Diffusion bonding method of IC21 single crystal superalloy based on multi-field assistance and high entropy intermediate layer

Abstract

The present invention discloses an IC21 single crystal high-temperature alloy diffusion welding method based on multi-field assistance and a high-entropy intermediate layer, belonging to the field of welding technology. The present invention adopts a nano-high-entropy intermediate layer foil composed of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5%, which is placed between two layers of IC21 single crystal high-temperature alloy. Liquid-phase diffusion welding is carried out in a vacuum diffusion welding furnace by introducing multi-field coupling of ultrasonic vibration field, pulsed magnetic field, and electric field. Multi-field coupling realizes energy field superposition through spatiotemporal coordination, and the pulse frequency of the ultrasonic vibration field is phase-matched with the alternating frequency of the magnetic field. The electric field opens the diffusion channel, and the mid-term superposition of ultrasonic vibration field and pulsed magnetic field realizes dendrite regulation and defect repair, ultimately achieving directional migration of the liquid film and suppression of dendrite segregation, breaking through the technical bottleneck of high-integrity connection of ultra-thin-wall structures of single crystal turbine blades, and supporting the extreme operating conditions service requirements of the sixth-generation engine.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and in particular to an IC21 single crystal high-temperature alloy diffusion welding method based on multi-field assistance and a high-entropy intermediate layer. Background Art

[0002] In the iterative upgrades of supersonic cruise and high thrust-to-weight ratio aircraft engines, single-crystal turbine blades, as core components of the hot end, face multiple challenges in their service environment, including extreme high temperatures (≥1100°C), high-frequency thermal cycling, and complex aerodynamic loads. IC21 single-crystal superalloy, due to its excellent high-temperature strength, thermal corrosion resistance, and single-crystal structure without grain boundary weakening, has become the material of choice for the new generation of single-crystal turbine blades. However, the complex air-cooling channels and ultra-thin wall structures (wall thickness ≤1mm) of single-crystal components require split-part precision casting followed by joining and forming. Maintaining the single-crystal continuity and controlling the interface structure are key manufacturing challenges.

[0003] The welding of single-crystal superalloys must strictly avoid recrystallization tendencies. Conventional fusion welding destroys the single-crystal structure of the parent material due to high heat input and is extremely prone to thermal cracking. Brazing is limited by the brittle phase formed by the reaction of low-melting-point brazing filler metal with the matrix, and the high-temperature strength performance of the joint is less than 50% of that of solid-phase diffusion welding. Although solid-phase diffusion welding can inhibit the formation of hot cracks and brittle phases, the low diffusion characteristics of single-crystal alloys require welding temperatures close to the dissolution temperature of the γ' phase (usually ≥1300°C), resulting in coarsening of the γ' strengthening phase of the parent material, local recrystallization, and interface element segregation. Traditional Ni-based interlayers have poor compatibility with the single-crystal composition, and the diffusion of high-melting-point elements such as Cr, Re, and Ta is retarded. Re-Ta-poor regions and Al2O3 oxide film barriers are easily formed at the interface, causing a significant decline in the high-temperature strength and creep resistance of the joint. Therefore, a technical solution to improve the high-temperature tensile strength of single-crystal superalloy joints is urgently needed. Summary of the Invention

[0004] In response to the difficulties mentioned in the background technology, the present invention proposes an IC21 single crystal high-temperature alloy diffusion welding method based on multi-field assistance and high-entropy intermediate layer, adopting the ultrasonic-magnetic field-electric field multi-physical field synergistic mechanism, and innovatively integrating the ultrasonic cavitation-acoustic streaming effect, the pulsed magnetic field Lorentz force regulation and the electric field electromigration-Joule heating effect, breaking through the limitations of a single energy field, and realizing precise control of the liquid phase diffusion welding interface reaction kinetics and microstructure.

[0005] To achieve the above objectives, the present invention proposes a diffusion bonding method for IC21 single crystal high temperature alloy based on multi-field assistance and high entropy intermediate layer, which specifically includes the following steps:

[0006] Step 1: preparing a high entropy intermediate layer foil; the chemical composition of the high entropy intermediate layer is composed of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5% by mass percentage;

[0007] Step 2: preparing a nano-high entropy intermediate layer foil; treating the high entropy intermediate layer foil with a laser surface impact treatment to obtain a nano-high entropy intermediate layer foil;

[0008] Step 3: Place the nano high-entropy intermediate layer foil between the upper and lower layers of IC21 single crystal high-temperature alloy, and perform liquid-phase diffusion welding in a vacuum diffusion welding furnace assisted by an electric field, a magnetic field, and an ultrasonic field; during the welding process, an electric field is applied during the heating stage, and an ultrasonic vibration field and a pulsed magnetic field are applied synchronously during the insulation stage to obtain an IC21 single crystal high-temperature alloy liquid-phase diffusion welding joint.

[0009] Preferably, the high entropy intermediate layer foil has a thickness of 50 μm-100 μm, a grain size of ≤200 nm, and a surface roughness Ra of ≤0.8 μm.

[0010] Preferably, the process of preparing the high entropy intermediate layer foil is: Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% are mixed by high-energy ball milling according to the above mass percentages, and placed in a vacuum melting furnace for vacuum melting, followed by multiple hot rolling and cold rolling to obtain the high entropy intermediate layer foil.

[0011] Preferably, the surface of the nano high entropy intermediate layer foil is a gradient nanostructure, and the surface grain size is 30nm-60nm.

[0012] Preferably, in the process of laser surface impact treatment of high entropy intermediate layer foil, the laser energy density is 4GW / cm 2 -6 GW / cm 2 , the laser energy is 8J-12J, the pulse width is 6ns-13ns, and the number of impacts is 2-4 times.

[0013] Preferably, in the process of liquid phase diffusion welding in the electric field-magnetic field-ultrasonic field assisted vacuum diffusion welding furnace, the vacuum diffusion welding furnace is first evacuated, and then when the temperature is raised to 50°C below the welding temperature, an electric field is applied, and when it reaches the insulation stage, an ultrasonic vibration field and a pulsed magnetic field are applied synchronously; the intensity of the electric field is 50V / cm-80V / cm; the frequency of the ultrasonic vibration field is 20kHz-30kHz, and the amplitude is 10μm-30μm; the intensity of the pulsed magnetic field is 0.5T-1.0T, and the frequency of the pulsed magnetic field is 30Hz-50Hz.

[0014] Preferably, the welding temperature is 1050° C.-1150° C., the heating rate is 10° C. / min, the holding time of the holding stage is 60 min-90 min, and the pressure is 4 MPa-6 MPa.

[0015] Preferably, the pulsed magnetic field is an alternating magnetic field, the application direction of the pulsed magnetic field deviates from the single crystal orientation of the IC21 single crystal high-temperature alloy by ≤5°, and the application direction of the electric field is perpendicular to the welding interface.

[0016] Preferably, the application direction of the ultrasonic vibration field is perpendicular to the welding interface, and is applied in a pulse mode of turning on the ultrasonic vibration field for 20 seconds and then turning off the ultrasonic vibration field for 10 seconds. The direction of the pulsed magnetic field is switched during the period when the ultrasonic vibration field is off. The ratio of the application time of the ultrasonic vibration field to the pulsed magnetic field is 1:2-1:3, and the phase difference between the ultrasonic vibration field and the pulsed magnetic field is 90°-180°.

[0017] Preferably, the vacuum degree of the vacuum diffusion welding furnace is ≤5×10 -3 Pa.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention breaks through the dual technical bottlenecks of interface structure control and high-temperature performance improvement in single-crystal high-temperature alloy liquid phase diffusion welding through the coordinated design of ultrasonic-magnetic-electric field multi-field coupling and nano high-entropy intermediate layer.

[0020] The present invention is based on the intermediate layer design of the Ni-Cr-Al-Re-Ta-Y-Si-B octal high entropy alloy, utilizes the multi-principal element mixed entropy effect to suppress the formation of brittle phases, and combines with the gradient nanostructure induced by laser shock to significantly reduce the element diffusion activation energy, significantly accelerate the migration rate of refractory elements, reduce the welding temperature to below that of traditional processes, greatly shorten the holding time, and effectively avoid the risks of coarsening and recrystallization of the strengthening phase of the single crystal parent material; ultrasonic vibration instantaneously peels off the interface oxide film through the cavitation effect, and the acoustic streaming effect promotes the uniform distribution of solutes. At the same time, high-density dislocations provide a fast channel for atomic diffusion; the pulsed magnetic field forces liquid dendrites to grow along the parent material single crystal orientation through the Lorentz force, thereby suppressing element segregation; the electric field drives the ion directional migration to compensate for the interface depleted area, and the Joule heat concentrates to dissolve the brittle clusters. Multi-field coupling significantly improves the efficiency of the interface metallurgical reaction. The method of the present invention significantly improves the high-temperature tensile strength of the joint, and is suitable for connecting ultra-thin-wall single-crystal turbine blades. The dimensional accuracy and thermal shock resistance are significantly better than those of traditional processes, providing a reliable solution to the manufacturing difficulties of hot-end parts such as single-crystal turbine blades of high thrust-to-weight ratio aircraft engines. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a SEM image of the microstructure of the IC21 single crystal high-temperature alloy diffusion bonded joint in Example 1 of the present invention.

[0022] Figure 2 This is a SEM image of the microstructure of the IC21 single crystal high-temperature alloy diffusion bonded joint in Example 4 of the present invention.

[0023] Figure 3 This is a SEM image of the microstructure of the IC21 single crystal high-temperature alloy diffusion bonded joint in Comparative Example 1 of the present invention.

[0024] Figure 4 This is a SEM image of the microstructure of the IC21 single crystal high-temperature alloy diffusion bonded joint in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0025] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] The present invention proposes a diffusion welding method for IC21 single crystal high temperature alloy based on multi-field assistance and high entropy intermediate layer, which specifically includes the following steps:

[0027] First, a high entropy middle layer foil is prepared; an octal high entropy alloy middle layer foil is prepared according to the mass percentage of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta5%, Y 2%, Si 7.5%, and B 1.5%, and the thickness is preferably 50-100 μm, for example, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, and 100 μm; and the grain size is ≤200 nm;

[0028] Specifically, the process of preparing the high entropy intermediate layer foil is as follows:

[0029] Step (1), mixing Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% according to the above mass percentages, and performing high-energy ball milling under argon protection, the ball-to-material ratio is preferably 10:1-15:1, for example, 10:1, 12:1, 15:1, the rotation speed is preferably 400-600 rpm, for example, 400 rpm, 500 rpm, 600 rpm, and the ball milling time is preferably 8-12 h, for example, 8 h, 10 h, 12 h, to obtain a nano-scale composite powder;

[0030] Step (2): Place the nano-scale composite powder in a vacuum melting furnace for vacuum melting, and the vacuum degree is ≤5×10 -3 Pa, the sintering temperature is preferably 1550-1650°C, for example, 1550°C, 1600°C, 1650°C, to obtain a pre-alloyed billet;

[0031] Step (3), processing the pre-alloyed billet into a foil with a thickness of 50-100 μm through multiple hot rolling and cold rolling (total deformation ≥ 80%); first preheating the ingot, placing it in a box-type resistance furnace, heating it to 500-600°C, for example, 500°C, 550°C, 600°C, keeping it warm for 2 hours, eliminating casting stress, and then first controlling the single pressure rate to preferably 20%-25%, for example, 20%, 23%, 25%, at a temperature in the range of 1100-1150°C, for example, 1100°C, 1125°C, 1150°C, and the rolling speed is preferably 0.5-1.0 m / s, for example, 0.5m / s, 0.7m / s, 1.0m / s, and two passes of slab rolling are performed; followed by finish rolling, rolling at 1050-1100℃, for example, 1050℃, 1075℃, 1100℃, and the single pressure rate is preferably controlled to be 15%-20%, for example, 15%, 17%, 80%, 20%, and the rolling speed is preferably 1.0-1.5m / s, for example, 1.0m / s, 1.25m / s, 1.5m / s. After each hot rolling, before air cooling to below 800℃, immediately return to the furnace and keep warm at the rolling temperature for 30 min (to prevent cracking caused by excessively low temperature); after air cooling to room temperature, stress relief annealing is performed, preferably at a temperature of 500-600°C, for example, 500°C, 550°C, or 600°C, and kept for 2 hours to eliminate rolling stress and provide a stable billet for cold rolling, ultimately obtaining a uniform equiaxed hot-rolled billet with a thickness of 20-30 mm; the hot-rolled billet is cut into strips with a width of 100-150 mm, for example, 100 mm, 125 mm, or 150 mm, the surface is polished to remove the oxide film, and a cold rolling lubricant is applied; the billet is then subjected to multiple cold rolling passes, including a rough rolling stage (1-3 passes) The single reduction rate is preferably 15-20%, for example, 15%, 17%, and 20%, and the rolling speed is preferably 0.3-0.5 m / s, for example, 0.3 m / s, 0.4 m / s, and 0.5 m / s; the single reduction rate in the finishing rolling stage (4-6 passes) is preferably 10-15%, for example, 10%, 13%, and 15%, and the rolling speed is preferably 0.5-0.8 m / s, for example, 0.5 m / s, 0.6 m / s, 0.7 m / s, and 0.8 m / s, and finally a foil with a thickness of 50-100 μm and a surface roughness Ra≤0.8 μm is prepared.

[0032] Secondly, a nano high entropy intermediate layer foil is prepared; the high entropy intermediate layer foil is treated by laser surface impact treatment to obtain a nano high entropy intermediate layer foil;

[0033] Specifically, during the laser surface impact treatment of the high entropy intermediate layer foil, the laser energy density is preferably 4GW / cm 2 -6 GW / cm 2 , for example, 4GW / cm 2 , 5GW / cm 2 , 6GW / cm 2 The laser energy is preferably 8J-12J, for example, 8J, 9J, 10J, 11J, 12J; the pulse width is preferably 6ns-13ns, for example, 6ns, 9ns, 11ns, 13ns; the number of impacts is preferably 2-4 times, for example, 2 times, 3 times, 4 times, so that the surface grains of the nano high entropy intermediate layer foil are refined to 30-60nm and a gradient nanostructure is formed.

[0034] Finally, the nano high-entropy intermediate layer foil is placed between the upper and lower layers of IC21 single crystal high-temperature alloy and liquid-phase diffusion welding is performed in a vacuum diffusion welding furnace assisted by electric field, magnetic field and ultrasonic field. The specific steps are as follows:

[0035] Step 1: The surface of the IC21 single crystal high-temperature alloy workpiece to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished using 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded workpiece is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated IC21 single crystal high-temperature alloy workpiece;

[0036] Step 2: Assemble the treated IC21 single crystal high temperature alloy workpieces, and assemble the nano high entropy alloy intermediate layer foil between the welding interfaces to obtain a sandwich structure of IC21 single crystal high temperature alloy-nano high entropy intermediate layer foil-IC21 single crystal high temperature alloy;

[0037] Step 3: Place the sandwich structure of IC21 single crystal high temperature alloy / nano high entropy intermediate layer foil / IC21 single crystal high temperature alloy into a vacuum diffusion welding furnace assisted by electric field, magnetic field and ultrasonic field, and evacuate the furnace until the vacuum degree in the furnace is ≤5×10 - 3Pa, start heating, and when it reaches 50°C below the welding temperature, apply an electric field, and the intensity of the electric field is preferably 50V / cm-80V / cm, for example, 50V / cm, 60V / cm, 70V / cm, 80V / cm; in the holding stage, synchronously apply an ultrasonic vibration field and a pulsed magnetic field, and the frequency of the ultrasonic vibration field is preferably 20kHz-30kHz, for example, 20kHz, 22kHz, 25kHz, 27kHz, 30kHz, and the amplitude is preferably 10μm-30μm, for example, 10μm, 15μm, 20μm, 25μm, 30μm; the intensity of the applied pulsed magnetic field is preferably 0.5T-1.0T, for example, 0.5T, 0.6T, 0.7T, 0.8T, 0.9T, 1.0T, the frequency of the pulsed magnetic field is preferably 30Hz-50Hz, for example, 30Hz, 40Hz, 50Hz; to achieve activation and directional migration of liquid metal at the interface; wherein, in the liquid phase diffusion welding process, the welding temperature is preferably 1050℃-1150℃, for example, 1050℃, 1070℃, 1090℃, 1100℃, 1130℃, 1150℃, the heating rate is preferably 10℃ / min, the holding time in the holding stage is preferably 60min-90min, for example, 60min, 70min, 80min, 90min, and the pressure is preferably 4MPa-6MPa, for example, 4MPa, 5MPa, 6MPa;

[0038] Specifically, the applied pulsed magnetic field is an alternating magnetic field, and the deviation between the direction of the pulsed magnetic field and the single crystal orientation of the IC21 single crystal high-temperature alloy is ≤5°, forcing the liquid dendrites to grow along the orientation of the parent material IC21 single crystal high-temperature alloy, and the dendrite orientation deviation angle is ≤3°; the application direction of the electric field is perpendicular to the welding interface; the application direction of the ultrasonic vibration field is perpendicular to the welding interface, and is applied in a pulse mode of turning on for 20 seconds and then off for 10 seconds, and the direction of the pulsed magnetic field is switched during the period when the ultrasonic vibration field is off to ensure that the phase difference between the ultrasonic vibration field and the pulsed magnetic field is 90°-180°, for example, it can be 90°, 120°, 150°, or 180°, wherein the ratio of the application time of the ultrasonic vibration field to the pulsed magnetic field is 1:2-1:3, for example, it can be 1:1, 1:2, or 1:3.

[0039] Step 4: Heat, keep warm, cool, and perform nondestructive testing on the IC21 single crystal high temperature alloy according to the set process to obtain a completed IC21 single crystal high temperature alloy liquid phase diffusion welded joint.

[0040] In some embodiments of the present invention, the Ni-Cr-Al-Re-Ta-Y-Si-B octal nano-high-entropy interlayer foil is prepared through a multi-element collaborative design of high-entropy alloys. Ni serves as the matrix to ensure lattice matching with the IC21 single crystal, while Cr and Al form a continuous Cr2O3-Al2O3 composite oxide film to inhibit interfacial oxidation. Re and Ta inhibit high-temperature element diffusion and segregation through solid solution strengthening, while also improving interfacial creep resistance. Si and B lower the liquidus temperature of the interlayer, promote diffusion interface activation, and eliminate micropore defects through wetting control. Y can achieve weld microstructure optimization and further enhance the high-temperature fatigue strength of the workpiece. Combined with the laser shock-induced gradient nanostructure of the high-entropy interlayer foil, it can significantly enhance element diffusion dynamics and reduce the welding temperature to 1050-1150°C (below the coarsening threshold of the γ' phase of the IC21 single crystal). Ultrasonic-magnetic-electric field multi-field coupling enables directional migration of the liquid film and suppression of dendrite segregation, breaking through the technical bottleneck of high-integrity connection of ultra-thin-wall structures of single-crystal turbine blades and supporting the extreme service conditions of the sixth-generation engine.

[0041] In some embodiments of the present invention, during the liquid phase diffusion welding process in a vacuum diffusion welding furnace assisted by an electric field, a magnetic field, and an ultrasonic field, the ultrasonic vibration field can induce a cavitation effect after the intermediate layer melts, promote the uniform distribution of solutes, and suppress element segregation. At the same time, the high-density dislocations introduced by ultrasound can significantly reduce the atomic diffusion activation energy, thereby increasing the migration rate of slow-diffusion elements such as Re and Ta by 3-5 times, effectively realizing dynamic recrystallization of nano-grains; the pulsed magnetic field forces the liquid metal dendrites to grow along the orientation of the parent material single crystal through the Lorentz force, and combines the magnetostrictive effect to suppress the segregation of heavy elements such as Re and W; the electric field drives the cations in the liquefied intermediate layer to migrate directionally to the parent material interface, compensating for the element depletion zone and improving the element diffusion of the weld. The uniformity of the dispersion is improved, and at the same time, the high resistance characteristics of the nano-grain boundaries in the intermediate layer will induce Joule heat concentration, which helps to promote the wetting of the nano-high entropy intermediate layer foil and the base material; multi-field coupling realizes the optimization of energy field superposition through spatiotemporal collaborative design: the pulse mode of the ultrasonic vibration field is phase-matched with the alternating frequency of the pulsed magnetic field to avoid energy cancellation; electric field pre-activation can open the diffusion channel, and the mid-term superposition of the ultrasonic vibration field and the magnetic field can realize dendrite regulation and defect repair; the heat-mechanical-electric synergy makes the actual welding thermodynamic conditions equivalent to the effect of 1300℃ / 120min when no external field is applied, while the welding process only needs 1090℃ / 60min, which effectively reduces the thermal damage of the base material, and the coarsening rate of its γ' strengthening phase is reduced from 20% to below 5%.

[0042] The present invention will be further described below with reference to the embodiments.

[0043] Example 1

[0044] This embodiment provides an IC21 single crystal high temperature alloy liquid phase diffusion bonding method based on electric field, magnetic field and ultrasonic field assistance, and the specific steps are as follows:

[0045] Step 1: The surface of the IC21 single crystal high-temperature alloy workpiece to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished using 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded workpiece is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated IC21 single crystal high-temperature alloy workpiece;

[0046] Step 2: Assemble the treated IC21 single crystal high temperature alloy workpieces, and assemble the nano high entropy alloy intermediate layer foil between the welding interfaces to obtain a sandwich structure of IC21 single crystal high temperature alloy-nano high entropy intermediate layer foil-IC21 single crystal high temperature alloy;

[0047] The method for preparing the nano high entropy alloy intermediate layer foil comprises the following steps:

[0048] Step (1) Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% are mixed according to the mass percentage of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5%, and subjected to argon protection high-energy ball milling (ball-to-material ratio 12:1, rotation speed 500 rpm, time 10 h) to obtain nano-scale composite powder;

[0049] Step (2) Place the nano-scale composite powder in a vacuum melting furnace for vacuum melting (vacuum degree ≤ 5×10 -3 Pa, sintering temperature 1600 ° C), to obtain a pre-alloyed billet; the pre-alloyed billet was subjected to multiple hot rolling and cold rolling, with the total deformation controlled at 85%, to prepare a foil with a thickness of 60 μm;

[0050] Laser shock processing of foil (energy density 5 GW / cm 2 , laser energy 10J, pulse width 7ns, impact number 4 times), so that the surface grains are refined to 30-60nm, and gradient nanostructures and high-density dislocations are formed.

[0051] Step 3: Place the sandwich structure obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 5×10 -3Pa, start heating, heating from room temperature to 300℃ at 10℃ / min, keeping warm for 10min, then heating to 700℃ at 10℃ / min, keeping warm for 10min, then heating to welding temperature 1090℃ at 10℃ / min, and when heating to 1040℃, apply electric field perpendicular to welding interface with electric field strength of 60V / cm, keep warm for 60min, apply pressure of 4MPa during the holding period, and simultaneously apply ultrasonic vibration field with frequency of 25kHz and amplitude of 15μm and pulse magnetic field with pulse magnetic field strength of 1.0T and pulse frequency of 40Hz, pulse The direction of the impulse magnetic field is ≤5° away from the orientation of the IC21 single crystal high-temperature alloy single crystal. The direction of the ultrasonic vibration field is perpendicular to the welding interface, and the ultrasonic vibration field is applied in a pulse mode of turning on for 20 seconds and then off for 10 seconds. The direction of the pulse magnetic field is switched during the period when the ultrasonic vibration field is off. The ratio of the application time of the ultrasonic vibration field to the pulse magnetic field is 1:2, ensuring that the phase difference between the ultrasonic vibration field and the pulse magnetic field is 150°. After the insulation is completed, the pressure is released, the electric field, magnetic field and ultrasonic field are turned off, and the furnace is cooled to room temperature. Non-destructive testing is performed to obtain the completed IC21 single crystal high-temperature alloy liquid phase diffusion welding joint. The microstructure of the joint is as follows: Figure 1 shown.

[0052] Example 2

[0053] This embodiment provides a multi-field assisted IC21 single crystal high temperature alloy liquid phase diffusion bonding method based on electric field, magnetic field and ultrasonic field, and the specific steps are as follows:

[0054] Step 1: The surface of the IC21 single crystal high-temperature alloy workpiece to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished using 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded workpiece is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated IC21 single crystal high-temperature alloy workpiece;

[0055] Step 2: Assemble the treated IC21 single crystal high temperature alloy workpieces, and assemble the nano high entropy alloy intermediate layer foil between the welding interfaces to obtain a sandwich structure of IC21 single crystal high temperature alloy-nano high entropy intermediate layer foil-IC21 single crystal high temperature alloy;

[0056] The method for preparing the nano high entropy alloy intermediate layer foil comprises the following steps:

[0057] Step (1) Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% are mixed according to the mass percentage of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5%, and subjected to argon protection high-energy ball milling (ball-to-material ratio 12:1, rotation speed 500 rpm, time 10 h) to obtain nano-scale composite powder;

[0058] Step (2) Place the nano-scale composite powder in a vacuum melting furnace for vacuum melting (vacuum degree ≤ 5×10 -3 Pa, sintering temperature 1600 ° C), to obtain a pre-alloyed billet; the pre-alloyed billet was subjected to multiple hot rolling and cold rolling, with the total deformation controlled at 90%, to prepare a foil with a thickness of 50 μm;

[0059] Laser shock processing of foil (energy density 5 GW / cm 2 , laser energy 10J, pulse width 7ns, impact number 4 times), so that the surface grains are refined to 30-60nm, and gradient nanostructures and high-density dislocations are formed.

[0060] Step 3: Place the sandwich structure obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 5×10 -3 Pa, start heating, heating from room temperature to 300℃ at 10℃ / min, keeping warm for 10min, then heating to 700℃ at 10℃ / min, keeping warm for 10min, then heating to welding temperature 1090℃ at 10℃ / min, and when heating to 1040℃, apply electric field perpendicular to the welding interface with electric field strength of 60V / cm, keep warm for 60min, apply 4MPa pressure during the holding period, and simultaneously apply ultrasonic vibration field with frequency of 25kHz, amplitude of 15μm and pulse with pulse magnetic field strength of 1.0T and pulse frequency of 40Hz The magnetic field, the direction of the pulsed magnetic field and the orientation deviation of the IC21 single crystal high-temperature alloy single crystal are ≤5°, the direction of the ultrasonic vibration field is perpendicular to the welding interface, and the ultrasonic vibration field is applied in a pulse mode of turning on for 20 seconds and then off for 10 seconds. The direction of the pulsed magnetic field is switched during the period when the ultrasonic vibration field is off. The ratio of the application time of the ultrasonic vibration field and the pulsed magnetic field is 1:2, ensuring that the phase difference between the ultrasonic vibration field and the pulsed magnetic field is 150°; after the insulation is completed, the pressure is released, the electric field, magnetic field and ultrasonic field are turned off, and the furnace is cooled to room temperature, and non-destructive testing is performed to obtain the completed IC21 single crystal high-temperature alloy liquid phase diffusion welding joint.

[0061] Example 3

[0062] This embodiment provides a multi-field assisted IC21 single crystal high temperature alloy liquid phase diffusion bonding method based on electric field, magnetic field and ultrasonic field, and the specific steps are as follows:

[0063] Step 1: The surface of the IC21 single crystal high-temperature alloy workpiece to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished using 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded workpiece is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated IC21 single crystal high-temperature alloy workpiece;

[0064] Step 2: Assemble the treated IC21 single crystal high temperature alloy workpieces, and assemble the nano high entropy alloy intermediate layer foil between the welding interfaces to obtain a sandwich structure of IC21 single crystal high temperature alloy-nano high entropy intermediate layer foil-IC21 single crystal high temperature alloy;

[0065] The method for preparing the nano high entropy alloy intermediate layer foil comprises the following steps:

[0066] Step (1) Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% are mixed according to the mass percentage of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5%, and subjected to argon protection high-energy ball milling (ball-to-material ratio 12:1, rotation speed 500 rpm, time 10 h) to obtain nano-scale composite powder;

[0067] Step (2) Place the nano-scale composite powder in a vacuum melting furnace for vacuum melting (vacuum degree ≤ 5×10 -3 Pa, sintering temperature 1600 ° C), to obtain a pre-alloyed billet; the pre-alloyed billet was subjected to multiple hot rolling and cold rolling, with the total deformation controlled at 80%, to prepare a foil with a thickness of 80 μm;

[0068] Laser shock processing of foil (energy density 5 GW / cm 2 , laser energy 10J, pulse width 7ns, impact number 4 times), so that the surface grains are refined to 30-60nm, and gradient nanostructures and high-density dislocations are formed.

[0069] Step 3: Place the sandwich structure obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 5×10 -3Pa, start heating, heating from room temperature to 300℃ at 10℃ / min, keeping warm for 10min, then heating to 700℃ at 10℃ / min, keeping warm for 10min, then heating to welding temperature 1090℃ at 10℃ / min, and when heating to 1040℃, apply electric field perpendicular to the welding interface with electric field strength of 60V / cm, keep warm for 60min, apply 4MPa pressure during the holding period, and simultaneously apply ultrasonic vibration field with frequency of 25kHz, amplitude of 15μm and pulse with pulse magnetic field strength of 1.0T and pulse frequency of 40Hz The magnetic field, the direction of the pulsed magnetic field and the orientation deviation of the IC21 single crystal high-temperature alloy single crystal are ≤5°, the direction of the ultrasonic vibration field is perpendicular to the welding interface, and the ultrasonic vibration field is applied in a pulse mode of turning on for 20 seconds and then off for 10 seconds. The direction of the pulsed magnetic field is switched during the period when the ultrasonic vibration field is off. The ratio of the application time of the ultrasonic vibration field and the pulsed magnetic field is 1:2, ensuring that the phase difference between the ultrasonic vibration field and the pulsed magnetic field is 150°; after the insulation is completed, the pressure is released, the electric field, magnetic field and ultrasonic field are turned off, and the furnace is cooled to room temperature, and non-destructive testing is performed to obtain the completed IC21 single crystal high-temperature alloy liquid phase diffusion welding joint.

[0070] Example 4

[0071] This embodiment provides a multi-field assisted IC21 single crystal high temperature alloy liquid phase diffusion bonding method based on electric field, magnetic field and ultrasonic field, and the specific steps are as follows:

[0072] Step 1: The surface of the IC21 single crystal high-temperature alloy workpiece to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished using 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded workpiece is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated IC21 single crystal high-temperature alloy workpiece;

[0073] Step 2: Assemble the treated IC21 single crystal high temperature alloy workpieces, and assemble the nano high entropy alloy intermediate layer foil between the welding interfaces to obtain a sandwich structure of IC21 single crystal high temperature alloy-nano high entropy intermediate layer foil-IC21 single crystal high temperature alloy;

[0074] The method for preparing the nano high entropy alloy intermediate layer foil comprises the following steps:

[0075] Step (1) Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% are mixed according to the mass percentage of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5%, and subjected to argon protection high-energy ball milling (ball-to-material ratio 12:1, rotation speed 500 rpm, time 10 h) to obtain nano-scale composite powder;

[0076] Step (2) Place the nano-scale composite powder in a vacuum melting furnace for vacuum melting (vacuum degree ≤ 5×10 -3 Pa, sintering temperature 1600 ° C), to obtain a pre-alloyed billet; the pre-alloyed billet was subjected to multiple hot rolling and cold rolling, with the total deformation controlled at 85%, to prepare a foil with a thickness of 60 μm;

[0077] Laser shock processing of foil (energy density 5 GW / cm 2 , laser energy 10J, pulse width 7ns, impact number 4 times), so that the surface grains are refined to 30-60nm, and gradient nanostructures and high-density dislocations are formed.

[0078] Step 3: Place the workpiece obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 5×10 -3 Pa, start heating, heating from room temperature to 300℃ at 10℃ / min, keeping warm for 10min, then heating to 700℃ at 10℃ / min, keeping warm for 10min, then heating to welding temperature 1130℃ at 10℃ / min, and when heating to 1080℃, apply electric field in the direction perpendicular to the welding interface with electric field strength of 60V / cm, keep warm for 60min, apply 4MPa pressure during the holding period, and simultaneously apply ultrasonic vibration field with frequency of 25kHz and amplitude of 15μm and pulse magnetic field with pulse magnetic field strength of 1.0T and pulse frequency of 40Hz, pulse The direction of the impulse magnetic field is ≤5° away from the orientation of the IC21 single crystal high-temperature alloy single crystal. The direction of the ultrasonic vibration field is perpendicular to the welding interface, and the ultrasonic vibration field is applied in a pulse mode of turning on for 20 seconds and then off for 10 seconds. The direction of the pulse magnetic field is switched during the period when the ultrasonic vibration field is off. The ratio of the application time of the ultrasonic vibration field to the pulse magnetic field is 1:2, ensuring that the phase difference between the ultrasonic vibration field and the pulse magnetic field is 150°. After the insulation is completed, the pressure is released, the electric field, magnetic field and ultrasonic field are turned off, and the furnace is cooled to room temperature. Non-destructive testing is performed to obtain the completed IC21 single crystal high-temperature alloy liquid phase diffusion welding joint. The microstructure of the joint is as follows: Figure 2 shown.

[0079] Comparative Example 1

[0080] This comparative example provides a multi-field assisted IC21 single crystal high temperature alloy liquid phase diffusion welding method using the simultaneous application of electric field, magnetic field, and ultrasonic field. The specific steps are as follows:

[0081] Step 1: The surface of the IC21 single crystal high-temperature alloy workpiece to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished using 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded workpiece is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated IC21 single crystal high-temperature alloy workpiece;

[0082] Step 2: Assemble the treated IC21 single crystal high temperature alloy workpieces, and assemble the nano high entropy alloy intermediate layer foil between the welding interfaces to obtain a sandwich structure of IC21 single crystal high temperature alloy-nano high entropy intermediate layer foil-IC21 single crystal high temperature alloy;

[0083] The method for preparing the nano high entropy alloy intermediate layer foil comprises the following steps:

[0084] Step (1) Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% are mixed according to the mass percentage of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5%, and subjected to argon protection high-energy ball milling (ball-to-material ratio 12:1, rotation speed 500 rpm, time 10 h) to obtain nano-scale composite powder;

[0085] Step (2) Place the nano-scale composite powder in a vacuum melting furnace for vacuum melting (vacuum degree ≤ 5×10 -3 Pa, sintering temperature 1600 ° C), to obtain a pre-alloyed billet; the pre-alloyed billet was subjected to multiple hot rolling and cold rolling, with the total deformation controlled at 85%, to prepare a foil with a thickness of 60 μm;

[0086] Step 3: Place the sandwich structure obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 5×10 -3Pa, start heating, heating from room temperature to 300℃ at 10℃ / min, keeping warm for 10min, then heating to 700℃ at 10℃ / min, keeping warm for 10min, then heating to welding temperature 1090℃ at 10℃ / min, and when heating to 1040℃, apply electric field perpendicular to welding interface with electric field strength of 60V / cm, keep warm for 60min, apply pressure of 4MPa during the holding period, and simultaneously apply ultrasonic vibration field with frequency of 25kHz and amplitude of 15μm and pulse magnetic field with pulse magnetic field strength of 1.0T and pulse frequency of 40Hz, pulse The direction of the impulse magnetic field is ≤5° away from the orientation of the IC21 single crystal high-temperature alloy single crystal. The direction of the ultrasonic vibration field is perpendicular to the welding interface, and the ultrasonic vibration field is applied in a pulse mode of turning on for 20 seconds and then off for 10 seconds. The direction of the pulse magnetic field is switched during the period when the ultrasonic vibration field is off. The ratio of the application time of the ultrasonic vibration field to the pulse magnetic field is 1:2, ensuring that the phase difference between the ultrasonic vibration field and the pulse magnetic field is 150°. After the insulation is completed, the pressure is released, the electric field, magnetic field and ultrasonic field are turned off, and the furnace is cooled to room temperature. Non-destructive testing is performed to obtain the completed IC21 single crystal high-temperature alloy liquid phase diffusion welding joint. The microstructure of the joint is as follows: Figure 3 shown.

[0087] Comparative Example 2

[0088] This comparative example provides a liquid phase diffusion bonding method for IC21 single crystal high temperature alloy, and the specific steps are as follows:

[0089] Step 1: The surface of the IC21 single crystal high-temperature alloy workpiece to be welded is polished in sequence using 160#, 400#, 600#, 1000#, 1500#, and 2000# metallographic sandpaper, and polished using 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The welded workpiece is ultrasonically cleaned at a frequency of 20kHz for 15 minutes using anhydrous ethanol, and blown dry with a nitrogen gun to obtain the treated IC21 single crystal high-temperature alloy workpiece;

[0090] Step 2: Assemble the treated IC21 single crystal high temperature alloy workpieces, and assemble the nano high entropy alloy intermediate layer foil between the welding interfaces to obtain a sandwich structure of IC21 single crystal high temperature alloy-nano high entropy intermediate layer foil-IC21 single crystal high temperature alloy;

[0091] The method for preparing the nano high entropy alloy intermediate layer foil comprises the following steps:

[0092] Step (1) Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% are mixed according to the mass percentage of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5%, and subjected to argon protection high-energy ball milling (ball-to-material ratio 12:1, rotation speed 500 rpm, time 10 h) to obtain nano-scale composite powder;

[0093] Step (2) Place the nano-scale composite powder in a vacuum melting furnace for vacuum melting (vacuum degree ≤ 5×10 -3 Pa, sintering temperature 1600 ° C), to obtain a pre-alloyed billet; the pre-alloyed billet was subjected to multiple hot rolling and cold rolling, with the total deformation controlled at 85%, to prepare a foil with a thickness of 60 μm;

[0094] Laser shock processing of foil (energy density 5 GW / cm 2 , laser energy 10J, pulse width 7ns, impact number 4 times), so that the surface grains are refined to 30-60nm, and gradient nanostructures and high-density dislocations are formed.

[0095] Step 3: Place the sandwich structure obtained in step 2 into a vacuum diffusion welding furnace and wait until the vacuum degree reaches 5×10 -3 Pa, heated from room temperature to 300℃ at 10℃ / min, kept warm for 10min, then heated to 700℃ at 10℃ / min, kept warm for 10min, then heated to 1070℃ at 10℃ / min, kept warm for 60min, applied 4MPa pressure during the holding period, released the pressure after the holding period, cooled to room temperature with the furnace, and non-destructive testing was performed to obtain the completed IC21 single crystal high temperature alloy liquid phase diffusion welded joint. The microstructure of the joint is as follows Figure 4 shown.

[0096] The tensile strength of the IC21 single crystal high-temperature alloy liquid phase diffusion welding joints in Examples 1-4, Comparative Examples 1-2 and the blank example was tested at room temperature in accordance with the standard "GB / T 228.1-2021: Tensile test of metallic materials Part 1: Room temperature test method". The specific test results are shown in Table 1. The blank example is a single crystal high-temperature alloy IC21 base material.

[0097] Table 1 Tensile strength of joints in examples and comparative examples

[0098]

[0099] According to the test results in Table 1, the IC21 single crystal high temperature alloy liquid phase diffusion welding joints prepared by Examples 1-4 of the present invention based on multi-field assistance have no surface defects and high structural uniformity. The designed nano high entropy intermediate layer has good wettability and diffusivity. In particular, the nano high entropy intermediate layer provided in Example 1 has the best effect of liquid phase diffusion welding joint under multi-field assistance. The tensile strength of the joint reaches 95% of the parent alloy, and the weld strength is high. Figure 1 From the SEM image of the diffusion welding joint microstructure, it can be seen that the welding effect of Example 1 is the best. The heat-mechanical-electrical synergy makes the actual welding thermodynamic conditions equivalent to the effect of 1300℃ / 120min when no external field is applied, and the welding process only requires 1090℃ / 60min, which effectively reduces the thermal damage of the base material. The γ' strengthening phase coarsening rate is reduced from 20% to less than 5%. The interface between the weld and the base material is straight, and there is a transition zone. The element gradient transition is gentle. The continuous diffusion layer indicates that the weld and the base material are fully metallurgically bonded, the weld is a uniform solid solution structure, no interface brittle phase is generated, and the connection interface is defect-free; the second is the welding effect of Example 4. Figure 2 From the SEM image of the diffusion welding joint microstructure, it can be seen that when the welding temperature is slightly increased, the weld is still a uniform solid solution structure, but the tensile strength of the joint is slightly lower than that of the joint in Example 1.

[0100] Comparative Example 1 lacks the laser shock step. In the multi-field assisted IC21 single crystal high-temperature alloy liquid phase diffusion welding process, the activation energy of the intermediate layer decreases and the element diffusion is insufficient due to the lack of the laser shock step. Figure 3 The SEM image of the diffusion welding joint microstructure shows that a large amount of white brittle phase is generated, which greatly reduces its mechanical properties. From Table 1, it can be seen that the tensile strength of the joint is greatly reduced compared with Example 1. In Comparative Example 2, the external composite field step is missing in the liquid phase diffusion welding process. Figure 4 It can be seen from the SEM image of the joint microstructure that a large amount of white brittle phase is generated inside the weld, which leads to serious deterioration of the joint strength, so the tensile strength of the final joint is the lowest.

[0101] The above contents are merely examples and explanations of the structure of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0102] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0103] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A diffusion bonding method for IC21 single crystal high temperature alloy based on multi-field assistance and high entropy intermediate layer, characterized in that: The following steps are involved: Step 1: preparing a high entropy intermediate layer foil; the chemical composition of the high entropy intermediate layer is composed of Ni 35%, Cr 22%, Al 20%, Re 7%, Ta 5%, Y 2%, Si 7.5%, and B 1.5% by mass percentage; Step 2: preparing a nano-high entropy intermediate layer foil; treating the high entropy intermediate layer foil with a laser surface impact treatment to obtain a nano-high entropy intermediate layer foil; Step 3: Place the nano high-entropy intermediate layer foil between the upper and lower layers of IC21 single crystal high-temperature alloy, and perform liquid-phase diffusion welding in a vacuum diffusion welding furnace assisted by an electric field, a magnetic field, and an ultrasonic field; during the welding process, an electric field is applied during the heating stage, and an ultrasonic vibration field and a pulsed magnetic field are applied synchronously during the insulation stage to obtain an IC21 single crystal high-temperature alloy liquid-phase diffusion welding joint.

2. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 1 is characterized in that: The high entropy intermediate layer foil has a thickness of 50 μm-100 μm, a grain size of ≤200 nm, and a surface roughness Ra of ≤0.8 μm.

3. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 1 is characterized in that: The process for preparing the high-entropy intermediate layer foil is as follows: Ni, Cr, Al, Re, Ta, Y, Si, and B metal powders with a purity greater than 99.9% are mixed according to the mass percentages by high-energy ball milling, placed in a vacuum melting furnace for vacuum melting, and then subjected to multiple hot rolling and cold rolling to obtain the high-entropy intermediate layer foil.

4. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 1 is characterized in that: The surface of the nano high entropy intermediate layer foil is a gradient nanostructure, and the surface grain size is 30nm-60nm.

5. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 1 is characterized in that: In the process of treating the high entropy intermediate layer foil with laser surface impact, the laser energy density is 4GW / cm 2 -6 GW / cm 2 , the laser energy is 8J-12J, the pulse width is 6ns-13ns, and the number of impacts is 2-4 times.

6. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 1 is characterized in that: During the liquid-phase diffusion welding process in the electric field-magnetic field-ultrasonic field assisted vacuum diffusion welding furnace, the vacuum diffusion welding furnace is first evacuated, and then when the temperature is raised to 50°C below the welding temperature, an electric field is applied. During the insulation stage, an ultrasonic vibration field and a pulsed magnetic field are synchronously applied; the intensity of the electric field is 50V / cm-80V / cm; the frequency of the ultrasonic vibration field is 20kHz-30kHz, and the amplitude is 10μm-30μm; the intensity of the pulsed magnetic field is 0.5T-1.0T, and the frequency of the pulsed magnetic field is 30Hz-50Hz.

7. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 6 is characterized in that: The welding temperature is 1050° C.-1150° C., the heating rate is 10° C. / min, the holding time of the holding stage is 60 min-90 min, and the pressure is 4 MPa-6 MPa.

8. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 6 is characterized in that: The pulsed magnetic field is an alternating magnetic field, the applied direction of the pulsed magnetic field deviates from the orientation of the IC21 single crystal high-temperature alloy by ≤5°, and the applied direction of the electric field is perpendicular to the welding interface.

9. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 8, characterized in that: The application direction of the ultrasonic vibration field is perpendicular to the welding interface, and is applied in a pulse mode of turning on the ultrasonic vibration field for 20 seconds and then turning off the ultrasonic vibration field for 10 seconds. The direction of the pulsed magnetic field is switched during the period when the ultrasonic vibration field is off. The ratio of the application time of the ultrasonic vibration field to the pulsed magnetic field is 1:2-1:3, and the phase difference between the ultrasonic vibration field and the pulsed magnetic field is 90°-180°.

10. The IC21 single crystal high temperature alloy diffusion bonding method based on multi-field assistance and high entropy intermediate layer according to claim 6, characterized in that: The vacuum degree of the vacuum diffusion welding furnace is ≤5×10 -3 Pa.

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