Eutectic high-entropy alloy and preparation method thereof
Equiaxial nanocrystalline eutectic high-entropy alloys were prepared by friction stirring, cold rolling, and short-time annealing, which solved the problems of strength and thermal stability of eutectic high-entropy alloys and achieved high strength and excellent thermal stability.
Patent Information
- Application Number
- CN202511388747.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-26
- Publication Date
- 2025-12-02
AI Technical Summary
Eutectic high-entropy alloys have coarse as-cast microstructures and low yield strength, making them difficult to apply under extreme conditions. Furthermore, nanocrystalline preparation is costly and has poor thermal stability.
Equiaxial nanocrystalline eutectic high-entropy alloys were prepared by friction stirring, cold rolling, and short-time annealing. Combining the slow diffusion effect and low-energy interface characteristics of high-entropy alloys, a distortion-free nanocrystalline structure was formed.
The tensile strength at room temperature exceeds 1800 MPa, and the grain growth temperature exceeds the melting point by 0.6 times, which significantly improves the strength and thermal stability of the material.
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Figure CN121046752A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-entropy alloy technology, specifically relating to a eutectic high-entropy alloy and its preparation method. Background Technology
[0002] High-entropy alloys, as multi-component alloys, often exhibit a series of excellent properties. However, their poor casting performance and severe compositional segregation significantly hinder their engineering applications. In contrast, eutectic high-entropy alloys possess the good casting fluidity and formability of eutectic alloys, while also exhibiting the unique structural characteristics and excellent comprehensive properties of high-entropy alloys, making them promising for applications in aerospace, weaponry, and offshore platforms.
[0003] However, the low yield strength of as-cast eutectic high-entropy alloys limits their applications. While fine-grained or ultrafine-grained structures can be prepared through plastic deformation processes to significantly improve their mechanical properties, the preparation of nanocrystalline eutectic high-entropy alloys for more extreme conditions still faces significant challenges. Although 3D printing technology can achieve the preparation of nanomaterials, the production cost of high-purity nanomaterial powders is high, and the rapid cooling rate of this technology easily leads to nanoparticle agglomeration, resulting in reduced strength. Furthermore, nanoparticle agglomeration can easily lead to abnormal local growth and poor thermal stability. Summary of the Invention
[0004] Therefore, the present invention provides a eutectic high-entropy alloy and its preparation method, the main purpose of which is to provide a method for preparing a eutectic high-entropy alloy with high strength at room temperature and excellent thermal stability at high temperature.
[0005] To address the above problems, this invention provides a method for preparing a eutectic high-entropy alloy, comprising the following steps:
[0006] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stir processing to obtain an equiaxed ultrafine grain structure and a eutectic high-entropy alloy after friction stir processing.
[0007] Step 2): The eutectic high-entropy alloy after friction stir processing is subjected to cold rolling to obtain a cold-rolled eutectic high-entropy alloy; the cold-rolled eutectic high-entropy alloy has a banded nanocrystalline structure;
[0008] Step 3): The cold-rolled eutectic high-entropy alloy is heat-treated to obtain a eutectic high-entropy alloy with an equiaxed nanocrystalline structure.
[0009] Furthermore, the size of the equiaxed ultrafine grain structure is 0.15-1 μm; the phase structure of the equiaxed ultrafine grain structure is a two-phase or multi-phase structure.
[0010] Furthermore, in step 2), the size of the strip-shaped nanocrystal structure is 10-100 nm.
[0011] Furthermore, in step 3), the size of the equiaxed nanocrystal structure is 10-100 nm.
[0012] Furthermore, in step 1), the parameters of the friction stir processing are as follows: rotation speed is 150-400 rpm, travel speed is 25-100 mm / min, and pressure is 0.2-1 mm.
[0013] Furthermore, in step 2), the deformation amount of the cold rolling process is 20%-80%.
[0014] Furthermore, in step 3), the heat treatment is annealing; the annealing temperature is 500-1000℃, and the annealing time is 10min-180min.
[0015] On the other hand, the present invention provides a eutectic high-entropy alloy, which is obtained by any of the preparation methods described above, and has a tensile strength exceeding 1800 MPa at room temperature, and its grain growth temperature exceeding 0.6 times the melting point of the eutectic high-entropy alloy.
[0016] The eutectic high-entropy alloy and its preparation method provided by this invention have the following beneficial effects:
[0017] 1. On one hand, the present invention provides a method for preparing a eutectic high-entropy alloy, comprising the following steps: subjecting a eutectic high-entropy alloy matrix to friction stirring to obtain an equiaxed ultrafine-grained structure; wherein the equiaxed structure has a biphasic or multiphasic structure; subjecting the equiaxed ultrafine-grained eutectic high-entropy alloy to cold rolling to obtain a eutectic high-entropy alloy with a nanocrystalline structure; and subjecting the nanocrystalline eutectic high-entropy alloy to short-time heat treatment to obtain an equiaxed nanocrystalline eutectic high-entropy alloy. Based on the above method, during friction stirring, the coarse structure in the eutectic high-entropy alloy matrix is refined under the action of external force, and significant recrystallization occurs under thermal action, forming fine new grains with undistorted ultrafine grain size at the grain boundaries. These new grains are composed of a biphasic or multiphasic structure. Further cold rolling further refines the equiaxed ultrafine-grained eutectic high-entropy alloy, forming a lamellar nanocrystalline structure with numerous dislocations and substructures. Based on this, a short-time annealing process is used to eliminate intragranular dislocations and substructures, resulting in a fine, distortion-free equiaxed nanocrystalline structure. The nanoscale grains and dual-phase or multiphase structure effectively hinder dislocation movement, significantly improving the strength of the eutectic high-entropy alloy. Furthermore, the distortion-free equiaxed nanocrystalline structure and low-energy coherent interfaces reduce the driving force for grain coarsening, thus achieving excellent thermal stability.
[0018] 2. Furthermore, friction stir processing is employed, combined with the unique slow diffusion effect and low-energy interface characteristics of eutectic high-entropy alloys, to achieve the preparation of equiaxed ultrafine-grained eutectic high-entropy alloys. This structure provides a prerequisite for the cold rolling process to prepare nanocrystals. Cold rolling, as a traditional plastic deformation process, has limited deformation capacity and cannot provide sufficiently large and uniform plastic strain to refine grains to the nanoscale, making it difficult to achieve one-step preparation from the as-cast state to nanocrystals. Based on the equiaxed ultrafine-grained structure with a high proportion of high-angle grain boundaries prepared by friction stir processing, cold rolling is then performed. During rolling, a large number of dislocations are generated within the ultrafine equiaxed grains, forming dislocation walls and finer cellular structures, as well as nanoscale subgrains. Further short-time annealing eliminates dislocations and crystal defects, forming a distortion-free equiaxed nanocrystal structure at the grain boundaries. Furthermore, the coherent structure of eutectic high-entropy alloys possesses a low-energy coherent interface. Combined with the unique slow diffusion effect of high-entropy alloys, this results in a lower grain boundary migration driving force during subsequent annealing, making it easier to obtain equiaxed nanocrystalline structures. Therefore, friction stir processing + cold rolling + short-time annealing are external factors, while the unique slow diffusion and low-energy interface of eutectic high-entropy alloys are internal factors; both are indispensable. This is the main reason why eutectic high-entropy alloys can be used to prepare equiaxed nanostructures.
[0019] On the other hand, the present invention provides a eutectic high-entropy alloy with a tensile strength exceeding 1800 MPa at room temperature and a grain growth temperature exceeding 0.6 times the melting point of the eutectic high-entropy alloy. Attached Figure Description
[0020] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.
[0021] Figure 1 This is a flowchart of the preparation process for a eutectic high-entropy alloy;
[0022] Figure 2 This is a metallographic diagram of a eutectic high-entropy alloy matrix;
[0023] Figure 3 This is a morphological diagram of a eutectic high-entropy alloy processed by friction stir. Detailed Implementation
[0024] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the specific embodiments, structures, features, and effects according to the present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.
[0025] This invention describes a friction stir process for as-cast eutectic high-entropy alloys. The intense plastic deformation induced by this process yields a uniform equiaxed ultrafine-grained structure without agglomeration. Further cold rolling and heat treatment processes produce a uniform equiaxed nanocrystalline structure, fundamentally eliminating particle agglomeration and resulting in a material with high strength and excellent thermal stability. The specific solution is as follows:
[0026] This invention provides a method for preparing a eutectic high-entropy alloy, comprising the following steps:
[0027] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stir processing to obtain an equiaxed ultrafine grain structure and a eutectic high-entropy alloy after friction stir processing.
[0028] The parameters for friction stir processing are as follows: rotation speed is 150-400 rpm, travel speed is 25-100 mm / min, and pressure is 0.2-1 mm; the size of the equiaxed ultrafine grain structure is 0.15-1 μm; the phase structure of the equiaxed ultrafine grain structure is a two-phase or multi-phase structure.
[0029] Step 2): The eutectic high-entropy alloy after friction stir processing is subjected to cold rolling to obtain a cold-rolled eutectic high-entropy alloy; the cold-rolled eutectic high-entropy alloy has a banded nanocrystalline structure;
[0030] The deformation amount of cold rolling is 20%-80%; the size of the strip-shaped nanocrystalline structure is 10-100nm.
[0031] Step 3): Heat-treat the cold-rolled eutectic high-entropy alloy to obtain a eutectic high-entropy alloy with an equiaxed nanocrystalline structure.
[0032] The heat treatment is annealing; the annealing temperature is 500-1000℃, and the annealing time is 10min-180min; the size of the equiaxed nanocrystalline structure is 10-100nm.
[0033] On the other hand, the present invention provides a eutectic high-entropy alloy, which is obtained by any of the above preparation methods, and has a tensile strength exceeding 1800 MPa at room temperature, and its grain growth temperature exceeds 0.6 times the melting point of the eutectic high-entropy alloy.
[0034] It should be noted that the above-mentioned eutectic high-entropy alloy matrix is a cast eutectic high-entropy alloy, and its microstructure is as follows: Figure 2 As shown, it can be seen that the structure is a coarse two-phase lamellar structure. Existing technologies that directly use rolling to prepare lamellar eutectic high-entropy alloys cannot produce nanocrystalline structures; their grain size is only fine / ultrafine crystalline lamellar structures.
[0035] Based on the above-described method of the present invention, during friction stir processing, the coarse microstructure in the eutectic high-entropy alloy matrix is refined under thermo-mechanical coupling, and significant recrystallization occurs under thermal action, forming distortion-free, ultrafine-sized new grains at the grain boundaries. These new grains consist of a two-phase or multi-phase structure; that is, friction stir processing enables the eutectic high-entropy alloy matrix to obtain a multiphase ultrafine-grained equiaxed microstructure. On this basis, the ultrafine-grained equiaxed eutectic high-entropy alloy is cold-rolled, further introducing high-density dislocations and numerous subgrain boundaries into the ultrafine-grained equiaxed microstructure, thus refining the ultrafine-grained microstructure into a nanocrystalline microstructure. Further short-time annealing eliminates dislocations and crystal defects, forming distortion-free equiaxed nanoscale new grains at the grain boundaries. Among them, the two-phase coherent structure of eutectic alloys has a low-energy coherent interface, which has a lower grain boundary migration driving force during subsequent annealing. Furthermore, the two-phase structure restricts each other. Combined with the unique slow diffusion effect of high-entropy alloys, the grain size is not easy to grow during annealing, and it is easier to obtain equiaxed nanocrystalline structures.
[0036] Through cold rolling, the material undergoes plastic deformation, introducing high-density crystal defects (numerous dislocations and substructures) into the equiaxed ultrafine-grained structure. Under work hardening, this equiaxed ultrafine-grained structure transforms into a nanoscale rolled strip structure. During rolling, the combination of soft and hard phases in the eutectic high-entropy alloy's two-phase or multiphase structure allows the soft phase to better coordinate deformation and dissipate energy through phase transformation, facilitating the deformation process. The coherent interface between the two phases has lower interfacial energy during subsequent heat treatment, resulting in a more stable two-phase or multiphase structure. This prevents abnormal grain growth during heat treatment, making it more conducive to obtaining nanoscale grains. The heat treatment process eliminates internal defects—specifically, through dislocation recovery and re-crystallization—transforming the rolled strip structure into an equiaxed nanocrystalline structure.
[0037] The present invention will be further described below with reference to specific embodiments and comparative examples.
[0038] Example 1
[0039] This embodiment provides a method for preparing a eutectic high-entropy alloy, including the following steps:
[0040] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0041] The eutectic high-entropy alloy matrix is a 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy with a microstructure as shown in the figure. Figure 2 As shown; the parameters for friction stir machining are as follows: rotational speed 250 rpm, feed rate 50 mm / min, and compressive force 0.9 mm; the equiaxed structure has ultrafine grains; the phase structure of the equiaxed structure includes FCC phase and B2 phase, and the grain sizes of the two phases are as follows. Figure 3 As shown, it is 180nm.
[0042] Step 2): The equiaxed ultrafine-grained eutectic high-entropy alloy is cold-rolled to obtain a eutectic high-entropy alloy with a nanocrystalline structure;
[0043] The deformation amount of cold rolling is 40%, and the grain size after deformation is 80nm.
[0044] Step 3): Perform short-time heat treatment on the eutectic high-entropy alloy with nanocrystalline structure to obtain an equiaxed nanocrystalline eutectic high-entropy alloy;
[0045] The heat treatment temperature was 700℃, the annealing time was 60nm, and the equiaxed nanocrystal size after annealing was 95nm.
[0046] The eutectic high-entropy alloy obtained in this embodiment has a tensile strength of 2 GPa, and the initial grain growth temperature is as high as 0.65 times the melting point. This demonstrates that the nanocrystalline equiaxed AlCoCrFeNi2.1 alloy successfully achieves high strength and excellent thermal stability. This indicates that nanocrystalline equiaxed crystals and the two-phase structure can effectively hinder dislocation movement, coordinate deformation between the two phases, and improve material strength. Furthermore, the low-energy interface of the two-phase nanocrystalline equiaxed structure limits and reduces the driving force for grain growth, effectively suppressing grain growth.
[0047] Example 2
[0048] This embodiment provides a method for preparing a eutectic high-entropy alloy, including the following steps:
[0049] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0050] The eutectic high-entropy alloy matrix is a 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy. The friction stir processing parameters are as follows: rotation speed is 150rpm, travel speed is 20mm / min, and pressure is 1mm. The equiaxed structure has ultrafine grains. The phase structure of the equiaxed structure includes FCC phase and B2 phase, and the grain size of the two phases is 150nm.
[0051] Step 2): The equiaxed ultrafine-grained eutectic high-entropy alloy is cold-rolled to obtain a eutectic high-entropy alloy with a nanocrystalline structure;
[0052] The deformation amount of cold rolling is 20%, and the grain size after deformation is 64nm.
[0053] Step 3): Perform short-time heat treatment on the eutectic high-entropy alloy with nanocrystalline structure to obtain an equiaxed nanocrystalline eutectic high-entropy alloy;
[0054] The heat treatment temperature was 900℃, the annealing time was 10nm, and the equiaxed nanocrystal size after annealing was 91nm.
[0055] The eutectic high-entropy alloy obtained in this embodiment has a tensile strength of 2.1 GPa and an initial grain growth temperature that is 0.63 times the melting point. It can be seen that the AlCoCrFeNi2.1 alloy with nanocrystalline equiaxed structure successfully achieves high strength and excellent thermal stability.
[0056] Example 3
[0057] This embodiment provides a method for preparing a eutectic high-entropy alloy, including the following steps:
[0058] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0059] The eutectic high-entropy alloy matrix is made of 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy. The friction stir processing parameters are as follows: rotation speed is 400rpm, travel speed is 100mm / min, and pressure is 0.2mm. The equiaxed structure has ultrafine grains. The phase structure of the equiaxed structure includes FCC phase and B2 phase, and the grain size of the two phases is 450nm.
[0060] Step 2): The equiaxed ultrafine-grained eutectic high-entropy alloy is cold-rolled to obtain a eutectic high-entropy alloy with a nanocrystalline structure;
[0061] The deformation amount of cold rolling is 80%, and the grain size after deformation is 50nm.
[0062] Step 3): Perform short-time heat treatment on the eutectic high-entropy alloy with nanocrystalline structure to obtain an equiaxed nanocrystalline eutectic high-entropy alloy;
[0063] The heat treatment temperature was 500℃, the annealing time was 180nm, and the equiaxed nanocrystal size after annealing was 75nm.
[0064] The eutectic high-entropy alloy obtained in this embodiment has a tensile strength of 2.5 GPa and an initial grain growth temperature that is 0.60 times the melting point. It can be seen that the AlCoCrFeNi2.1 alloy with nanocrystalline equiaxed structure successfully achieves high strength and excellent thermal stability.
[0065] Comparative Example 1
[0066] This comparative example provides a method for preparing a eutectic high-entropy alloy, comprising the following steps:
[0067] Step 1): The eutectic high-entropy alloy matrix (2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy) is directly cold-rolled to obtain a two-phase lamellar AlCoCrFeNi2.1 alloy with a lamellar thickness of 500nm.
[0068] This comparative example shows that direct cold rolling of the as-cast AlCoCrFeNi2.1 eutectic high-entropy alloy cannot produce an equiaxed microstructure with nanocrystalline dimensions.
[0069] Comparative Example 2
[0070] This comparative example provides a method for preparing a eutectic high-entropy alloy, comprising the following steps:
[0071] The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0072] The eutectic high-entropy alloy matrix is made of 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy; the friction stir processing parameters are as follows: rotation speed is 100rpm, travel speed is 10mm / min, and pressure is 1.5mm.
[0073] The processing zone in this comparative example exhibits significant tunnel defects, making subsequent cold rolling and heat treatment impossible. This is because the heat input of the friction stir processing is too low, making it impossible to obtain a defect-free processing zone.
[0074] Comparative Example 3
[0075] This comparative example provides a method for preparing a eutectic high-entropy alloy, comprising the following steps:
[0076] The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0077] The eutectic high-entropy alloy matrix is made of 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy; the parameters of friction stir processing are as follows: rotation speed is 500rpm, travel speed is 150mm / min, and pressure is 0.1mm.
[0078] The processed area in this comparative example was not clearly formed and could not be subjected to superplastic stretching. This is because the heat input of the friction stir processing was too low, making it impossible to obtain a defect-free processed area.
[0079] Comparative Example 4
[0080] This comparative example provides a method for preparing a eutectic high-entropy alloy, comprising the following steps:
[0081] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0082] The eutectic high-entropy alloy matrix is made of 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy. The friction stir processing parameters are as follows: rotation speed is 250rpm, travel speed is 50mm / min, and pressure is 0.9mm. The equiaxed structure has ultrafine grains. The phase structure of the equiaxed structure includes FCC phase and B2 phase, and the grain size of the two phases is 180nm.
[0083] Step 2): The equiaxed ultrafine-grained eutectic high-entropy alloy is cold-rolled to obtain a eutectic high-entropy alloy with a nanocrystalline structure;
[0084] The deformation amount of cold rolling is 10%, and the grain size after deformation is 130nm.
[0085] The eutectic high-entropy alloy obtained by cold rolling in this comparative example has a small deformation amount and cannot obtain a nanocrystalline structure.
[0086] Comparative Example 5
[0087] This comparative example provides a method for preparing a eutectic high-entropy alloy, comprising the following steps:
[0088] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0089] The eutectic high-entropy alloy matrix is made of 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy. The friction stir processing parameters are as follows: rotation speed is 250rpm, travel speed is 50mm / min, and pressure is 0.9mm. The equiaxed structure has ultrafine grains. The phase structure of the equiaxed structure includes FCC phase and B2 phase, and the grain size of the two phases is 180nm.
[0090] Step 2): The equiaxed ultrafine-grained eutectic high-entropy alloy is cold-rolled to obtain a eutectic high-entropy alloy with a nanocrystalline structure;
[0091] Of these, the deformation rate for cold rolling is 90%.
[0092] Due to its small grain size, the comparative example has high strength, making it difficult for traditional equipment to achieve excessive deformation during cold rolling.
[0093] Comparative Example 6
[0094] This embodiment provides a method for preparing a eutectic high-entropy alloy, including the following steps:
[0095] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0096] The eutectic high-entropy alloy matrix is made of 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy. The friction stir processing parameters are as follows: rotation speed is 250rpm, travel speed is 50mm / min, and pressure is 0.9mm. The equiaxed structure has ultrafine grains. The phase structure of the equiaxed structure includes FCC phase and B2 phase, and the grain size of the two phases is 180nm.
[0097] Step 2): The equiaxed ultrafine-grained eutectic high-entropy alloy is cold-rolled to obtain a eutectic high-entropy alloy with a nanocrystalline structure;
[0098] The deformation amount of cold rolling is 40%, and the grain size after deformation is 80nm.
[0099] Step 3): Perform short-time heat treatment on the eutectic high-entropy alloy with nanocrystalline structure to obtain an equiaxed nanocrystalline eutectic high-entropy alloy;
[0100] The heat treatment temperature was 400℃ and the annealing time was 180min.
[0101] Because the annealing temperature of this comparative example is relatively low, it is difficult to eliminate dislocations and substructures in a short time, and its microstructure is still an elongated deformed structure.
[0102] Comparative Example 7
[0103] This embodiment provides a method for preparing a eutectic high-entropy alloy, including the following steps:
[0104] Step 1): The eutectic high-entropy alloy matrix is subjected to friction stirring to obtain an equiaxed ultrafine grain structure.
[0105] The eutectic high-entropy alloy matrix is made of 2mm thick cast AlCoCrFeNi2.1 eutectic high-entropy alloy. The friction stir processing parameters are as follows: rotation speed is 250rpm, travel speed is 50mm / min, and pressure is 0.9mm. The equiaxed structure has ultrafine grains. The phase structure of the equiaxed structure includes FCC phase and B2 phase, and the grain size of the two phases is 180nm.
[0106] Step 2): The equiaxed ultrafine-grained eutectic high-entropy alloy is cold-rolled to obtain a eutectic high-entropy alloy with a nanocrystalline structure;
[0107] The deformation amount of cold rolling is 40%, and the grain size after deformation is 80nm.
[0108] Step 3): Perform short-time heat treatment on the eutectic high-entropy alloy with nanocrystalline structure to obtain an equiaxed nanocrystalline eutectic high-entropy alloy;
[0109] The heat treatment temperature was 1000℃ and the annealing time was 10min.
[0110] Due to the relatively low annealing temperature, the nano-sized grains in this comparative example grew rapidly in a short period of time, unable to maintain the nanostructure, and transformed into an ultrafine crystalline structure.
[0111] As demonstrated by the above examples and comparative examples, the eutectic high-entropy alloy with a nanocrystalline equiaxed structure prepared by friction stir processing + cold rolling + short-time annealing can significantly improve its ability to impede dislocation movement, thus giving it high strength. Furthermore, the low-energy coherent interface gives it excellent thermal stability at high temperatures.
[0112] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.
[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.
Claims
1. A method for preparing a eutectic high-entropy alloy, characterized in that, Includes the following steps: Step 1): The eutectic high-entropy alloy matrix is subjected to friction stir processing to obtain an equiaxed ultrafine grain structure and a eutectic high-entropy alloy after friction stir processing. Step 2): The eutectic high-entropy alloy after friction stir processing is subjected to cold rolling to obtain a cold-rolled eutectic high-entropy alloy; The cold-rolled eutectic high-entropy alloy has a banded nanocrystalline structure. Step 3): The cold-rolled eutectic high-entropy alloy is heat-treated to obtain a eutectic high-entropy alloy with an equiaxed nanocrystalline structure.
2. The method for preparing the eutectic high-entropy alloy according to claim 1, characterized in that, In step 1), the size of the equiaxed ultrafine grain structure is 0.15-1 μm.
3. The method for preparing the eutectic high-entropy alloy according to claim 1, characterized in that, In step 2), the size of the strip-shaped nanocrystal structure is 10-100 nm.
4. The method for preparing the eutectic high-entropy alloy according to claim 1, characterized in that, In step 3), the size of the equiaxed nanocrystal structure is 10-100 nm.
5. The method for preparing a stirred eutectic high-entropy alloy according to claim 1, characterized in that, In step 1), the parameters of the friction stir processing are as follows: rotation speed is 150-400 rpm, travel speed is 25-100 mm / min, and pressure is 0.2-1 mm.
6. The method for preparing the eutectic high-entropy alloy according to claim 1, characterized in that, In step 2), the deformation amount of the cold rolling process is 20%-80%.
7. The method for preparing the eutectic high-entropy alloy according to claim 1, characterized in that, In step 3), the heat treatment is annealing; the annealing temperature is 500-1000℃ and the annealing time is 10min-180min.
8. A eutectic high-entropy alloy, characterized in that, The eutectic high-entropy alloy is obtained by the preparation method according to any one of claims 1-7; the tensile strength of the eutectic high-entropy alloy exceeds 1800 MPa at room temperature.