A high-entropy alloy coating containing multi-scale pores and preparation and application thereof

Abstract

The present application relates to the technical field of welding, in particular to a high-entropy alloy coating containing multi-scale holes and preparation and application thereof. A loose high-entropy alloy powder is pre-placed on the surface of a base material, under a certain vacuum degree, by adjusting the sintering temperature, a certain metal element in the powder reaches its saturation vapor pressure and escapes, and the powder is partially melted, so that holes are formed on the powder particles, and the particles are bonded with each other to form a high-entropy alloy coating containing multi-scale holes which is combined with the surface of the base material, the specific surface area of the base material is changed, and a unique three-dimensional connected high-entropy alloy coating containing multi-scale holes is obtained. In the brazing process, the capillary action is greatly enhanced, and then the wetting and spreading power of the filler metal in the brazing process is improved, the performance of the brazed joint is improved, and the application prospect is excellent.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and in particular to a high-entropy alloy coating containing multi-scale pores, its preparation and application. Background Technology

[0002] Dissimilar metal joints can maximize the performance of metallic materials, reduce the use of expensive materials, replace some rare metals, and significantly reduce production costs, effectively improving economic efficiency. However, dissimilar metals have significant differences in physical properties (melting point, coefficient of linear expansion, specific heat capacity, thermal conductivity, etc.) and chemical properties, which makes them prone to uneven heating and internal stress during welding, as well as the formation of brittle intermetallic compounds in the joint, reducing joint performance. When thick and coarse-shaped brittle intermetallic compounds are formed, it will hinder the wetting and spreading of the brazing filler metal on the steel substrate surface.

[0003] Currently, those skilled in the art employ various process optimization methods to improve the wettability of brazing filler metals on metal surfaces, including composite brazing filler metals (particle-reinforced composite brazing filler metals, fiber-reinforced composite brazing filler metals, two-dimensional material-reinforced composite brazing filler metals), multi-layer brazing seam structures (powder interlayer, metal foil interlayer, three-dimensional structure interlayer), and surface processing modification of the base material (chemical etching, micromachining, laser processing, surface coating). These methods can also alleviate internal stress in brazed joints, resulting in defect-free and high-performance heterogeneous material brazed joints. However, each process optimization method has its advantages and limitations. 1) In the composite brazing filler metal method, adding phases can refine the brazed joint interface structure, reduce the thermal expansion coefficient of the brazed seam structure, optimize the brazed joint structure, and improve the brazed joint performance. However, the introduction of added phases increases the viscosity of the brazing filler metal, reducing its filling ability in the brazed seam and thus forming defects. 2) Although the multi-layer brazing seam structure method can alleviate residual stress in the joint and improve the strength of the brazed joint, the introduction of multiple interlayers can easily form large-volume compound phases or result in insufficient reaction in the interlayer. Therefore, defects such as cracks formed in the brazing seam will reduce the performance of the brazed joint; 3) The base material surface processing modification method involves micro-texturing and chemical plating on the base material surface to promote the wetting and spreading performance of droplets on the metal surface. However, in some dissimilar metal brazed joints, although the filler metal has good wetting performance on the base material surface, the joint is relatively weak due to the excessively thin reaction layer at the material interface.

[0004] Porous metals, as a novel lightweight material, possess outstanding deformation and absorption capabilities due to their unique three-dimensional framework structure, leading to their wide application in numerous fields. Researchers have utilized the structural properties of porous metals as an intermediate layer material, combining them with traditional brazing filler metal powder or foil. During brazing, the liquid metal filler metal fills into the pores of the porous metal through capillary action, forming a cross-distribution structure of filler metal alloy and porous metal. This process effectively releases residual stress in the brazed joint and optimizes the brazing of dissimilar materials.

[0005] High-entropy alloys, composed of multiple main elements, exhibit a high-entropy effect. This effect promotes the formation of solid solution phases with body-centered cubic or face-centered cubic structures and inhibits the formation of brittle intermetallic compounds.

[0006] Therefore, it is necessary to develop a high-entropy porous layer with fast preparation rate, simple preparation process, good wettability, and high specific surface area to overcome the defects such as thermal stress and brittle intermetallic compounds that are easily generated during the welding of dissimilar metals, improve the performance of dissimilar metal welding, and enhance the industrial application of dissimilar metal materials. Summary of the Invention

[0007] To address the aforementioned problems, the present invention aims to provide a high-entropy alloy coating containing multi-scale pores, its preparation, and its application. This invention seeks to overcome the defects such as thermal stress and brittle intermetallic compounds that easily arise during dissimilar metal brazing, thereby improving the wetting and spreading ability of the brazing filler metal on the substrate surface. Furthermore, it provides a method for preparing a high-entropy alloy coating containing multi-scale pores that is fast, simple to process, has good wettability, and a high specific surface area.

[0008] This invention involves pre-depositing a loose layer of high-entropy alloy powder on the surface of a substrate material and then sintering it at high temperature under vacuum conditions. This results in the formation of 1-2 μm micropores on the high-entropy alloy powder particles, with the particles bonding together to form a high-entropy alloy coating with a thickness of 300 μm, a porosity of 44.03%, an average pore size of 15.05 μm, and bonding to the surface of the substrate material. Furthermore, the same solder can completely wet the steel plate with the sintered high-entropy alloy coating containing multi-scale pores, which is superior to the wettability of the steel plate without the sintered high-entropy alloy coating containing multi-scale pores. The method of this invention involves controlling the sintering temperature under a certain vacuum condition, causing a certain metal element in the powder to reach its saturated vapor pressure and escape, resulting in partial melting of the powder. This creates pores on the powder particles, which then bond together to form a high-entropy alloy coating with multi-scale pores that adheres to the surface of the substrate material. This alters the specific surface area of ​​the substrate material, resulting in a unique three-dimensional interconnected high-entropy alloy coating with multi-scale pores. This coating significantly enhances capillary action during brazing, thereby improving the wetting and spreading power of the brazing filler metal and enhancing the performance of the brazed joint. It has great application potential.

[0009] The objective of this invention can be achieved through the following technical solutions:

[0010] The first objective of this invention is to provide a method for preparing a high-entropy alloy coating containing multi-scale pores, comprising the following steps:

[0011] The dried high-entropy alloy powder was laid on the surface of the pretreated matrix material and vacuum sintered to obtain a high-entropy alloy coating containing multi-scale pores.

[0012] The high-entropy alloy powder is Fe-Co-Ni-Cr-Mn powder.

[0013] In one embodiment of the present invention, the drying process takes 2 hours and the temperature is 60°C.

[0014] In one embodiment of the present invention, the molar ratio of Fe, Co, Ni, Cr and Mn in the high-entropy alloy powder is 1-3:1-3:1-3:1-3:1-3:1-3;

[0015] The coverage thickness is 100μm to 500μm;

[0016] The base material is Q235 cold-rolled steel.

[0017] In one embodiment of the present invention, the pretreatment involves sanding with sandpaper, ultrasonic cleaning in anhydrous ethanol, and then drying.

[0018] In one embodiment of the present invention, the vacuum degree reaches 10 during the vacuum sintering process. -3 Pa~10 -5 Pa.

[0019] In one embodiment of the present invention, the vacuum sintering process includes a first heating stage, a first holding stage, a second heating stage, and a second holding stage.

[0020] In one embodiment of the present invention, during the first heating stage, the temperature is increased to 500°C at a heating rate of 20°C / min to 30°C / min.

[0021] In one embodiment of the present invention, during the first heat preservation stage, the temperature is 500°C and the time is 30 minutes.

[0022] In one embodiment of the present invention, during the second heating stage, the temperature is increased to 1200°C to 1350°C at a heating rate of 20°C / min to 30°C / min.

[0023] In one embodiment of the present invention, during the second heat preservation stage, the temperature is 1200℃~1350℃ and the time is 60min~180min.

[0024] In this invention, if the sintering temperature is too low, the saturated vapor pressure of Mn will not be reached, and Mn will not escape, so micropores will not be generated on the powder particles. If the sintering temperature is too high, the high-entropy alloy powder will completely melt, and a three-dimensional interconnected porous structure layer will not be generated.

[0025] In one embodiment of the present invention, the post-processing is to allow the furnace to cool naturally to room temperature.

[0026] The second objective of this invention is to provide a high-entropy alloy coating containing multi-scale pores prepared by the above method.

[0027] The third objective of this invention is to provide an application of a high-entropy alloy coating containing multi-scale pores in the brazing process of dissimilar metals.

[0028] In this invention, a high-entropy alloy coating with multi-scale pores, which is combined with the steel surface by vacuum high-temperature sintering, increases the specific surface area of ​​the steel, obtains a unique three-dimensional interconnected structure, improves the wetting and spreading power of the brazing filler metal on the steel surface, and reduces the residual stress of the joint. Due to the high-entropy effect generated by the high-entropy alloy coating with multi-scale pores, a single-phase solid solution is formed on the steel surface, which enhances the bonding performance between the steel and the high-entropy alloy coating with multi-scale pores.

[0029] Specifically, when a high-entropy alloy coating containing multi-scale pores is further applied to the brazing process, the micropores distributed on the surface of the high-entropy alloy powder particles can enhance capillary forces, thereby improving the wetting and spreading power of the brazing filler metal. The mutual adhesion between the high-entropy alloy powder particles forms an open porous layer with randomly distributed pores and pore sizes, altering the specific surface area of ​​the steel. This unique three-dimensional interconnected porous structure has excellent deformation and absorption capabilities, which can inhibit the excessively rapid growth of brittle intermetallic compounds, alleviate residual stress in the brazed joint, and thus improve the wetting and spreading ability of the brazing filler metal and enhance the performance of the welded joint. Compared with existing technologies that use other processes to improve the wettability of brazing filler metals on metal surfaces, this invention provides a new method for brazing dissimilar metals.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] This invention discloses a method for preparing a high-entropy alloy coating containing multi-scale pores. The high-entropy alloy coating containing multi-scale pores is sintered on a steel surface in a vacuum sintering furnace. The high-entropy alloy coating and the steel plate exhibit excellent metallurgical bonding. This high-entropy alloy coating containing multi-scale pores significantly enhances capillary action during brazing, thereby improving the wetting and spreading power of the brazing filler metal and enhancing the performance of the brazed joint. Compared to existing technologies that use other processes to improve the wettability of the filler metal on the metal surface, this invention provides a novel method for brazing dissimilar metals. Due to the high-entropy effect of the high-entropy alloy, this effect can promote the formation of solid solution phases with body-centered cubic or face-centered cubic structures on the steel surface and inhibit the formation of intermetallic compounds. Attached Figure Description

[0032] Figure 1 The image shows the original morphology of the high-entropy alloy powder under a scanning electron microscope.

[0033] Figure 2 A process flow diagram for preparing high-entropy alloy coatings containing multi-scale pores;

[0034] Figure 3 In the image, (a) shows the surface morphology of the vacuum high-temperature sintered high-entropy alloy coating under a scanning electron microscope, and (b) shows the cross-sectional view of the high-entropy alloy coating under an optical microscope.

[0035] Figure 4 In the figure, (a) is a top view of Al-12Si alloy / high entropy alloy coated steel under a scanning electron microscope, and (b) is a cross-sectional view of Al-12Si alloy / high entropy alloy coated steel under a scanning electron microscope.

[0036] Figure 5 A bar chart comparing the wetting contact angles of Al-12Si alloy on high-entropy alloy coated steel and uncoated steel surfaces;

[0037] Figure 6 SEM morphology and EDS analysis of the interface of Al-12Si alloy / high-entropy alloy coated steel;

[0038] Figure 7 Interfacial XRD analysis of Al-12Si alloy / high-entropy alloy coated steel. Detailed Implementation

[0039] This invention provides a method for preparing a high-entropy alloy coating containing multi-scale pores, comprising the following steps:

[0040] The dried high-entropy alloy powder was laid on the surface of the pretreated matrix material and vacuum sintered to obtain a high-entropy alloy coating containing multi-scale pores.

[0041] The high-entropy alloy powder is Fe-Co-Ni-Cr-Mn powder.

[0042] In one embodiment of the present invention, the drying process takes 2 hours and the temperature is 60°C.

[0043] In one embodiment of the present invention, the molar ratio of Fe, Co, Ni, Cr and Mn in the high-entropy alloy powder is 1-3:1-3:1-3:1-3:1-3:1-3;

[0044] The coverage thickness is 100μm to 500μm;

[0045] The base material is Q235 cold-rolled steel.

[0046] In one embodiment of the present invention, the pretreatment involves sanding with sandpaper, ultrasonic cleaning in anhydrous ethanol, and then drying.

[0047] In one embodiment of the present invention, the vacuum degree reaches 10 during the vacuum sintering process. -3 Pa~10 -5 Pa.

[0048] In one embodiment of the present invention, the vacuum sintering process includes a first heating stage, a first holding stage, a second heating stage, and a second holding stage.

[0049] In one embodiment of the present invention, during the first heating stage, the temperature is increased to 500°C at a heating rate of 20°C / min to 30°C / min.

[0050] In one embodiment of the present invention, during the first heat preservation stage, the temperature is 500°C and the time is 30 minutes.

[0051] In one embodiment of the present invention, during the second heating stage, the temperature is increased to 1200°C to 1350°C at a heating rate of 20°C / min to 30°C / min.

[0052] In one embodiment of the present invention, during the second heat preservation stage, the temperature is 1200℃~1350℃ and the time is 60min~180min.

[0053] In one embodiment of the present invention, the post-processing is to allow the furnace to cool naturally to room temperature.

[0054] This invention provides a high-entropy alloy coating containing multi-scale pores prepared by the above method.

[0055] This invention provides an application of a high-entropy alloy coating containing multi-scale pores in the brazing process of dissimilar metals.

[0056] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0057] Unless otherwise specified, all reagents used in the following embodiments are commercially available reagents, and all detection methods and techniques used are conventional detection methods and techniques in the art.

[0058] In the following examples, the high-entropy alloy powder is an equimolar ratio of Fe-Co-Ni-Cr-Mn.

[0059] Example 1

[0060] This embodiment provides a high-entropy alloy coating containing multi-scale pores and its preparation method, including the following steps:

[0061] (1) Cut large Q235 steel plates into 40x50x1.8mm substrates, and polish them sequentially with 600-grit, 800-grit, 1000-grit, and 1200-grit sandpaper. Then, immerse them in anhydrous ethanol solution for ultrasonic cleaning for 10 minutes. Place the high-entropy alloy powder in a drying oven at 60°C for 2 hours. The high-entropy alloy powder is spherical, such as... Figure 1 As shown;

[0062] (2) A layer of high-entropy alloy powder with a thickness of 300 μm is pre-placed on the surface of Q235 steel using a powder spreader, and then placed in a vacuum sintering furnace for high-temperature sintering to form a high-entropy porous layer. The sintering process is as follows: Figure 2 As shown. The initial heating rate of the high-temperature sintering furnace was 25℃ / min. When the temperature reached 500℃, it was held for 30 min, then the rate was increased to 1200℃ at 25℃ / min and held for 60 min. Finally, the furnace was allowed to cool naturally to room temperature, resulting in a high-entropy alloy coating with multi-scale pores. The sintered coating surface showed a large number of submicron-sized pores, forming a three-dimensional interconnected open structure with randomly distributed pore sizes. The layer thickness was approximately 285 μm. Figure 3 As shown.

[0063] After immersing the sintered high-entropy alloy coating containing multi-scale pores in an anhydrous ethanol solution and ultrasonically cleaning it for 10 minutes, an in-situ wetting and spreading test was performed. The specific operation of the test is as follows:

[0064] 50 mg of Al-12Si solder was placed on the steel substrate (uncoated steel) and high-entropy alloy coated steel prepared in steps (1) and (2), respectively (Q235 steel substrate prepared in step (1) was the reference group, and high-entropy alloy coated steel prepared in step (2) was the experimental group). The whole thing was then placed in a high-temperature heating table. Under the protection of 99.999% high-purity argon, the initial heating rate was 6.67℃ / min. When the temperature reached 200℃, the heating rate increased to 12℃ / min. When the temperature reached 800℃, it was held for 10 minutes and then cooled to room temperature with the furnace.

[0065] After the experiment, the two substrates (a steel substrate and a high-entropy alloy coated steel) were ultrasonically cleaned in anhydrous ethanol for 10 min, and then analyzed by SEM and EDS, respectively. Figure 4 The SEM top and cross-sectional views after wetting and spreading reveal that the resolidified Al-12Si alloy exhibits an irregular morphology, displaying local anisotropy during wetting and spreading. Although the high-entropy alloy coating containing multi-scale pores generally exhibits an isotropic structure, the random size and distribution of these pores lead to variations in local capillary forces within the porous coating, resulting in the aforementioned phenomenon. Figure 4 (b) It can be seen that the Al-12Si alloy is completely wetted into the high-entropy alloy coating structure containing multi-scale pores, achieving a complete wetting effect (apparent contact angle of 0°); at the same time, the cross-sectional morphology also confirms that the high-entropy alloy coating containing multi-scale pores is a three-dimensional interconnected open structure.

[0066] Figure 5 The apparent contact angle represents the wetting and spreading of Al-12Si alloy on a steel substrate (uncoated steel) and a high-entropy alloy coated steel surface. Compared to the uncoated steel, the high-entropy porous coating, with its unique three-dimensional interconnected open structure, increases the specific surface area of ​​the steel substrate, enhances the capillary force on the material surface, and promotes the wettability and spreading of the Al-Si alloy / steel reactive wetting system. Its apparent contact angle is 0°, achieving complete wetting. Under the combined effect of the high-entropy alloy's retarded diffusion and the high-entropy effect, the formation of intermetallic compounds in the interfacial reaction layer is significantly hindered. The interfacial phase structure consists of a eutectic structure of Cr-rich FCC, AlFe-rich BCC, and AlNi-rich B2+ and Al-rich BCC. Figure 6 and 7 As shown.

[0067] Verification has shown that sintering a high-entropy alloy coating with multi-scale pores on the surface of Q235 steel in a vacuum furnace results in excellent metallurgical bonding between the high-entropy alloy coating and Q235 steel. This unique high-entropy alloy coating with multi-scale pores significantly enhances capillary action during brazing, thereby improving the wetting and spreading power of the brazing filler metal and enhancing the performance of the brazed joint. This provides a new method for brazing dissimilar metals. Due to the high-entropy effect of the high-entropy alloy, this effect can promote the formation of solid solution phases with body-centered cubic or face-centered cubic structures, inhibit the formation of intermetallic compounds, and improve the performance of dissimilar metal brazed joints.

[0068] Example 2

[0069] This embodiment provides a high-entropy alloy coating containing multi-scale pores and its preparation method, including the following steps:

[0070] (1) Cut a large Q235 steel plate into a substrate of 40x50x1.8mm, and polish it with 600#, 800#, 1000# and 1200# sandpaper in sequence. Then immerse it in anhydrous ethanol solution and ultrasonically clean it for 10 minutes. Place the high entropy alloy powder in a drying oven at 60°C and dry it for 2 hours. The high entropy alloy powder is spherical.

[0071] (2) A layer of high-entropy alloy powder with a thickness of 300 μm was pre-placed on the surface of Q235 steel using a powder spreader, and then placed in a vacuum sintering furnace for high-temperature sintering to form a high-entropy porous layer. The initial heating rate of the high-temperature sintering furnace was 25℃ / min. When the temperature reached 500℃, it was held for 30 min, and then the temperature was increased to 1200℃ at 25℃ / min and held for 120 min. Finally, the furnace was allowed to cool naturally to room temperature to obtain a high-entropy alloy coating with multi-scale pores. After sintering, a large number of submicron-sized pores appeared on the surface of the coating, which were three-dimensional interconnected open structures with randomly distributed pore sizes and a layer thickness of about 275 μm.

[0072] Example 3

[0073] This embodiment provides a high-entropy alloy coating containing multi-scale pores and its preparation method, including the following steps:

[0074] (1) Cut a large Q235 steel plate into a substrate of 40x50x1.8mm, and polish it with 600#, 800#, 1000# and 1200# sandpaper in sequence. Then immerse it in anhydrous ethanol solution and ultrasonically clean it for 10 minutes. Place the high entropy alloy powder in a drying oven at 60°C and dry it for 2 hours. The high entropy alloy powder is spherical.

[0075] (2) A layer of high-entropy alloy powder with a thickness of 300 μm was pre-placed on the surface of Q235 steel using a powder spreader, and then placed in a vacuum sintering furnace for high-temperature sintering to form a high-entropy porous layer. The initial heating rate of the high-temperature sintering furnace was 25℃ / min. When the temperature reached 500℃, it was held for 30 min, and then the temperature was increased to 1200℃ at 25℃ / min and held for 180 min. Finally, the furnace was allowed to cool naturally to room temperature to obtain a high-entropy alloy coating with multi-scale pores. After sintering, a large number of submicron-sized pores appeared on the surface of the coating, which were three-dimensional interconnected open structures with randomly distributed pore sizes and a layer thickness of about 265 μm.

[0076] Example 4

[0077] This embodiment provides a high-entropy alloy coating containing multi-scale pores and its preparation method, including the following steps:

[0078] (1) Cut a large Q235 steel plate into a substrate of 40x50x1.8mm, and polish it with 600#, 800#, 1000# and 1200# sandpaper in sequence. Then immerse it in anhydrous ethanol solution and ultrasonically clean it for 10 minutes. Place the high entropy alloy powder in a drying oven at 60°C and dry it for 2 hours. The high entropy alloy powder is spherical.

[0079] (2) A layer of high-entropy alloy powder with a thickness of 300 μm was pre-placed on the surface of Q235 steel using a powder spreader, and then placed in a vacuum sintering furnace for high-temperature sintering to form a high-entropy porous layer. The initial heating rate of the high-temperature sintering furnace was 25℃ / min. When the temperature reached 500℃, it was held for 30 min, and then the temperature was increased to 1250℃ at 25℃ / min and held for 180 min. Finally, the furnace was allowed to cool naturally to room temperature to obtain a high-entropy alloy coating with multi-scale pores. After sintering, a large number of submicron-sized pores appeared on the surface of the coating, which were three-dimensional interconnected open structures with randomly distributed pore sizes and a layer thickness of about 260 μm.

[0080] Example 5

[0081] This embodiment provides a high-entropy alloy coating containing multi-scale pores and its preparation method, including the following steps:

[0082] (1) Cut a large Q235 steel plate into a substrate of 40x50x1.8mm, and polish it with 600#, 800#, 1000# and 1200# sandpaper in sequence. Then immerse it in anhydrous ethanol solution and ultrasonically clean it for 10 minutes. Place the high entropy alloy powder in a drying oven at 60°C and dry it for 2 hours. The high entropy alloy powder is spherical.

[0083] (2) A layer of high-entropy alloy powder with a thickness of 300 μm was pre-placed on the surface of Q235 steel using a powder spreader, and then placed in a vacuum sintering furnace for high-temperature sintering to form a high-entropy porous layer. The initial heating rate of the high-temperature sintering furnace was 25℃ / min. When the temperature reached 500℃, it was held for 30 min, and then the temperature was increased to 1300℃ at 25℃ / min and held for 120 min. Finally, the furnace was allowed to cool naturally to room temperature to obtain a high-entropy alloy coating with multi-scale pores. After sintering, a large number of submicron-sized pores appeared on the surface of the coating, which were three-dimensional interconnected open structures with randomly distributed pore sizes and a layer thickness of about 255 μm.

[0084] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.

Claims

1. Use of a high-entropy alloy coating containing multi-scale pores in a dissimilar metal brazing process, characterized in that, The preparation method of the high-entropy alloy coating containing multi-scale pores comprises the following steps: The dried high-entropy alloy powder is laid on the surface of the pretreated base material, vacuum sintering is carried out, and then the furnace is naturally cooled to room temperature to obtain the high-entropy alloy coating containing multi-scale pores; The high-entropy alloy powder is Fe-Co-Ni-Cr-Mn powder. In the vacuum sintering process, the first temperature rising stage, the first holding stage, the second temperature rising stage and the second holding stage are included; in the first temperature rising stage, the temperature is raised to 500 DEG C at a temperature rising rate of 20 DEG C / min to 30 DEG C / min; in the first holding stage, the temperature is 500 DEG C, and the time is 30 min; in the second temperature rising stage, the temperature is raised to 1200 DEG C to 1350 DEG C at a temperature rising rate of 20 DEG C / min to 30 DEG C / min; in the second holding stage, the temperature is 1200 DEG C to 1350 DEG C, and the time is 60 min to 180 min.

2. The use of a high-entropy alloy coating containing multi-scale pores in the process of dissimilar metal brazing according to claim 1, characterized in that, In the high-entropy alloy powder, the molar ratio of Fe, Co, Ni, Cr and Mn is 1 to 3: 1 to 3: 1 to 3: 1 to 3: 1 to 3; The laying thickness is 100 mu m to 500 mu m; The base material is Q235 cold-rolled steel.

3. The use of a high-entropy alloy coating containing multi-scale pores in the process of dissimilar metal brazing according to claim 1, characterized in that, During vacuum sintering, the vacuum degree reaches 10 -3 Pa -5 Pa.

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