High-entropy alloy intermediate layer for GH5188 instantaneous liquid phase diffusion bonding and bonding method of high-entropy alloy intermediate layer

Abstract

The invention provides a high-entropy alloy intermediate layer for GH5188 instantaneous liquid phase diffusion bonding and a bonding method of the high-entropy alloy intermediate layer, and relates to the technical field of metal welding, the high-entropy alloy intermediate layer is composed of Co, Ni, Cr, Al, Ta, Ge, Zr and Y according to the atomic ratio of 25: 20: 20: 15: 10: 5: 3: 2, and the element purity is larger than 99.99 wt.%. The invention further provides the bonding method of GH5188 instantaneous liquid phase diffusion bonding. The high-entropy alloy intermediate layer is arranged in the middle of the base metal GH5188 and is arranged in the vacuum diffusion welding furnace for welding, and compared with conventional instantaneous liquid-phase diffusion bonding, formation of brittle compounds can be inhibited, and improvement of the comprehensive performance of an interface is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of metal welding, and in particular to a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion connection and a connection method thereof. Background Art

[0002] As aviation power systems evolve towards high thrust and high thrust-to-weight ratio, material properties have become the core factor restricting engine technology breakthroughs. GH5188 (Co-Ni-Cr based solid solution strengthened deformable high temperature alloy) occupies an irreplaceable core position in the manufacturing of hot end components of aviation engines due to its excellent high temperature creep resistance, long-lasting strength and oxidation corrosion resistance.

[0003] However, the fusion welding process of high-temperature alloys is prone to thermal cracks, and direct diffusion welding is prone to problems such as unwelded parts and holes. The intermediate layer conventionally used for transient liquid phase diffusion bonding often causes brittle phases in the joint due to the introduction of traditional melting-reducing elements, resulting in a decrease in joint strength and hardness. Therefore, designing a new intermediate layer to assist GH5188 transient liquid phase diffusion bonding has become a key issue. Summary of the invention

[0004] In view of the deficiencies in the background technology, the present invention mainly solves the problem of insufficient joint mechanical properties caused by the presence of a brittle phase in the joint during the conventional GH5188 instantaneous liquid phase diffusion connection process.

[0005] A first aspect of the present invention provides a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding, wherein the constituent elements of the high entropy alloy intermediate layer are composed of elements in the following atomic ratio: Co:Ni:Cr:Al:Ta:Ge:Zr:Y=25:20:20:15:10:5:3:2, and the element purity is greater than 99.99wt.%.

[0006] A second aspect of the present invention provides a method for preparing a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding, the method for preparing the high entropy alloy intermediate layer comprising the following steps: Step 1: Weigh pure metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y according to the atomic ratio of the constituent elements of the high entropy alloy intermediate layer, and wash them; Step 2: preparing alloy ingots by arc melting the pure metal element particles weighed in step 1; Step 3: cold-roll the alloy ingot prepared in step 2 for multiple passes to obtain a cold-rolled sheet, cut the cold-rolled sheet into sections and grind the upper and lower surfaces to obtain a target intermediate layer, and then polish, corrode, clean and dry to obtain the high entropy alloy intermediate layer.

[0007] Preferably, the cleaning process in step 1 is to clean the surface of the weighed pure metal element particles with anhydrous ethanol and place them in a drying oven for 1 hour.

[0008] Preferably, in the process of preparing the alloy ingot by the arc melting method in step 2, the pure metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y in step 1 are placed in a copper crucible in order from low to high according to their melting points; the arc melting method is adopted, forward and reverse melting is performed more than 5 times, and electromagnetic stirring is performed to obtain the alloy ingot.

[0009] Preferably, the cutting and flattening treatment is performed before the multiple cold rolling in step three, and the process is to cut the alloy ingot into regular rectangular parallelepiped and use a grinder to flatten the cut surface so that the reference flatness error of the cut surface is ≤0.05mm.

[0010] Preferably, the multiple cold rolling in step three adopts multiple reciprocating rolling, the single-pass reduction is 0.2mm-0.4mm, the thickness of the cold-rolled sheet is 0.1mm-0.2mm, the grinding adopts a double-sided nano-grinding machine for mirror grinding, the thickness of the target intermediate layer is 50μm-80μm, and the thickness error is ±5μm.

[0011] Preferably, the polishing in step three is performed mechanically by using a diamond suspension with a particle size of 0.25 μm; the etching is performed by using Keller reagent to remove the surface oxide layer; the cleaning is performed by using anhydrous ethanol ultrasonic cleaning; and the drying is performed by blowing and drying with high-purity nitrogen.

[0012] The third aspect of the present invention provides a connection method for GH5188 instantaneous liquid phase diffusion bonding, which is to place the above-mentioned high entropy alloy intermediate layer or the high entropy alloy intermediate layer prepared by the above-mentioned preparation method between the upper and lower layers of base material GH5188, and then place the whole in a vacuum diffusion welding furnace for welding.

[0013] Preferably, the welding adopts a staged heating and pressurizing method, and the specific welding process is as follows: in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 300°C at a rate of 10°C / min, and kept warm for 10 minutes; in the second stage, the temperature is increased from 300°C to 700°C at a rate of 10°C / min, and kept warm for 10 minutes; in the third stage, the temperature is increased from 700°C to 900°C at a rate of 10°C / min, and kept warm for 10 minutes; in the fourth stage, the temperature is increased from 900°C to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth stage, the temperature is kept at the welding temperature of 1150°C for 1 hour, a pressure of 5MPa is applied, and then the furnace is cooled to room temperature; the vacuum degree of the vacuum diffusion welding furnace is ≤4×10 -3 Pa.

[0014] Preferably, before welding in the vacuum diffusion welding furnace, the base material GH5188 is ground and polished with sandpaper and polishing liquid; after the grinding and polishing, the base material GH5188 is ultrasonically cleaned in anhydrous ethanol.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The high entropy alloy intermediate layer for GH5188 instantaneous liquid phase diffusion bonding proposed in the present invention has Ta element replacing W element existing in traditional high entropy alloy, optimizing interface concentration gradient in welding process, inhibiting grain coarsening at high temperature and improving joint mechanical properties; Ge replaces traditional melting-reducing elements B and Si to avoid forming brittle phases of boride and silicide; Zr element is used to refine grains and improve joint mechanical properties; Y and Al act synergistically to improve oxidation resistance.

[0016] The connection method of using a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion connection proposed in the present invention improves the oxidation resistance of the joint, inhibits the precipitation of brittle phase, and improves the mechanical properties of the joint under the combined action of high entropy effect, kinetic hysteresis diffusion, solid solution strengthening and other mechanisms compared to the traditional GH5188 transient liquid phase diffusion connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is an interface microstructure diagram of GH5188 using the high entropy alloy intermediate layer provided by the present invention to perform instantaneous liquid phase diffusion connection.

[0018] Figure 2 This is the interface microstructure diagram of GH5188 using a traditional intermediate layer for instantaneous liquid phase diffusion bonding.

[0019] Figure 3 This is an electron microscope image of the fracture morphology of GH5188 using the high entropy alloy intermediate layer provided by the present invention for instantaneous liquid phase diffusion bonding.

[0020] Figure 4 This is an electron microscope image of the fracture morphology of GH5188 using a traditional intermediate layer for instantaneous liquid phase diffusion bonding. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without creative work also fall within the scope of protection of the present disclosure.

[0022] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by those skilled in the art to which the subject matter of the present disclosure belongs. It will be further understood that terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the specification and the relevant art, and will not be interpreted in an idealized or overly formal form unless otherwise explicitly defined herein.

[0023] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase "embodiments" in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0024] The present invention provides a high entropy alloy intermediate layer for GH5188 instantaneous liquid phase diffusion bonding, wherein the constituent elements of the high entropy alloy intermediate layer are composed of elements in the following atomic ratio: Co: Ni: Cr: Al: Ta: Ge: Zr: Y = 25: 20: 20: 15: 10: 5: 3: 2, wherein the element purity is required to be greater than 99.99wt.%, and pure metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y are stored in a vacuum.

[0025] The preparation method of the above-mentioned high entropy alloy intermediate layer is: Step 1: Weigh pure metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y according to the atomic ratio of the constituent elements of the high entropy alloy intermediate layer, clean the surface with anhydrous ethanol, and place in a drying oven for 1 hour; Step 2: The pure metal element particles weighed in step 1 are used to prepare an alloy ingot by arc melting; the pure metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y are placed in a copper crucible in order from low to high according to their melting points in step 1; the low melting point material is placed at the bottom of the crucible, and the high melting point material is placed at the top, and the arc melting method is used, and the forward and reverse melting is performed for more than 5 times, and electromagnetic stirring is performed to obtain the alloy ingot; In the process of arc melting, the weight of a single melting is usually 50g-120g. If the weight is too large, it needs to be melted in batches for multiple times. After melting, multiple alloy ingots are fused to ensure that the metal particles are fully fused. Step 3: Prepare the high entropy alloy intermediate layer; cut the alloy ingot into regular rectangular specimens (25mm×25mm×5mm), use a grinder to flatten the cut surface, eliminate the surface texture caused by wire cutting, and ensure that the reference flatness error is ≤0.05mm; pre-treat the rolls, and evenly coat the surface of the working rolls with a high-viscosity cold rolling lubricant; during the multi-pass cold rolling process, the single-pass reduction is controlled at 0.2mm-0.4mm; after each rolling pass, a laser thickness gauge is used to detect the thickness deviation, and the material is gradually thinned to the target thickness through multiple reciprocating rolling passes. Standard thickness (0.1mm-0.2mm); Use precision shearing machine to cut the cold-rolled thin sheet into target size, and use double-sided nano-grinding machine for mirror grinding, and the final thickness error is controlled within ±5μm (target thickness 50μm-80μm); Use diamond suspension (particle size 0.25μm) for mechanical polishing to reduce surface roughness; First, use Keller reagent (2% HF+3% HNO3+95% H2O) to corrode and remove the surface oxide layer, then place it in anhydrous ethanol for ultrasonic cleaning for 10 minutes, and finally blow dry with high-purity nitrogen to obtain a high-entropy alloy intermediate layer; If the prepared high entropy alloy intermediate layer needs to be preserved, after grinding and polishing, the surface sealing film is placed in a drying dish for preservation, and the above-mentioned corrosion and cleaning steps are repeated for subsequent use.

[0026] In some embodiments of the present invention, the method for preparing the high entropy alloy intermediate layer is not limited to the above-mentioned preparation method, and other existing preparation methods can also be used to obtain the high entropy alloy intermediate layer.

[0027] The present invention also provides a connection method of GH5188 instantaneous liquid phase diffusion connection, wherein the high entropy alloy intermediate layer is placed in the middle of the base material GH5188, and the joint welding is completed using a vacuum diffusion welding furnace.

[0028] Before welding in the vacuum diffusion welding furnace, the base material GH5188 was ground and polished with 240#, 400#, 800#, 1000#, 1500#, 2000# sandpaper and polishing liquid (SiO2:H2O2=8:2) in sequence; after the grinding and polishing, the base material GH5188 was ultrasonically cleaned in anhydrous ethanol; The welding process in the vacuum diffusion welding furnace adopts a segmented heating and pressurizing method. The specific process is as follows: in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 300°C at a rate of 10°C / min and kept warm for 10 minutes; in the second stage, the temperature is increased to 700°C at a rate of 10°C / min and kept warm for 10 minutes; in the third stage, the temperature is increased to 900°C at a rate of 10°C / min and kept warm for 10 minutes; in the fourth stage, the temperature is increased to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth stage, the welding temperature is kept at 1150°C for 1 hour, and a pressure of 5MPa is applied. Then the sample is cooled to room temperature with the furnace, and the welding is completed; the vacuum degree of the vacuum diffusion welding furnace is always ≤4×10 -3 Pa.

[0029] The present invention will be further described below by means of specific examples.

[0030] Example 1

[0031] This embodiment uses Co 25 Ni 20 Cr 20 Al 15 Ta 10 Ge5Zr3Y2 is used as the middle layer to perform instantaneous liquid phase diffusion connection on GH5188. The specific steps are as follows: Step 1, preparing alloy ingots: using a precision electronic balance to weigh metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y, the element atomic ratio of Co: Ni: Cr: Al: Ta: Ge: Zr: Y = 25: 20: 20: 15: 10: 5: 3: 2, the element purity is greater than 99.9wt.%, cleaning the surface of the weighed metal element particles with anhydrous ethanol, and drying them in a drying oven for 1 hour, placing the metal element particles Co, Ni, Cr, W, Fe, B, and Si in a copper crucible according to their melting points, with low-melting-point materials placed at the bottom of the crucible and high-melting-point materials placed at the top; forward and reverse smelting at least 5 times, and electromagnetic stirring, thereby ensuring that the metal particles are fully fused; Step 2: Prepare the high-entropy alloy intermediate layer. Cut the alloy ingot into regular rectangular specimens (25mm×25mm×5mm). Use a grinder to flatten the cut surface to eliminate the surface texture caused by wire cutting and ensure that the reference flatness error is ≤0.05mm. Pre-treat the rollers and evenly coat the surface of the working rollers with a high-viscosity cold rolling lubricant. During the multi-pass cold rolling process, the single-pass reduction is controlled at 0.3mm. After each rolling pass, a laser thickness gauge is used to detect the thickness deviation, and the material is gradually thinned through multiple reciprocating rolling passes. To the target thickness (0.15mm); use a precision shearing machine to divide the cold-rolled thin sheet into the target size, and use a double-sided nano-grinding machine for mirror grinding, and the final thickness error is controlled at ±5μm (target thickness 65μm); use diamond suspension (particle size 0.25μm) for mechanical polishing to reduce the surface roughness; first use Keller reagent (2% HF+3% HNO3+95% H2O) to corrode and remove the surface oxide layer, then place it in anhydrous ethanol for ultrasonic cleaning for 10 minutes, and finally blow dry with high-purity nitrogen to obtain a high-entropy alloy intermediate layer.

[0032] Step 3, GH5188 instantaneous liquid phase diffusion connection; (1) Grind and polish the base material GH5188 with 240#, 400#, 800#, 1000#, 1500#, and 2000# sandpaper and polishing liquid (SiO2:H2O2=8:2) in sequence; after the grinding and polishing, the base material GH5188 is ultrasonically cleaned in anhydrous ethanol; (2) placing the prepared high entropy alloy intermediate layer in the middle of the cleaned base material GH5188 and welding them in a vacuum diffusion welding furnace; (3) The welding process in the vacuum diffusion welding furnace is as follows: in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 300°C at a rate of 10°C / min and kept at this temperature for 10 min; in the second stage, the temperature is increased to 700°C at a rate of 10°C / min and kept at this temperature for 10 min; in the third stage, the temperature is increased to 900°C at a rate of 10°C / min and kept at this temperature for 10 min; in the fourth stage, the temperature is increased to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth stage, the welding temperature is kept at 1150°C for 1 h, and a pressure of 5 MPa is applied. Then, the sample is cooled to room temperature with the furnace, and the welding is completed; during the entire welding process, the vacuum degree of the vacuum diffusion welding furnace is always ≤4×10 -3 Pa.

[0033] Figure 1 , Figure 3The microstructure diagram and fracture morphology diagram of the welded joint obtained by instantaneous liquid phase diffusion bonding using a high entropy alloy intermediate layer in this embodiment are observed using a scanning electron microscope (SEM), and no white brittle phase appears in the organization; the mechanical properties of the welded joint of this embodiment are tested using an INSTRON3382 electronic universal material testing machine, and the shear strength of the joint can reach 932 MPa, and the fracture mode of the joint is ductile fracture.

[0034] Example 2

[0035] This embodiment uses Co 25 Ni 20 Cr 20 Al 15 Ta 10 Ge5Zr3Y2 is used as the middle layer to perform instantaneous liquid phase diffusion connection on GH5188. The specific steps are as follows: Step 1, preparing alloy ingots: using a precision electronic balance to weigh metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y, the element atomic ratio of Co: Ni: Cr: Al: Ta: Ge: Zr: Y = 25: 20: 20: 15: 10: 5: 3: 2, the element purity is greater than 99.9wt.%, cleaning the surface of the weighed metal element particles with anhydrous ethanol, and drying them in a drying oven for 1 hour, placing the metal element particles Co, Ni, Cr, W, Fe, B, and Si in a copper crucible according to their melting points, with low-melting-point materials placed at the bottom of the crucible and high-melting-point materials placed at the top; forward and reverse smelting at least 5 times, and electromagnetic stirring, thereby ensuring that the metal particles are fully fused; Step 2: Prepare the high entropy alloy intermediate layer. Cut the alloy ingot into regular rectangular specimens (25mm×25mm×5mm). Use a grinder to flatten the cut surface to eliminate the surface texture caused by wire cutting and ensure that the reference flatness error is ≤0.05mm. Pre-treat the rolls and evenly coat the surface of the work rolls with a high-viscosity cold rolling lubricant. During the multi-pass cold rolling process, the single-pass reduction is controlled at 0.4mm. After each pass of rolling, a laser thickness gauge is used to detect the thickness deviation. The material is gradually reduced through multiple reciprocating rolling. Thin to the target thickness (0.1mm); use a precision shearing machine to divide the cold-rolled thin sheet into the target size, and use a double-sided nano-grinding machine for mirror grinding, and the final thickness error is controlled at ±5μm (target thickness 50μm); use diamond suspension (particle size 0.25μm) for mechanical polishing to reduce surface roughness; first use Keller reagent (2% HF+3% HNO3+95% H2O) to corrode and remove the surface oxide layer, then place it in anhydrous ethanol for ultrasonic cleaning for 10 minutes, and finally blow dry with high-purity nitrogen to obtain a high-entropy alloy intermediate layer.

[0036] Step 3, GH5188 instantaneous liquid phase diffusion connection; (1) Grind and polish the base material GH5188 with 240#, 400#, 800#, 1000#, 1500#, and 2000# sandpaper and polishing liquid (SiO2:H2O2=8:2) in sequence; after the grinding and polishing, the base material GH5188 is ultrasonically cleaned in anhydrous ethanol; (2) placing the prepared high entropy alloy intermediate layer in the middle of the cleaned base material GH5188 and welding them in a vacuum diffusion welding furnace; (3) The welding process in the vacuum diffusion welding furnace is as follows: in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 300°C at a rate of 10°C / min and kept at this temperature for 10 min; in the second stage, the temperature is increased to 700°C at a rate of 10°C / min and kept at this temperature for 10 min; in the third stage, the temperature is increased to 900°C at a rate of 10°C / min and kept at this temperature for 10 min; in the fourth stage, the temperature is increased to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth stage, the welding temperature is kept at 1150°C for 1 h, and a pressure of 5 MPa is applied. Then, the sample is cooled to room temperature with the furnace, and the welding is completed; during the entire welding process, the vacuum degree of the vacuum diffusion welding furnace is always ≤4×10 -3 Pa.

[0037] Example 3

[0038] This embodiment uses Co 25 Ni 20 Cr 20 Al 15 Ta 10 Ge5Zr3Y2 is used as the middle layer to perform instantaneous liquid phase diffusion connection on GH5188. The specific steps are as follows: Step 1, preparing alloy ingots: using a precision electronic balance to weigh metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y, the element atomic ratio of Co: Ni: Cr: Al: Ta: Ge: Zr: Y = 25: 20: 20: 15: 10: 5: 3: 2, the element purity is greater than 99.9wt.%, cleaning the surface of the weighed metal element particles with anhydrous ethanol, and drying them in a drying oven for 1 hour, placing the metal element particles Co, Ni, Cr, W, Fe, B, and Si in a copper crucible according to their melting points, with low-melting-point materials placed at the bottom of the crucible and high-melting-point materials placed at the top; forward and reverse smelting at least 5 times, and electromagnetic stirring, thereby ensuring that the metal particles are fully fused; Step 2: Prepare the high entropy alloy intermediate layer. Cut the alloy ingot into regular rectangular specimens (25mm×25mm×5mm). Use a grinder to flatten the cut surface to eliminate the surface texture caused by wire cutting and ensure that the reference flatness error is ≤0.05mm. Pre-treat the rolls and evenly coat the work roll surface with a high-viscosity cold rolling lubricant. During the multi-pass cold rolling process, the single-pass reduction is controlled at 0.2mm. After each pass of rolling, a laser thickness gauge is used to detect the thickness deviation. The material is gradually reduced through multiple reciprocating rolling. Thin to the target thickness (0.2mm); use a precision shearing machine to divide the cold-rolled thin sheet into the target size, and use a double-sided nano-grinding machine for mirror grinding, and the final thickness error is controlled within ±5μm (target thickness 80μm); use diamond suspension (particle size 0.25μm) for mechanical polishing to reduce surface roughness; first use Keller reagent (2% HF+3% HNO3+95% H2O) to corrode and remove the surface oxide layer, then place it in anhydrous ethanol for ultrasonic cleaning for 10 minutes, and finally blow dry with high-purity nitrogen to obtain a high-entropy alloy intermediate layer.

[0039] Step 3, GH5188 instantaneous liquid phase diffusion connection; (1) Grind and polish the base material GH5188 with 240#, 400#, 800#, 1000#, 1500#, and 2000# sandpaper and polishing liquid (SiO2:H2O2=8:2) in sequence; after the grinding and polishing, the base material GH5188 is ultrasonically cleaned in anhydrous ethanol; (2) placing the prepared high entropy alloy intermediate layer in the middle of the cleaned base material GH5188 and welding them in a vacuum diffusion welding furnace; (3) The welding process in the vacuum diffusion welding furnace is as follows: in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 300°C at a rate of 10°C / min and kept at this temperature for 10 min; in the second stage, the temperature is increased to 700°C at a rate of 10°C / min and kept at this temperature for 10 min; in the third stage, the temperature is increased to 900°C at a rate of 10°C / min and kept at this temperature for 10 min; in the fourth stage, the temperature is increased to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth stage, the welding temperature is kept at 1150°C for 1 h, and a pressure of 5 MPa is applied. Then, the sample is cooled to room temperature with the furnace, and the welding is completed; during the entire welding process, the vacuum degree of the vacuum diffusion welding furnace is always ≤4×10 -3 Pa.

[0040] Comparative Example 1 This comparative example uses a conventional middle layer Co 32 Cr 28 Ni 28 B5Si2, instantaneous liquid phase diffusion bonding of GH5188, the specific steps are as follows: Step 1, prepare alloy ingots: use a precision electronic balance to weigh metal element particles Co, Ni, Cr, B, Si, the atomic ratio of the elements Co: Ni: Cr: B: Si = 32: 28: 28: 5: 2, the element purity is greater than 99.9wt.%, clean the surface of the weighed metal element particles with anhydrous ethanol, and place them in a drying oven for 1 hour, and place them in a copper crucible according to the melting point of the element particles Co, Ni, Cr, B, Si, with the low melting point material placed at the bottom of the crucible and the high melting point material placed at the top. Perform forward and reverse smelting at least 5 times, and perform electromagnetic stirring to ensure that the metal particles are fully fused; Step 2: Prepare the middle layer. Cut the alloy ingot into regular rectangular samples (25mm×25mm×5mm). Use a grinder to flatten the cut surface to eliminate the surface texture caused by wire cutting and ensure that the reference flatness error is ≤0.05mm. Pre-treat the rolls and evenly coat the surface of the work rolls with a high-viscosity cold rolling lubricant. During the multi-pass cold rolling process, the single-pass reduction is controlled at 0.3mm. After each pass of rolling, a laser thickness gauge is used to detect the thickness deviation. The material is gradually thinned to the target thickness through multiple reciprocating rolling. The target thickness is 0.15 mm. The cold-rolled sheet is divided into target sizes by a precision shearing machine and mirror-polished by a double-sided nano-grinding machine. The final thickness error is controlled within ±5 μm (target thickness 65 μm). Diamond suspension (particle size 0.25 μm) is used for mechanical polishing to reduce the surface roughness. The surface oxide layer is first corroded and removed by Keller reagent (2% HF + 3% HNO3 + 95% H2O), and then ultrasonically cleaned in anhydrous ethanol for 10 minutes. Finally, it is purged and dried with high-purity nitrogen to obtain a high-entropy alloy intermediate layer.

[0041] Step 3, GH5188 instantaneous liquid phase diffusion connection; (1) Grind and polish the base material GH5188 with 240#, 400#, 800#, 1000#, 1500#, and 2000# sandpaper and polishing liquid (SiO2:H2O2=8:2) in sequence; after the grinding and polishing, the base material GH5188 is ultrasonically cleaned in anhydrous ethanol; (2) placing the prepared intermediate layer in the middle of the cleaned base material GH5188 and welding it in a vacuum diffusion welding furnace; (3) The welding process in the vacuum diffusion welding furnace is as follows: in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 300°C at a rate of 10°C / min and kept at this temperature for 10 min; in the second stage, the temperature is increased to 700°C at a rate of 10°C / min and kept at this temperature for 10 min; in the third stage, the temperature is increased to 900°C at a rate of 10°C / min and kept at this temperature for 10 min; in the fourth stage, the temperature is increased to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth stage, the welding temperature is kept at 1150°C for 1 h, and a pressure of 5 MPa is applied. Then, the sample is cooled to room temperature with the furnace, and the welding is completed; during the entire welding process, the vacuum degree of the vacuum diffusion welding furnace is always ≤4×10 -3 Pa.

[0042] Figure 2 , Figure 4 The present comparative example adopts a traditional intermediate layer for instantaneous liquid phase diffusion bonding to obtain a welded joint, and the microstructure diagram and fracture morphology diagram observed by a scanning electron microscope (SEM); compared with Example 1, the traditional intermediate layer of the present comparative example does not contain Ge element and contains melting-reducing elements B and Si, so white brittle phases of boride and silicide appear in its structure. In addition, due to the lack of Zr in the traditional intermediate layer to refine the grains and Ta in the traditional intermediate layer to inhibit the coarsening of grains at high temperatures, the mechanical properties of the welded joint of the present comparative example were tested using an INSTRON3382 electronic universal material testing machine, and the shear strength of the joint was only 776 MPa. The fracture surface was observed to find that the fracture mode of the joint was a mixed fracture.

[0043] Combined with Figure 1~Figure 4 By comparing the interface microstructures of different intermediate layers, it can be found that when the high entropy alloy intermediate layer provided by the present invention is used for instantaneous liquid phase diffusion connection, the white brittle phase can no longer be observed in the welded joint. On the contrary, when the traditional intermediate layer is used for instantaneous liquid phase diffusion connection, not only the white brittle phase will appear in the interface, but also some holes will appear. Due to the appearance of brittle phase and holes, the comprehensive mechanical properties of the joint are restricted, and the strength and plasticity of the joint are reduced. Through subsequent mechanical properties tests combined with fracture morphology analysis, it can be obtained that when the traditional intermediate layer is used for instantaneous liquid phase diffusion connection of GH5188, the shear strength of the joint is 776MPa, and the fracture mode of the joint is mixed fracture when observing the fracture; when the high entropy alloy intermediate layer provided by the present invention is used for instantaneous liquid phase diffusion connection, the shear strength of the joint can reach 932MPa, and the fracture mode of the joint is converted into ductile fracture; thus, the high entropy alloy intermediate layer provided by the present invention effectively improves the mechanical properties of the joint.

[0044] The above embodiments are preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential additions and substitutions made by those skilled in the art based on the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding, characterized in that: The constituent elements of the high entropy alloy intermediate layer are composed of the following atomic ratios: Co:Ni:Cr:Al:Ta:Ge:Zr:Y=25:20:20:15:10:5:3:2, and the element purity is greater than 99.99wt.%.

2. A method for preparing a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding, characterized in that: The method for preparing the high entropy alloy intermediate layer comprises the following steps: Step 1: weigh pure metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y according to the atomic ratio of the constituent elements of the high entropy alloy intermediate layer according to claim 1, and wash them; Step 2: preparing alloy ingots by arc melting the pure metal element particles weighed in step 1; Step three, the alloy ingot prepared in step two is subjected to multiple cold rolling to obtain a cold-rolled sheet, the cold-rolled sheet is cut into sections and the upper and lower surfaces are ground to obtain a target intermediate layer, and then polished, corroded, cleaned and dried to obtain the high entropy alloy intermediate layer.

3. The method for preparing a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding according to claim 2, characterized in that: The cleaning process in step 1 is to clean the surface of the weighed pure metal element particles with anhydrous ethanol and place them in a drying oven for 1 hour.

4. The method for preparing a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding according to claim 2, characterized in that: In the process of preparing the alloy ingot by the arc melting method in step 2, the pure metal element particles Co, Ni, Cr, Al, Ta, Ge, Zr, and Y are placed in a copper crucible in order from low to high according to their melting points in step 1; the arc melting method is adopted, forward and reverse melting is performed more than 5 times, and electromagnetic stirring is performed to obtain the alloy ingot.

5. The method for preparing a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding according to claim 2, characterized in that: In step 3, the cutting and flattening treatment is performed before the multiple cold rolling. The process is to cut the alloy ingot into regular rectangular parallelepipeds and use a grinder to flatten the cut surface so that the reference flatness error of the cut surface is ≤0.05mm.

6. The method for preparing a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding according to claim 2, characterized in that: The multiple cold rolling in step three adopts multiple reciprocating rolling, the single-pass reduction is 0.2mm-0.4mm, the thickness of the cold-rolled sheet is 0.1mm-0.2mm, the grinding adopts a double-sided nano-grinding machine for mirror grinding, the thickness of the target intermediate layer is 50μm-80μm, and the thickness error is ±5μm.

7. The method for preparing a high entropy alloy intermediate layer for GH5188 transient liquid phase diffusion bonding according to claim 2, characterized in that: The polishing in step three is performed mechanically using a diamond suspension with a particle size of 0.25 μm; the corrosion is performed using Keller reagent corrosion to remove the surface oxide layer, the cleaning is performed using anhydrous ethanol ultrasonic cleaning, and the drying is performed by blowing and drying with high-purity nitrogen.

8. A GH5188 transient liquid phase diffusion bonding method, characterized in that: The connection method is: placing the high entropy alloy intermediate layer described in claim 1 or the high entropy alloy intermediate layer prepared by the preparation method described in claim 2 between the upper and lower layers of the base material GH5188, and then placing the whole in a vacuum diffusion welding furnace for welding.

9. A GH5188 transient liquid phase diffusion bonding method according to claim 8, characterized in that: The welding adopts a staged heating and pressurizing method. The specific welding process is as follows: in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 300°C at a rate of 10°C / min and kept warm for 10 minutes; in the second stage, the temperature is increased from 300°C to 700°C at a rate of 10°C / min and kept warm for 10 minutes; in the third stage, the temperature is increased from 700°C to 900°C at a rate of 10°C / min and kept warm for 10 minutes; in the fourth stage, the temperature is increased from 900°C to the welding temperature of 1150°C at a rate of 10°C / min; in the fifth stage, the temperature is kept at the welding temperature of 1150°C for 1 hour, a pressure of 5MPa is applied, and then the furnace is cooled to room temperature; the vacuum degree of the vacuum diffusion welding furnace is ≤4×10 -3 Pa.

10. A GH5188 transient liquid phase diffusion bonding method according to claim 8, characterized in that: Before welding in the vacuum diffusion welding furnace, the base material GH5188 was ground and polished with sandpaper and polishing liquid; after the grinding and polishing, the base material GH5188 was ultrasonically cleaned in anhydrous ethanol.

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