A Mg-based hydrogen storage alloy with Mg2Cu / Mg2Ni dual-phase synergistic catalysis and its preparation method

Abstract

This invention relates to a method for preparing a Mg-based hydrogen storage alloy with Mg2Cu / Mg2Ni dual-phase synergistic catalysis, comprising the following steps: S1: Mg2Cu / Mg2Ni hydrogen storage alloy with atomic percentage of general formula... 40 Ni 10‑x Cu x S2: Weigh the raw materials according to the specified proportions; S3: Place the raw materials in the crucible of the melting furnace and melt them under a protective atmosphere. During the melting process, intermittent electromagnetic stirring is performed. After cooling, a cast alloy ingot is obtained; S4: After surface polishing and cyclic deep cryogenic treatment, the cast alloy ingot is mechanically crushed into particles with a particle size of less than 2 mm; S5: Place the particles in a ball mill jar and perform high-energy ball milling under an inert protective gas. After ball milling, the particles are sieved to obtain a hydrogen storage alloy. This invention forms an interwoven and coupled Mg2Cu / Mg2Ni dual-phase synergistic structure through appropriate doping of Cu, which significantly improves the hydrogen absorption and desorption kinetics while maintaining a high hydrogen storage capacity. The method is process-controllable, has uniform composition, and is suitable for large-scale preparation.

Description

Technical Field

[0001] This invention relates to the field of solid-state hydrogen storage, specifically to a Mg-based hydrogen storage alloy with Mg2Cu / Mg2Ni dual-phase synergistic catalysis and its preparation method. Background Technology

[0002] Hydrogen energy, as a clean and efficient renewable energy source, is widely regarded as an important component of the future energy system due to its wide availability, high calorific value, and ability to achieve true zero carbon emissions. It is especially strategic in promoting the transformation of the energy structure.

[0003] However, its large-scale application is still constrained by the bottleneck of safe and efficient hydrogen storage technology. Among many hydrogen storage materials, Mg-Ni alloys possess excellent thermodynamic hydrogen storage properties, but in practical applications, they still face key challenges such as slow hydrogen absorption and desorption kinetics and high activation energies, which restrict their commercialization process. Traditional alloying modification is a common method, but it is often accompanied by a series of problems, such as the addition of alloying elements leading to a decrease in theoretical hydrogen storage capacity, uneven element distribution causing segregation, difficulty in uniformly dispersing the catalytic phase, or the reliance on complex and demanding preparation processes to obtain specific structures, thus affecting the stability and reproducibility of material performance. Therefore, it is urgent to propose a Mg-based hydrogen storage alloy with Mg2Cu / Mg2Ni dual-phase synergistic catalysis and its preparation method. Summary of the Invention

[0004] Purpose of the invention This invention aims to address the contradictions in existing technologies, such as poor hydrogen absorption and desorption kinetics and high apparent activation energy of hypereutectic Mg-Ni-based hydrogen storage alloys, as well as the significant decrease in hydrogen storage capacity caused by traditional alloying. The invention proposes a Mg-based hydrogen storage alloy with Mg2Cu / Mg2Ni dual-phase synergistic catalysis and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A Mg-based hydrogen storage alloy with Mg₂Cu / Mg₂Ni dual-phase synergistic catalysis, wherein the atomic percentage of the Mg-based hydrogen storage alloy with Mg₂Cu / Mg₂Ni dual-phase synergistic catalysis is Mg 40 Ni 10-x Cu x , of which 0 <x≤4。

[0006] As a further description of the above scheme, the microstructure of the Mg2Cu / Mg2Ni dual-phase synergistic catalytic Mg-based hydrogen storage alloy includes a primary Mg2Ni phase and a eutectic structure composed of the Mg2Cu phase, the Mg2Ni phase and the Mg matrix; the Mg2Cu phase and the Mg2Ni phase form an interwoven and coupled dual-phase structure within the eutectic structure, which varies with the Cu content ( x As the value increases, the morphology of the eutectic structure changes as follows: whenx When = 0, the eutectic structure is a layered structure; when 2 ≤ x When <4, the eutectic structure is a lath-like structure; when x When the ≥4, the eutectic structure is a rod-shaped structure.

[0007] A method for preparing the above-mentioned hydrogen storage alloy comprises the following steps: S1: Mg by atomic percentage (general formula) 40 Ni 10-x Cu x Weigh the raw materials according to the specified proportions; S2: Place the raw materials weighed in step S1 into the crucible of the melting furnace and melt them at 850-920°C under a protective atmosphere. During the melting process, intermittent electromagnetic stirring is performed, and after cooling, a cast alloy ingot is obtained. S3: After surface polishing and cyclic deep cryogenic treatment, the cast alloy ingot obtained in step S2 is mechanically crushed into particles with a particle size of less than 2 mm. S4: Place the crushed particles from step S3 into a ball mill jar and perform high-energy ball milling under an inert protective gas. After ball milling, sieve to obtain the hydrogen storage alloy.

[0008] As a further description of the above scheme, in step S1, when weighing the raw materials, an additional 2 wt.% of pure magnesium is added to compensate for the loss of Mg during the smelting process. As a further description of the above scheme, in step S1, the raw materials for preparing the alloy are pure magnesium, pure copper and Mg-Ni master alloy, wherein the purity of pure magnesium and pure copper is higher than 99.9 wt.%.

[0009] As a further description of the above scheme, the protective atmosphere in step S2 is a mixture of SF6 and CO2, and the smelting furnace is an electric resistance furnace.

[0010] As a further description of the above scheme, the intermittent electromagnetic stirring operation in step S2 is as follows: take out the crucible containing the raw materials, place it in the induction heating coil for a short time of heating for 2-3 seconds, and then put it back into the melting furnace. Repeat the operation until the alloy melt composition is uniform.

[0011] As a further description of the above scheme, the cryogenic treatment in step S3 involves placing the polished alloy ingot in liquid nitrogen for 0.5-1.5 hours, removing it, and then placing it in liquid nitrogen for another 0.5-1.5 hours after the temperature returns to room temperature.

[0012] As a further description of the above scheme, in step S4, the inert protective gas is argon; the parameters of the high-energy ball mill are: ball-to-material mass ratio of 30:1, rotation speed of 150-250 r / min, adopting a forward and reverse alternating operation mode, with each ball milling cycle consisting of 15 minutes followed by a 5-minute interval, repeating the above cycle units until the cumulative ball milling time reaches 2-3 hours; after ball milling, the powder is passed through a 200-mesh sieve to obtain alloy powder with a particle size of less than 75 μm.

[0013] Advantages and effects of the present invention: I. This invention introduces a controllable amount of Cu into a hypereutectic Mg-Ni matrix, simultaneously forming a primary Mg2Ni phase and a multi-element eutectic structure composed of Mg2Ni / Mg2Cu and the Mg matrix in the as-cast microstructure. The Mg2Ni phase provides the main basis for hydrogen storage capacity, while the introduced Mg2Cu phase not only undergoes a reversible reaction during hydrogen absorption and desorption, but its product MgCu2 can also serve as a highly efficient catalyst. The thermodynamic mutual instability between the Mg2Cu / MgCu2 system and the Mg2Ni / Mg2NiH4 hydride effectively reduces the overall stability of the hydride, providing a strong thermodynamic driving force for rapid dehydrogenation.

[0014] Second, this two-phase structure achieves a good balance between capacity and kinetics, improving hydrogen storage capacity while simultaneously increasing hydrogen absorption and desorption rates. For example, Mg 40 The Ni8Cu2 alloy has a maximum hydrogen storage capacity of 4.47 wt.% at 280°C and 2.0 MPa, which is higher than the theoretical value of the traditional Mg2Ni alloy. At the same time, its hydrogen desorption kinetics are significantly accelerated, and it can completely desorb hydrogen within tens of minutes at 280°C and 0.02 MPa.

[0015] Third, resistance melting is assisted by electromagnetic stirring. Resistance melting has a low temperature, which reduces the volatilization and oxidation of Mg. Pulsed electromagnetic stirring causes the melt temperature to rise briefly and flow under the action of a magnetic field, ensuring the uniformity and accuracy of the composition.

[0016] Fourth, the innovative combination of casting, cryogenic treatment, and high-energy ball milling allows for precise composition control, clear process parameters, and easy large-scale production. Cryogenic treatment induces lattice shrinkage and distortion, increases dislocation density, promotes subgrain formation, and refines grains. It also reduces plasticity, facilitating ball milling and improving powder output efficiency. High-energy ball milling not only refines alloy particles and increases specific surface area but also introduces numerous crystal defects, providing a rapid pathway for hydrogen diffusion, further enhancing kinetic properties.

[0017] Fifth, by adjusting the relative content of Ni and Cu, the ratio, morphology and distribution of Mg2Ni and Mg2Cu phases in the alloy can be precisely controlled, thereby enabling customized material design for different application scenarios. Attached Figure Description

[0018] Figure 1 The Mg of the present invention 40 Ni 10 Scanning electron microscope micrograph of hydrogen storage alloy; Figure 2 The Mg of the present invention 40 Scanning electron microscope image of Ni8Cu2 hydrogen storage alloy; Figure 3 The Mg of the present invention 40 Scanning electron microscope image of Ni6Cu4 hydrogen storage alloy; Figure 4 The Mg of the present invention 40 Ni 10 Mg 40 Ni8Cu2 and Mg 40 X-ray diffraction pattern of Ni6Cu4 hydrogen storage alloy powder after ball milling; Figure 5 The Mg of the present invention 40 Ni 10 Mg 40 Ni8Cu2 and Mg 40 Isothermal hydrogen absorption kinetics curve of Ni6Cu4 hydrogen storage alloy at 280°C; Figure 6 The Mg of the present invention 40 Ni 10 Mg 40 Ni8Cu2 and Mg 40 Isothermal hydrogen desorption kinetics curve of Ni6Cu4 hydrogen storage alloy at 280°C. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] A Mg-based hydrogen storage alloy with Mg₂Cu / Mg₂Ni dual-phase synergistic catalysis, wherein the atomic percentage of the Mg-based hydrogen storage alloy with Mg₂Cu / Mg₂Ni dual-phase synergistic catalysis is given by the general formula Mg. 40 Ni 10-x Cu x , of which 0 <x≤4。

[0021] The microstructure of the Mg-based hydrogen storage alloy with Mg2Cu / Mg2Ni dual-phase synergistic catalysis of the present invention includes a primary Mg2Ni phase and a eutectic structure composed of the Mg2Cu phase, the Mg2Ni phase and the Mg matrix; the Mg2Cu phase and the Mg2Ni phase form an interwoven and coupled dual-phase structure within the eutectic structure, and the morphology of the eutectic structure changes as the Cu content (x value) increases: when x When = 0, the eutectic structure is a layered structure; when 2 ≤ x When <4, the eutectic structure is lath-like; when x When the concentration is ≥4, the eutectic structure is rod-shaped. This application introduces a controllable amount of Cu into the hypereutectic Mg-Ni matrix, enabling the simultaneous formation of a primary Mg2Ni phase and a multi-element eutectic structure composed of Mg2Ni / Mg2Cu and the Mg matrix in the as-cast structure. The Mg2Ni phase provides the primary basis for hydrogen storage capacity, while the introduced Mg2Cu phase not only undergoes a reversible reaction during hydrogen absorption and desorption, but its product MgCu2 can also serve as a highly efficient catalyst. The Mg2Cu / MgCu2 system and the Mg2Ni / Mg2NiH4 hydride exhibit thermodynamic instability, effectively reducing the overall stability of the hydride and providing a strong thermodynamic driving force for rapid dehydrogenation. Simultaneously, by adjusting the relative content of Ni and Cu, this application can precisely control the ratio, morphology, and distribution of the Mg2Ni and Mg2Cu phases in the alloy, thereby enabling customized material design for different application scenarios.

[0022] A method for preparing the above-mentioned hydrogen storage alloy, comprising the following steps: S1: Mg according to the atomic percentage general formula 40 Ni 10-x Cu x Weigh the raw materials according to the specified proportions; S2: Place the raw materials weighed in step S1 into the crucible of the melting furnace and melt them at 850-920℃ under a protective atmosphere. During the melting process, intermittent electromagnetic stirring is performed, and after cooling, a cast alloy ingot is obtained. S3: After surface polishing and cyclic deep cryogenic treatment, the cast alloy ingot obtained in step S2 is mechanically crushed into particles with a particle size of less than 2mm. S4: Place the crushed particles from step S3 into a ball mill jar and perform high-energy ball milling under an inert protective gas. After ball milling, sieve to obtain a hydrogen storage alloy.

[0023] In step S1 of this invention, when weighing the raw materials, an additional 2 wt.% of pure magnesium is added to compensate for the loss of Mg during the smelting process. In step S1 of the present invention, the raw materials for preparing the alloy are pure magnesium, pure copper and Mg-Ni master alloy, wherein the purity of pure magnesium and pure copper is higher than 99.9 wt.%.

[0024] In step S2 of the present invention, the protective atmosphere is a mixture of SF6 and CO2, and the smelting furnace is an electric resistance furnace.

[0025] In step S2 of this invention, the intermittent electromagnetic stirring operation is as follows: the crucible containing the raw materials is removed, placed in an induction heating coil for a short heating time of 2-3 seconds, and then returned to the melting furnace. This operation is repeated until the alloy melt composition is uniform. The resistance melting process in this application is assisted by electromagnetic stirring. The resistance melting temperature is low, reducing the volatilization and oxidation of Mg; the pulsed electromagnetic stirring causes the melt temperature to rise briefly and flow under the influence of a magnetic field, ensuring uniform and accurate composition.

[0026] The cryogenic treatment described in step S3 of the present invention involves placing the polished alloy ingot in liquid nitrogen for 0.5-1.5 hours, removing it, and then placing it in liquid nitrogen for another 0.5-1.5 hours after the temperature returns to room temperature.

[0027] In step S4 of this invention, the inert protective gas is argon. The parameters for high-energy ball milling are: ball-to-material mass ratio of 30:1, rotation speed of 150-250 r / min, alternating forward and reverse rotation, with each 15-minute cycle consisting of a 5-minute interval, repeated until the cumulative working time reaches 2-3 hours. After ball milling, the powder is passed through a 200-mesh sieve to obtain alloy powder with a particle size of less than 75 μm. This application innovatively employs a combination of casting, cryogenic treatment, and high-energy ball milling, resulting in precise composition control, clear process parameters, and ease of large-scale preparation. Cryogenic treatment causes lattice shrinkage and distortion, increases dislocation density, promotes subgrain formation, and refines grains. It also reduces plasticity, facilitating ball milling and improving powder output efficiency. High-energy ball milling not only refines alloy particles and increases specific surface area but also introduces a large number of crystal defects, providing a rapid channel for hydrogen diffusion, thus jointly promoting the improvement of kinetic properties. Example 1

[0028] A hypereutectic Mg 40 Ni 10 Alloy preparation I. Using pure magnesium with a purity higher than 99.9 wt.% and Mg-30 wt.% Ni master alloy, according to atomic percentage Mg 40 Ni 10 Weigh the raw materials. To compensate for melting losses, add an additional 2 wt.% of magnesium.

[0029] 2. Place the raw materials in a resistance furnace, introduce a protective gas mixture of SF6 and CO2, and heat to 900°C until completely melted. During the melting process, intermittent electromagnetic stirring is performed to ensure accurate composition. The procedure involves removing the crucible, quickly placing it in an induction heating coil for a short heating time of 2-3 seconds, and then returning it to the resistance furnace until the alloy melt has a uniform composition. After cooling, a cast alloy ingot is obtained.

[0030] 3. Grind the surface of the cast alloy ingot to remove oxide scale and smooth the surface. Place the alloy ingot in liquid nitrogen for 0.5 hours for cryogenic treatment, then remove it and wait for the temperature to return to room temperature. Then place it in liquid nitrogen for another 0.5 hours and then crush it into particles with a particle size of less than 2 mm by mechanical crushing.

[0031] IV. After mechanically crushing the alloy ingot, take a portion of the sample and perform high-energy ball milling (ball-to-material ratio 30:1, 200 r / min, argon protection, 2 hours) until it passes through a 200-mesh sieve to obtain test powder.

[0032] XRD and SEM analyses indicate that the alloy mainly consists of primary Mg₂Ni phase and lamellar Mg-Mg₂Ni eutectic. The primary Mg₂Ni is primarily discontinuous and irregularly blocky, while the Mg-Mg₂Ni eutectic structure is lamellar. Due to element diffusion during solidification and the influence of interfacial energy, larger Mg phases appear around the primary Mg₂Ni. The direction of the eutectic lamellae is perpendicular to the plane of the primary Mg₂Ni. Mg and Mg₂Ni phases alternately nucleate and grow, and their synergistic growth leads to the final formation of the lamellar Mg-Mg₂Ni eutectic. At 280°C and 2.0 MPa hydrogen pressure, the alloy reaches its peak hydrogen absorption capacity after 120 min, with a maximum hydrogen absorption capacity of 4.16 wt.%.

[0033] Example 2

[0034] A Mg with a dual-phase synergistic structure 40 Preparation of Ni8Cu2 alloy I. Using pure magnesium, Mg-Ni master alloy and pure copper, according to atomic percentage Mg 40 Weigh the raw materials Ni8Cu2. To compensate for smelting losses, add an additional 2 wt.% of magnesium.

[0035] 2. Place the raw materials in a resistance furnace, introduce a protective gas mixture of SF6 and CO2, and heat to 900°C until completely melted. During the melting process, intermittent electromagnetic stirring is performed to ensure accurate composition. The procedure involves removing the crucible, quickly placing it in an induction heating coil for a short heating time of 2-3 seconds, and then returning it to the resistance furnace until the alloy melt has a uniform composition. After cooling, a cast alloy ingot is obtained.

[0036] 3. Grind the surface of the cast alloy ingot to remove oxide scale and smooth the surface. Place the alloy ingot in liquid nitrogen for 1 hour for cryogenic treatment, then remove it and wait for the temperature to return to room temperature. Then, place it in liquid nitrogen for another hour and then crush it into particles with a particle size of less than 2 mm by mechanical crushing.

[0037] IV. After mechanically crushing the alloy ingot, take a portion of the sample and perform high-energy ball milling (ball-to-material ratio 30:1, 200 r / min, argon protection, 2 hours) until it passes through a 200-mesh sieve to obtain test powder.

[0038] XRD and SEM analyses revealed significant changes in the alloy's microstructure. Besides the primary Mg₂Ni phase, the eutectic region consisted of three phases: Mg, Mg₂Ni, and Mg₂Cu, forming a Mg-Mg₂Ni / Mg₂Cu composite eutectic structure with a predominantly banded morphology. At 280°C and 2.0 MPa, the maximum hydrogen absorption capacity increased to 4.47 wt.%. The two-phase structure formed by Mg₂Cu and Mg₂Ni provided a much richer array of phase interfaces than single-phase alloys. These interfaces, acting as rapid diffusion channels for hydrogen atoms and catalytic sites for reactions, synergistically lowered the energy barrier for hydride decomposition, thereby significantly improving kinetic performance while maintaining high capacity. The two-phase structure of this application achieves a good balance between capacity and kinetics, increasing both hydrogen storage capacity and hydrogen absorption / desorption rates, enabling complete hydrogen desorption within tens of minutes at 280°C and 0.02 MPa.

[0039] Example 3

[0040] A Mg with a dual-phase synergistic structure 40 Preparation of Ni6Cu4 alloy Using pure magnesium, Mg-Ni master alloy and pure copper, Mg is added according to atomic percentage. 40 Weigh the raw materials Ni6Cu4. To compensate for smelting losses, add an additional 2 wt.% magnesium.

[0041] 2. Place the raw materials in a resistance furnace, introduce a protective gas mixture of SF6 and CO2, and heat to 900°C until completely melted. During the melting process, intermittent electromagnetic stirring is performed to ensure accurate composition. The procedure involves removing the crucible, quickly placing it in an induction heating coil for a short heating time of 2-3 seconds, and then returning it to the resistance furnace until the alloy melt has a uniform composition. After cooling, a cast alloy ingot is obtained.

[0042] 3. Grind the surface of the cast alloy ingot to remove oxide scale and smooth the surface. Place the alloy ingot in liquid nitrogen for 1.5 hours for cryogenic treatment, then remove it and wait for the temperature to return to room temperature. Then place it in liquid nitrogen for another 1.5 hours and then crush it into particles with a particle size of less than 2 mm by mechanical crushing.

[0043] IV. After mechanically crushing the alloy ingot, take a portion of the sample and perform high-energy ball milling (ball-to-material ratio 30:1, 200 r / min, argon protection, 2 hours) until it passes through a 200-mesh sieve to obtain test powder.

[0044] XRD and SEM analyses showed that the primary phase further grew into elongated shapes, the eutectic structure completely transformed into rod-like structures, and a dispersed distribution of the Mg2Cu phase appeared in some areas. The Mg2Cu phase content in the alloy further increased, the primary Mg2Ni phase became somewhat coarser, and the eutectic structure became more developed. At 280°C and 2.0 MPa, Mg... 40 Ni6Cu4 exhibits the fastest initial hydrogen absorption rate, with a maximum hydrogen absorption capacity of 3.42 wt.%, which is lower than that of Mg. 40 Ni 10 Mg 40 The maximum hydrogen absorption capacity of Ni8Cu2 alloy. Moderate Cu substitution ( x =2) Hydrogen storage capacity is increased through "solid solution + defect enhancement", with excess Cu ( x =4) The hydrogen storage capacity decreases due to the formation of the non-hydrogen-storing phase Mg2Cu, but the optimization of the eutectic morphology improves the stability of the hydrogen absorption rate.

[0045] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A Mg-based hydrogen storage alloy with Mg2Cu / Mg2Ni dual-phase synergistic catalysis, characterized in that, The atomic percentage formula of the Mg-based hydrogen storage alloy catalyzed by the Mg2Cu / Mg2Ni dual-phase synergistic catalyst is Mg 40 Ni 10-x Cu x , where 0 < x ≤4.

2. The Mg-based hydrogen storage alloy with Mg₂Cu / Mg₂Ni dual-phase synergistic catalysis according to claim 1, characterized in that, The microstructure of the Mg-based hydrogen storage alloy with Mg2Cu / Mg2Ni dual-phase synergistic catalysis includes a primary Mg2Ni phase and a eutectic structure composed of the Mg2Cu phase, the Mg2Ni phase, and the Mg matrix; the Mg2Cu phase and the Mg2Ni phase form an interwoven and coupled dual-phase structure within the eutectic structure, which varies with the Cu content ( x As the value increases, the morphology of the eutectic structure changes as follows: when x When = 0, the eutectic structure is a layered structure; when 2 ≤ x When <4, the eutectic structure is a lath-like structure; when x When the ≥4, the eutectic structure is a rod-shaped structure.

3. A method for preparing the hydrogen storage alloy according to any one of claims 1-2, characterized in that, The steps are as follows: S1: Mg by atomic percentage (general formula) 40 Ni 10-x Cu x Weigh the raw materials according to the specified proportions; S2: Place the raw materials weighed in step S1 into the crucible of the melting furnace and melt them at 850-920°C under a protective atmosphere. During the melting process, intermittent electromagnetic stirring is performed, and after cooling, a cast alloy ingot is obtained. S3: After surface polishing and cyclic deep cryogenic treatment, the cast alloy ingot obtained in step S2 is mechanically crushed into particles with a particle size of less than 2 mm. S4: Place the crushed particles from step S3 into a ball mill jar and perform high-energy ball milling under an inert protective gas. After ball milling, sieve to obtain the hydrogen storage alloy.

4. The preparation method according to claim 3, characterized in that, In step S1, when weighing the raw materials, an additional 2 wt.% of pure magnesium is added to compensate for the loss of Mg during the smelting process.

5. The preparation method according to claim 4, characterized in that, In step S1, the raw materials for preparing the alloy are pure magnesium, pure copper, and Mg-Ni master alloy, wherein the purity of pure magnesium and pure copper is higher than 99.9 wt.%.

6. The preparation method according to claim 3, characterized in that, The protective atmosphere in step S2 is a mixture of SF6 and CO2, and the smelting furnace is an electric resistance furnace.

7. The preparation method according to claim 3, characterized in that, The intermittent electromagnetic stirring operation in step S2 is as follows: take out the crucible containing the raw materials, place it in the induction heating coil for a short time of 2-3 seconds, and then put it back into the melting furnace. Repeat the operation until the alloy melt composition is uniform.

8. The preparation method according to claim 3, characterized in that, The cryogenic treatment in step S3 involves placing the polished alloy ingot in liquid nitrogen for 0.5-1.5 hours, removing it, and then placing it in liquid nitrogen for another 0.5-1.5 hours after the temperature returns to room temperature.

9. The preparation method according to any one of claims 3-8, characterized in that, In step S4, the inert protective gas is argon; the parameters of the high-energy ball mill are: ball-to-material mass ratio of 30:1, rotation speed of 150-250 r / min, and alternating forward and reverse rotation operation mode. The ball milling cycle is 15 minutes with a 5-minute interval, and the above cycle is repeated until the cumulative working time of the ball milling reaches 2-3 hours; after ball milling, the powder is passed through a 200-mesh sieve to obtain alloy powder with a particle size of less than 75 μm.

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