

[0016] The CoCrFeNi high entropy alloy is prepared based on a vacuum arc melting method.

[0017] Preferably, the current of the vacuum arc melting is 160A-220A;

[0018] Preferably, during the vacuum arc melting, the oxygen absorbing carrier is first subjected to at least three cycles of pulse melting, and then the raw material is subjected to at least four cycles of continuous melting.

[0019] Preferably, during the vacuum arc melting, when the raw materials are completely melted and in liquid state, magnetic stirring is performed using a 0.4T to 0.6T alternating magnetic field to achieve uniform mixing of the raw materials; and the continuous melting process is synchronously coupled with the magnetic stirring.

[0020] Preferably, the oxygen absorption carrier is a Ti ingot.

[0021] Compared with the prior art, the present invention selects a CoCrFeNi-based high-entropy alloy with specific doping elements and doping ratios to meet the requirements of synergy between high strength and high plasticity.

[0022] The present invention constructs a two-phase coherent structure including at least FCC phase and Laves phase, or even a three-phase eutectic structure of FCC phase, BCC phase and Laves phase, which has the effect of fine grain strengthening and significantly improves the comprehensive mechanical properties of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 XRD comparison diagram of NA2-10 alloy in Example 1 of the present invention and NA0-12 alloy and NA0-0 alloy in comparative examples;

[0024] Figure 2 The scanning electron microscope images of the NA2-10 alloy in Example 1 of the present invention and the comparative examples NA0-0 alloy and NA0-12 alloy are shown;

[0025] Figure 3 Compression performance curves of the NA2-10 alloy in Example 1 of the present invention and the NA0-0 alloy in the comparative example;

[0026] Figure 4 A microstructure diagram of a high entropy alloy in the prior art having the same elements as those of the present invention;

[0027] Figure 5 A microstructure diagram of a high entropy alloy in the prior art having similar elements to the present invention;

[0028] Figure 6 XRD comparison charts of the NA8-4 alloy in Example 2 of the present invention and the NA4-8 alloy, NA6-6 alloy, and NA10-2 alloy of the comparative examples;

[0029] Figure 7 The scanning electron microscope images of the NA8-4 alloy in Example 2 of the present invention and the NA4-8 alloy, NA6-6 alloy, and NA10-2 alloy of the comparative examples are shown;

[0030] Figure 8 for Figure 7 Enlarged images of the eutectic structures of the NA8-4 alloy and the comparative examples NA4-8 alloy, NA6-6 alloy, and NA10-2 alloy;

[0031] Figure 9 Compression curves of the NA8-4 alloy in Example 2 of the present invention and the NA4-8 alloy, NA6-6 alloy, NA10-2 alloy, and NA12-0 alloy of the comparative examples;

[0032] Figure 10 This is a bright field image of the eutectic region of the NA8-4 alloy in Example 2 of the present invention;

[0033] Figure 11The two-phase diffraction spot pattern of the NA8-4 alloy in Example 2 of the present invention and the lattice fringe pattern obtained by inverse Fourier transform thereof;

[0034] Figure 12 This is a transmission electron microscope image of the interface between the FCC phase and the Laves phase in the high entropy alloy of the prior art. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific implementation cases described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] The corresponding CoCrFeNi high entropy alloys were prepared by smelting method and named according to the corresponding method in Table 1.

[0037] A method for preparing a CoCrFeNi-based high entropy alloy comprises the following steps:

[0038] S1, weighing Al, Co, Cr, Fe, Ni, and Nb metal raw materials (purity ≥99.95%) according to preset atomic percentage requirements, performing rotary surface polishing using a 240-mesh abrasive belt, and then performing gradient ultrasonic cleaning (40 kHz / 5 min → 28 kHz / 5 min) in anhydrous ethanol solution; after cleaning, the surface is dehydrated and stored in a vacuum bag containing molecular sieves;

[0039] S2: A high-entropy alloy oxygen absorbing carrier (Ti ingot) is placed in the central crucible of the vacuum melting equipment. Materials are placed in the main melting crucible in ascending order of melting point of the alloy elements (Al→Cr→Fe→Co→Ni→Nb) from bottom to top, with the main melting crucibles arranged around the central crucible.

[0040] S3: Start the mechanical pump to pre-evacuate the melting chamber to below 50 Pa, then flush argon into the melting chamber to establish an initial protective atmosphere; then use the molecular pump to evacuate the chamber to below 50 Pa for the second time, and gradually introduce Ar gas to a slightly negative pressure state (-0.03 to -0.07 kPa). After repeating the evacuation and inflation three times, turn off the mechanical pump and prepare for melting;

[0041] S4, the CoCrFeNi series high entropy alloy is prepared based on the vacuum arc melting method; during the melting process, after controlling the gap between the electrode and the raw material to about 3 mm, the arc is turned on to start melting; according to the current fluctuation characteristics, a 10ms-level response adjustment is implemented in the range of 160A-220A (200A is used in the following embodiment); when the raw material ingot is completely melted and in liquid state, magnetic stirring is performed using an alternating magnetic field of about 0.5T to allow the ingot to be evenly mixed; first complete the pulse melting of the oxygen absorbing carrier (3 cycles), and then perform 5 continuous melting and magnetic field stirring synchronously coupled.

[0042] Specifically, the chemical composition expression of high entropy alloy is (CoCrFeNi) 100-x-y Nb x Al y , wherein x is the atomic percentage of Nb, y is the atomic percentage of Al, and x+y=11 to 13 (preferably 12); the high entropy alloy includes at least a coherent structure of an FCC phase and a Laves phase.

[0043] Preferably, x = 2 to 8, y = 4 to 10. More preferably, x = 2, y = 10, forming a three-phase eutectic structure of FCC phase, BCC phase and Laves phase in the high-entropy alloy; or, x = 8, y = 4, forming a two-phase coherent structure of FCC phase and Laves phase in the high-entropy alloy.

[0044] Table 1

[0045]

[0046] Example 1

[0047] This embodiment is a high entropy alloy (CoCrFeNi) with a three-phase eutectic structure. 88 Nb2Al 10 .

[0048] Figure 1 The XRD patterns of NA2-10 alloy, NA0-12 alloy and NA0-0 alloy are shown. Figure 1 As can be seen in the NA0-0 alloy, three strong peaks appear at [44.3°], [51.5°], and [74.1°], which are essentially consistent with the diffraction peak positions of Ni (PDF#: 00-001-1258), indicating that the NA0-0 alloy exhibits a single FCC crystal structure. The NA0-12 alloy exhibits both FCC and BCC diffraction peaks. The NA2-10 alloy, in addition to its FCC crystal structure, also exhibits characteristic peaks of the hexagonal C14 Laves phase, which are essentially consistent with the diffraction peak positions of Fe2Nb (PDF#: 03-065-3574). This indicates that the Laves phase in the alloy is a secondary phase.

[0049] Figure 2 The scanning electron micrographs of NA0-0 alloy, NA2-10 alloy and NA0-12 alloy are shown in Table 2. Figure 2 The point scanning results of each area in NA0-0 alloy are shown in Figure 2. Figure 2 As shown in (a), Figure 2 As can be seen in (a), the alloy presents a single-phase structure, combined with Figure 2 The XRD results show that it has an FCC crystal structure. Figure 2(b) is a scanning electron microscope image of NA2-10 alloy. With the introduction of Nb and Al elements, the solidification path of the alloy changes significantly, and the microstructure of Nb2-Al10 shows the coexistence of three phases. Combined with the point scanning results in Table 2, it can be seen that the light gray matrix A is rich in Co / Cr / Ni / Fe and other elements. Since the CoCrFeNi high entropy alloy is a single-phase FCC crystal structure, combined with Figure 2 The XRD results show that the light gray matrix is an FCC crystal structure. The Nb and Al atoms therein enter the FCC crystal structure by solid solution. The Al content in the dark gray secondary phase B is as high as 10.12%. According to the existing technology, Al can promote the formation of BCC phase, so B can be inferred to be BCC phase. It should be noted that the BCC phase is not Figure 2 It was detected by XRD because its content was small and it was not sensitive to diffraction. Figure 2 In (c) NA0-12, the secondary phase C is scanned and found to be rich in Al. Figure 2 The diffraction peak of the BCC phase was detected by XRD. Therefore, it can be basically confirmed that the dark gray secondary phase of NA2-10 is the BCC phase.

[0050] The eutectic area of NA2-10 alloy is magnified locally. Figure 2 As shown in (d), it is found to be composed of three phases. The point scanning results of the three phases are shown in Table 2. Among them, point D and point E are similar to the composition of the FCC phase and BCC phase discussed above. Combined with the XRD results, it can be seen that they are FCC and BCC phases. Point F in the white area is rich in Nb elements. Figure 2 The XRD results show that it is a Laves phase crystal structure. This indicates that the BCC phase precipitates before the Laves phase, and the residual liquid phase reaches the ternary eutectic point due to Nb enrichment, and then a eutectic reaction (L→FCC+BCC+Laves) occurs.

[0051] Table 2

[0052]

[0053] Because ternary eutectic alloys possess a fine eutectic structure, this fine structure effectively hinders the movement of dislocations. When the metal is subjected to external forces, dislocations are less likely to slide freely within the crystal, thereby enhancing the material's strength. Furthermore, its microstructure is more complex, with stronger interactions and synergies between phases. During solidification, the ternary eutectic's morphology and phase composition are more diverse, allowing each to leverage its mechanical properties in different directions and locations, significantly improving the alloy's overall strength.

[0054] Figure 3The following is a comparison of the compression performance curves of NA2-10 and NA0-0. It can be seen from the curve that the compressive yield strength of NA2-10 is 506MPa, while that of NA0-0 is 140MPa. In other words, the yield strength of NA2-10 is 3.6 times that of the NA0-0 alloy. In terms of plasticity, NA2-10 also exhibits high plasticity, just like NA0-0.

[0055] While the ternary eutectic structure contributes to the alloy's excellent performance, not all high-entropy alloys exhibit a ternary eutectic point, as the composition range for this point is generally very small. Furthermore, even if phase diagram simulations reveal that some high-entropy alloys exhibit a composition range where a ternary eutectic point occurs, during actual solidification, due to the influence of solid solution, metal atoms in the liquid will inevitably dissolve into the primary phase during cooling, preventing the uncooled liquid metal from reaching the theoretical ternary eutectic composition point and ultimately failing to achieve a ternary eutectic structure.

[0056] In order to further reflect the characteristics of Example 1 of the present invention, Figure 4 Several high entropy alloys of the same elements are displayed. It can be clearly seen from the microstructure that no ternary eutectic structure is found. Figure 5 For high entropy alloys of several similar element types, no ternary eutectic structure was found. Figure 4 as well as Figure 5 These examples of existing technologies are merely illustrative. In reality, no alloys containing relevant elements have been found in existing literature to form a ternary eutectic structure. Therefore, the presence of a ternary eutectic structure in Example 1 of the present invention is an unexpected technical feature, and also has the unexpected effect of improving the mechanical properties of the material.

[0057] Example 2

[0058] This embodiment is a high entropy alloy (CoCrFeNi) with a two-phase coherent structure. 88 Nb8Al4.

[0059] Figure 6 The XRD of NA4-8 alloy, NA6-6 alloy, NA8-4 alloy and NA10-2 alloy are shown. Figure 6 It can be seen that in addition to the matrix phase FCC, the above alloys all have a second phase (Laves phase).

[0060] Figure 7 (a)-(d) are scanning electron microscope images of NA4-8 alloy, NA6-6 alloy, NA8-4 alloy and NA10-2 alloy respectively. Figure 6The XRD results show that only FCC and Laves phases are present in all the alloys mentioned above. Furthermore, the corresponding areas were scanned for data, as shown in Table 3. The scan data in Table 3 indicate that the white structure is the Laves phase, and the gray structure is the FCC phase. Figure 8 (a)-(d) correspond to Figure 7 The enlarged view of the alloy eutectic structure shows that the eutectic regions of the above-mentioned alloys are all binary eutectics, which are obviously different from the ternary eutectic of the above-mentioned Example 1.

[0061] Table 3

[0062]

[0063] Figure 9 Table 4 is the compression curve of the alloy and the corresponding properties are summarized in Table 4. Figure 9 It can be seen that the yield strength of NA8-4 is 1231MPa, which is 8.8 times that of NA0-0. Compared with other Nb / Al co-doped alloys, NA8-4 has excellent comprehensive mechanical properties. Figure 9 A performance pattern can be observed: as the Nb content increases, the compressive strength of the alloy is generally positively correlated with the Nb content. However, the plasticity decreases. It is important to note that while the compressive strength of the NA8-4 alloy is almost identical to that of the NA12-0 alloy, its plasticity is 1.46 times that of the NA12-0 alloy.

[0064] Table 4

[0065]

[0066] Figure 10 This is a bright-field image of the NA8-4 eutectic. After selected-area electron diffraction of the two phases in the eutectic, the white area was calibrated with Ni (PDF#: 00-001-1258) and the gray area was calibrated with Fe2Nb (PDF#: 03-065-3574), further confirming that the alloy is composed of FCC phase and Laves phase.

[0067] right Figure 10 After analyzing the diffraction spots of the two phases, it was found that the (1, 1, 1) crystal plane of the FCC phase and the (2, -1, -1, 0) crystal plane of the Laves phase were parallel, as shown in Figure 2. Figure 11 As shown in (a) and (b), the red line in (b) is translated from Figure a. In (b), the red line completely coincides with the <2,-1,-1,0> crystal direction. Then, the inverse Fourier transform is performed to obtain the lattice fringes, as shown in Figure 1. Figure 11 In (c) and (d), after measuring the interplanar spacing, it was found that the interplanar spacing of FCC is The interplanar spacing of the Laves phase is

[0068] according to Mismatch The calculation result is 2.325%. It is generally believed by those skilled in the art that when the mismatch is less than 5%, the FCC phase and Laves phase of the NA8-4 alloy are coherent, which explains the excellent overall mechanical properties of the NA8-4 alloy. This is especially true when compared to the NA12-0 alloy, which, despite its higher Nb content, has a compressive strength nearly identical to that of the NA8-4 alloy.

[0069] It's important to note that coherence refers to the phenomenon in which the lattices of two phases have the same crystallographic orientation at the interface, with some atoms arranged directly and continuously at the interface. This is like two puzzle pieces whose edge shapes and patterns perfectly match at the joint. Generally speaking, the prerequisite for two phases to form coherence is that the lattice constants are similar and the lattice type is the same.

[0070] For high-entropy alloys, the lattice constants of the phases formed by each high-entropy alloy component are different, and the lattice constants of the FCC and Laves phases of the present invention cannot be inferred from existing technologies. Furthermore, the solid solubility of atoms in the FCC and Laves phases differs, thus affecting their interplanar spacing. Taking all of these factors into account, the coherence of the two phases in the NA8-4 alloy is an unexpected effect and contributes to the optimal overall mechanical properties of NA8-4.

[0071] It is generally accepted in materials science that incoherent interfaces between secondary phases and the matrix can induce significant stress concentration and crack nucleation, significantly reducing the toughness and fatigue resistance of the material. For example, the σ phase formed by transition metal elements, while possessing a wide solid solubility range and not adhering to strict stoichiometric relationships, has a low-symmetry crystal structure and complex atomic arrangement that severely hinders dislocation slip motion. This microscopic mechanism directly leads to a decrease in the material's plastic deformation capacity and significant embrittlement. When the σ phase forms in an alloy system, the incoherent interface between it and the matrix is unable to effectively transfer external loads, resulting in severe localized stress concentration at the interface. This condition creates favorable conditions for crack propagation, ultimately leading to brittle fracture failure. Typical experimental data show that in the CoCrFeMnNiMo alloy system, the presence of the σ phase reduces the compressive strain before fracture by up to 19%. Based on this analysis, this explains why the Nb12-0 alloy exhibits little strength improvement relative to the NA8-4 alloy, while exhibiting significantly lower ductility.

[0072] Specifically, in the NA8-4 alloy, the addition of appropriate Nb and Al elements to CoCrFeNi results in a near-equivalent (1,1,1) interplanar spacing of the FCC phase and the (2,-1,1,0) interplanar spacing of the Laves phase, with virtually no phase difference between the two phases (a mismatch of only 2.325%). This results in a coherent interface between the Laves and FCC phases, effectively reducing dislocation blockage at the interface and thus relieving stress concentration at the interface, thereby inhibiting crack propagation. However, the NA12-0 alloy, which should have increased compressive strength with increasing Nb content, did not achieve the expected compressive strength. This is primarily due to changes in the content and type of doping elements, which altered the interplanar spacing between the FCC and 1aves phases and the phase difference between the two phases. This prevented the two phases from forming a coherent interface, leading to severe localized stress concentration at the interface. This condition favored crack propagation, ultimately causing the NA12-0 alloy to fail prematurely due to brittle fracture.

[0073] like Figure 12 As shown in Figure 2, although high entropy alloy systems containing FCC phase and Laves phase have been developed in the prior art, there has been no successful case of constructing a two-phase coherent structure. Figure 12 In (a), Guan et al. studied a new W / FeCoCrNi-based in-situ generated high entropy alloy gradient coating with Laves-FCC dual-phase structure and synergistic friction behavior. The coating they prepared ultimately formed only a semi-coherent interface with a matching rate of 10.5%. Figure 12 In (b), Fan et al. studied the synergistic effect of Nb and Mo alloying on the microstructure and mechanical properties of CoCrFeNi HEA. The results show that through synergistic alloying, a Laves phase that is semi-coherent with the matrix is formed in the FCC matrix. It should be noted that in this high entropy alloy system, there are very few relevant literatures on the formation of semi-coherent interfaces, and for the coherent interface in the present invention, no relevant researchers have found it in the existing literature. It is worth noting that in the study of adding Nb element alone to the CoCrFeNi based high entropy alloy (the resulting alloy phase composition is the same as the present invention, both of which are FCC phase and Laves phase coexistence systems), the formation of a coherent relationship between the two phases was still not observed. This phenomenon highlights the particularity of the Nb-Al synergistic doping strategy in the present invention. Comparative analysis shows that Example 2 of the present invention realizes the FCC / laves coherent structure in the CoCrFeNi based high entropy alloy for the first time, providing important theoretical support for the design of a new alloy system with both high strength and good plasticity.

[0074] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A CoCrFeNi-based high entropy alloy, characterized in that: The chemical composition expression of the high entropy alloy is (CoCrFeNi) 100-x-y Nb x Al y , wherein x is the atomic percentage of Nb, y is the atomic percentage of Al, and x+y=11 to 13; The high entropy alloy includes at least an FCC phase and a Laves phase.

2. A CoCrFeNi-based high entropy alloy according to claim 1, characterized in that: (CoCrFeNi) 100-x- y Nb x Al y In the example, x+y=12.

3. A CoCrFeNi-based high entropy alloy according to claim 2, characterized in that: (CoCrFeNi) 100-x- y Nb x Al y In the equation ( ), x=2~8, y=4~10.

4. A CoCrFeNi-based high entropy alloy according to claim 3, characterized in that: (CoCrFeNi) 100-x- y Nb x Al y , x=2, y=10; a three-phase eutectic structure of FCC phase, BCC phase and Laves phase is formed in the high entropy alloy.

5. The CoCrFeNi high entropy alloy according to claim 3, characterized in that: (CoCrFeNi) 100-x- y Nb x Al y , x=8, y=4, and a two-phase coherent structure of FCC phase and Laves phase is formed in the high entropy alloy.

6. The method for preparing a CoCrFeNi-based high entropy alloy according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: Weigh Al, Co, Cr, Fe, Ni, and Nb metal raw materials according to the preset atomic percentage requirements and perform impurity removal pretreatment; A high entropy alloy oxygen absorbing carrier is placed in the central crucible of the vacuum melting equipment, and the raw materials are placed in the main melting crucible in order from low to high melting points and from bottom to top according to the melting points of the alloy elements in the raw materials. The main melting crucibles are arranged around the central crucible; Evacuate the vacuum melting equipment and inflate it to create an initial protective atmosphere. Repeat the vacuuming and inflation process at least three times to create a slightly negative pressure protective atmosphere melting environment. The CoCrFeNi high entropy alloy is prepared based on a vacuum arc melting method.

7. The method for preparing a CoCrFeNi-based high entropy alloy according to claim 6, wherein: The current of the vacuum arc melting is 160A-220A.

8. The method for preparing a CoCrFeNi-based high entropy alloy according to claim 6, wherein: During the vacuum arc melting, the oxygen absorbing carrier is first subjected to at least three cycles of pulse melting, and then the raw material is subjected to at least four cycles of continuous melting.

9. The method for preparing a CoCrFeNi-based high entropy alloy according to claim 8, wherein: During the vacuum arc melting, when the raw materials are completely melted and in liquid state, magnetic stirring is performed using a 0.4T to 0.6T alternating magnetic field to achieve uniform mixing of the raw materials; and the magnetic stirring is synchronously coupled during the continuous melting process.

10. The method for preparing a CoCrFeNi-based high entropy alloy according to claim 6, wherein: The oxygen absorption carrier is a Ti ingot.

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