A method for bonding a high-entropy alloy to a steel

Abstract

The application provides a high-entropy alloy and steel combination method, relates to the alloy preparation process technical field, and comprises the following steps: step 1) placing an intermediate layer between the alloy and the steel to assemble an alloy-intermediate layer-steel combination; the intermediate layer comprises one of niobium metal foil, vanadium metal foil and vanadium-copper composite metal foil; step 2) performing hot pressure connection on the high-entropy alloy-intermediate layer-ultra-high-strength steel combination to combine the alloy and the steel, so that an alloy / intermediate layer / steel composite material is obtained. The application selects an intermediate layer material with good thermodynamic and metallurgical compatibility with a base body, adopts a non-traditional high-temperature large deformation process, effectively controls the generation of harmful phases at the interface, and thus solves the problem of low interface strength of the existing high-entropy alloy / ultra-high-strength steel composite material.

Description

Technical Field

[0001] This invention relates to the field of alloy preparation technology, and specifically to a method for combining high-entropy alloys with steel. Background Technology

[0002] High-entropy alloys are a new type of multi-principal-element metallic material that has emerged in recent years, composed of multiple elements in equimolar or near-equimolar ratios. They possess superior properties that traditional alloys cannot simultaneously exhibit, such as high strength, high hardness, high plasticity, resistance to low-temperature embrittlement, resistance to high-temperature softening, radiation resistance, and wear resistance. In the development of important industrial fields such as ultra-high-temperature materials for hypersonic vehicle engines, radiation-resistant nuclear energy materials, high-performance warhead materials, materials for polar icebreakers, lightweight armor protection materials, and materials for cryogenic service devices, high-entropy alloys have already provided key material options and support, rapidly becoming a research hotspot in the international materials science field. Reports have indicated that high-entropy alloys have a very promising future in the next decade, and are expected to provide key high-performance material options in areas where the performance of traditional materials has reached its limits and is difficult to overcome.

[0003] Steel, as the most thoroughly researched, widely used, extensively applied, and mature industrial material, has permeated all aspects of production and daily life. Among them, ultra-high-strength steel, with a strength grade exceeding 1.3 GPa, possesses both extremely high strength and toughness, providing material support for many advanced high-end equipment fields. The preparation of high-entropy alloy / ultra-high-strength steel composite materials can combine the unique alloying properties of high-entropy alloys (high properties, high corrosion resistance, and high radiation resistance) with the excellent mechanical properties of ultra-high-strength steel, creating significant demand in numerous fields.

[0004] However, due to the significant differences in the physicochemical and metallurgical properties between the two types of materials, achieving a high-quality connection is extremely difficult. Currently, there are two processes for achieving composite joining of dissimilar materials: fusion welding and solid-state welding.

[0005] However, the inventors found that: (1) when using fusion welding to connect high-entropy alloys and ultra-high-strength steel, the weld often faces problems such as the formation of complex and large harmful intermediate phases by the reaction of liquid metal and the excessive heat-affected zone, which lead to interface embrittlement; (2) when using conventional solid-state welding (such as diffusion welding and friction stir welding) to connect high-entropy alloys and ultra-high-strength steel, the elements Fe and Ni in the high-strength steel easily react with the elements Ti, Zr, Al and other elements in the high-entropy alloy to form brittle intermetallic compounds, which reduces the strength of the interface between the high-entropy alloy and ultra-high-strength steel composite materials. This seriously hinders the effective preparation and application of high-entropy alloy and ultra-high-strength steel composite materials, which are in high demand. Summary of the Invention

[0006] Therefore, the present invention provides a method for combining high-entropy alloys with steel to solve the problem of low interface strength in existing high-entropy alloy / ultra-high-strength steel composite materials.

[0007] To address the above problems, this invention provides a method for combining high-entropy alloys with steel, comprising the following steps:

[0008] Step 1) Assemble a high-entropy alloy-intermediate layer-steel composite by placing an intermediate layer between the alloy and the steel; the intermediate layer includes one of niobium metal foil, vanadium metal foil, and vanadium-copper composite metal foil;

[0009] Step 2) Hot-press the high-entropy alloy-intermediate layer-steel assembly to bond the alloy and steel together to obtain an alloy / intermediate layer / steel composite material.

[0010] Furthermore, in step 1), the high-entropy alloy includes elements Al, Nb, Ti, and Zr; and / or the steel has a yield strength greater than 1.3 GPa.

[0011] Furthermore, in step 1), the high-entropy alloy is an Al-Nb-Ti-V-Zr-Hf energetic high-entropy alloy;

[0012] Preferably, the high-entropy alloy is an energetic high-entropy alloy of AlNbTi3Zr1.5;

[0013] And / or, the steel is one of 18Ni200, 18Ni250, 18Ni300, and 18Ni350.

[0014] Furthermore, in step 1), the thickness of the intermediate layer is 100-200 μm; and / or the purity of the intermediate layer is 99.95% or higher; and / or the surface roughness of the intermediate layer is less than Ra 0.6 μm.

[0015] Furthermore, in step 1), the high-entropy alloy has the same dimensions as the steel.

[0016] Furthermore, in step 1), the high-entropy alloy and the steel each have a first surface and a second surface, which are respectively used to contact the intermediate layer, and the roughness of the first surface and the second surface is lower than Ra 0.8 μm.

[0017] Furthermore, in the hot-pressing connection step, the compression temperature is 800-950℃; and / or the compression strain rate is 0.01-1s. -1 ; and / or the compression deformation is greater than or equal to 40%; and / or the high vacuum degree is higher than 0.1 Pa.

[0018] Furthermore, the compression temperature is 850°C; and / or the compression strain rate is 0.1 s⁻¹. -1; and / or the compressive deformation is 40%.

[0019] The present invention also provides a high-entropy alloy / steel composite material, wherein the interface of the high-entropy alloy / steel composite material is free of pores, cracks, and large intermetallic compounds, and the element diffusion width is narrow; preferably, the high-entropy alloy / steel composite material is obtained by combining the methods described in any one of the above.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention provides a method for bonding high-entropy alloys with steel. By adding an intermediate layer, the diffusion of elements with strong compound-forming capabilities between the matrix materials and direct chemical reactions are effectively blocked (elements such as Fe and Ni in high-strength steel readily react with elements such as Ti, Zr, and Al in high-entropy alloys to form brittle intermetallic compounds), effectively controlling the formation of harmful phases at the interface. Under vacuum, high temperature, high pressure, and large deformation (deformation greater than or equal to 40%), the metal atoms at the interface of high-entropy alloy-intermediate layer and intermediate layer-ultra-high-strength steel approach the range of atomic force action, forming strong metallic bonds. A small number of residual micropores gradually disappear under diffusion, enabling metallurgical bonding at the interface.

[0022] 2. This invention selects materials such as niobium metal foil, vanadium metal foil, and vanadium-copper composite metal foil, which have good thermodynamic and metallurgical compatibility with high-strength steel and high-entropy alloys, as the intermediate layer. These materials can achieve good metallurgical bonding with the parent materials on both sides (high-strength steel and high-entropy alloys) under pressure and diffusion.

[0023] 3. The intermediate layer of this invention possesses a certain thickness, which is a necessary condition for effectively preventing matrix elements from crossing the intermediate layer. It also provides a wider reaction space for minor diffusion reactions of elements in the matrix, reducing the impact on the interface. Since interface brittleness is highly sensitive to elemental reactions, high-purity foil is essential to ensure no additional "elemental contamination" occurs. A clean and smooth surface facilitates direct metallurgical contact between metals and promotes the formation of interfacial metal bonds. Maintaining low roughness facilitates the welding of interfacial voids during the connection process, improving the quality of the interfacial connection.

[0024] 4. During the hot-pressing process, the intermediate layer of this invention exhibits an in-situ induced strengthening effect. This means that certain alloying elements in the matrix material diffuse fully into the intermediate layer, forming a thermodynamically stable solid solution. This results in a significant solid solution strengthening effect, increasing the strength of the intermediate layer. Simultaneously, alloying elements with extremely negative enthalpy of mixing in the matrix material meet within the intermediate layer, generating finely dispersed intermetallic compound particles, thus producing a precipitation strengthening effect. Both factors simultaneously strengthen the intermediate layer material, enabling it to achieve strength close to that of the two matrix materials on either side, thereby truly ensuring high strength of the overall interface. Attached Figure Description

[0025] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0026] Figure 1 Flowchart for preparing AlNbTi3Zr1.5 high-entropy alloy / 18Ni(350) ultra-high-strength steel composite material with high interfacial bonding strength by adding an intermediate layer;

[0027] Figure 2 middle: Figure 2 a and 2b are microstructure diagrams of the interface of the high-entropy alloy / ultra-high-strength steel material obtained by adding a niobium interlayer; Figure 2 c and 2d are the interface microstructure diagrams of the high-entropy alloy / ultra-high-strength steel material obtained by adding a vanadium interlayer; Figure 2 e and 2f are the interface microstructure diagrams of the high-entropy alloy / ultra-high-strength steel materials obtained by adding a vanadium-copper composite intermediate layer;

[0028] Figure 3 The tensile strength of the interface between high-entropy alloys / ultra-high-strength steel materials with added niobium (Nb), vanadium (V), and vanadium-copper (V-Cu) interlayers.

[0029] Figure 4 middle: Figure 4 a, 4b, and 4c represent the interfacial bonding of the high-entropy alloy / ultra-high-strength steel materials obtained in Comparative Examples 1, 2, and 3, respectively. Detailed Implementation

[0030] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0031] This invention provides a method for bonding high-entropy alloys with steel, specifically including the following steps:

[0032] Step 1) Assemble an alloy-intermediate-steel composite by placing an intermediate layer between the high-entropy alloy and the steel; the intermediate layer includes one of niobium metal foil, vanadium metal foil, and vanadium-copper composite metal foil;

[0033] Step 2) Hot-press the high-entropy alloy-intermediate layer-steel assembly to bond the high-entropy alloy with the steel, thereby obtaining an alloy / intermediate layer / steel composite material.

[0034] Based on the above method, the addition of an intermediate layer effectively blocks the diffusion and direct chemical reaction of elements with strong compound-forming ability between matrix materials (such as Fe and Ni in ultra-high strength steel easily reacting with Ti, Zr, Al and other elements in high-entropy alloys to form brittle intermetallic compounds), effectively controlling the formation of harmful phases at the interface; under vacuum, high temperature, high pressure and large deformation conditions, the metal atoms at the interface of high-entropy alloy-intermediate layer and intermediate layer-ultra-high strength steel approach the range of atomic force action, forming strong metallic bonds, and a small number of residual micropores gradually disappear under the diffusion effect, so that the interface achieves metallurgical connection.

[0035] In some embodiments, in step 1), the high-entropy alloy includes the elements Al, Nb, Ti, and Zr; and / or, the steel has a yield strength greater than 1.3 GPa.

[0036] In some embodiments, in step 1), the high-entropy alloy is an Al-Nb-Ti-V-Zr-Hf energetic high-entropy alloy;

[0037] Preferably, the high-entropy alloy is an energetic high-entropy alloy of AlNbTi3Zr1.5;

[0038] And / or, the steel is one of 18Ni200, 18Ni250, 18Ni300, and 18Ni350. This invention is applicable to ultra-low carbon ultra-high strength steels.

[0039] In some embodiments, in step 1), the thickness of the intermediate layer is 100-200 μm; and / or the purity of the intermediate layer is 99.95% or higher; and / or the surface of the intermediate layer is smooth with a surface roughness of less than Ra 0.6 μm.

[0040] A certain thickness in the interlayer is essential for effectively preventing elements from the matrix material (ultra-high strength steel and high-entropy alloys) from crossing the interlayer. It also provides a wider reaction space for minor diffusion reactions of elements in the matrix material, reducing the impact on the interface. Because interface brittleness is highly sensitive to elemental reactions, high-purity foil is a necessary requirement to ensure no additional "elemental contamination." A clean and smooth surface facilitates direct metallurgical contact between metals and promotes the formation of interfacial metal bonds. Maintaining low roughness facilitates the welding of interfacial voids during the bonding process, improving the quality of the interfacial connection.

[0041] In some embodiments, in step 1), the high-entropy alloy is the same size as the steel to ensure efficient bonding of the joint surfaces.

[0042] In some embodiments, in step 1), the high-entropy alloy and the steel each have a first surface and a second surface, which are respectively used to contact the intermediate layer. The roughness of the first surface and the second surface is lower than Ra 0.8μm, which is beneficial to the welding of interface pores during the connection process and improves the interface connection quality.

[0043] In some embodiments, a Gleeble hot compression simulation tester is used in step 2) to hot-press the high-entropy alloy-intermediate layer-ultra-high-strength steel assembly.

[0044] In some embodiments, during the hot-pressing connection step, the compressive stress direction remains perpendicular to the structure interface, the heating rate is 3-10℃ / s; and / or the compression temperature is 800-900℃; and / or the compressive strain rate is 0.01-1s. -1 ; and / or the compression deformation is greater than or equal to 40%; the vacuum degree is higher than 0.1 Pa.

[0045] In some embodiments, the heating rate is 5°C / s; and / or the compression temperature is 850°C; and / or the compression strain rate is 0.1 s. -1 ; and / or compressive deformation of 40%. 850℃ is the optimal temperature for effectively balancing the diffusion bonding of alloying elements and the formation of harmful intermetallic compounds; compressive deformation of 40% and compressive strain rate of 0.1 s⁻¹. -1 Larger deformation is an effective means of eliminating interfacial pores and forming metallic bonds through interfacial atomic metallurgical contact; a vacuum value greater than 0.1 Pa and air cooling after compression can effectively prevent oxidation at the connection interface and the formation of a thick oxide film that hinders metallurgical contact and connection between materials.

[0046] The present invention also provides a high-entropy alloy / steel composite material, wherein the interface of the alloy / steel composite material is free of pores, cracks and bulk intermetallic compounds; preferably, the alloy / steel composite material is obtained by combining the methods described in any one of the above-mentioned methods.

[0047] In embodiments of the present invention, high-entropy alloys are prepared using a vacuum induction furnace or a vacuum suspension melting furnace, and high-quality ultra-high-strength steel is prepared using vacuum induction melting combined with vacuum arc remelting. Both types undergo high-temperature forging, from which small billets are cut for surface grinding and cleaning. Figure 1 As shown in a and 1b; the cut high-entropy alloy and ultra-high-strength steel have parallel upper and lower surfaces; the foil used as the intermediate layer is niobium foil, vanadium foil, and copper foil after rolling and annealing; the high-entropy alloy billet / intermediate layer / ultra-high-strength steel billet are assembled in sequence, as shown in the assembly method. Figure 1As shown in c; subsequently, the high-entropy alloy-intermediate layer-ultra-high-strength steel assembly was vacuum-sealed, and thermo-pressed together under vacuum to achieve complete interface bonding. The thermo-pressing process is as follows: Figure 1 As shown in d, a high-quality high-entropy alloy / ultra-high-strength steel composite material with high interfacial strength is thus prepared, such as... Figure 1 As shown in e.

[0048] The present invention will be further described in detail below through specific embodiments:

[0049] Example 1

[0050] This embodiment provides a method for combining high-entropy alloys with ultra-high-strength steel, specifically including the following steps:

[0051] Step 1) High-quality, defect-free AlNbTi3Zr1.5 (Al, Nb, Ti, Zr molar ratio of 1:1:3:1.5) high-entropy alloy and 18Ni(350) ultra-high-strength steel billet were prepared using a vacuum induction melting furnace, and then forged at high temperature to obtain forging billets; small billets for connection were cut from them, each with a size of 10mm×10mm×10mm, and the surface of the billet was milled to ensure that the initial billet size was consistent, the connection surface was smooth and straight, and the surface roughness was lower than Ra 0.8μm; the sides were smooth without wrinkles, defects or sharp edges, and the dimensions of each layer of billet were consistent around the perimeter, with a tolerance of no more than 0.5mm; before constructing the connection, the surface to be connected was cleaned with methanol to avoid oil stains and foreign matter remaining at the interface;

[0052] AlNbTi3Zr1.5 high-entropy alloy, niobium metal foil, and 18Ni(350) ultra-high strength steel were assembled in sequence to form an AlNbTi3Zr1.5 high-entropy alloy-intermediate layer-18Ni(350) ultra-high strength steel sandwich structure, and fixed with conductive tape to ensure that the connection interface is not contaminated and does not slip or misalign during the assembly process.

[0053] Step 2) Load the assembled billet into the Gleeble hot compression simulation tester, keeping the pressure direction perpendicular to the interface; then proceed according to... Figure 1 The hot-pressing connection process shown in d is as follows: heating rate of 5℃ / s, compression temperature of 850℃, and compression strain rate of 0.1s. -1 The compression deformation is 40%, and the material is air-cooled after compression. The vacuum degree is maintained above 0.1 Pa throughout the heating, compression and cooling process to obtain a high-quality high-entropy alloy / ultra-high-strength steel composite material with high interfacial strength.

[0054] The interfacial strength of the AlNbTi3Zr1.5 high-entropy alloy / intermediate layer / 18Ni(350) ultra-high strength steel composite material obtained in this embodiment was measured to be 1006 MPa. Figure 3As shown; the interface is organized as follows Figure 2 As shown in a and 2b, it can be seen that there are no pores, cracks, or large metal compounds at the interface, and the connection is in good condition.

[0055] Example 2

[0056] This embodiment provides a method for combining high-entropy alloys with ultra-high-strength steel, specifically including the following steps:

[0057] Step 1) High-quality, defect-free AlNbTi3Zr1.5 (Al, Nb, Ti, Zr molar ratio of 1:1:3:1.5) high-entropy alloy and 18Ni(350) ultra-high-strength steel billet were prepared using a vacuum induction melting furnace, and then forged at high temperature to obtain forging billets; small billets for connection were cut from them, each with a size of 10mm×10mm×10mm, and the surface of the billet was milled to ensure that the initial billet size was consistent, the connection surface was smooth and straight, and the surface roughness was lower than Ra 0.8μm; the sides were smooth without wrinkles, defects or sharp edges, and the dimensions of each layer of billet were consistent around the perimeter, with a tolerance of no more than 0.5mm; before constructing the connection, the surface to be connected was cleaned with methanol to avoid oil stains and foreign matter remaining at the interface;

[0058] AlNbTi3Zr1.5 high-entropy alloy, vanadium metal foil, and 18Ni(350) ultra-high strength steel were assembled in sequence to form an AlNbTi3Zr1.5 high-entropy alloy-intermediate layer-18Ni(350) ultra-high strength steel sandwich structure, and fixed with conductive tape to ensure that the connection interface is not contaminated and does not slip or misalign during the assembly process.

[0059] Step 2) Load the assembled billet into the Gleeble hot compression simulation tester, keeping the pressure direction perpendicular to the interface; then proceed according to... Figure 1 The hot-pressing connection process shown in d is as follows: heating rate of 5℃ / s, compression temperature of 850℃, and compression strain rate of 0.1s. -1 The compression deformation is 40%, and the material is air-cooled after compression. The vacuum degree is maintained above 0.1 Pa throughout the heating, compression and cooling process to obtain a high-quality high-entropy alloy / ultra-high-strength steel composite material with high interfacial strength.

[0060] The interfacial strength of the AlNbTi3Zr1.5 high-entropy alloy / intermediate layer / 18Ni(350) ultra-high strength steel composite material obtained in this embodiment was measured to be 690.4 MPa. (See [link to relevant documentation]). Figure 3 The interfacial microstructure of the hot-pressed AlNbTi3Zr1.5 high-entropy alloy / intermediate layer / 18Ni(350) ultra-high strength steel composite material is as follows: Figure 2As shown in c and 2d, it can be seen that there are no pores, cracks, or large metal compounds at the interface, and the connection is in good condition.

[0061] Example 3

[0062] This embodiment provides a method for combining high-entropy alloys with ultra-high-strength steel, specifically including the following steps:

[0063] Step 1) High-quality, defect-free AlNbTi3Zr1.5 (Al, Nb, Ti, Zr molar ratio of 1:1:3:1.5) high-entropy alloy and 18Ni(350) ultra-high-strength steel billet were prepared using a vacuum induction melting furnace, and then forged at high temperature to obtain forging billets; small billets for connection were cut from them, each with a size of 10mm×10mm×10mm, and the surface of the billet was milled to ensure that the initial billet size was consistent, the connection surface was smooth and straight, and the surface roughness was lower than Ra 0.8μm; the sides were smooth without wrinkles, defects or sharp edges, and the dimensions of each layer of billet were consistent around the perimeter, with a tolerance of no more than 0.5mm; before constructing the connection, the surface to be connected was cleaned with methanol to avoid oil stains and foreign matter remaining at the interface;

[0064] AlNbTi3Zr1.5 high-entropy alloy, vanadium metal foil, copper metal foil, and 18Ni(350) ultra-high strength steel are assembled in sequence to form an AlNbTi3Zr1.5 high-entropy alloy-intermediate layer-18Ni(350) ultra-high strength steel sandwich structure, and fixed with conductive tape to ensure that the connection interface is not contaminated and does not slip or misalign during the assembly process.

[0065] Step 2) Load the assembled billet into the Gleeble hot compression simulation tester, keeping the pressure direction perpendicular to the interface; then proceed according to... Figure 1 The hot-pressing connection process shown in d is as follows: heating rate of 5℃ / s, compression temperature of 850℃, and compression strain rate of 0.1s. -1 The compression deformation is 40%, and the material is air-cooled after compression. The vacuum degree is maintained above 0.1 Pa throughout the heating, compression and cooling process to obtain a high-quality high-entropy alloy / ultra-high-strength steel composite material with high interfacial strength.

[0066] The interfacial strength of the AlNbTi3Zr1.5 high-entropy alloy / intermediate layer / 18Ni(350) ultra-high strength steel composite material obtained in this embodiment was measured to be 517.25 MPa. (See [link to relevant documentation]). Figure 3 The interfacial microstructure of the hot-pressed AlNbTi3Zr1.5 high-entropy alloy / intermediate layer / 18Ni(350) ultra-high strength steel composite material is as follows: Figure 2 As shown in e and 2f, it can be seen that there are no pores, cracks, or large metal compounds at the connection interface, and the connection is in good condition.

[0067] Comparative Example 1

[0068] This comparative example demonstrates the bonding of AlNbTi3Zr1.5 high-entropy alloy with 18Ni(350) ultra-high-strength steel without an intermediate layer, specifically including the following steps:

[0069] Step 1) High-quality, defect-free AlNbTi3Zr1.5 (Al, Nb, Ti, Zr molar ratio of 1:1:3:1.5) high-entropy alloy and 18Ni(350) ultra-high-strength steel billet were prepared using a vacuum induction melting furnace, and then forged at high temperature to obtain forging billets; small billets for connection were cut from them, each with a size of 10mm×10mm×10mm, and the surface of the billet was milled to ensure that the initial billet size was consistent, the connection surface was smooth and straight, and the surface roughness was lower than Ra 0.8μm; the sides were smooth without wrinkles, defects or sharp edges, and the dimensions of each layer of billet were consistent around the perimeter, with a tolerance of no more than 0.5mm; before constructing the connection, the surface to be connected was cleaned with methanol to avoid oil stains and foreign matter remaining at the interface;

[0070] AlNbTi3Zr1.5 high-entropy alloy and 18Ni(350) ultra-high strength steel were assembled in sequence and fixed with conductive tape to ensure that the connection interface was not contaminated and did not slip or misalign during the assembly process.

[0071] Step 2) Load the assembled billet into the Gleeble hot compression simulation tester, keeping the pressure direction perpendicular to the interface; then proceed according to... Figure 1 The hot-pressing connection process shown in d is as follows: heating rate of 5℃ / s, compression temperature of 850℃, and compression strain rate of 0.1s. -1 The compression deformation is 40%, and the material is air-cooled after compression. The vacuum level is maintained above 0.1 Pa throughout the heating, compression and cooling process to obtain a high-entropy alloy / ultra-high-strength steel composite material.

[0072] In this comparative example, a large number of bulk intermetallic compounds appeared at the interface between the AlNbTi3Zr1.5 high-entropy alloy and the 18Ni(350) ultra-high-strength steel, such as Figure 4 As shown in figure a, the interface exhibits extreme brittleness, making it almost impossible to cut samples for mechanical property testing.

[0073] Comparative Example 2

[0074] The difference between this comparative example and Example 1 lies in the process parameters for high-temperature large deformation, specifically including the following steps:

[0075] Step 1) High-quality, defect-free AlNbTi3Zr1.5 (Al, Nb, Ti, Zr molar ratio of 1:1:3:1.5) high-entropy alloy and 18Ni(350) ultra-high-strength steel billet were prepared using a vacuum induction melting furnace, and then forged at high temperature to obtain forging billets; small billets for connection were cut from them, each with a size of 10mm×10mm×10mm, and the surface of the billet was milled to ensure that the initial billet size was consistent, the connection surface was smooth and straight, and the surface roughness was lower than Ra 0.8μm; the sides were smooth without wrinkles, defects or sharp edges, and the dimensions of each layer of billet were consistent around the perimeter, with a tolerance of no more than 0.5mm; before constructing the connection, the surface to be connected was cleaned with methanol to avoid oil stains and foreign matter remaining at the interface;

[0076] AlNbTi3Zr1.5 high-entropy alloy, niobium metal foil, and 18Ni(350) ultra-high strength steel were assembled in sequence to form an AlNbTi3Zr1.5 high-entropy alloy-intermediate layer-18Ni(350) ultra-high strength steel sandwich structure, and fixed with conductive tape to ensure that the connection interface is not contaminated and does not slip or misalign during the assembly process.

[0077] Step 2) Load the assembled billet into the Gleeble hot compression simulation tester, keeping the pressure direction perpendicular to the interface; then proceed according to... Figure 1 The hot-pressing connection process shown in d is as follows: heating rate of 5℃ / s, compression temperature of 850℃, and compression strain rate of 0.1s. -1 The compression deformation is 10%, and the material is air-cooled after compression. The vacuum level is maintained above 0.1 Pa throughout the heating, compression and cooling process to obtain a high-entropy alloy / ultra-high-strength steel composite material.

[0078] The strength of the material interface obtained in this comparative example was lower than that in Example 1, and its interface structure was as follows: Figure 4 As shown in b, it can be seen that there are unwelded holes at the connection interface, and the interface strength is low.

[0079] Comparative Example 3

[0080] The difference between this comparative example and Example 1 is that refractory metal tungsten is selected as the intermediate layer, specifically including the following steps:

[0081] Step 1) High-quality, defect-free AlNbTi3Zr1.5 (Al, Nb, Ti, Zr molar ratio of 1:1:3:1.5) high-entropy alloy and 18Ni(350) ultra-high-strength steel billet were prepared using a vacuum induction melting furnace, and then forged at high temperature to obtain forging billets; small billets for connection were cut from them, each with a size of 10mm×10mm×10mm, and the surface of the billet was milled to ensure that the initial billet size was consistent, the connection surface was smooth and straight, and the surface roughness was lower than Ra 0.8μm; the sides were smooth without wrinkles, defects or sharp edges, and the dimensions of each layer of billet were consistent around the perimeter, with a tolerance of no more than 0.5mm; before constructing the connection, the surface to be connected was cleaned with methanol to avoid oil stains and foreign matter remaining at the interface;

[0082] AlNbTi3Zr1.5 high-entropy alloy, tungsten foil, and 18Ni(350) ultra-high strength steel were assembled in sequence to form an AlNbTi3Zr1.5 high-entropy alloy-intermediate layer-18Ni(350) ultra-high strength steel sandwich structure, and fixed with conductive tape to ensure that the connection interface is not contaminated and does not slip or misalign during the assembly process.

[0083] Step 2) Load the assembled billet into the Gleeble hot compression simulation tester, keeping the pressure direction perpendicular to the interface; then proceed according to... Figure 1 The hot-pressing connection process shown in d is as follows: heating rate of 5℃ / s, compression temperature of 850℃, and compression strain rate of 0.1s. -1 The compression deformation is 40%, and the material is air-cooled after compression. The vacuum level is maintained above 0.1 Pa throughout the heating, compression and cooling process to obtain a high-entropy alloy / ultra-high-strength steel composite material.

[0084] The interfacial microstructure of the hot-pressed AlNbTi3Zr1.5 high-entropy alloy / intermediate layer / 18Ni(350) ultra-high-strength steel composite material in this comparative example is as follows: Figure 4 As shown in Figure c, there are still unbonded areas at the interface, resulting in extremely poor bonding performance and making it impossible to prepare samples for mechanical property testing.

[0085] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A method of joining a high-entropy alloy to a steel, characterized by, The method comprises the following steps: Step 1) placing an intermediate layer between a high-entropy alloy and a steel to assemble a high-entropy alloy-intermediate layer-steel assembly; the intermediate layer comprises one of a niobium metal foil, a vanadium metal foil, and a vanadium-copper composite metal foil; Step 2) performing thermal pressure bonding on the high-entropy alloy-intermediate layer-steel assembly to combine the high-entropy alloy and the steel, thereby obtaining a high-entropy alloy / intermediate layer / steel composite material; The high-entropy alloy comprises elements Al, Nb, Ti, and Zr. The thickness of the intermediate layer is 100-200 μm. In the step of hot-pressing connection, the compression temperature is 800-950 ℃; the compression strain rate is 0.01-1 s -1 ; the compression deformation is greater than or equal to 40 %; and the vacuum degree is higher than 0.1 Pa.

2. The method of claim 1, wherein the high-entropy alloy and the steel are combined by, In the step 1), the yield strength of the steel is greater than 1.3 GPa.

3. The method of joining a high-entropy alloy to a steel according to claim 1 or 2, characterized in that, In the step 1), the high-entropy alloy is an Al-Nb-Ti-V-Zr-Hf-based energetic high-entropy alloy. And / or, the steel is one of 18Ni200, 18Ni250, 18Ni300, and 18Ni350.

4. The method of joining a high-entropy alloy to a steel according to claim 1 or 2, characterized in that, In the step 1), the high-entropy alloy is an AlNbTi3Zr1.5 energetic high-entropy alloy.

5. The method of claim 1, wherein the high-entropy alloy and the steel are combined by, In the step 1), the purity of the intermediate layer is greater than 99.95 %, and / or the surface roughness Ra of the intermediate layer is less than 0.6 μm.

6. The method of claim 1, wherein the high-entropy alloy and the steel are combined by, In the step 1), the high-entropy alloy and the steel have the same size.

7. The method of claim 1, wherein the high-entropy alloy and the steel are combined by, In the step 1), the high-entropy alloy and the steel each have a first surface and a second surface, the first surface and the second surface are respectively used to contact the intermediate layer, and the roughness Ra of the first surface and the second surface is less than 0.8 μm.

8. The method of claim 1, wherein the high-entropy alloy and the steel are combined by, the compression temperature is 850 °C; and / or the compression strain rate is 0.1 s -1 ; and / or the compression deformation is 40 %.

9. A high-entropy alloy / steel composite material, characterized by, The high-entropy alloy / steel composite material connection interface is free of holes, cracks, and large intermetallic compounds, and has a narrow element diffusion width. The high-entropy alloy / steel composite material is obtained by the method of any one of claims 1 to 8.

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