Near-eutectic high-entropy alloy material combined with subzero treatment, preparation method and subzero treatment device

Abstract

The invention relates to a preparation method of a near-eutectic high-entropy alloy material combined with subzero treatment, which comprises the following steps: smelting, coating an Al elementary substance with Ni foil, placing the coated Al elementary substance in a Fe capsule shell, placing the Fe capsule shell on a crucible, uniformly covering the Fe capsule shell with the residual mass of Cr elementary substance, Fe elementary substance, Co elementary substance and Ni elementary substance in a layered manner according to the melting points from high to low, and carrying out heat treatment to obtain the near-eutectic high-entropy alloy material combined with subzero treatment. Performing vacuum arc melting under protective gas to obtain an initial alloy ingot; and subzero treatment is conducted, specifically, the initial alloy cast ingot is firstly cooled to the temperature range of-116 DEG C to 96 DEG C at the preset cooling rate and then soaked in liquid nitrogen, subzero treatment is conducted, and the alloy with the improved performance is obtained in combination with bottom ultrasonic vibration. The method has the advantages that elements easy to burn out are smelted after being subjected to a double-layer coating method, and element burning loss is obviously reduced; and the use of the ultrasonic vibration device is easier to realize dislocation-precipitated phase synergistic reinforcement.

Description

Technical Field

[0001] This application belongs to the field of high-entropy alloy materials, specifically relating to a near-eutectic high-entropy alloy material combined with cryogenic treatment, its preparation method, and a cryogenic treatment apparatus. Background Technology

[0002] High-entropy alloys are alloys formed by five or more metals in equal or approximately equal molar amounts. Compared with traditional alloys, high-entropy alloys have advantages such as high strength and hardness, good fracture resistance, corrosion resistance, and excellent oxidation resistance. However, most face-centered cubic (FCC) high-entropy alloys have good plasticity but low strength, while body-centered cubic (BCC) high-entropy alloys have high strength but low plasticity. Obtaining high-entropy alloys that combine high strength, high toughness, and excellent overall performance remains a challenge in high-entropy alloy research.

[0003] Traditional methods for preparing high-entropy alloy materials, such as obtaining them through rolling processes, may result in unstable nanocrystalline structures, leading to poor plastic deformation capabilities and thus limiting the application of high-entropy alloy materials.

[0004] Among existing methods, isothermal heat treatment of high-entropy alloys refines the grain size through traditional isothermal treatment followed by quenching. This method can increase the hardness of high-entropy alloys, but it sacrifices their plasticity. For example, Chinese invention patent application CN114214579A discloses an isothermal heat treatment method for high-entropy alloys. This method refines the grain size through traditional isothermal treatment followed by quenching, which can increase the hardness of the material, but it significantly reduces the material's plasticity.

[0005] Furthermore, near-eutectic high-entropy alloys are a newly developed multi-principal-element alloy system in recent years, possessing intentional casting fluidity and rich compositional and structural variation characteristics. They offer ample space for microstructure and performance control and provide a regularly arranged lamellar microstructure basis for the successful preparation of in-situ composite materials. Although only a few near-eutectic high-entropy alloy systems have received widespread attention, researchers in this field have achieved significant results due to their enormous potential performance. Studies have shown that preparing ultrafine-grained dual-phase microstructures using cold rolling and annealing processes can effectively strengthen near-eutectic high-entropy alloys; however, some limitations exist. Traditional deformation strengthening methods, such as introducing dislocation density, often lead to a significant reduction in plasticity. In addition, while near-eutectic high-entropy alloys with nanostructures obtained at liquid nitrogen temperatures through rolling processes exhibit high strength, they are not suitable for industrial production and may lead to unstable nanocrystalline structures and poor plastic deformation capabilities. These problems severely limit the application of this material in load-bearing critical components. Therefore, there is an urgent need to propose a near-eutectic high-entropy alloy material and a near-eutectic high-entropy alloy material combined with cryogenic treatment, as well as its preparation method. Summary of the Invention

[0006] Purpose of the invention The purpose of this invention is to provide a near-eutectic high-entropy alloy material, preparation method, and deep cryogenic treatment apparatus that combine cryogenic treatment, so as to solve the problem that the near-eutectic high-entropy alloy material prepared by the existing preparation method has poor mechanical properties.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, this application provides a cryogenic treatment apparatus for near-eutectic high-entropy alloys, comprising: an ultrasonic vibration platform, a lifting device, a support, a temperature-controlled cryogenic chamber, a liquid nitrogen device, and an ultrasonic vibration device, wherein the ultrasonic vibration platform is provided with a reserved hole for an ultrasonic vibration rod. The temperature-controlled cryogenic chamber is disposed on the upper surface of the ultrasonic vibration platform. The interior of the temperature-controlled cryogenic chamber is divided into an upper chamber and a lower chamber by a horizontally arranged double-opening partition. The double-opening partition is slidably connected to the inner wall of the temperature-controlled cryogenic chamber. The bracket is installed on the outside of the temperature-controlled cryogenic chamber; The lifting device includes a motor, a drive wheel, a fixed pulley, a low-temperature resistant stainless steel wire rope, and a sample box. The motor is mounted on a support, and a connecting shaft is mounted on the drive shaft of the motor, extending into the upper chamber. The drive wheel is located at the end of the connecting shaft extending into the upper chamber. The fixed pulley is located inside the upper chamber and is positioned above the drive wheel. One end of the low-temperature resistant stainless steel wire rope is wound around the groove of the drive wheel, and the other end is wound around the fixed pulley, then passes through the double-opening partition and extends downwards to be fixedly connected to the top of the sample box. The sample box can be raised and lowered between the upper and lower chambers of the temperature-controlled cryogenic chamber by the drive wheel driven by the motor and by the low-temperature resistant stainless steel wire rope. The liquid nitrogen device includes a liquid nitrogen storage unit, a valve, a delivery pipeline, and a flow meter. The liquid nitrogen storage unit is located outside the ultrasonic vibration platform. One end of the delivery pipeline is connected to the liquid nitrogen storage unit through the valve, and the other end of the delivery pipeline extends into the lower chamber. The flow meter is located on the delivery pipeline. The ultrasonic vibration assembly includes an ultrasonic vibration rod and an adjustment base. The top end of the ultrasonic vibration rod passes through the platform and the reserved hole of the ultrasonic vibration rod and is tightly fitted to the bottom of the temperature-controlled cryogenic chamber. The bottom end of the ultrasonic vibration rod is connected to the adjustment base.

[0008] A method for preparing near-eutectic high-entropy alloy materials combined with cryogenic treatment includes: Melting: In a protective gas environment, a double-layer coating method is used to perform vacuum arc melting on raw materials such as Al, which have low melting points and are easily burned. After heating and melting, the materials are water-cooled in a protective gas environment to obtain an initial alloy ingot. Deep cryogenic treatment involves first cooling the initial alloy ingot to a temperature range of -116℃ to -96℃ at a predetermined cooling rate, then immersing it in liquid nitrogen, and combining this with a bottom ultrasonic vibration rod to perform deep cryogenic treatment, thereby obtaining a near-eutectic high-entropy alloy material with improved performance.

[0009] Furthermore, the preparation method involves first melting high-melting-point metals to form an alloy, then lowering the overall melting point, and finally melting the bottom capsule shell to reduce the burn-off of low-melting-point elements. The double-layer coating method involves first placing the Al elemental particles coated with Ni foil inside an Fe capsule shell on a crucible, and then uniformly layering the remaining Cr, Fe, Co, and Ni elements onto the Fe capsule shell according to their melting points from high to low.

[0010] Furthermore, in the double-layer coating method, the volume of each Fe capsule shell is 100 mm². 3 Up to 220mm 3 The volume of the Ni foil-coated Al sphere is 45 mm².3 Up to 100mm 3 .

[0011] Furthermore, in the melting step, a non-consumable vacuum arc furnace is used to melt the material, and the working pressure range of the melting is 0.04 Pa to 0.05 Pa; the vacuum degree range of the vacuuming stage of the melting is 7.5 × 10⁻⁶. -4 Pa ~ 8.5 × 10 -4 Pa; the melting current range is 75A~500A, the current rise and fall rate is 80A / min~100A / min, after the melting current reaches 300A, the electromagnetic stirring power supply is turned on until the single melting of the alloy ingot is completed, the electromagnetic stirring is turned off, and the electromagnetic stirring speed is controlled at 10-18rpm; the melting time for each ingot on one side is 300s~500s; after the melting step and before the cryogenic treatment step, it also includes: repeated melting, repeating the melting of the initial alloy ingot n times, where n is not less than 2 and n is not greater than 6.

[0012] Further, in the cryogenic treatment step, firstly, the top cover of the temperature-controlled cryogenic chamber is opened, the motor is started to raise the sample box along the steel wire rope to the highest point, and then the motor is turned off; the high-entropy alloy sample to be treated is placed into the sample box, and the top cover of the temperature-controlled cryogenic chamber is closed; the heating resistance wire is turned on to control the amount of liquid nitrogen evaporating from the liquid nitrogen box in order to control the cooling rate, and after the temperature reaches the set temperature, the heating resistance wire is turned off, and the gas pressure is adjusted and balanced; the motor is started to raise the sample box along the steel wire rope through the double-opening partition to the bottom of the temperature-controlled cryogenic chamber, and then... Start the ultrasonic vibrator, open the valve to introduce liquid nitrogen and observe the flow meter reading. Control the amount of liquid nitrogen added, then close the valve. At this point, start recording the cryogenic time. After the cryogenic treatment is completed, turn off the ultrasonic vibrator and start the motor to make the sample box pass through the double-opening partition along the steel wire rope to reach the highest point inside the temperature-controlled cryogenic chamber. Turn on the heating resistance wire to control the amount of liquid nitrogen evaporating from the liquid nitrogen box. After the temperature reaches the specified temperature, turn off the heating resistance wire, open the top cover of the temperature-controlled cryogenic chamber, take out the sample, and wipe the surface with a non-woven cloth. This completes the entire cryogenic treatment process.

[0013] Furthermore, in the cryogenic treatment step, the predetermined cooling rate is 8℃ / min~12℃ / min. After the temperature drops to the range of -116℃~-96℃, it is immersed in liquid nitrogen in a cryogenic chamber for cryogenic treatment. After the cryogenic treatment step is completed, the temperature is raised to the range of 20℃~25℃ at a heating rate of 8℃ / min~12℃ / min to obtain the near-eutectic high-entropy alloy material.

[0014] Furthermore, in the cryogenic treatment step, a 20000Hz ultrasonic vibration rod is used. The ultrasonic vibration rod is fixed on the base. By adjusting the height of the base, the ultrasonic vibration rod passes through the ultrasonic vibration rod pre-drilled hole in the middle of the platform and the support, and fits tightly against the bottom of the temperature-controlled cryogenic chamber. The cryogenic treatment time range is 10h~240h.

[0015] A near-eutectic high-entropy alloy material, wherein the near-eutectic high-entropy alloy material is prepared by the preparation method of any one of claims 2 to 8; the near-eutectic high-entropy alloy material comprises Al, Co, Cr, Fe and Ni elements in a molar ratio of 1:1:1:1:2.0 to 2.2; the near-eutectic high-entropy alloy material has a two-phase structure with 70% to 75% face-centered cubic phase and 25% to 30% body-centered cubic phase.

[0016] Advantages and effects of the present invention: 1. The preparation method described in this application involves first melting high-melting-point metals to form an alloy → lowering the overall melting point → then melting the bottom capsule shell → reducing the burn-off of low-melting-point elements. The double-layer coating method refers to first placing Al particles coated with Ni foil inside an Fe capsule shell on a crucible, then uniformly placing the remaining Cr, Fe, Co, and Ni elements on the Fe capsule shell according to their melting points from highest to lowest, significantly reducing the Al element loss rate. Simultaneously, electromagnetic stirring is activated during melting, combined with water cooling, which reduces the dendrite spacing of the initial alloy ingot, lowers the elemental segregation index, and increases the microstructure density, providing a uniform matrix for cryogenic treatment.

[0017] 2. This application proposes a novel strategy for achieving synergistic dislocation-precipitation strengthening in near-eutectic high-entropy alloys by controlling the heating and cooling rates and performing ultrasonic vibration before cryogenic treatment, thereby generating a wider range of dislocations. This has certain reference value for broadening effective means of non-destructively strengthening the mechanical properties of high-entropy alloy ingots.

[0018] 3. This application promotes the increase of dislocation density and the number of nano-precipitates through cryogenic treatment at low temperatures. Moreover, cryogenic treatment can further refine the grains and reduce element segregation, making the distribution of each element in the near-eutectic high-entropy alloy material more uniform, thus obtaining a near-eutectic high-entropy alloy material with FCC and BCC dual-phase structure, and improving the mechanical properties of the near-eutectic high-entropy alloy material.

[0019] 4. This application utilizes an ultrasonic vibration device installed at the bottom of the cryogenic treatment chamber to increase dislocation density and promote the formation of precipitated phases. Compared to placing a vibrating rod inside the cryogenic chamber, there is no air leakage problem at the interface. Attached Figure Description

[0020] Figure 1 This is a schematic diagram illustrating the double-layer coating method used for raw materials in a method for preparing a near-eutectic high-entropy alloy material provided in this application embodiment; Figure 2 This is a schematic diagram of the cryogenic processing equipment according to an embodiment of this application; Figure 3 This is a schematic diagram of the internal structure of the cryogenic processing equipment according to an embodiment of this application; Figure 4 This is a schematic diagram of the transmission device structure according to an embodiment of this application; Figure 5 This is a schematic diagram of a double-opening partition structure according to an embodiment of this application; Figure 6 This is a transmission electron microscope (TEM) image of the near-eutectic high-entropy alloy material obtained in Example 1 of this application; Figure 7 This is a transmission electron microscope (TEM) image of the near-eutectic high-entropy alloy material obtained in Example 2 of this application; Figure 8 This is a graph showing the relationship between temperature and time in some embodiments of the cryogenic treatment in this application; Figure 9 The mechanical properties of the near-eutectic high-entropy alloy material obtained in Example 1 of this application and the near-eutectic high-entropy alloy obtained in Comparative Example 1 are shown in the diagram. Figure 10 The mechanical properties of the near-eutectic high-entropy alloy material obtained in Example 2 of this application and the near-eutectic high-entropy alloy obtained in Comparative Example 1 are shown in the diagram.

[0021] Figure 1 The labels are as follows: 1, Fe capsule shell; 101, Al element; 102, Ni foil; Figure 2 The components are labeled as follows: 2. Ultrasonic vibration platform; 3. Lifting device; 4. Temperature-controlled cryogenic chamber; 407. Double-leaf partition; 406. Control panel and temperature gauge; 5. Liquid nitrogen device; 6. Ultrasonic vibration device. Figure 3 The components are labeled as follows: 201, fixed bracket; 202, reserved hole for ultrasonic vibrating rod; 401, top cover; 402, pressure relief valve; 403, top cover lock; 404, liquid nitrogen box; 405, resistance wire; 501, liquid nitrogen tank; 502, valve; 503, flow meter; 504, delivery pipeline; 601, ultrasonic vibrating rod; 602, base; Figure 4 The labels are as follows: 301, electric motor; 302, control power supply; 303, fixed pulley; 304, low-temperature resistant stainless steel wire rope; 305, sample box; 306, high-entropy alloy sample.

[0022] Figure 5 The markings are as follows: 408, wire rope reserved hole; 409, handle. Detailed Implementation

[0023] 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.

[0024] All the following raw materials mentioned in this application are commercially available products and are intended to fully disclose the raw materials in this application. They should not be construed as limiting the source of the raw materials.

[0025] A cryogenic treatment device for near-eutectic high-entropy alloys includes: an ultrasonic vibration platform 2, a lifting device 3, a support 201, a temperature-controlled cryogenic chamber 4, a liquid nitrogen device 5, and an ultrasonic vibration device 6. The ultrasonic vibration platform 2 is provided with a reserved hole 202 for an ultrasonic vibration rod. The temperature-controlled cryogenic chamber 4 is located on the upper surface of the ultrasonic vibration platform 2. An operation panel and a thermometer 406 are located on the outside of the chamber to display the internal temperature and cryogenic time in real time, and to control the start / stop and parameter adjustment of the equipment. The interior of the temperature-controlled cryogenic chamber 4 is divided into an upper chamber and a lower chamber by a horizontally arranged double-leaf partition 407. The double-leaf partition 407 is slidably connected to the inner wall of the temperature-controlled cryogenic chamber 4. To accommodate the lifting and lowering movement of the sample box 305, the double-leaf partition 407 has a wire rope pre-drilled hole 408 corresponding to the lifting path of the sample box 305. The diameter of the wire rope pre-drilled hole 408 is compatible with the diameter of the low-temperature resistant stainless steel wire rope 304. Additionally, a handle 409 is fixedly installed on the outer edge of the double-leaf partition 407, allowing the operator to manually control the opening and closing of the double-leaf partition 407 by pulling the handle 409, thus improving the ease of operation of the equipment.

[0026] The bracket 201 is installed on the outside of the temperature-controlled cryogenic chamber 4; The lifting device 3 includes a motor 301, a drive wheel, a fixed pulley 303, a low-temperature resistant stainless steel wire rope 304, and a sample box 305. The motor 301 is mounted on the bracket 201 and has a control power supply 302. A connecting shaft is mounted on the drive shaft of the motor 301, extending into the upper chamber. Specifically, the connection between the connecting shaft and the side wall of the temperature-controlled cryogenic chamber 4 is sealed with a seal. The drive wheel is located at the end of the connecting shaft that extends into the upper chamber. The fixed pulley 303 is... The sample box 305 is placed in the upper chamber, with the fixed pulley 303 located above the drive wheel. One end of the low-temperature resistant stainless steel wire rope 304 is wound around the groove of the drive wheel, and the other end of the low-temperature resistant stainless steel wire rope 304 is wound around the fixed pulley 303. It then passes through the double-opening partition 407 and extends downward to be fixedly connected to the top of the sample box 305. The sample box 305 can be raised and lowered between the upper and lower chambers of the temperature-controlled cryogenic chamber 4 by the drive wheel driven by the motor 301 and by the low-temperature resistant stainless steel wire rope 304. The liquid nitrogen device 5 includes a liquid nitrogen storage unit 501, a valve 502, a delivery pipeline 504, and a flow meter 503. The liquid nitrogen storage unit 501 is located on the outside of the ultrasonic vibration platform 2. One end of the delivery pipeline 504 is connected to the liquid nitrogen storage unit 501 through the valve 502, and the other end of the delivery pipeline 504 extends into the lower chamber. The flow meter 503 is installed on the delivery pipeline 504. The ultrasonic vibration assembly 6 includes an ultrasonic vibration rod 601 and an adjusting base 602. The top end of the ultrasonic vibration rod 601 passes through the platform 1 and the ultrasonic vibration rod pre-drilled hole 202 and is tightly fitted to the bottom of the temperature-controlled cryogenic chamber 4. The bottom end of the ultrasonic vibration rod 601 is connected to the adjusting base 602. Specifically, the adjusting base 602 is a screw adjustment structure, including a fixed seat, a lifting screw, and a locking nut. By rotating the lifting screw, the vertical height of the ultrasonic vibration rod 601 is changed, so that the ultrasonic vibration rod 601 passes through the ultrasonic vibration rod pre-drilled hole 202 between the platform and the support 2 and is tightly fitted to the bottom of the temperature-controlled cryogenic chamber 4.

[0027] Embodiments of this application provide a near-eutectic high-entropy alloy material combined with cryogenic treatment and a method for preparing the same. The method for preparing the near-eutectic high-entropy alloy material includes: S1, Melting: Under a protective gas environment, a double-layer coating method is used for vacuum arc melting of raw materials such as Al, which have low melting points and are easily burned. After heating and melting, the mixture is water-cooled under a protective gas environment to obtain an initial alloy ingot. In the double-layer coating method, the volume of each Fe capsule shell 1 is 100 mm². 3 Up to 220mm 3 The volume of the sphere of Al 101 coated with Ni foil 102 is 45 mm². 3 Up to 100mm 3 This minimizes the loss rate of Al elements. S2, cryogenic treatment: The initial alloy ingot is first cooled to a temperature range of -116℃ to -96℃ at a predetermined cooling rate, and then immersed in liquid nitrogen. Combined with the bottom ultrasonic vibration rod 601, cryogenic treatment is carried out at a temperature of -196℃ to obtain a near-eutectic high-entropy alloy material with improved performance.

[0028] For example, the temperature before cryogenic treatment can be -116℃, -110℃, -100℃, -96℃, etc., and there is no limit here.

[0029] In the S1 smelting process, under a protective gas environment (such as argon), particles of Al 101 coated with Ni foil 102 are first placed inside Fe capsule shell 1 and then placed on a crucible. The remaining mass of Cr, Fe, Co, and Ni are then evenly layered and covered on the Fe capsule shell 1 according to their melting points from high to low. Al has a low melting point, while Co, Cr, Fe, and Ni have high melting points that are very close to each other. The boiling point of Al is close to the melting points of Co, Cr, Fe, and Ni. Directly mixing them together for smelting would result in significant loss of Al 101. Placing particles of Al 101 coated with Ni foil 102 inside Fe capsule shell 1 can reduce the loss of Al during the smelting process. Using this method, the ingots cast after smelting in a non-consumable vacuum arc furnace show no significant segregation and have a dense microstructure.

[0030] S2 cryogenic treatment involves first cooling the initial alloy ingot to a temperature range of -116℃ to -96℃ at a certain cooling rate, then immersing it in liquid nitrogen. Combined with the bottom ultrasonic vibration rod 601, cryogenic treatment is carried out at a temperature of -196℃ (77K). The ultrasonic vibration will increase the dislocation density at low temperature, making it easier to meet the conditions for dislocation formation. The number of nano-precipitates increases during immersion in liquid nitrogen. Moreover, cryogenic treatment can further refine the grains and reduce element segregation, making the distribution of each element in the near-eutectic high-entropy alloy material more uniform. This results in a near-eutectic high-entropy alloy material with a dual-phase structure of FCC and BCC, which improves the mechanical properties of the near-eutectic high-entropy alloy material.

[0031] The above preparation method involves first melting high-melting-point metals to form an alloy, then lowering the overall melting point, and then melting the bottom capsule shell to reduce the burn-off of low-melting-point elements. The double-layer coating method involves first coating Al element 101 with Ni foil 102 to form particles, placing them inside Fe capsule shell 1, and then placing them on a crucible. The remaining mass of Cr element, Fe element, Co element and Ni element are then uniformly layered and coated on the Fe capsule shell 1 according to their melting points from high to low.

[0032] In the above-mentioned cryogenic treatment, firstly, the top cover 401 of the temperature-controlled cryogenic chamber 4 is opened, and the motor 301 is started to raise the sample box 305 to its highest point along the low-temperature resistant stainless steel wire rope 304 (specifically, the low-temperature resistant stainless steel wire rope 304 is a steel wire rope). Then, the motor 301 is turned off. The high-entropy alloy sample 306 to be treated is placed into the sample box 305, the top cover 401 of the temperature-controlled cryogenic chamber 4 is closed, and the top cover lock 403 is tightened. The heating resistance wire 405 is turned on to control the amount of liquid nitrogen evaporating from the liquid nitrogen box 404, so that... Control the cooling rate, and turn off the heating resistance wire 405 after the temperature reaches the set temperature. The pressure relief valve 402 can automatically adjust the balance gas pressure. Start the motor 301 to make the sample box 305 pass through the double-opening partition 407 along the steel wire rope to the bottom of the temperature-controlled cryogenic chamber 4. Turn on the ultrasonic vibration rod 601, open the valve 502 to introduce liquid nitrogen and observe the reading of the flow meter 503. Control the amount of liquid nitrogen added according to the number of samples. After the amount of liquid nitrogen added reaches the predetermined value, close the valve 502. At this time, start recording the cryogenic time. After the cryogenic treatment is completed for the predetermined time, the ultrasonic vibration rod 601 is turned off, and the motor 301 is started to make the sample box 305 pass through the double-opening partition 407 along the steel wire rope to reach the highest point inside the temperature-controlled cryogenic chamber 4; the heating resistance wire 405 is turned on to control the amount of liquid nitrogen evaporating in the liquid nitrogen box 404 in order to control the heating rate; after the temperature reaches the specified temperature, the heating resistance wire 405 is turned off, the top cover 401 of the temperature-controlled cryogenic chamber 4 is opened and the sample is taken out, and the surface is wiped with non-woven cloth. The entire cryogenic treatment process is now complete.

[0033] For example, such as Figure 4 The graph shown shows the relationship between temperature and time in S2 cryogenic treatment. The horizontal axis represents the time of cryogenic treatment, and the vertical axis represents the temperature of cryogenic treatment.

[0034] In some embodiments, the S2 cryogenic treatment includes: cooling the initial alloy ingot in a temperature-controlled cryogenic chamber 4 at a cooling rate of 8°C / min to 12°C / min to a temperature range of -116°C to -96°C, and then immersing it in liquid nitrogen in the lower chamber of the temperature-controlled cryogenic chamber 4 for cryogenic treatment; after the cryogenic treatment step is completed, heating the ingot at a heating rate of 8°C / min to 12°C / min to a temperature range of 20°C to 25°C to obtain a near-eutectic high-entropy alloy material.

[0035] This application, by controlling the cooling rate and heating rate within the range of 8℃ / min to 12℃ / min, can avoid stress concentration caused by excessively rapid heating or cooling rates, thus preventing thermal stress cracks, maintaining structural stability, and further improving the hardness and stability of near-eutectic high-entropy alloy materials.

[0036] In some embodiments, the time range of S2 cryogenic treatment is 10h to 240h.

[0037] For example, the cryogenic treatment time for S2 can be 10h, 15h, 24h, 28h, 36h, 50h or 120h, etc., and there is no limit here.

[0038] The S2 cryogenic treatment of this application for 10h~240h can significantly increase dislocation density, promote uniform distribution of nano-precipitates, and reduce element segregation, thereby balancing the strength and toughness of near-eutectic high-entropy alloy materials. When the time exceeds 240h, the dislocation density and the volume fraction of precipitates are close to saturation, and the mechanical properties of near-eutectic high-entropy alloy materials cannot be further improved.

[0039] In some embodiments, the pressure range of S1 melting is 0.04 Pa to 0.05 Pa.

[0040] For example, the pressure for S1 melting can be 0.04Pa, 0.044Pa, 0.046Pa, 0.048Pa or 0.05Pa, etc., and there is no limit here.

[0041] Understandably, a vacuum level of 0.04 Pa to 0.05 Pa can effectively reduce the residual oxygen, nitrogen and other gases during the melting process, avoid alloy oxidation and the formation of impurity phases; it also helps to promote the full mutual solubility of elements such as Co, Cr, Fe, and Ni, reduce component segregation, and is conducive to the uniform distribution of nano-precipitates in the S2 cryogenic treatment stage.

[0042] In some embodiments, the vacuum degree of S1 melting ranges from 7.5 × 10⁻⁶. -4 Pa ~ 8.5 × 10 -4 Pa.

[0043] For example, the vacuum degree of S1 melting can be 7.5 × 10⁻⁶. -4 Pa, 7.75×10 -4 Pa, 8×10 -4 Pa, 8.25×10 -4 Pa or 8.5 × 10 -4 Pa, etc., are not limited here.

[0044] Understandably, the vacuum level for S1 melting is in the range of 7.5 × 10⁻⁶. -4 Pa ~ 8.5 × 10 -4 Pa can effectively remove residual gases such as O2 and N2 during the smelting process, reduce the formation of oxide and nitride inclusions; help promote the uniform miscibility of multi-principal alloys (such as FeCoNiCr system) and avoid compositional segregation; it can also make the initial alloy ingot have a lower impurity content, which is beneficial for subsequent S2 cryogenic treatment.

[0045] In some embodiments, the S1 melting process is vacuum arc melting. The current range of S1 melting is 75A~500A, and the current rise and fall rate is 80A / min~100A / min. After the melting current reaches 300A, the electromagnetic stirring power supply is turned on until the single melting of the alloy ingot is completed. Then the electromagnetic stirring is turned off, and the electromagnetic stirring speed is controlled at 10-18 rpm.

[0046] For example, the current for S1 melting can be 75A, 100A, 200A, 230A, 300A, 350A, 400A or 500A, etc., and there is no limit here.

[0047] The non-consumable vacuum arc furnace is used for melting. Melting under vacuum conditions can avoid the oxidation loss of active elements such as aluminum, ensuring that the composition of near-eutectic high-entropy alloy materials is precisely controllable. The maximum melting temperature of this melting device can reach 3500℃, which can well meet the melting requirements of high-entropy alloys with the addition of high-melting-point elements, and improve the performance of high-entropy alloys in different application environments.

[0048] Understandably, a melting current range of 75A to 500A can make the nano-precipitates in BCC structural alloys more uniform in size, balance strength and plasticity, and regulate the layered structure of near-eutectic high-entropy alloys of BCC and FCC.

[0049] In some embodiments, the time range for single-sided melting of S1 ingot is 300s to 500s.

[0050] For example, the melting time for one side of the S1 ingot can be 300s, 350s, 400s, 450s or 500s, etc., and there is no limit here.

[0051] Adjusting the melting time of S1 to 300s~500s can reduce the volatilization or burn-off of low-melting-point elements; it can also reduce the segregation index of eutectic high-entropy alloys, thereby increasing the tensile strength of near-eutectic high-entropy alloy materials.

[0052] In some embodiments, after S1 melting and before S2 cryogenic treatment, the process further includes: Repeat S1 melting, and repeat the initial alloy ingot melting n times, where n is greater than or equal to 2 and less than or equal to 6.

[0053] For example, n can be 2, 3, or 4, etc., and there is no limit here.

[0054] Repeated S1 melting 2 to 6 times can significantly reduce elemental segregation and decrease the dendrite spacing of near-eutectic high-entropy alloys. It can also further remove low-melting-point impurities such as hydrogen and lead, thus reducing the oxygen content. In addition, repeated S1 melting can further increase the dislocation density of BCC structure alloys, providing more nucleation sites for S2 cryogenic treatment.

[0055] The embodiments of this application provide a near-eutectic high-entropy alloy material. This near-eutectic high-entropy alloy material is prepared by the above-described method for preparing near-eutectic high-entropy alloy materials.

[0056] The beneficial effects of the near-eutectic high-entropy alloy material provided in this application are the same as those of the near-eutectic high-entropy alloy material prepared by the above-mentioned preparation method, and will not be repeated here.

[0057] In some embodiments, the near-eutectic high-entropy alloy material includes Al, Co, Cr, Fe, and Ni elements in a molar ratio of 1:1:1:1:2 to 2.2. The near-eutectic high-entropy alloy material formed within this range has a two-phase structure with 70% to 75% face-centered cubic phase and 25% to 30% body-centered cubic phase.

[0058] For example, the elemental percentage of Ni can be 2.0, 2.1, or 2.2, etc., and there is no limit here.

[0059] Example 1

[0060] A method for preparing a near-eutectic high-entropy alloy material includes: steps (1) to (5).

[0061] Step (1): Provide raw materials, using Al metal, Co metal, Cr metal, Fe metal and Ni metal as raw materials, with a purity ≥99.5%.

[0062] Al metal oxide film removal is achieved by alkaline washing: Al elemental 101 is placed in a 5%~10% sodium hydroxide solution, and 5% sodium nitrate is added to prevent excessive corrosion. The oxide film is removed by reacting at 50℃~60℃ for 2min~5min. Then, Al elemental 101 is taken out and immediately rinsed with clean water 2~3 times to remove residual alkali solution. The surface moisture is then wiped dry with non-woven cloth.

[0063] The surfaces of Co, Cr, Fe, and Ni metals are first polished to remove oxides and impurities. After polishing, they are immersed in alcohol for ultrasonic cleaning for 10 to 15 minutes to further remove surface stains. The cleaned Co, Cr, Fe, and Ni metals are then placed in a drying oven and dried at 70 to 90 degrees Celsius for 10 to 15 minutes to ensure complete drying.

[0064] The double-layer coating method refers to first placing the Al element 101 particles coated with Ni foil 102 inside the Fe capsule shell 1 and placing them on the crucible, and then uniformly layering the remaining Cr element, Fe element, Co element and Ni element on the Fe capsule shell 1 according to their melting points from high to low.

[0065] Step (2): Weigh the raw materials according to the molar ratio of each element in the AlCoCrFeNi2 near-eutectic high-entropy alloy using an electronic balance, and put the weighed raw materials into the same copper crucible.

[0066] Step (3): Evacuate and fill with protective gas. After closing the furnace door of the non-consumable vacuum arc melting furnace, begin evacuation. First, use a mechanical pump to evacuate the vacuum level inside the furnace to 1.0 × 10⁻⁶. -1 The vacuum level is then reduced to below 8.0 × 10⁻⁴ Pa. The mechanical pump is then turned off, and the molecular pump is turned on. The molecular pump is used to continue pumping the vacuum level to below 8.0 × 10⁻⁴ Pa. The power supply to the molecular pump and the mechanical pump is then turned off to stop pumping. Argon gas with a purity of not less than 99.9 wt.% is then introduced as a protective gas. After the protective gas is introduced, the pressure inside the furnace is controlled within the range of 0.04 Pa to 0.05 Pa.

[0067] Step (4): Start melting. During the melting process, adjust the position of the tungsten electrode. The initial position of the tungsten electrode is 1mm~2mm away from the material to be melted. The final position of the tungsten electrode is raised to 5mm~8mm away from the sample to be melted and kept stationary. The moving speed is 1mm / s. Set the melting current. The initial value is 75A~110A. The current is increased at a rate of 100A / min. When the current reaches 230A~260A, the metal is completely melted. At this time, adjust the position of the tungsten electrode and turn on the electromagnetic stirring. The electromagnetic stirring speed is 15rpm. Gradually increase the current to 450A~500A and hold for 30-40s. After the melting is completed, gradually reduce the current value. When the current is reduced to 100A, turn off the electromagnetic stirring first. After an interval of 10s~15s, turn off the melting power supply. Finally, control the tungsten electrode to rise. After each melting is completed, cool the copper crucible with water for more than 5 minutes. Then, flip the gold ingot over and perform the next melting. Each ingot is melted 4 times to obtain the initial AlCoCrFeNi2 alloy ingot.

[0068] Step (5): Cryogenic treatment includes: First, open the top cover 401 of the temperature-controlled cryogenic chamber 4, start the motor 301 to make the sample box 305 rise to the highest point along the steel wire rope, and then turn off the motor 301; put the high-entropy alloy sample 306 to be treated into the sample box 305, close the top cover 401 of the temperature-controlled cryogenic chamber 4, and lock the top cover lock 403; turn on the heating resistance wire 405 to control the amount of liquid nitrogen evaporating in the liquid nitrogen box 404, control the cooling rate to 12℃ / min, and turn off the heating resistance wire 405 after the temperature reaches the set temperature of -100℃. The pressure relief valve 402 can automatically adjust the balance pressure; start the motor 301 to make the sample box 305 pass through the double-opening partition 407 along the steel wire rope to the bottom of the temperature-controlled cryogenic chamber 4, turn on the ultrasonic vibration rod 601, open the valve 502 to introduce liquid nitrogen and observe the reading of the flow meter 503; after the amount of liquid nitrogen added reaches 25L, close the valve 502, and start recording the cryogenic time. After completing the cryogenic treatment for the predetermined 24-hour cryogenic time, the ultrasonic vibration rod 601 is turned off, and the motor 301 is started to make the sample box 305 pass through the double-opening partition 407 along the steel wire rope to reach the highest point inside the temperature-controlled cryogenic chamber 4; the heating resistance wire 405 is turned on to control the amount of liquid nitrogen evaporating in the liquid nitrogen box 404 so as to control the heating rate at 12℃ / min. After the temperature reaches 25℃, the heating resistance wire 405 is turned off, the top cover 401 of the temperature-controlled cryogenic chamber 4 is opened and the sample is taken out. The surface is wiped with non-woven cloth, thus completing the entire cryogenic treatment process.

[0069] like Figure 6 The image shows a transmission electron microscope (TEM) image of the near-eutectic high-entropy alloy material obtained in Example 1. As can be seen from the image, the near-eutectic high-entropy alloy material has a large number of dislocations and nano-precipitates.

[0070] like Figure 7 The image shows a scanning electron microscope (SEM) image of the near-eutectic high-entropy alloy material obtained in Example 1. The black part represents the BCC phase, and the light part represents the FCC phase. As can be seen from the image, the near-eutectic high-entropy alloy material has a two-phase structure with both BCC and FCC phases.

[0071] Example 2

[0072] Example 2 provides a method for preparing a near-eutectic high-entropy alloy material, which is the same as the method for preparing the near-eutectic high-entropy alloy material in Example 1, except that the cryogenic treatment time is 50 hours.

[0073] Comparative Example 1 Comparative Example 1 provides a method for preparing a high-entropy alloy ingot, including steps (1) to (4).

[0074] Step (1): Provide raw materials, using Al metal, Co metal, Cr metal, Fe metal and Ni metal as raw materials, with a purity ≥99.5%.

[0075] For example, Al metal is treated with alkaline washing to remove the oxide film: Al elemental 101 is placed in a 5%~10% sodium hydroxide solution, and then 5% sodium nitrate is added to prevent excessive corrosion. The oxide film is removed by reacting at a temperature of 50℃~60℃ for 2min~5min. Then, Al elemental 101 is taken out and immediately rinsed with clean water 2~3 times to remove the residual alkali solution, and the surface moisture is wiped dry with non-woven cloth.

[0076] For example, the surfaces of Co, Cr, Fe, and Ni metals are first polished to remove oxides and impurities. After polishing, they are immersed in alcohol for ultrasonic cleaning for 10 to 15 minutes to further remove stains from the surface of the raw materials. The cleaned Co, Cr, Fe, and Ni metals are then placed in a drying oven and dried at a temperature of 70°C to 90°C for 10 to 15 minutes to ensure complete drying.

[0077] Step (2): Weigh the raw materials according to the molar ratio of each element in the AlCoCrFeNi2 near-eutectic high-entropy alloy using an electronic balance, and put the weighed raw materials into the same copper crucible.

[0078] Step (3): Evacuate and fill with protective gas. After closing the furnace door of the non-consumable vacuum arc melting furnace, begin evacuation. First, use a mechanical pump to evacuate the vacuum level inside the furnace to 1.0 × 10⁻⁶. -1 Once the pressure drops below 8 Pa, turn off the mechanical pump, turn on the molecular pump, and continue using the molecular pump to evacuate the vacuum to 8.0 × 10⁻⁶ Pa. -4 The pressure is below Pa, then the power supply to the molecular pump and the mechanical pump is turned off to stop the pumping. Then, argon gas with a purity of not less than 99.9 wt.% is introduced as a protective gas. After the protective gas is introduced, the pressure inside the furnace is controlled within the range of 0.04 Pa to 0.05 Pa.

[0079] Step (4): Start melting. During the melting process, adjust the position of the tungsten electrode. Initially, the tungsten electrode position is 1mm~2mm away from the material to be melted. Finally, the tungsten electrode position rises to 5mm~8mm away from the sample to be melted and remains stationary. The moving speed is 1mm / s. Set the melting current. The initial value is 75A~110A. Increase the current at a rate of 100A / min. When the current reaches 230A~260A, the metal is completely melted. At this time, adjust the position of the tungsten electrode and turn on the electromagnetic stirring. The electromagnetic stirring speed is 15rpm. Gradually increase the current to 450A~500A and hold for 30-40s. After the melting is completed, gradually reduce the current value. When the current drops to 100A, first turn off the electromagnetic stirring. After an interval of 10s~15s, turn off the melting power supply. Finally, control the tungsten electrode to rise. After each melting is completed, cool the copper crucible with water for more than 5 minutes. Then, flip the gold ingot over and perform the next melting. Melt each ingot 4 times to obtain AlCoCrFeNi2 high-entropy alloy ingot.

[0080] Performance testing Tensile properties were tested on the near-eutectic high-entropy alloy materials obtained in Examples 1 and 2 and the high-entropy alloy ingot obtained in Comparative Example 1. like Figure 9 As shown, the material properties of the near-eutectic high-entropy alloy obtained in Comparative Example 1 are compared with those of the near-eutectic high-entropy alloy in Example 1. The engineering stress of the near-eutectic high-entropy alloy in Example 1 increased from 977 MPa to 1015 MPa, and the engineering strain increased from 19.4% to 22.3%.

[0081] like Figure 10 As shown, the material properties of the near-eutectic high-entropy alloy obtained in Comparative Example 1 are compared with those of the near-eutectic high-entropy alloy in Example 2. The engineering stress of the near-eutectic high-entropy alloy in Example 2 increased from 977 MPa to 1035 MPa, and the engineering strain increased from 19.4% to 21.7%.

[0082] This application expands the effective means of enhancing the mechanical properties of high-entropy alloys through non-destructive methods and has reference value.

[0083] 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 cryogenic treatment apparatus for near-eutectic high-entropy alloys, characterized in that, include: The ultrasonic vibration platform (2), lifting device (3), support (201), temperature-controlled cryogenic chamber (4), liquid nitrogen device (5) and ultrasonic vibration device (6) are provided. The ultrasonic vibration platform (2) is provided with ultrasonic vibration rod reserved hole (202). The temperature-controlled cryogenic chamber (4) is disposed on the upper surface of the ultrasonic vibration platform (2). The interior of the temperature-controlled cryogenic chamber (4) is divided into an upper chamber and a lower chamber by a horizontally arranged double-opening partition (407). The double-opening partition (407) is slidably connected to the inner wall of the temperature-controlled cryogenic chamber (4). The bracket (201) is located on the outside of the temperature-controlled cryogenic chamber (4); The lifting device (3) includes a motor (301), a drive wheel, a fixed pulley (303), a low-temperature resistant stainless steel wire rope (304), and a sample box (305); the motor (301) is mounted on a bracket (201), and a connecting shaft is mounted on the drive shaft of the motor (301), the connecting shaft extending into the upper chamber; the drive wheel is mounted at one end of the connecting shaft extending into the upper chamber; the fixed pulley (303) is mounted inside the upper chamber, and the fixed pulley (303) is located above the drive wheel; the low-temperature resistant stainless steel wire rope (304) is mounted on a sample box (305). One end of the low-temperature stainless steel wire rope (304) is wound in the groove of the drive wheel, and the other end of the low-temperature resistant stainless steel wire rope (304) is wound on the fixed pulley (303), and then passes through the double-opening partition (407) and extends downward to be fixedly connected to the top of the sample box (305); the sample box (305) can be raised and lowered between the upper and lower chambers of the temperature-controlled cryogenic chamber (4) by the drive wheel driven by the motor (301) and by the low-temperature resistant stainless steel wire rope (304). The liquid nitrogen device (5) includes a liquid nitrogen storage unit (501), a valve (502), a delivery pipeline (504), and a flow meter (503). The liquid nitrogen storage unit (501) is located on the outside of the ultrasonic vibration platform (2). One end of the delivery pipeline (504) is connected to the liquid nitrogen storage unit (501) through the valve (502), and the other end of the delivery pipeline (504) extends into the lower chamber. The flow meter (503) is located on the delivery pipeline (504). The ultrasonic vibration assembly (6) includes an ultrasonic vibration rod (601) and an adjustment base (602). The top end of the ultrasonic vibration rod (601) passes through the platform (1) and the ultrasonic vibration rod pre-drilled hole (202) and is tightly fitted to the bottom of the temperature-controlled cryogenic chamber (4). The bottom end of the ultrasonic vibration rod (601) is connected to the adjustment base (602).

2. A method for preparing near-eutectic high-entropy alloy materials combined with cryogenic treatment, characterized in that, include: Melting: Under a protective gas environment, the Al raw material is melted using a double-layer coating method in a vacuum arc melting process. After being heated and melted, it is water-cooled under a protective gas environment to obtain an initial alloy ingot. Deep cryogenic treatment involves first cooling the initial alloy ingot to a temperature range of -116℃ to -96℃ at a predetermined cooling rate, then immersing it in liquid nitrogen, and combining this with a bottom ultrasonic vibration rod (601) to perform deep cryogenic treatment, thereby obtaining a near-eutectic high-entropy alloy material.

3. The method for preparing a near-eutectic high-entropy alloy material combined with cryogenic treatment according to claim 2, characterized in that, The preparation method involves first melting high-melting-point metals to form an alloy, then lowering the overall melting point, and then melting the bottom capsule shell to reduce the burn-off of low-melting-point elements. The double-layer coating method involves first coating Al elemental (101) with Ni foil (102) to form particles, placing them inside the Fe capsule shell (1), and then placing them on a crucible. The remaining mass of Cr elemental, Fe elemental, Co elemental and Ni elemental are then uniformly layered and covered on the Fe capsule shell (1) according to their melting points from high to low.

4. The method for preparing a near-eutectic high-entropy alloy material combined with cryogenic treatment according to claim 3, characterized in that, In the double-layer coating method, the volume of each Fe capsule shell (1) is 100 mm. 3 Up to 220mm 3 The spherical volume of Al elemental (101) coated with Ni foil (102) is 45 mm. 3 Up to 100mm 3 .

5. The method for preparing a near-eutectic high-entropy alloy material combined with cryogenic treatment according to claim 2, characterized in that, In the melting step, a non-consumable vacuum arc furnace is used to melt the material. The working pressure range of the melting is 0.04 Pa to 0.05 Pa; the vacuum degree range of the vacuuming stage of the melting is 7.5 × 10⁻⁶. -4 Pa ~ 8.5 × 10 -4 Pa; the melting current range is 75A~500A, the current rise and fall rate is 80A / min~100A / min, after the melting current reaches 300A, the electromagnetic stirring power supply is turned on until the single melting of the alloy ingot is completed, the electromagnetic stirring is turned off, and the electromagnetic stirring speed is controlled at 10-18rpm; the melting time for each ingot on one side is 300s~500s; after the melting step and before the cryogenic treatment step, it also includes: repeated melting, repeating the melting of the initial alloy ingot n times, where n is not less than 2 and n is not greater than 6.

6. The method for preparing a near-eutectic high-entropy alloy material combined with cryogenic treatment according to claim 2, characterized in that, In the cryogenic treatment step, firstly, open the top cover (401) of the temperature-controlled cryogenic chamber (4), start the motor (301) to make the sample box (305) rise to the highest point along the low-temperature resistant stainless steel wire rope (304), and then turn off the motor (301); place the high-entropy alloy sample (306) to be treated into the sample box (305), close the top cover (401) of the temperature-controlled cryogenic chamber (4), and lock the top cover lock (403); turn on the heating resistance wire (405) to control the amount of liquid nitrogen evaporating in the liquid nitrogen box (404) in order to control the cooling rate, and turn off the heating resistance wire (405) after the temperature reaches the set temperature, and adjust and balance the gas pressure; start the motor (301) to make the sample box (305) pass through the double-opening partition (407) along the low-temperature resistant stainless steel wire rope (304) to reach the highest point. At the bottom of the temperature-controlled cryogenic chamber (4), turn on the ultrasonic vibration rod (601), open the valve (502) to introduce liquid nitrogen and observe the reading of the flow meter (503), control the amount of liquid nitrogen added, close the valve (502), and start recording the cryogenic time; after the cryogenic treatment is completed, turn off the ultrasonic vibration rod (601), start the motor (301) to make the sample box (305) pass through the double-opening partition (407) along the low-temperature resistant stainless steel wire rope (304) to reach the highest point inside the temperature-controlled cryogenic chamber (4); turn on the heating resistance wire (405) to control the amount of liquid nitrogen evaporating in the liquid nitrogen box (404), and turn off the heating resistance wire (405) after the temperature reaches the specified temperature, open the top cover (401) of the temperature-controlled cryogenic chamber (4) to take out the sample, wipe the surface with non-woven cloth, and the entire cryogenic treatment process is completed.

7. The method for preparing a near-eutectic high-entropy alloy material combined with cryogenic treatment according to claim 2, characterized in that, In the cryogenic treatment, the predetermined cooling rate is 8℃ / min~12℃ / min. After the temperature drops to the range of -116℃~-96℃, it is immersed in liquid nitrogen in a cryogenic chamber for cryogenic treatment. After the cryogenic treatment step is completed, the temperature is raised to the range of 20℃~25℃ at a heating rate of 8℃ / min~12℃ / min to obtain the near-eutectic high-entropy alloy material.

8. The method for preparing a near-eutectic high-entropy alloy material combined with cryogenic treatment according to claim 2, characterized in that, In the cryogenic treatment step, a 20000Hz ultrasonic vibration rod (601) is used. The ultrasonic vibration rod (601) is fixed on the adjustment base (602). By adjusting the height of the base (602), the ultrasonic vibration rod (601) passes through the ultrasonic vibration rod reserved hole (202) in the middle of the platform and the support (2) and fits tightly with the bottom of the temperature-controlled cryogenic chamber (4). The time range of the cryogenic treatment is 10h~240h.

9. A near-eutectic high-entropy alloy material, characterized in that, The near-eutectic high-entropy alloy material is prepared by the method for preparing near-eutectic high-entropy alloy materials as described in any one of claims 2 to 8; The near-eutectic high-entropy alloy material includes Al, Co, Cr, Fe, and Ni elements in a molar ratio of 1:1:1:1:2.0~2.

2. The near-eutectic high-entropy alloy material has a two-phase structure with 70%~75% face-centered cubic phase and 25%~30% body-centered cubic phase.

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