Iron-based high-entropy alloy and method for manufacturing the same

Abstract

The present application provides an iron-based high-entropy alloy and a method for manufacturing the same. The microstructure of the iron-based high-entropy alloy consists of a multi-directional annealed twin structure, a nanocrystalline structure, and an ultrafine-grained structure. The multi-directional annealed twin structure has twin boundaries in different directions. The twin boundaries in different directions can effectively hinder dislocation movement and interact with dislocations to enhance the yield strength of the iron-based high-entropy alloy. The nanocrystalline structure further enhances the yield strength of the iron-based high-entropy alloy. The ultrafine-grained structure can enhance the plastic deformation ability of the iron-based high-entropy alloy. Therefore, the multi-directional annealed twin structure, the nanocrystalline structure, and the ultrafine-grained structure can exert a synergistic effect, enabling the iron-based high-entropy alloy to simultaneously achieve excellent yield strength and plasticity.

Description

Technical Field

[0001] The present application relates to the technical field of high entropy alloys, and in particular to an iron-based high entropy alloy and a method for manufacturing the same. Background Art

[0002] As people's requirements for alloy performance increase, traditional alloy materials can no longer meet the requirements. In order to meet the increasingly stringent performance requirements, researchers have developed multi-principal element alloys, also known as high-entropy alloys (HEAs). Compared with traditional alloy materials, high-entropy alloys are a new type of alloy that does not contain a single principal element and is mixed in an equiatomic ratio or a near-equiatomic ratio through smelting, sintering and other processes. This type of alloy has a variety of excellent properties, such as excellent low-temperature mechanical properties, high thermal stability, excellent radiation resistance and good corrosion resistance. Therefore, the above-mentioned high-entropy alloys have good application prospects in fields such as turbine blades, heat exchangers and as aerospace materials.

[0003] However, in the related art, high entropy alloys cannot simultaneously achieve excellent yield strength and plasticity. Summary of the Invention

[0004] The present application provides an iron-based high-entropy alloy and a preparation method thereof, wherein the iron-based high-entropy alloy can simultaneously achieve excellent yield strength and plasticity.

[0005] In a first aspect, an embodiment of the present application provides an iron-based high-entropy alloy, the microstructure of which consists of a multi-directional annealed twin structure, a nanocrystalline structure, and an ultrafine grain structure.

[0006] In the iron-based high-entropy alloy provided in the embodiment of the present application, the microstructure of the iron-based high-entropy alloy is composed of a multi-directional annealed twin structure, a nanocrystalline structure, and an ultrafine grain structure. Among them, the multi-directional annealed twin structure has twin boundaries in different directions. The twin boundaries in different directions can effectively hinder the movement of dislocations and can interact with dislocations to strengthen the yield strength of the iron-based high-entropy alloy; the nanocrystalline structure further strengthens the yield strength of the iron-based high-entropy alloy; and the ultrafine grain structure can enhance the plastic deformation ability of the iron-based high-entropy alloy. Therefore, the multi-directional annealed twin structure, the nanocrystalline structure, and the ultrafine grain structure can play a synergistic effect, so that the iron-based high-entropy alloy can simultaneously take into account excellent yield strength and plasticity.

[0007] According to any of the aforementioned embodiments of the first aspect of the present application, the multidirectional annealed twinned structure has grains smaller than or equal to 1 μm.

[0008] According to any of the aforementioned embodiments of the first aspect of the present application, the nanocrystalline structure has grains less than or equal to 50 nm.

[0009] According to any of the aforementioned embodiments of the first aspect of the present application, the ultrafine-grained microstructure has grains less than or equal to 700 nm.

[0010] According to any of the aforementioned embodiments of the first aspect of the present application, the nanocrystalline structure has a plate-like shape.

[0011] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the multidirectional annealing twin structure in the microstructure is less than or equal to 25%.

[0012] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the multidirectional annealing twin structure in the microstructure is less than or equal to 20%.

[0013] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the multidirectional annealing twin structure in the microstructure is less than or equal to 15%.

[0014] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the nanocrystalline structure in the microstructure is less than or equal to 45%.

[0015] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the nanocrystalline structure in the microstructure is less than or equal to 40%.

[0016] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the nanocrystalline structure in the microstructure is less than or equal to 20%.

[0017] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the ultrafine grain structure in the microstructure is less than or equal to 55%.

[0018] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the ultrafine grain structure in the microstructure is less than or equal to 45%.

[0019] According to any of the aforementioned embodiments of the first aspect of the present application, the volume fraction of the ultrafine grain structure in the microstructure is less than or equal to 40%.

[0020] In a second aspect, an embodiment of the present application provides a method for manufacturing an iron-based high entropy alloy as described in the first aspect of the present application, comprising:

[0021] Cold rolling process, in which the iron-based forging alloy is subjected to multiple cold rolling processes at liquid nitrogen temperature;

[0022] In the annealing process, the cold-rolled iron-based forging alloy is annealed to obtain an iron-based high-entropy alloy.

[0023] According to any of the aforementioned embodiments of the second aspect of the present application, in the cold rolling process, the iron-based forging alloy is rolled with a reduction in thickness of 90% to 95%.

[0024] According to any of the aforementioned embodiments of the second aspect of the present application, the rolling reduction in each pass is 2% to 6%.

[0025] According to any of the aforementioned embodiments of the second aspect of the present application, in the cold rolling process, the iron-based wrought alloy has a face-centered cubic crystal structure.

[0026] According to any of the aforementioned embodiments of the second aspect of the present application, in the annealing process, the annealing temperature is 600° C. to 650° C., and the annealing time is 5 min to 30 min.

[0027] The above description is only an overview of the technical solution of this specification. In order to more clearly understand the technical means of this specification, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of this specification more obvious and easy to understand, the specific implementation methods of this specification are listed below.

[0028] Figures in the specification

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1 An image of the microstructure of the iron-based high entropy alloy provided in Example 1 of the present application is shown, wherein: Figure 1 a is a bright field image, b is a dark field image;

[0031] Figure 2 An image of the microstructure of the iron-based high entropy alloy provided in Example 2 of the present application is shown, wherein: Figure 2 a is a bright field image, b is a dark field image;

[0032] Figure 3 An image of the microstructure of the iron-based high entropy alloy provided in Example 3 of the present application is shown, wherein: Figure 3 a is a bright field image, b is a dark field image;

[0033] Figure 4 An image of the microstructure of the iron-based high entropy alloy provided in Comparative Example 1 is shown, wherein: Figure 4 a is a bright field image, b is a dark field image;

[0034] Figure 5 An image of the microstructure of the iron-based high entropy alloy provided in Comparative Example 2 is shown, wherein: Figure 5 In the figure, a is the bright field image, and b is the dark field image. DETAILED DESCRIPTION

[0035] As used herein, "ranges" are defined in terms of lower and upper limits. A given range is defined by selecting a lower limit and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges defined in this manner may be inclusive or exclusive and may be combined arbitrarily, i.e., any lower limit may be combined with any upper limit to form a range.

[0036] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of the present application.

[0037] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form new technical solutions, and such technical solutions should be deemed to be included in the disclosure of this application.

[0038] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0039] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0040] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0041] Unless otherwise specified, the terms used in this application have the common meanings that are commonly understood by those skilled in the art.

[0042] Unless otherwise stated, the numerical values ​​of the parameters mentioned in this application can be measured using various test methods commonly used in the art, for example, they can be measured according to the test methods given in the embodiments of this application.

[0043] Currently, coarse-grained iron-based high-entropy alloys, such as CoCrFeNi high-entropy alloys, have good plasticity at room temperature, but their yield strength is low (no more than 300 MPa), which severely limits their application areas. In related art, the yield strength of iron-based high-entropy alloys is enhanced by adding a small amount of aluminum to form intermetallic compounds. Although the yield strength of iron-based high-entropy alloys is improved, their plasticity is significantly reduced, making it impossible for iron-based high-entropy alloys to simultaneously achieve excellent yield strength and plasticity.

[0044] In view of this, an embodiment of the present application provides an iron-based high-entropy alloy and a preparation method thereof, wherein the iron-based high-entropy alloy can simultaneously have excellent yield strength and plasticity.

[0045] In a first aspect, an embodiment of the present application provides an iron-based high-entropy alloy, the microstructure of which consists of a multi-directional annealed twin structure, a nanocrystalline structure, and an ultrafine grain structure.

[0046] In the iron-based high entropy alloy provided in the embodiment of the present application, the microstructure of the iron-based high entropy alloy consists of a multi-directional annealed twin structure, a nanocrystalline structure and an ultrafine grain structure, wherein the multi-directional annealed twin structure generally refers to annealed twins in multiple directions inside the grains. Taking the face-centered cubic crystal as an example: it has four twin planes: (111), and Annealing twins can be formed in four directions within the same grain. Compared to the large number of dislocations in the twin planes of deformation twins, the twin planes in annealing twins have a small number of dislocations (or basically no dislocations). Therefore, the twin planes in the multi-directional annealing twin structure interact with the dislocations to produce a strengthening effect, thereby enhancing the yield strength of the iron-based high entropy alloy. Nanocrystalline structure generally refers to a grain structure with a grain size of more than ten nanometers to tens of nanometers, which usually has a higher yield strength characteristic. Ultrafine grain structure generally refers to a grain structure with a grain size distribution from hundreds of nanometers to several microns, and ultrafine grains generally have better plastic deformation ability. Therefore, the multi-directional annealing twin structure, nanocrystalline structure and ultrafine grain structure in the iron-based high entropy alloy can play a synergistic effect, so that the iron-based high entropy alloy can simultaneously take into account excellent yield strength and plasticity.

[0047] In the embodiments of the present application, the multidirectional annealed twin structure, nanocrystalline structure and ultrafine grain structure can be observed and characterized using instruments and methods well known in the art, such as a transmission electron microscope (TEM).

[0048] In some embodiments of the present application, the multi-directional annealed twin structure has grains less than or equal to 1 μm. The grain size distribution of the multi-directional annealed twin structure is within the above range, which can make the high entropy alloy have a higher yield strength.

[0049] In some examples, the grain size of the multi-directional annealed twin structure may be, but is not limited to, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, or a range consisting of any two of the foregoing values. For example, the grain size of the multi-directional annealed twin structure may be, but is not limited to, 0.1 μm-1 μm, 0.2 μm-0.8 μm, 0.3 μm-0.7 μm, or 0.4 μm-0.6 μm.

[0050] In some embodiments of the present application, the nanocrystalline structure has grains less than or equal to 50 nm. When the grain size distribution of the nanocrystalline structure is within the above range, the yield strength of the high entropy alloy can be further improved. In some examples, the particle size of the grains in the nanocrystalline structure can be, but is not limited to, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm, 31 nm, 32 nm, 33 nm, 34 nm, 35 nm, 36 nm, 37 nm, 38 nm, 39 nm, 40 nm, 41 nm, 42 nm, 43 nm, 44 nm, 45 nm, 46 nm, 47 nm, 48 nm, 49 nm, 50 nm, or a range of any two of the above values. For example, the size range of the grains in the nanocrystalline structure may be, but is not limited to, 1 nm-50 nm, 4 nm-45 nm, 8 nm-40 nm, 10 nm-35 nm, and 15 nm-30 nm.

[0051] In some embodiments of the present application, the ultrafine-grained microstructure has grains less than or equal to 700 nm. When the grain size distribution of the ultrafine-grained microstructure is within the above range, the plastic deformation ability of the high-entropy alloy can be further improved.

[0052] In some examples, the size of the grains in the ultrafine grained structure may be, but is not limited to, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm, 150 nm, 155 nm, or the like. The particle size of the ultrafine grains may be in the range of 10 nm to 700 nm, 30 nm to 600 nm, 40 nm to 550 nm, 60 nm to 500 nm, 80 nm to 450 nm, 90 nm to 400 nm, or a range consisting of any two of the above values.

[0053] In some embodiments of the present application, the nanocrystalline structure has a plate-like shape.

[0054] In some embodiments of the present application, the volume fraction of the multidirectional annealing twin structure in the microstructure is less than or equal to 25%.

[0055] In some embodiments of the present application, the volume fraction of the multidirectional annealing twin structure in the microstructure is less than or equal to 20%.

[0056] In some embodiments of the present application, the volume fraction of the multidirectional annealing twin structure in the microstructure is less than or equal to 15%.

[0057] In some examples, the volume fraction of the multi-directional annealed twin structure in the microstructure can be, but is not limited to, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or a range consisting of any two of the above values. For example, the volume fraction of the multi-directional annealed twin structure in the microstructure can be, but is not limited to, 10%-28%, 12%-26%, 14%-24%, 15%-22%, or 16%-20%.

[0058] In some embodiments of the present application, the volume fraction of the nanocrystalline structure in the microstructure is less than or equal to 45%.

[0059] In some embodiments of the present application, the volume fraction of the nanocrystalline structure in the microstructure is less than or equal to 40%.

[0060] In some embodiments of the present application, the volume fraction of the nanocrystalline structure in the microstructure is less than or equal to 20%.

[0061] In some examples, the volume fraction of the nanocrystalline structure in the microstructure can be, but is not limited to, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, or a range consisting of any two of the above values. For example, the volume fraction of the nanocrystalline structure in the microstructure can be, but is not limited to, 20%-45%, 21%-42%, 23%-40%, 25%-38%, or 27%-36%.

[0062] In some embodiments of the present application, the volume fraction of the ultrafine grain structure in the microstructure is less than or equal to 55%.

[0063] In some embodiments of the present application, the volume fraction of the ultrafine grain structure in the microstructure is less than or equal to 45%.

[0064] In some embodiments of the present application, the volume fraction of the ultrafine grain structure in the microstructure is less than or equal to 40%.

[0065] In some examples, the volume fraction of the ultrafine grained structure in the microstructure may be, but is not limited to, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, or a range consisting of any two of the above values. For example, the volume fraction of the ultrafine grained structure in the microstructure may be, but is not limited to, 20%-55%, 22%-52%, 25%-50%, 30%-45%, or 35%-40%.

[0066] In a second aspect, an embodiment of the present application provides a method for manufacturing an iron-based high entropy alloy as described in the first aspect of the present application, comprising:

[0067] S100, a cold rolling process, performing multiple cold rolling processes on the iron-based forging alloy at liquid nitrogen temperature;

[0068] S200, annealing process, annealing the cold-rolled iron-based forging alloy to obtain an iron-based high-entropy alloy.

[0069] In some embodiments of the present application, in the cold rolling process, the iron-based wrought alloy is rolled with a reduction in thickness of 90% to 95%.

[0070] In some embodiments of the present application, the rolling reduction in each pass is 2% to 6%.

[0071] In this application, the rolling reduction per pass is generally relative to the thickness of the original billet.

[0072] In some embodiments of the present application, during the cold rolling process, the iron-based wrought alloy has a face-centered cubic crystal structure.

[0073] In some embodiments of the present application, in the annealing process, the annealing temperature is 600° C. to 650° C., and the annealing time is 5 min to 30 min.

[0074] Example

[0075] The embodiments described below are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents a specific embodiment of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without departing from the principles of the present application and without making creative work are within the scope of protection of the present application.

[0076] Example 1

[0077] This embodiment provides a method for manufacturing an iron-based high-entropy alloy. In this embodiment, a wrought CoCrFeNi high-entropy alloy having a face-centered cubic structure is used to prepare a block sample with a thickness of 10 mm, a length of 32 mm, and a width of 32 mm by electric spark cutting. The manufacturing method includes the following steps:

[0078] In the cold rolling process, the block sample is subjected to multiple cold rolling deformations using a rolling mill at liquid nitrogen temperature, with each rolling reduction of 0.2 mm, and finally a cold-rolled thin plate with a thickness of 0.9 mm is obtained. The rolling reduction of the sample is 91%.

[0079] In the annealing process, the cold-rolled thin plate is annealed in an air atmosphere at a temperature of 600°C for 15 minutes. After the power is turned off, the cold-rolled thin plate is cooled to room temperature in the furnace to obtain a CoCrFeNi high-entropy alloy including a multi-directional annealed twin structure, a nanocrystalline structure and an ultrafine grain structure.

[0080] The microstructure of the CoCrFeNi high entropy alloy prepared in this embodiment is as follows: Figure 1 As shown, Figure 1 (a) is the bright field image, (b) is the dark field image. Figure 1 Three types of microstructures can be seen in the sample, namely, multidirectional annealing twin structure (content ~16%), ultrafine grain structure (content ~43%) and lamellar nanocrystalline structure (content ~41%).

[0081] Example 2

[0082] This embodiment provides a method for manufacturing an iron-based high-entropy alloy. In this embodiment, a wrought CoCrFeNi high-entropy alloy having a face-centered cubic structure is used to prepare a block sample with a thickness of 10 mm, a length of 32 mm, and a width of 32 mm by electric spark cutting. The manufacturing method includes the following steps:

[0083] In the cold rolling process, the forged CoCrFeNi high entropy alloy is subjected to multiple cold rolling deformations using a rolling mill at liquid nitrogen temperature, with each rolling reduction of 0.2 mm, to obtain a cold-rolled sheet with a thickness of 0.9 mm. The rolling reduction of the sample is 91%;

[0084] In the annealing process, the cold-rolled thin plate is annealed in an air atmosphere at a temperature of 600°C for 30 minutes. After the power is turned off, the cold-rolled thin plate is cooled to room temperature in the furnace to obtain a CoCrFeNi high-entropy alloy including a multi-directional annealed twin structure, a nanocrystalline structure and an ultrafine grain structure.

[0085] The microstructure of the CoCrFeNi high entropy alloy prepared in this embodiment is as follows: Figure 2 As shown, Figure 2 (a) is the bright field image, (b) is the dark field image. Figure 2 Three types of microstructures can be seen in the sample, namely, multidirectional annealed twin structure (content ~24%), ultrafine grain structure (content ~55%) and lamellar nanocrystalline structure (content ~21%).

[0086] Example 3

[0087] This embodiment provides a method for manufacturing an iron-based high-entropy alloy. In this embodiment, a wrought CoCrFeNi high-entropy alloy having a face-centered cubic structure is used to prepare a block sample with a thickness of 10 mm, a length of 32 mm, and a width of 32 mm by electric spark cutting. The manufacturing method includes the following steps:

[0088] In the cold rolling process, the block sample is subjected to multiple cold rolling deformations using a rolling mill at liquid nitrogen temperature, with each rolling reduction of 0.2 mm, and finally a cold-rolled thin plate with a thickness of 0.9 mm is obtained. The rolling reduction of the sample is 91%.

[0089] In the annealing process, the cold-rolled thin plate is annealed in an air atmosphere at a temperature of 650°C for 5 minutes. After the power is turned off, it is cooled to room temperature in the furnace. After the power is turned off, it is cooled to room temperature in the furnace to obtain a CoCrFeNi high-entropy alloy including a multi-directional annealed twin structure, a nanocrystalline structure and an ultrafine grain structure.

[0090] The microstructure of the CoCrFeNi high entropy alloy prepared in this embodiment is as follows: Figure 3 As shown, Figure 3 (a) is a bright field image, and (b) is a dark field image. Three types of microstructures can be seen in the figure, namely, multidirectional annealing twin structure (content ~22%), ultrafine grain structure (content ~41%), and lamellar nanocrystalline structure (content ~37%).

[0091] Comparative Example 1

[0092] The difference from Example 1 is that the annealing temperature is 650° C. and the time is 10 minutes.

[0093] The microstructure of the CoCrFeNi high entropy alloy prepared in this comparative example is as follows: Figure 4 As shown, Figure 4 (a) is the bright field image, (b) is the dark field image. Figure 4 Its microstructure consists of only annealed twin structure and ultrafine grain structure, lacks high-strength nanocrystalline structure, and does not have the characteristics of heterogeneous metals.

[0094] Comparative Example 2

[0095] The difference from Example 1 is that the annealing temperature is 550° C. and the time is 30 minutes.

[0096] The microstructure of the CoCrFeNi high entropy alloy prepared in this comparative example is as follows: Figure 5 As shown, Figure 5 (a) is a bright field image, and (4) is a dark field image. From the figure, we can see that its structure is still a complete nanocrystalline structure, without ultrafine grain structure and multidirectional annealing twin structure.

[0097] Test section

[0098] (1) Microstructure test of CoCrFeNi high entropy alloy

[0099] The microstructure of the CoCrFeNi high entropy alloy was detected using a transmission electron microscope (TEM) under bright field and dark field scenes to obtain TEM bright field images and TEM dark field images, such as Figure 1-5 As shown, through Figure 1-3 It can be seen that the microstructures of the CoCrFeNi high entropy alloys in Examples 1-3 include a multidirectional annealed twin structure, a nanocrystalline structure, and an ultrafine grain structure. Figure 4 and Figure 5 It can be seen that the microstructure of the CoCrFeNi high-entropy alloy in Comparative Example 1 consists only of annealed twin structure and ultrafine grain structure, while the microstructure of the CoCrFeNi high-entropy alloy in Comparative Example 2 is a complete nanocrystalline structure without ultrafine grain structure and multidirectional annealed twin structure.

[0100] (2) Mechanical properties test:

[0101] Room temperature mechanical tensile tests were carried out on CoCrFeNi high entropy alloy using a universal testing machine to obtain the yield strength and plasticity of the material.

[0102] Table 1 lists the mechanical properties of the microstructure of the CoCrFeNi high entropy alloy in Examples 1-3 and Comparative Examples 1-2, namely, yield strength and plasticity.

[0103]

[0104]

[0105] According to Table 1, by comparing the experimental data of Examples 1-3 and Comparative Examples 1-2, it can be seen that the microstructure of the high-entropy alloy provided in the embodiments of the present application consists of a multi-directional annealed twin structure, a nanocrystalline structure, and an ultrafine grain structure, so that the iron-based high-entropy alloy can simultaneously have excellent yield strength and plasticity.

[0106] Finally, it should be noted that the above experimental examples are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned experimental examples, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned experimental examples, or replace some or all of the technical features therein with equivalents. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the experimental examples of the present application.

Claims

1. An iron-based high entropy alloy, characterized in that The microstructure of the iron-based high entropy alloy consists of a multi-directional annealed twin structure, a nanocrystalline structure and an ultrafine grain structure; The multidirectional annealed twinned microstructure has grains less than or equal to 1 μm; The nanocrystalline structure has grains less than or equal to 50 nm; The ultrafine grain structure has grains less than or equal to 700 nm; The iron-based high entropy alloy is a CoCrFeNi high entropy alloy; The volume fraction of the multidirectional annealed twin structure in the microstructure is between greater than or equal to 10% and less than or equal to 25%; The volume fraction of the nanocrystalline structure in the microstructure is between greater than or equal to 20% and less than or equal to 45%; The volume fraction of the ultrafine grain structure in the microstructure is between greater than or equal to 20% and less than or equal to 55%.

2. The iron-based high entropy alloy according to claim 1, characterized in that The nanocrystalline structure has a plate-like shape.

3. A method for producing an iron-based high entropy alloy according to any one of claims 1 to 2, characterized in that: include: Cold rolling process, in which the iron-based forging alloy is subjected to multiple cold rolling processes at liquid nitrogen temperature; The annealing step is to anneal the cold-rolled iron-based forging alloy to obtain an iron-based high-entropy alloy.

4. The manufacturing method according to claim 3, characterized in that In the cold rolling process, the iron-based forging alloy is rolled with a reduction in thickness of 90% to 95%; The rolling reduction per pass is 2% to 6%.

5. The manufacturing method according to claim 4, characterized in that In the cold rolling process, the iron-based wrought alloy has a face-centered cubic crystal structure.

6. The manufacturing method according to claim 3, characterized in that In the annealing process, the annealing temperature is 600° C. to 650° C., and the annealing time is 5 min to 30 min.

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