MnAlCu co-doped CoCrFeNi-based high-entropy alloy and preparation method thereof

Abstract

The invention provides a MnAlCu co-doped CoCrFeNi-based high-entropy alloy and a preparation method thereof, and belongs to the field of metal materials, the chemical general formula of the high-entropy alloy is CoaCrbFecNidMneAlxCuy, a, b, c, d, e, x and y respectively represent the molar ratio of the corresponding elements, the ratio of a to b to c to d to e is 1: (0.8-1.2): (0.8-1.2): (0.8-1.2): (0.1 lt), and the sum of the molar ratio of a to b to c to d to e is 1: (0.8-1.2): (0.8-1.2): (0.1 lt). X is less than or equal to 3, 0.1 lt; y < = 3. By introducing co-doping of three elements of Mn, Al and Cu, the strength, plasticity and corrosion resistance of the alloy are considered, and the comprehensive performance is remarkably improved; meanwhile, the microstructure and phase composition of the alloy can be flexibly controlled by adjusting the molar ratio of all the elements, so that the requirements of different application scenes are met, the preparation process is simple and convenient, and large-scale production is easy.

Description

Technical Field

[0001] This invention relates to the field of metallic materials technology, specifically to a MnAlCu co-doped CoCrFeNi-based high-entropy alloy and its preparation method. Background Technology

[0002] High-entropy alloys are a new type of multi-principal element alloy that has been developed in recent years. Their core design concept is to contain multiple main elements (usually ≥5), with the atomic percentage of each element ranging from 5% to 35%. CoCrFeNi-based face-centered cubic (FCC) high-entropy alloys are one of the most typical systems, and have attracted widespread attention due to their excellent toughness, ductility, and corrosion resistance.

[0003] However, CoCrFeNi-based high-entropy alloys with a single FCC structure have relatively low strength and hardness, especially those containing Cl. - The corrosion resistance in harsh environments (such as seawater and chemical media) still has room for improvement, which limits its application in marine engineering, chemical equipment, and other demanding environments. Currently, researchers are strengthening the material through solid solution by adding dopants (such as Al, Ti, and Cu). For example, adding Al can form B2 or BCC ordered phases, improving strength but often severely sacrificing toughness; adding Cu may provide some strengthening effect due to the formation of Cu-rich enriched regions, but Cu and the CoCrFeNi matrix have significant lattice distortion and negative mixing enthalpy, which easily leads to compositional segregation, deteriorating the material's plasticity, and resulting in limited and uncontrollable strengthening effects.

[0004] Therefore, there is an urgent need in this field for a new method that can significantly improve the hardness, strength and wear resistance of high-entropy alloys while maintaining their good plasticity and corrosion resistance. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the present invention provides a MnAlCu co-doped CoCrFeNi-based high-entropy alloy and its preparation method, aiming to solve the technical problem that it is difficult to simultaneously achieve strength, plasticity and corrosion resistance in existing high-entropy alloys.

[0006] In a first aspect, the present invention provides a MnAlCu co-doped CoCrFeNi-based high-entropy alloy, the chemical formula of which is Co. a Cr b Fe c Ni d Mn e Al x Cu y, where a, b, c, d, e, x, and y respectively represent the molar ratios of the corresponding elements, a:b:c:d:e is 1:(0.8 - 1.2):(0.8 - 1.2):(0.8 - 1.2):(0.8 - 1.2), the value range of x is 0.1 < x ≤ 3, and the value range of y is 0.1 < y ≤ 3.

[0007] Preferably, a:b:c:d:e is 1:1:1:1:1.

[0008] Preferably, the value range of x is 0.5 ≤ x ≤ 2, and the value range of y is 0.5 ≤ y ≤ 2.

[0009] Preferably, the ratio of x to y is (0.5 - 4):1.

[0010] Preferably, the ratio of x to y is 3:1.

[0011] Preferably, the atomic percentage content of Mn element is 16% - 24%.

[0012] Preferably, the chemical formula of the MnAlCu co-doped CoCrFeNi-based high-entropy alloy is Co1Cr1Fe1Ni1Mn1Al 1.5 Cu 0.5 .

[0013] In a second aspect, the present invention provides a preparation method for a MnAlCu co-doped CoCrFeNi-based high-entropy alloy, comprising the following steps: S1. Weigh high-purity metal blocks of each metal element according to the proportional ratio, and repeatedly melt them in a vacuum metallurgical equipment under argon protection to obtain a molten alloy liquid; S2. Pour the molten alloy liquid into a water-cooled copper mold to obtain an ingot; S3. Perform homogenization heat treatment on the ingot to obtain a MnAlCu co-doped CoCrFeNi-based high-entropy alloy.

[0014] Preferably, the vacuum metallurgical equipment includes a vacuum arc melting furnace or a vacuum induction melting furnace.

[0015] Preferably, the homogenization heat treatment is specifically: perform vacuum annealing treatment on the ingot at 1000 - 1200 °C, hold for 10 - 48 hours, and then cool with the furnace or water quench. Compared with the prior art, the beneficial effects of the present invention are: The MnAlCu co-doped CoCrFeNi-based high-entropy alloy provided by the present invention not only improves the corrosion resistance of the matrix alloy by introducing Mn, but also forms multi-element solid solution strengthening with Al and Cu, generating a synergistic effect of "1+1+1>3", further optimizing the comprehensive mechanical properties of the alloy, and significantly improving the hardness and strength while maintaining high plasticity. By precisely controlling the molar ratio of each element and the heat treatment process, the present invention realizes effective regulation of the alloy's microstructure, solves the problem that it is difficult to balance the strength, plasticity and corrosion resistance of existing high-entropy alloys, and has a simple preparation process and is easy to scale up production. Specific Embodiments

[0016] The embodiments of the technical solution of the present invention will be described in detail below. The following embodiments are only used to illustrate the technical solution of the present invention more clearly, so they are only examples and cannot be used to limit the protection scope of the present invention.

[0017] In order to solve the technical problem that it is difficult to balance the strength, plasticity and corrosion resistance of existing high-entropy alloys, the present invention provides a MnAlCu co-doped CoCrFeNi-based high-entropy alloy and its preparation method. Among them, by introducing specific proportions of Mn, Al and Cu elements into the alloy, the synergistic improvement of strength, plasticity and corrosion resistance is achieved.

[0018] In the first aspect, an embodiment of the present invention provides a MnAlCu co-doped CoCrFeNi-based high-entropy alloy, whose chemical general formula is Co a Cr b Fe c Ni d Mn e Al x Cu y , where a, b, c, d, e, x, and y respectively represent the molar ratios of the corresponding elements, and a:b:c:d:e is 1:(0.8~1.2):(0.8~1.2):(0.8~1.2):(0.8~1.2), the value range of x is 0.1 < x ≤ 3, and the value range of y is 0.1 < y ≤ 3.

[0019] In the technical solution of the embodiment of the present invention, the introduction of Mn element can further stabilize the FCC structure, promote the formation of a dense passivation film, improve the corrosion resistance of the alloy in the Cl - environment, and at the same time form multi-element solid solution strengthening with Al and Cu, thereby effectively improving the strength and hardness of the alloy. By precisely regulating the contents of Al and Cu, the phenomenon of composition segregation can be inhibited, and the adverse effects of lattice distortion on the material properties can be reduced, so that the alloy shows excellent wear resistance and corrosion resistance while maintaining good ductility.

[0020] Furthermore, in some embodiments, a:b:c:d:e is 1:1:1:1:1.

[0021] Furthermore, in some embodiments, the value range of x is 0.5≤x≤2, and the value range of y is 0.5≤y≤2.

[0022] Furthermore, in some embodiments, the ratio of x to y is (0.5~4):1.

[0023] In the technical solution of this invention embodiment, the content of Al and Cu elements is controlled within this range, which can not only avoid the increase in brittleness caused by excessive addition, but also ensure the comprehensive performance of the alloy under harsh environments.

[0024] Furthermore, in some embodiments, the ratio of x to y is 3:1.

[0025] Furthermore, in some embodiments, the atomic percentage of Mn is 16% to 24%.

[0026] In the technical solution of this invention embodiment, the alloy with Mn element content within this range has better corrosion resistance and mechanical properties.

[0027] Furthermore, in some embodiments, the chemical formula of the MnAlCu co-doped CoCrFeNi-based high-entropy alloy is Co1Cr1Fe1Ni1Mn1Al 1.5 Cu 0.5 .

[0028] Secondly, embodiments of the present invention provide a method for preparing a MnAlCu co-doped CoCrFeNi-based high-entropy alloy, comprising the following steps: S1. Weigh out high-purity metal blocks of each metal element according to the proportion, and repeatedly melt them in a vacuum metallurgical equipment under argon protection to obtain molten alloy liquid. S2. Pour the molten alloy liquid into a water-cooled copper mold to obtain an ingot; S3. The ingot is subjected to homogenization heat treatment to obtain a MnAlCu co-doped CoCrFeNi-based high-entropy alloy.

[0029] In the technical solution of this invention embodiment, the alloy composition is ensured by repeatedly melting the alloy by precisely controlling the proportion of each element during preparation; homogenization heat treatment of the ingot can effectively avoid compositional segregation and lattice distortion problems, thereby ensuring the uniformity and stability of the alloy in microstructure.

[0030] Furthermore, in some embodiments, the vacuum metallurgical equipment includes a vacuum arc melting furnace or a vacuum induction melting furnace.

[0031] Furthermore, in some embodiments, the homogenization heat treatment specifically involves: vacuum annealing the ingot at 1000~1200℃ for 10~48 hours, followed by furnace cooling or water quenching.

[0032] The following are some specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0033] Example 1 A high-entropy alloy based on CoCrFeNi co-doped MnAlCu, with the composition CoCrFeNiMnAl 0.5 Cu 0.5 (Elemental molar ratio), that is, the atomic percentage of each element is: Co 16.68%, Cr 16.68%, Fe 16.68%, Ni 16.68%, Mn 16.68%, Al 8.3%, Cu 8.3%.

[0034] The specific steps of the preparation method are as follows: (1) Weigh out the high-purity metal blocks of each metal element according to the proportion, and repeatedly turn them over and melt them 5 times in a vacuum arc melting furnace under argon protection to ensure that the alloy composition is uniform and to obtain molten alloy liquid. (2) The molten alloy liquid is poured into a water-cooled copper mold to obtain an ingot; (3) The as-cast alloy was vacuum annealed at 1100℃ for 24 hours and then water quenched to obtain a MnAlCu co-doped CoCrFeNi-based high-entropy alloy.

[0035] Example 2 A high-entropy alloy based on CoCrFeNi co-doped MnAlCu, with the composition CoCrFeNiMnAl 0.5 Cu 1.0 (Elemental molar ratio), the specific steps of the preparation method are as follows: (1) Weigh out the high-purity metal blocks of each metal element according to the proportion, and repeatedly turn them over and melt them 5 times in a vacuum arc melting furnace under argon protection to ensure that the alloy composition is uniform and to obtain molten alloy liquid. (2) The molten alloy liquid is poured into a water-cooled copper mold to obtain an ingot; (3) The as-cast alloy was vacuum annealed at 1200℃ and held for 12 hours, and then water quenched to obtain a MnAlCu co-doped CoCrFeNi-based high-entropy alloy.

[0036] Example 3 A high-entropy alloy based on CoCrFeNi co-doped MnAlCu, with the composition CoCrFeNiMnAl 1.0 Cu 1.0 (Elemental molar ratio), the specific steps of the preparation method are as follows: (1) Weigh out the high-purity metal blocks of each metal element according to the proportion, and repeatedly turn them over and melt them 5 times in a vacuum arc melting furnace under argon protection to ensure that the alloy composition is uniform and to obtain molten alloy liquid. (2) The molten alloy liquid is poured into a water-cooled copper mold to obtain an ingot; (3) The as-cast alloy was vacuum annealed at 1100℃ and held for 24 hours, and then cooled in the furnace to obtain a MnAlCu co-doped CoCrFeNi-based high-entropy alloy.

[0037] Example 4 A high-entropy alloy based on CoCrFeNi co-doped MnAlCu, with the composition CoCrFeNiMnAl 1.5 Cu 1.0 (Elemental molar ratio), the preparation method is the same as in Example 1.

[0038] Example 5 A high-entropy alloy based on CoCrFeNi co-doped MnAlCu, with the composition CoCrFeNiMnAl 1.5 Cu 0.5 (Elemental molar ratio), the preparation method is the same as in Example 1.

[0039] Example 6 A high-entropy alloy based on CoCrFeNi co-doped MnAlCu, with the composition CoCrFeNiMnAl 2.0 Cu 0.5 (Elemental molar ratio), the preparation method is the same as in Example 1.

[0040] Comparative Example 1 This comparative example provides a high-entropy alloy with the composition CoCrFeNi (elemental molar ratio), and the preparation method is the same as in Example 1.

[0041] Comparative Example 2 This comparative example provides a high-entropy alloy with the composition CoCrFeNiMn (elemental molar ratio), and the preparation method is the same as in Example 1.

[0042] Comparative Example 3 This comparative example provides a high-entropy alloy with the composition CoCrFeNiMnAl. 0.5 (Elemental molar ratio), the preparation method is the same as in Example 1.

[0043] Comparative Example 4 This comparative example provides a high-entropy alloy with the composition CoCrFeNiMnCu. 1.0 (Elemental molar ratio), the preparation method is the same as in Example 1.

[0044] Comparative Example 5 This comparative example provides a high-entropy alloy with the composition CoCrFeNiMnAl. 5.0 Cu 1.0 (Elemental molar ratio), the preparation method is the same as in Example 1.

[0045] Performance Testing and Results Analysis The alloy samples prepared in each embodiment and comparative example were subjected to performance tests, and the test results are shown in Table 1. The mechanical property testing methods were as follows: hardness was tested using a Rockwell hardness tester, and tensile strength was tested using a universal testing machine; the wear resistance testing method was as follows: wear testing machine was used with a load of 50 N and a sliding speed of 0.1 m / s; the corrosion resistance testing method was as follows: the corrosion resistance of the alloy samples was tested using a salt spray test chamber (test conditions: 5.0 ± 0.5% NaCl solution, 500 hours).

[0046] Table 1

[0047] Table 1 shows that the MnAlCu co-doped CoCrFeNi-based high-entropy alloys prepared in the embodiments of the present invention exhibit significant improvements in hardness, wear resistance, and corrosion resistance. Especially with the synergistic addition of Al and Cu, the overall performance of the alloy is further optimized. Appropriate Al and Cu co-doping not only effectively improves the strength and hardness of the alloy but also maintains its good plasticity and corrosion resistance to a certain extent. Furthermore, the wear volume and corrosion rate data show that Examples 4 and 5 demonstrate particularly outstanding performance, indicating that when the ratio of Al to Cu is controlled within a reasonable range, the optimal balance of performance can be achieved. Comparative Examples 1 and 2 show that simply adding Mn to CoCrFeNi can improve corrosion resistance to a certain extent, but the improvement in strength and hardness is relatively limited. Comparative Examples 3 and 4, when using MnAl or MnCu co-doping, still show unsatisfactory overall results. In Comparative Example 5, excessive Al addition leads to a significant decrease in the alloy's plasticity, and the corrosion resistance also fails to reach the expected level. This indicates that the type and ratio of elements need to be precisely controlled to achieve a comprehensive improvement in performance.

[0048] It should be noted that the present invention is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments that have the same structure and perform the same effects as the technical concept within the scope of the present invention are included within the scope of the present invention. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of the present invention, are also included within the scope of the present invention.

Claims

1. A MnAlCu co-doped CoCrFeNi-based high-entropy alloy, characterized in that, The chemical general formula of the MnAlCu co-doped CoCrFeNi-based high-entropy alloy is Co a Cr b Fe c Ni d Mn e Al x Cu y , where a, b, c, d, e, x, and y represent the molar ratios of the corresponding elements respectively. a:b:c:d:e is 1:(0.8 - 1.2):(0.8 - 1.2):(0.8 - 1.2):(0.8 - 1.2), the value range of x is 0.1 < x ≤ 3, and the value range of y is 0.1 < y ≤ 3.

2. The MnAlCu co-doped CoCrFeNi-based high-entropy alloy according to claim 1, characterized in that, The ratio of a:b:c:d:e is 1:1:1:1:

1.

3. The MnAlCu co-doped CoCrFeNi-based high-entropy alloy according to claim 1, characterized in that, The value of x is in the range of 0.5 ≤ x ≤ 2, and the value of y is in the range of 0.5 ≤ y ≤ 2.

4. The MnAlCu co-doped CoCrFeNi-based high-entropy alloy according to claim 1, characterized in that, The ratio of x to y is (0.5~4):

1.

5. The MnAlCu co-doped CoCrFeNi-based high-entropy alloy according to claim 4, characterized in that, The ratio of x to y is 3:

1.

6. The MnAlCu co-doped CoCrFeNi-based high-entropy alloy according to claim 1, characterized in that, The atomic percentage of the Mn element is 16% to 24%.

7. The MnAlCu co-doped CoCrFeNi-based high-entropy alloy according to claim 1, characterized in that, The chemical formula of the MnAlCu co-doped CoCrFeNi-based high-entropy alloy is Co1Cr1Fe1Ni1Mn1Al 1.5 Cu 0.5 .

8. The method for preparing MnAlCu co-doped CoCrFeNi-based high-entropy alloys as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Weigh out high-purity metal blocks of each metal element according to the proportion, and repeatedly melt them in a vacuum metallurgical equipment under argon protection to obtain molten alloy liquid. S2. Pour the molten alloy liquid into a water-cooled copper mold to obtain an ingot; S3. The ingot is subjected to homogenization heat treatment to obtain the MnAlCu co-doped CoCrFeNi-based high-entropy alloy.

9. The method for preparing MnAlCu co-doped CoCrFeNi-based high-entropy alloy according to claim 8, characterized in that, The vacuum metallurgical equipment includes a vacuum arc melting furnace or a vacuum induction melting furnace.

10. The method for preparing the MnAlCu co-doped CoCrFeNi-based high-entropy alloy according to claim 8, characterized in that, The homogenization heat treatment specifically involves: vacuum annealing the ingot at 1000~1200℃ for 10~48 hours, followed by furnace cooling or water quenching.

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