High-strength, high-plasticity and hydrogen embrittlement-resistant biphase eutectic high-entropy alloy as well as preparation method and application thereof

Abstract

The invention relates to the technical field of high-entropy alloys, in particular to a high-strength high-plasticity hydrogen embrittlement-resistant double-phase eutectic high-entropy alloy and a preparation method and application thereof.The eutectic high-entropy alloy is of a double-phase structure composed of an FCC phase and a B2 phase, the FCC phase is rich in Co, Cr and Fe elements, the B2 phase is rich in Al and Ni elements, the atomic ratio of Al to Co to Cr to Fe to Ni in the eutectic high-entropy alloy is 1: 1: 1: 1: 2.1, and the general formula of the eutectic high-entropy alloy is AlCoCrFeNi2.1. According to the high-strength high-plasticity hydrogen embrittlement-resistant double-phase eutectic high-entropy alloy as well as the preparation method and the application thereof, the technical problems that an existing AlCoCrFeNi-based eutectic high-entropy alloy is poor in hydrogen embrittlement resistance, difficult in strong plasticity balance and insufficient in process adaptability and cannot meet the requirements of complex working conditions of hydrogen energy equipment are solved.

Description

Technical Field

[0001] This invention relates to the field of high-entropy alloy technology, and in particular to a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy, its preparation method, and its applications. Background Technology

[0002] Hydrogen energy, as a clean and efficient secondary energy source, is a key carrier for achieving the "dual carbon" goal. Its large-scale application depends on the safe and stable operation of hydrogen energy equipment (such as deep-sea hydrogen pipelines, high-pressure hydrogen storage containers, and seawater hydrogen production devices). These devices operate in hydrogen-rich environments for extended periods and often face complex conditions such as seawater corrosion and low temperatures / high pressures. This places stringent demands on the performance of core materials. They must possess sufficient strength to withstand system pressure, maintain good plasticity to avoid brittle fracture, and resist material embrittlement failure caused by hydrogen atom intrusion, as well as corrosion damage caused by seawater.

[0003] Traditional metallic materials cannot simultaneously meet the above requirements: for example, although 316L stainless steel has a certain degree of corrosion resistance, its tensile strength is generally lower than 700MPa in hydrogen-containing environments, and its hydrogen embrittlement factor is likely to exceed 40%, making it unsuitable for high-pressure hydrogen energy systems; although conventional low-alloy high-strength steel meets the strength requirements, its high hydrogen diffusion coefficient often results in a plasticity loss of more than 50% after 24 hours of hydrogen charging, and its poor resistance to seawater corrosion makes it prone to hydrogen-induced cracking and corrosion-induced synergistic failure.

[0004] The emergence of high-entropy alloys offers a new direction for solving this problem. These alloys, with 5-13 elements as their main components, exhibit superior comprehensive properties compared to traditional alloys due to the high-entropy effect, slow diffusion effect, lattice distortion effect, and cocktail effect. These properties include high strength, excellent high-temperature stability, and corrosion resistance, and have shown application potential in fields such as nuclear power and mold making. Among them, eutectic high-entropy alloys, combining the performance advantages of high-entropy alloys with the excellent casting fluidity of eutectic alloys, have become one of the most promising high-entropy alloy types for industrial applications.

[0005] In the eutectic high-entropy alloy system, AlCoCrFeNi-based alloys exhibit outstanding room-temperature and low-temperature mechanical properties due to their ability to form face-centered cubic (FCC) and ordered body-centered cubic (B2) dual-phase structures. The fracture strength of the cast alloy can exceed 1 GPa, while maintaining a certain tensile plasticity. Many of its indicators are superior to traditional marine metal materials, and it is regarded as a candidate material for core components of hydrogen energy equipment. However, existing AlCoCrFeNi-based eutectic high-entropy alloys still have two major technical bottlenecks: (1) Insufficient resistance to hydrogen embrittlement: High-strength materials generally face a more severe risk of hydrogen embrittlement. Although AlCoCrFeNi-based alloys have high strength, hydrogen atoms tend to accumulate at defects such as grain boundaries and phase boundaries, resulting in a significant decrease in plasticity after hydrogen filling. Existing research shows that after conventional as-cast AlCoCrFeNi alloys are charged with hydrogen for 72 hours, the hydrogen embrittlement factor often exceeds 45%, and the tensile strain loss is more than 40%, which cannot meet the long-term safe operation requirements of hydrogen energy equipment; (2) Poor balance between strength and plasticity and process adaptability: In order to improve the resistance to hydrogen embrittlement, existing technologies mostly adopt cold rolling or high-temperature heat treatment processes. However, cold rolling is prone to causing alloy cracking, especially for dual-phase alloys, which are prone to stress concentration due to the difference in plasticity between the two phases. High-temperature heat treatment will cause grain coarsening, resulting in a significant reduction in strength. For example, after annealing at 850℃ or above, the tensile strength can decrease by more than 200MPa, making it difficult to achieve the synergistic optimization of high strength, high plasticity, and low hydrogen embrittlement sensitivity.

[0006] Furthermore, the complex operating conditions of hydrogen energy equipment further exacerbate the material challenges: seawater hydrogen production devices must simultaneously withstand the coupled effects of hydrogen embrittlement and seawater corrosion. Traditional AlCoCrFeNi-based alloys often exhibit corrosion current densities exceeding 0.15 μA in simulated seawater environments with 3.5 wt% NaCl, and hydrogen atoms can easily penetrate the material's interior through the corrosion interface, accelerating hydrogen-induced damage. Deep-sea hydrogen pipelines, on the other hand, must withstand low temperatures (-40℃ to 0℃) and high pressures (above 10 MPa). Existing alloys exhibit a 15%-25% increase in plasticity loss rate under low-temperature hydrogen-exposed environments compared to room temperature environments, which can easily lead to sudden pipeline fractures.

[0007] Although existing research has explored the hydrogen embrittlement behavior of high-entropy alloys (such as the CoCrFeNiMo studied by Ma et al.), 0.35 While hot rolling can achieve grain refinement in AlCoCrFeNi2 alloys (Du Cuiwei et al. proposed a cold rolling-heat treatment process), these methods either fail to optimize the process for the two-phase structure characteristics of AlCoCrFeNi-based eutectic high-entropy alloys, or fail to achieve a long-term stable balance between hydrogen embrittlement resistance and high plasticity. Furthermore, they lack adaptability verification for typical operating conditions of hydrogen energy equipment, such as seawater and cryogenic environments. Therefore, there is an urgent need to develop a high-strength, high-plasticity, and hydrogen embrittlement-resistant AlCoCrFeNi-based eutectic high-entropy alloy with a simple process, excellent performance, and adaptability to the complex operating conditions of hydrogen energy equipment, to promote the large-scale application of hydrogen energy. Summary of the Invention

[0008] The purpose of this invention is to provide a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy, its preparation method, and its application, solving the technical problems of poor hydrogen embrittlement resistance, difficulty in balancing strength and plasticity, insufficient process adaptability, and inability to meet the complex operating conditions of hydrogen energy equipment in existing AlCoCrFeNi-based eutectic high-entropy alloys.

[0009] To achieve the above objectives, this invention provides a high-strength, high-plasticity, and hydrogen-embrittlement-resistant biphase eutectic high-entropy alloy. The eutectic high-entropy alloy has a biphase structure composed of an FCC phase and a B2 phase. The FCC phase is rich in Co, Cr, and Fe elements, while the B2 phase is rich in Al and Ni elements. The atomic ratio of each element in the eutectic high-entropy alloy is Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1, and the general formula of the eutectic high-entropy alloy is AlCoCrFeNi. 2.1 .

[0010] The preparation method of the above-mentioned high-strength, high-plasticity, and hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy includes the following steps: S1. Prepare raw materials according to the atomic ratio Al:Co:Cr:Fe:Ni=1:1:1:1:2.1. Clean the raw materials with anhydrous ethanol in an ultrasonic instrument, dry them, and then put them into water-cooled copper crucibles in order of melting point from low to high. S2. Place the water-cooled copper crucible in a non-consumable vacuum arc melting furnace, evacuate the furnace, and then backfill with argon gas. In the argon atmosphere, perform arc melting on the Ti preform to remove residual oxygen inside the furnace. Then, perform arc melting on the raw material from S1 to completely melt the raw material into molten metal. Apply electromagnetic stirring during the arc melting process. After melting, cool to obtain a button ingot sample. S3. Repeatedly perform electric arc melting on the button ingot sample obtained in S2. Before each electric arc melting, flip the button ingot sample. After the electric arc melting is completed, cool it to room temperature to obtain the as-cast eutectic high-entropy alloy.

[0011] Preferably, Al, Co, Cr, Fe and Ni in S1 are all industrial-grade pure raw materials with a purity higher than 99.9wt%, wherein Al and Ni are placed at the bottom of the water-cooled copper crucible and Cr is placed at the top of the water-cooled copper crucible.

[0012] Preferably, the washing time in S1 is 5 minutes, the drying temperature is 80°C, and the drying time is 10 minutes.

[0013] Preferably, vacuum is drawn to 2×10 in S2. -3 Pa-3×10 -3 Pa, backfill with argon gas to 0.03-0.05 MPa, the current for arc melting is 280-320 A, and the melting time for each melting is 0.5-1.5 min.

[0014] Preferably, the stirring rate of the electromagnetic stirrer in S2 is 500 r / min.

[0015] Preferably, the number of repeated arc melting in S3 is at least 5 times.

[0016] Preferably, it also includes a rolling process: rolling the as-cast AlCoCrFeNi obtained in S3. 2.1 The eutectic high-entropy alloy was treated at 1000℃ for 12 hours to obtain the as-cast AlCoCrFeNi alloy after heat treatment. 2.1 A 5mm thick sheet was cut from a eutectic high-entropy alloy. The sheet was heated to 800℃ and held for 10 minutes, then rolled until the thickness was 3mm. It was then held at that temperature for another 10 minutes, removed, and air-cooled to obtain rolled AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0017] Preferably, the rolling process is performed in 3-5 passes, with a total reduction of 2 mm for each pass and a reduction of 0.4-0.67 mm for each pass. The roll speed is 15-20 r / min.

[0018] The above-mentioned high-strength, high-plasticity, hydrogen-embrittlement-resistant biphase eutectic high-entropy alloy is applied to key components of hydrogen energy equipment, including deep-sea hydrogen pipelines, high-pressure hydrogen storage containers, or seawater hydrogen production devices.

[0019] Therefore, the present invention, employing the above-mentioned high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy, its preparation method, and its application, has the following beneficial effects: (1) This invention combines a specific element ratio (Al:Co:Cr:Fe:Ni=1:1:1:1:2.1) with a preparation method of vacuum arc melting and low temperature hot rolling, so that the obtained eutectic high entropy alloy has high strength, high plasticity, low hydrogen embrittlement sensitivity and excellent corrosion resistance, which solves the problem of traditional alloys having difficulty in balancing strength and plasticity, and difficulty in taking into account both hydrogen embrittlement resistance and corrosion resistance. (2) This invention ensures uniform composition by using repeated vacuum arc melting, eliminates internal stress by heat treatment at 1000℃, avoids alloy cracking by low-temperature hot rolling at 800℃, and introduces dislocation strengthening and grain refinement strengthening through multiple rolling passes, which significantly improves the performance of eutectic high-entropy alloy. The process is simple and controllable, and is suitable for large-scale industrial production. (3) The eutectic high-entropy alloy of the present invention exhibits small performance degradation under typical operating conditions of hydrogen energy equipment such as low temperature, high pressure, and seawater corrosion, which can meet the long-term use requirements of key components such as deep-sea hydrogen pipelines, high-pressure hydrogen storage containers, and seawater hydrogen production devices, and provide material support for the large-scale application of hydrogen energy.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 The AlCoCrFeNi prepared in Examples 1-2 of this invention 2.1 XRD patterns of eutectic high-entropy alloys, where Figure 1 (a) in the figure represents the as-cast AlCoCrFeNi. 2.1 XRD pattern of a eutectic high-entropy alloy. Figure 1 (b) in the figure represents the rolled state AlCoCrFeNi 2.1 XRD pattern of a eutectic high-entropy alloy; Figure 2 The AlCoCrFeNi prepared in Examples 1-2 of this invention 2.1 SEM images of eutectic high-entropy alloys, where Figure 2 (a) in the figure represents the as-cast AlCoCrFeNi. 2.1 SEM images of eutectic high-entropy alloys. Figure 2 (b) in the figure represents the rolled state AlCoCrFeNi 2.1 SEM images of eutectic high-entropy alloys. Figure 2 (a1) in the figure represents the as-cast AlCoCrFeNi. 2.1 EDS diagram of eutectic high-entropy alloy; Figure 3 The AlCoCrFeNi prepared in Examples 1-2 of this invention 2.1 Combined SEM images of the eutectic high-entropy alloy before and after hydrogen charging for 72 hours. Figure 2 (a) in the figure represents the as-cast AlCoCrFeNi. 2.1 SEM images of eutectic high-entropy alloys without hydrogen charging. Figure 2 (b) in the figure represents the rolled state AlCoCrFeNi 2.1 SEM images of eutectic high-entropy alloys without hydrogen charging. Figure 2 (c) represents the as-cast AlCoCrFeNi 2.1 SEM image of a eutectic high-entropy alloy after 72 hours of hydrogen charging. Figure 2 (d) in the figure represents the rolled state AlCoCrFeNi 2.1 SEM image of a eutectic high-entropy alloy after hydrogen charging for 72 hours; Figure 4 The AlCoCrFeNi prepared in Examples 1-2 of this invention 2.1 Stress-strain diagrams of eutectic high-entropy alloys, where Figure 4 (a) in the figure represents the as-cast AlCoCrFeNi. 2.1 Stress-strain diagrams of eutectic high-entropy alloys Figure 4 (b) in the figure represents the rolled state AlCoCrFeNi 2.1 Stress-strain diagram of eutectic high-entropy alloys; Figure 5 This is the as-cast AlCoCrFeNi obtained in Example 1 of the present invention. 2.1 Schematic diagram of the potentiodynamic polarization curves of a eutectic high-entropy alloy; Figure 6 This is the as-cast AlCoCrFeNi obtained in Example 1 of the present invention. 2.1 SEM fracture morphology of eutectic high-entropy alloy before and after hydrogen charging, among which... Figure 6 (a) shows the SEM fracture morphology without hydrogen charging. Figure 6 (a1) in the middle is Figure 6 A magnified view of (a) in the image. Figure 6 (a2) in the middle is Figure 6 A magnified view of (a1) in the image. Figure 6 (b) shows the SEM fracture morphology after 24 hours of hydrogen charging. Figure 6 (b1) in the middle is Figure 6 A magnified view of (b) in the image. Figure 6 (b2) in the middle is Figure 6 A magnified view of (b1) in the image. Figure 6 (c) shows the SEM fracture morphology after 72 hours of hydrogen charging. Figure 6 (c1) in the middle is Figure 6 A magnified view of (c) in the image. Figure 6 (c2) in the middle is Figure 6 A magnified view of (c) in the image; Figure 7 This is the rolled AlCoCrFeNi obtained in Example 2 of the present invention. 2.1 SEM fracture morphology of eutectic high-entropy alloy before and after hydrogen charging, among which... Figure 7 (a) shows the SEM fracture morphology without hydrogen charging. Figure 7 (a1) in the middle is Figure 7 A magnified view of (a) in the image. Figure 7 (a2) in the middle is Figure 7 A magnified view of (a1) in the image. Figure 7 (a3) in the middle is Figure 7 A magnified view of (a2) in the image. Figure 7 (b) shows the SEM fracture morphology after 24 hours of hydrogen charging. Figure 7 (b1) in the middle is Figure 7 A magnified view of (b) in the image. Figure 7 (b2) in the middle is Figure 7 A magnified view of (b1) in the image. Figure 7 (b3) in the middle is Figure 7 A magnified view of (b2) in the image. Figure 7 (c) shows the SEM fracture morphology after 72 hours of hydrogen charging. Figure 7(c1), (c2), and (c3) are... Figure 7 A magnified view of (c) in the image; Figure 8 These are the as-cast and rolled AlCoCrFeNi samples obtained in Examples 1 and 2 of this invention. 2.1 SEM image of the area near the fracture edge of a eutectic high-entropy alloy. Figure 8 Image (a) in the image is a SEM image of the area near the edge of the as-cast fracture. Figure 8 (b) in the middle is Figure 8 A magnified view of (a) in the image. Figure 8 (c) in the middle is Figure 8 A magnified view of (b) in the image. Figure 8 (a1) in the image is a SEM image of the area near the edge of the fracture in the rolled state. Figure 8 (b1) in the middle is Figure 8 A magnified view of (a1) in the image. Figure 8 (c1) in the middle is Figure 8 A magnified view of (b1) in the image. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0023] This invention provides a high-strength, high-plasticity, and hydrogen-embrittlement-resistant biphase eutectic high-entropy alloy, its preparation method, and its applications. The eutectic high-entropy alloy has a biphase structure composed of an FCC phase and a B2 phase. The FCC phase is rich in Co, Cr, and Fe elements, while the B2 phase is rich in Al and Ni elements. The atomic ratio of each element in the eutectic high-entropy alloy is Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1, and the general formula of the eutectic high-entropy alloy is AlCoCrFeNi. 2.1 .

[0024] In this invention, Al can improve the mechanical properties of the alloy, Cr can improve the corrosion resistance of the alloy, and Co, Fe, and Ni can ensure the stability of the alloy structure; Cr and Co can improve the alloy's resistance to hydrogen embrittlement.

[0025] The preparation method of the above-mentioned high-strength, high-plasticity, and hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy includes the following steps: S1. Prepare raw materials according to the atomic ratio Al:Co:Cr:Fe:Ni=1:1:1:1:2.1. Clean the raw materials with anhydrous ethanol in an ultrasonic instrument, dry them, and then put them into water-cooled copper crucibles in order of melting point from low to high. S2. Place the water-cooled copper crucible in a non-consumable vacuum arc melting furnace, evacuate the furnace, and then backfill with argon gas. In the argon atmosphere, perform arc melting on the Ti preform. Utilize the strong oxygen absorption property of Ti to remove the residual oxygen inside the furnace. Then, perform arc melting on the raw material from S1 to completely melt the raw material into molten metal. Apply electromagnetic stirring during the arc melting process. After melting, cool to obtain a button ingot sample. S3. Repeatedly perform electric arc melting on the button ingot sample obtained in S2. Before each electric arc melting, flip the button ingot sample. After the electric arc melting is completed, cool it to room temperature to obtain the as-cast eutectic high-entropy alloy.

[0026] Preferably, Al, Co, Cr, Fe, and Ni in S1 are all industrial-grade pure raw materials with a purity of over 99.9 wt%, to avoid the adverse effects of impurity elements (such as C, O, and S) on the alloy's resistance to hydrogen embrittlement and structural stability; Al and Ni are placed at the bottom of the water-cooled copper crucible, and Cr is placed at the top of the water-cooled copper crucible to avoid premature melting of low-melting-point raw materials, which would lead to element burn-off.

[0027] Preferably, in S1, the cleaning time is 5 minutes, the drying temperature is 80°C, and the drying time is 10 minutes; this removes oil and oxide layers from the surface of the raw materials.

[0028] Preferably, vacuum is drawn to 2×10 in S2. -3 Pa-3×10 -3 Pa, backfill with argon gas to 0.03-0.05 MPa to form an inert protective atmosphere; the current for arc melting is 280-320 A, and the melting time for each melting is 0.5-1.5 min.

[0029] Preferably, the stirring rate of the electromagnetic stirrer in S2 is 500 r / min to ensure uniform composition of the molten metal.

[0030] Preferably, the number of repeated electric arc melting in S3 is at least 5 times to ensure that all elements are fully mixed.

[0031] Preferably, it also includes a rolling process: rolling the as-cast AlCoCrFeNi obtained in S3. 2.1 The eutectic high-entropy alloy was treated at 1000℃ for 12 hours to eliminate internal stress in the as-cast structure and optimize the two-phase distribution. A 5mm thick plate was cut from the heat-treated as-cast eutectic high-entropy alloy, heated to 800℃ and held for 10 minutes to ensure uniform temperature throughout the plate, and then rolled until the plate thickness was 3mm. After holding for 10 minutes, the plate was removed and air-cooled to obtain the rolled eutectic high-entropy alloy.

[0032] Preferably, the rolling process is performed in 3-5 passes, with a total reduction of 2 mm for each pass and a reduction of 0.4-0.67 mm for each pass. The roll speed is 15-20 r / min.

[0033] Mechanical properties and resistance to hydrogen embrittlement of the eutectic high-entropy alloy of this invention: As-cast eutectic high-entropy alloy: In the uncharged state, tensile strength ≥947MPa, tensile strain ≥11.7%; after 24h of hydrogen charging, tensile strength ≥940MPa, tensile strain ≥8.5%, hydrogen embrittlement factor ≤26.09%; after 72h of hydrogen charging, tensile strength ≥901MPa, tensile strain ≥7.2%, hydrogen embrittlement factor ≤37.39%. The rolled eutectic high-entropy alloy of this invention has the following properties: in the uncharged state, tensile strength ≥1110MPa, tensile strain ≥12.77%; after 24h of hydrogen charging, tensile strength ≥1012MPa, tensile strain ≥10.92%, and hydrogen embrittlement factor ≤14.3%; after 72h of hydrogen charging, tensile strength ≥968MPa, tensile strain ≥7.8%, and hydrogen embrittlement factor ≤38.9%.

[0034] The above-mentioned high-strength, high-plasticity, hydrogen-embrittlement-resistant biphase eutectic high-entropy alloy is applied to key components of hydrogen energy equipment, including deep-sea hydrogen pipelines, high-pressure hydrogen storage containers, or seawater hydrogen production devices.

[0035] Example 1 This invention provides a high-strength, high-plasticity, and hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy prepared by the following method, comprising the following steps: S1. Select industrial-grade pure Al, Co, Cr, Fe, and Ni with a purity higher than 99.9 wt%, and prepare the raw materials according to the atomic ratio Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1. Clean the raw materials with anhydrous ethanol in an ultrasonic instrument for 5 minutes, dry them at 80℃, and then place them in a water-cooled copper crucible according to their melting points from low to high. Place Al and Ni at the bottom of the water-cooled copper crucible and Cr at the top. At the same time, place the Ti preform into the water-cooled copper crucible.

[0036] S2. Place the water-cooled copper crucible in a non-consumable vacuum arc melting furnace and evacuate it to a vacuum level of 3×10. -3 The pressure was increased to 0.05 MPa, then argon was backfilled to 0.05 MPa. The Ti preform was then subjected to arc melting in an argon atmosphere to remove residual oxygen from the furnace. The S1 raw material was then subjected to arc melting at a current of 300 A for 1.0 min per melting cycle, ensuring complete melting of the raw material into molten metal. Electromagnetic stirring was applied during the arc melting process at a stirring rate of 500 r / min. After melting, the material was cooled to obtain a button-shaped ingot sample.

[0037] S3. The button ingot sample obtained in S2 is subjected to five repeated electric arc melting processes. Before each electric arc melting process, the button ingot sample is flipped. After the electric arc melting is completed, it is cooled to room temperature to obtain as-cast AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0038] Example 2 This invention provides a high-strength, high-plasticity, and hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy prepared by the following method, comprising the following steps: S1. Select industrial-grade pure Al, Co, Cr, Fe, and Ni with a purity higher than 99.9 wt%, and prepare the raw materials according to the atomic ratio Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1. Clean the raw materials with anhydrous ethanol in an ultrasonic instrument for 5 minutes, dry them at 80℃, and then place them in a water-cooled copper crucible according to their melting points from low to high. Place Al and Ni at the bottom of the water-cooled copper crucible and Cr at the top. At the same time, place the Ti preform into the water-cooled copper crucible.

[0039] S2. Place the water-cooled copper crucible in a non-consumable vacuum arc melting furnace and evacuate it to a vacuum level of 3×10. -3 The pressure was increased to 0.05 MPa, then argon was backfilled to 0.05 MPa. The Ti preform was then subjected to arc melting in an argon atmosphere to remove residual oxygen from the furnace. The S1 raw material was then subjected to arc melting at a current of 300 A for 1.5 minutes each time, ensuring complete melting of the raw material into molten metal. Electromagnetic stirring was applied during the arc melting process at a stirring rate of 500 r / min. After melting, the material was cooled to obtain button-shaped ingot samples.

[0040] S3. The button ingot sample obtained in S2 is subjected to five repeated electric arc melting processes. Before each electric arc melting process, the button ingot sample is flipped. After the electric arc melting is completed, it is cooled to room temperature to obtain as-cast AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0041] S4. The as-cast AlCoCrFeNi obtained in S3 2.1 The eutectic high-entropy alloy was treated at 1000℃ for 12 hours to obtain the as-cast AlCoCrFeNi alloy after heat treatment. 2.1 A 5mm thick sheet was cut from a eutectic high-entropy alloy. The sheet was heated to 800℃ and held for 10 minutes, then rolled in 5 passes until the sheet thickness was 3mm. The total reduction for the multiple passes was 2mm, with a reduction of 0.4mm per pass. The roll speed was 15r / min. After holding at 800℃ for 10 minutes, the sheet was removed and air-cooled to obtain rolled AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0042] Example 3 This invention provides a high-strength, high-plasticity, and hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy prepared by the following method, comprising the following steps: S1. Select industrial-grade pure Al, Co, Cr, Fe, and Ni with a purity higher than 99.9 wt%, and prepare the raw materials according to the atomic ratio Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1. Clean the raw materials with anhydrous ethanol in an ultrasonic instrument for 5 minutes, dry them at 80℃, and then place them in a water-cooled copper crucible according to their melting points from low to high. Place Al and Ni at the bottom of the water-cooled copper crucible and Cr at the top. At the same time, place the Ti preform into the water-cooled copper crucible.

[0043] S2. Place the water-cooled copper crucible in a non-consumable vacuum arc melting furnace and evacuate it to a vacuum level of 2×10⁻⁶. -3 The pressure was increased to 0.03 MPa, then argon was backfilled to 0.03 MPa. The Ti preform was then subjected to arc melting in an argon atmosphere to remove residual oxygen from the furnace. The S1 raw material was then subjected to arc melting at a current of 280 A for 1.5 minutes each time, ensuring complete melting of the raw material into molten metal. Electromagnetic stirring was applied during the arc melting process at a stirring rate of 500 r / min. After melting, the material was cooled to obtain button-shaped ingot samples.

[0044] S3. The button ingot sample obtained in S2 is subjected to five repeated electric arc melting processes. Before each electric arc melting process, the button ingot sample is flipped. After the electric arc melting is completed, it is cooled to room temperature to obtain as-cast AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0045] S4. The as-cast AlCoCrFeNi obtained in S3 2.1 The eutectic high-entropy alloy was treated at 1000℃ for 12 hours to obtain the as-cast AlCoCrFeNi alloy after heat treatment. 2.1 A 5mm thick sheet was cut from a eutectic high-entropy alloy. The sheet was heated to 800℃ and held for 10 minutes, then rolled in four passes until the sheet thickness was 3mm. The total reduction for the multiple passes was 2mm, with a reduction of 0.5mm per pass. The roll speed was 20r / min. After holding at 800℃ for 10 minutes, the sheet was removed and air-cooled to obtain rolled AlCoCrFeNi. 2.1 Eutectic high-entropy alloy.

[0046] Performance testing The eutectic high-entropy alloys prepared in Examples 1-2 were subjected to XRD phase analysis, and the results are as follows: Figure 1 As shown, the eutectic high-entropy alloys obtained in Examples 1-2 all exhibit a two-phase structure of FCC and B2 phases. Rolling did not change their phase composition, but the intensity of the FCC phase diffraction peaks increased, indicating that the FCC phase underwent preferred orientation during the rolling process.

[0047] The eutectic high-entropy alloys obtained in Examples 1-2 were subjected to SEM scanning to characterize their microstructure. The compositional distribution in different regions of the rolled eutectic high-entropy alloy obtained in Example 2 was tested using EDS, and the results are as follows: Figure 2 As shown in the figure, the dark and bright areas are represented by A and B, respectively. EDS analysis results indicate that phase A is rich in Co, Cr, and Fe elements, and poor in Al and Ni elements, while phase B is rich in Ni and Al elements. Combined with... Figure 1 The XRD results show that phase A has an FCC phase (face-centered cubic structure) and phase B is an Al and Ni-rich B2 phase (ordered body-centered cubic structure). The microstructure after rolling still maintains the two-phase composition.

[0048] Figure 3 (a) and Figure 3 Image (b) shows the microstructure of the eutectic high-entropy alloys prepared in Examples 1-2 before hydrogen charging. Both the cast and rolled eutectic high-entropy alloys exhibit eutectic cell morphology, with each eutectic cell consisting of alternating layers of FCC phase (dark) and B2 phase (bright). Multiple planar B2 phases are present at the center of the eutectic cell, and the lamellar thickness increases at the cell boundaries. The B2 phase, acting as a strengthening phase, is uniformly distributed within the FCC phase and provides strength support through dislocation resistance. The FCC phase possesses good plasticity, which can alleviate stress concentration in the B2 phase under stress, avoiding the problems of a single-phase structure being either too strong and brittle or too tough and weak.

[0049] Figure 3 (c) and Figure 3 (d) shows the microstructure of the eutectic high-entropy alloys prepared in Examples 1-2 after hydrogen charging for 72 hours. The microstructure of the cast and rolled eutectic high-entropy alloys showed significant changes, with hydrogen-induced microstructure distortion and slight interphase corrosion at the FCC / B2 phase interface. However, the overall phase composition remained unchanged.

[0050] The mechanical response differences of the eutectic high-entropy alloys prepared in Examples 1-2 under conditions of no hydrogen charging (0h), hydrogen charging for 24h, and hydrogen charging for 72h were tested. Tensile tests were completed within 5 minutes after hydrogen charging, and the hydrogen charging current density was 30mA / cm during the tensile performance test. 2 The stretching speed was 0.6 mm / min. A 0.5 mol / L H₂SO₄ solution and 2 g / L CS(NH₂)₂ were used as poisoning agents to promote the entry of hydrogen atoms. The results are shown in [Figure number missing]. Figure 4 .

[0051] Depend on Figure 4As shown in (a), the as-cast eutectic high-entropy alloy has a tensile strength of 947 MPa and a tensile strain of 11.7% in the uncharged state. After 24 h and 72 h of hydrogen charring, the tensile strengths are 940 MPa and 901 MPa, respectively, with tensile strains of 8.5% and 7.2%, and hydrogen embrittlement factors of 26.09% and 37.39%, respectively. Figure 4 As can be seen from (b) in the figure, the rolled AlCoCrFeNi 2.1 The mechanical properties of the eutectic high-entropy alloy are significantly improved. The tensile strength without hydrogen embrittlement is 1110 MPa with a tensile strain of 12.77%. After 24 h and 72 h of hydrogen embrittlement, the tensile strengths are 1231 MPa and 1165 MPa, respectively, with tensile strains of 10.92% and 7.8%, and hydrogen embrittlement factors of 14.3% and 38.9%, respectively. Compared to the as-cast alloy, rolling further improves the properties of AlCoCrFeNi. 2.1 The mechanical properties of the eutectic high-entropy alloy are improved, and its resistance to hydrogen embrittlement is reduced.

[0052] Prolonged high-current-density hydrogen purging (72h) leads to irreversible hydrogen damage (micropores and fine cracks) and corrosion on the alloy surface, resulting in geometric softening. This explains the slight decrease in the tensile strength of the alloy after 72h. The electrochemical corrosion behavior of the as-cast eutectic high-entropy alloy prepared in Example 1 under simulated marine environment was investigated, and the potentiodynamic polarization curves are shown below. Figure 5 As shown, it exhibits good corrosion resistance in 3.5wt% NaCl solution, with a self-corrosion potential (Ecorr) of -0.248V and a corrosion current density (Icorr) of 0.0902μA.

[0053] The fractured samples after tensile testing—namely, as-cast eutectic high-entropy alloy tensile specimens after non-hydrogen charging, hydrogen charging for 24 hours, and hydrogen charging for 72 hours—were subjected to electron microscopy to characterize the as-cast AlCoCrFeNi alloy. 2.1 SEM morphology of the fracture surface of the eutectic high-entropy alloy before and after hydrogen charging, the results are as follows: Figure 6 As shown, the fracture surface of the uncharged hydrogen alloy exhibits a uniform dimple morphology, indicating that AlCoCrFeNi 2.1 The eutectic high-entropy alloy underwent uniform plastic deformation during stretching. After hydrogen charging, AlCoCrFeNi... 2.1 The fracture morphology of the eutectic high-entropy alloy exhibits a gradient change, which is due to the gradient change in hydrogen concentration across the cross-section after hydrogen charging. Furthermore, the dimple morphology changes after hydrogen charging, with the dimples becoming shallower and smaller. The results show that the fracture characterization does not reveal hydrogen-induced embrittlement, only changes in dimple size and morphology; hydrogen charging has almost no effect on strength, and the fracture strength remains above 900 MPa. This indicates that AlCoCrFeNi... 2.1 It exhibits low sensitivity to hydrogen.

[0054] Tensile specimens of rolled eutectic high-entropy alloys, including those without hydrogen charging, hydrogen-charged for 24 hours, and hydrogen-charged for 72 hours, were characterized by electron microscopy scanning to characterize the rolled AlCoCrFeNi alloy. 2.1 SEM morphology of the fracture surface of the eutectic high-entropy alloy before and after hydrogen charging, the results are shown in [Figure number missing]. Figures 7-8 As shown, Figure 7 As shown, the fracture surface of the rolled alloy exhibits an elongated dimple fracture morphology, and the fracture surface is relatively smooth. This fracture formation is attributed to the elongation of the alloy grains due to rolling deformation and changes in the internal texture of the alloy. The rolled AlCoCrFeNi alloy after 24 hours of hydrogen charging... 2.1 The tensile fracture surface of the eutectic high-entropy alloy showed significant changes, primarily manifested as inhomogeneity of dimples. Some areas formed larger dimples, while others formed smaller, aggregated micropores, approximately 0.5 μm in size. The typical dimple morphology of the rolled state disappeared, transforming into micropore aggregate regions at the edges. This was caused by local dislocation pinning, a mechanism that allows hydrogen to promote dislocation pinning, ultimately hindering the formation of larger dimples. Regarding overall deformation, hydrogen charging reduced the uniformity of the alloy's deformation, leading to premature fracture. After 72 hours of hydrogen charging, the tensile fracture surface showed partial micropore aggregate regions, with quasi-cleavage morphology observed at the edges. The results indicate that the rolled AlCoCrFeNi alloy after hydrogen charging... 2.1 The fracture surface still maintains the fracture mode dominated by ductile fracture. No obvious embrittlement region was observed. Furthermore, compared to the as-cast state, its strength increased by more than 200 MPa, and it is superior to the as-cast AlCoCrFeNi in both strength and ductility. 2.1 Matrix.

[0055] like Figure 8 As shown, AlCoCrFeNi near the edge in both cast and rolled states 2.1 The fracture morphology of eutectic high-entropy alloys shows that the as-cast state mainly exhibits uniform equiaxed dimples, with no significant difference from the internal fracture surface. However, the rolled state fracture surface shows elongated dimples and some equiaxed dimples, neither of which shows uneven dimple distribution due to inhomogeneous plastic deformation. This indicates that rolling alters the banded orientation distribution of the two phases (such as FCC / L12 and BCC / B2) along the rolling direction (RD), forming a texture. While this improves strength (tensile and yield strength) in the rolling direction, the uniformity of plastic deformation may decrease due to texture limitations. Furthermore, the transverse (TD) properties are significantly weaker than those in the rolling direction.

[0056] Therefore, the present invention adopts the above-mentioned high-strength, high-plasticity, hydrogen-resistant dual-phase eutectic high-entropy alloy, its preparation method and application. The resulting dual-phase eutectic high-entropy alloy has high strength, plasticity and hydrogen resistance. At the same time, the preparation method is simple and reliable, and can be considered for application in hydrogen-resistant components that need to withstand high stress, such as high-pressure hydrogen storage containers, seawater hydrogen production devices and deep-sea hydrogen pipelines.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A high-strength high-ductility hydrogen embrittlement resistant dual-phase eutectic high-entropy alloy, characterized in that: The eutectic high-entropy alloy is a dual-phase structure composed of an FCC phase and a B2 phase, wherein the FCC phase is rich in Co, Cr and Fe elements, and the B2 phase is rich in Al and Ni elements, the atomic ratio of each element in the eutectic high-entropy alloy is Al:Co:Cr:Fe:Ni = 1:1:1:1:2.1, and the general formula of the eutectic high-entropy alloy is AlCoCrFeNi 2.1 .

2. The preparation method of the high-strength high-plasticity hydrogen embrittlement resistant dual-phase eutectic high-entropy alloy according to claim 1, characterized in that: Comprising the following steps: S1, configure raw materials according to the atomic ratio Al:Co:Cr:Fe:Ni=1:1:1:1:2.1, clean the raw materials with anhydrous ethanol in an ultrasonic instrument, and place them in a water-cooled copper crucible according to the melting point from low to high after drying; S2, place the water-cooled copper crucible in a non-consumable vacuum arc melting furnace, perform vacuum pumping, then reverse charge argon, arc melt the Ti preform under the argon environment, remove the residual oxygen inside the furnace body, then arc melt the raw materials of S1 to completely melt the raw materials into a metal liquid, apply electromagnetic stirring during the arc melting process, cool to obtain a button ingot sample after the melting is completed; S3, the button ingot sample obtained in S2 is repeatedly arc melted for multiple times, the button ingot sample is turned over before each arc melting, and is cooled to room temperature after the arc melting is completed, to obtain as-cast AlCoCrFeNi 2.1 eutectic high-entropy alloy.

3. The method for preparing a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy according to claim 2, characterized in that: In S1, Al, Co, Cr, Fe and Ni are all selected from industrial-grade pure raw materials with a purity higher than 99.9wt%, wherein Al and Ni are placed at the bottom of the water-cooled copper crucible, and Cr is placed at the top of the water-cooled copper crucible.

4. The method for preparing a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy according to claim 2, characterized in that: In S1, the cleaning time is 5min, the drying temperature is 80℃, and the drying time is 10min.

5. The method for preparing a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy according to claim 2, characterized in that: S2 vacuum to 2 x 10 -3 Pa-3 x 10 -3 Pa, backfilled with argon to 0.03-0.05 MPa, the current for arc melting was 280-320 A, and the time for each melting was 0.5-1.5 min.

6. The method for preparing a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy according to claim 2, characterized in that: In S2, the stirring rate of electromagnetic stirring is 500r / min.

7. The method for preparing a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy according to claim 2, characterized in that: In S3, the number of repeated arc melting is at least 5 times.

8. The method for preparing a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy according to claim 2, characterized in that: Also included is a rolling treatment step: the as-cast AlCoCrFeNi 2.1 eutectic high-entropy alloy is treated at 1000℃ for 12h, and the as-cast AlCoCrFeNi 2.1 eutectic high-entropy alloy is cut into a plate with a thickness of 5mm, the plate is heated to 800℃ and kept for 10min, the plate is subjected to a rolling treatment until the thickness of the plate is 3mm, then kept for 10min, taken out and air-cooled to obtain the rolled AlCoCrFeNi 2.1 eutectic high-entropy alloy.

9. The method for preparing a high-strength, high-plasticity, hydrogen-embrittlement-resistant dual-phase eutectic high-entropy alloy according to claim 8, characterized in that: The rolling treatment is divided into 3-5 passes, the total reduction of multi-pass rolling is 2mm, the reduction of each pass is 0.4-0.67mm, and the roller rotation speed is 15-20r / min.

10. The use of a high-strength high-ductility hydrogen embrittlement resistant dual-phase eutectic high-entropy alloy according to claim 1, characterized in that: It is applied to hydrogen energy equipment key components, and the hydrogen energy equipment key components include deep-sea hydrogen delivery pipeline, high-pressure hydrogen storage container or seawater hydrogen production device components.

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