Joining Method of DD10 Single Crystal Superalloy Based on Intermediate Layer and Magnetic Field Assistance

Abstract

The present invention discloses a DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field, which belongs to the technical field of metal welding. 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 The middle layer is placed between the upper and lower layers of DD10 single crystal high-temperature alloy, and diffusion connection is carried out in a vacuum diffusion welding furnace embedded with a magnetic field generator to obtain a welded part of DD10 single crystal high-temperature alloy; under the synergistic effect of the two, the material microstructure and physical and chemical processes are regulated, atomic diffusion is promoted, the microstructure is optimized, the grain size is refined, the liquid surface deformation is controlled, and inclusions are removed, thereby improving the mechanical properties of the joint, significantly improving the welding quality and efficiency, and realizing the excellent performance of low-temperature welded workpieces for high-temperature service, providing a high-reliability solution for the efficient welding and manufacturing of DD10 single crystal high-temperature alloy for aircraft engine blades.

Description

Technical Field

[0001] The present invention relates to the technical field of metal welding, and in particular to a DD10 single crystal high-temperature alloy connection method based on an intermediate layer and magnetic field assistance. Background Art

[0002] As the thrust-to-weight ratio of aircraft engines increases, the operating conditions of high-pressure turbine blades become increasingly harsh. Complex aerodynamic, thermal stresses, and mechanical loads can all contribute to blade failure. Therefore, selecting a material with excellent overall performance is crucial. Nickel-based single-crystal superalloy DD10, due to its excellent creep resistance, durability, and casting properties, is the optimal choice for this component. Precisely because of the blade's unique structure, effectively joining the DD10 single-crystal superalloy has become a pressing issue.

[0003] Regarding the connection technology of high-temperature alloys, traditional fusion welding methods often cause a tendency to thermal cracking due to the high heat input, resulting in a significant decrease in the mechanical properties of the joints. Although direct diffusion welding technology avoids the heat input problem of fusion welding, it is prone to poor interface bonding such as unwelded defects and large-area holes in actual applications. When using conventional commercially available intermediate layers for transient liquid phase diffusion welding, although low-temperature connection can be achieved by introducing the melting-reducing elements B and Si, the brittle compound phases produced thereby will significantly weaken the joint strength. More importantly, the traditional transient liquid phase diffusion welding process usually requires a holding time of more than several hours to ensure sufficient diffusion of the elements. This inefficient process parameter not only increases production costs, but also seriously restricts the feasibility of industrial mass production.

[0004] Therefore, in response to the above challenges, the present invention introduces a new intermediate layer and combines it with magnetic field-assisted welding to complete the transient liquid phase diffusion welding of nickel-based single crystal high-temperature alloy DD10, thereby improving the welding efficiency while ensuring the mechanical properties of the joint. Summary of the Invention

[0005] In view of the shortcomings of the background technology, the main purpose of the present invention is to improve the mechanical properties of the joint while increasing the welding efficiency by introducing a new intermediate layer of independent design and combining it with the electromagnetic assisted welding method.

[0006] To achieve the above objectives, the present invention proposes a DD10 single crystal high-temperature alloy connection method based on an intermediate layer and a magnetic field, comprising the following steps:

[0007] Step 1: Prepare the intermediate layer; the atomic ratio of the intermediate layer is NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 ;

[0008] Step 2: Embed a magnetic field generator into the inner wall of the vacuum diffusion welding furnace;

[0009] Step 3: Transient liquid phase diffusion welding; place the middle layer of step one between the upper and lower layers of DD10 single crystal high temperature alloy base material, and place it in the vacuum diffusion welding furnace of step two for transient liquid phase diffusion welding. During the welding process, an alternating magnetic field is applied in a direction perpendicular to the surface to be welded, and heating and applying the magnetic field are carried out simultaneously, finally obtaining a welded part of DD10 single crystal high temperature alloy.

[0010] Preferably, the process of preparing the intermediate layer in step one is to weigh metal element particles Ni, Co, Cr, W, Mo, Ta, Ge, Re, Hf, and La with a purity greater than 99.99 wt% according to the atomic ratio of the elements, put them into a smelting furnace after cleaning, and smelt them to obtain alloy rods, and then use the alloy melt spinning technology in a single-roller spinning machine to prepare the amorphous foil intermediate layer.

[0011] Preferably, the thickness of the amorphous foil intermediate layer is 50 μm-80 μm.

[0012] Preferably, the smelting temperature is 1300°C.

[0013] Preferably, the process of preparing the amorphous foil intermediate layer using the alloy melt spinning technology is as follows: the alloy rod is encapsulated in a quartz tube, fixed vertically to the center of the induction coil of a single-roller spinning machine, and heated to 150°C above the liquidus line of the alloy rod under the protection of a vacuum and argon atmosphere. The melt is pressurized and sprayed onto the surface of the copper roller, and solidified to form an amorphous foil intermediate layer.

[0014] Preferably, the intensity of the magnetic field applied in step three is 0.1T-0.5T, and the magnetic field intensity increases gradiently, and the alternating frequency is 30HZ.

[0015] Preferably, the heating process in step three adopts a segmented heating method. In the first section, the vacuum diffusion welding furnace is heated from room temperature to 500°C at a rate of 10°C / min, and kept at 500°C for 10 minutes. When the temperature is raised to 300°C, a magnetic field is applied. In the second section, the temperature is raised to 900°C at a rate of 10°C / min, and kept at 900°C for 10 minutes. In the third section, the temperature is raised to the welding temperature of 1175°C at a rate of 10°C / min. In the fourth section, the temperature is kept at a welding temperature of 1175°C for 1 hour, and a pressure of 5 MPa is applied to keep the temperature and pressure.

[0016] Preferably, during the transient liquid phase diffusion welding process, when the heat preservation and pressure holding are completed, the pressure is first unloaded, the welded parts are cooled along with the furnace, and when the temperature of the vacuum diffusion welding furnace drops to 300°C, the magnetic field generator is turned off. When the temperature of the vacuum diffusion welding furnace drops to room temperature, the welding is completed.

[0017] Preferably, before the transient liquid phase diffusion welding in step 3, the DD10 single crystal high temperature alloy is polished in sequence using 400# to 2000# sandpaper, and after polishing, it is mechanically polished using a polishing liquid and ultrasonically cleaned in anhydrous ethanol.

[0018] Preferably, the vacuum degree of the vacuum diffusion welding furnace in step 3 is .

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention adopts NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 The intermediate layer and magnetic field-assisted transient liquid-phase diffusion welding of DD10 single-crystal high-temperature alloy, the synergistic effect of the intermediate layer and the electromagnetic field, regulates the material microstructure and physical and chemical processes, promotes atomic diffusion, optimizes the microstructure, refines the grains, controls liquid surface deformation and removes inclusions, improves the mechanical properties of the joint, significantly improves the welding quality and efficiency, and enables low-temperature welded workpieces to have excellent performance for high-temperature service. Through the joint action of the new intermediate layer and the magnetic field, the welding temperature can be appropriately reduced to achieve the effect of high-temperature welding, effectively improving the welding efficiency. The non-contact nature of the electromagnetic assistance and the workpiece has greatly broadened the scope of application. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of sample clamping before transient liquid phase diffusion welding and the direction of magnetic field applied during welding in Example 1 of the present invention.

[0022] Figure 2 This is an SEM image of the joint microstructure after transient liquid phase diffusion welding in Example 1 of the present invention.

[0023] Figure 3 This is the SEM image of the joint microstructure in Comparative Example 1 of the present invention.

[0024] Figure 4 This is the SEM image of the joint microstructure 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 DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field, which specifically includes the following steps:

[0027] Step 1: The surface of the DD10 single crystal high-temperature alloy to be welded is polished with 400#, 600#, 1000#, 1500#, and 2000# sandpaper in sequence, and polished with 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The polished alloy is ultrasonically cleaned with anhydrous ethanol at a frequency of 20kHz for 15 minutes, and blown dry with a nitrogen gun to obtain the treated DD10 single crystal high-temperature alloy base material;

[0028] Step 2: Prepare the intermediate layer and clamp the intermediate layer and the DD10 single crystal high-temperature alloy base material in a sandwich structure of "base material-intermediate layer-base material";

[0029] The process of preparing the intermediate layer includes the following steps:

[0030] Step 1: According to the atomic ratio of the elements NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 Weigh metal element particles Ni, Co, Cr, W, Mo, Ta, Ge, Re, Hf, and La with a purity greater than 99.99 wt%, clean the surface with a dilute sulfuric acid solution, and then ultrasonically clean them in an alcohol solution;

[0031] Step 2, Melting: The cleaned raw materials are loaded into a medium frequency induction melting furnace. The mechanical pump and Roots pump are started in sequence to create a vacuum environment. High-purity argon gas is then filled in as a protective atmosphere to maintain dynamic pressure balance. The medium frequency power supply is activated for gradient heating. During the heating process, electromagnetic stirring combined with flux covering technology is used to perform slag removal and refining treatment to eliminate non-metallic inclusions and complete the alloying melting process. The above process is repeated three times, and the alloy is poured into a mold and cooled to obtain alloy bars with consistent specifications. The melting temperature is 1300°C.

[0032] Step 3, strip spinning: The alloy rod is encapsulated in a high-purity quartz tube and fixed vertically to the center of the induction coil of the single-roll strip spinning machine. After the vacuum system is interlocked and started, high-purity argon gas is filled for protection. Medium-frequency induction heating is performed to 150°C above the alloy liquidus. The melt is pressurized and sprayed onto the surface of a rapidly rotating copper roller. It is rapidly cooled and solidified to form an amorphous foil intermediate layer with a thickness of 50μm-80μm. The required process parameters are: beryllium copper diameter is 400mm, copper roller speed is 1800rpm, cooling rate is greater than 106℃ / sec; nozzle width is 12mm, diameter is 1.5mm; nozzle to copper roller surface distance is 0.5mm; argon injection pressure is 45kPa;

[0033] Step 3: Vacuum diffusion welding furnace cavity modification: Figure 1 As shown, a magnetic field generator is embedded in the inner wall of the vacuum diffusion welding furnace to facilitate the application of the magnetic field. An alternating magnetic field is selected as the applied magnetic field type. The direction of the magnetic field is perpendicular to the surface to be welded, and the magnetic field strength is adjusted. For the magnetic field-assisted transient liquid phase diffusion welding test, the magnetic field strength needs to be strictly controlled. The magnetic field strength is 0.1-0.5T, for example, it can be 0.1T, 0.2T, 0.3T, 0.4T, 0.5T, and the alternating frequency is 30HZ to avoid deterioration of joint performance caused by magnetic field strength imbalance.

[0034] Step 4: Place the "base material-intermediate layer-base material" structure in step 2 in the vacuum diffusion welding furnace modified in step 3 for transient liquid phase diffusion welding;

[0035] During the welding process, the magnetic field application process needs to be carried out simultaneously with heating, and the magnetic field intensity gradient is applied at the same time; during the heating process, in the first section, the vacuum diffusion welding furnace is heated from room temperature to 500°C at a rate of 10°C / min, and kept at 500°C for 10 minutes. It is worth noting that the magnetic field is applied while the temperature rises to 300°C. In the second section, the temperature is raised to 900°C at a rate of 10°C / min, and kept at 900°C for 10 minutes. In the third section, the temperature is raised to the welding temperature of 1175°C at a rate of 10°C / min. In the fourth section, the welding temperature is kept at 1175°C for 1 hour, and a pressure of 5MPa is applied for insulation and pressure maintenance. At the end of insulation and pressure maintenance, the pressure is unloaded first, and the weldment cools with the furnace. When the temperature of the vacuum diffusion welding furnace drops to 300°C, the magnetic field generator is turned off. When the temperature of the vacuum diffusion welding furnace drops to room temperature, the welding is completed. The vacuum degree during the entire welding process is always no higher than .

[0036] In some embodiments of the present invention, during the transient liquid phase diffusion welding process, NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2The role of each element in the intermediate layer during the welding process and its synergistic effect with the magnetic field are as follows: Ni-Co-Cr is used as the main framework during welding, forming a continuous composition transition with the DD10 base material, and the Ni / Co matrix forms a continuous solid solution during welding, which significantly reduces the interface lattice mismatch and promotes the mutual diffusion of elements between the base material and the intermediate layer, effectively alleviating the interface residual stress; W and Mo, as the main solid solution strengthening elements, form a stable solid solution in the γ phase matrix, and produce lattice distortion strengthening through atomic size differences; Re element, with its unique grain boundary segregation characteristics, forms dislocation barriers in the interface area, synergistically improving the high-temperature creep resistance of the joint; the introduction of Ge element forms a controllable transient liquid layer in the early stage of welding by lowering the liquidus temperature of the alloy; combined with magnetic Field-assisted process, the liquid phase layer can optimize the solute distribution during isothermal solidification, inhibit the formation of brittle intermetallic compounds, and promote dense metallurgical bonding; Ta, Hf, and La multi-component systems will form an oxide layer during high-temperature oxidation, and the oxides constitute a dense barrier layer, which significantly improves the anti-oxidation stability of the joint under high-temperature environment; at the same time, during the welding process, the application of an electromagnetic field can promote the spreading and filling behavior of the liquid intermediate layer, thereby improving the wettability; the flow velocity of the liquid intermediate layer is proportional to the current peak and the static magnetic field strength; the application of an electromagnetic field can regulate the microstructure and physical and chemical processes of the material, promote atomic diffusion, optimize the microstructure, refine the grains, control the liquid surface deformation, and remove inclusions, thereby improving the mechanical properties of the joint and ensuring welding quality and efficiency.

[0037] The present invention will be further described below with reference to the embodiments.

[0038] Example 1

[0039] This embodiment uses NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 As the intermediate layer, a magnetic field is applied to assist in transient liquid phase diffusion welding of nickel-based single crystal high-temperature alloy DD10. The specific steps are as follows:

[0040] Step 1: The surface of the DD10 single crystal high-temperature alloy to be welded is polished with 400#, 600#, 1000#, 1500#, and 2000# sandpaper in sequence, and polished with 0.15μm silica polishing liquid until there are no obvious scratches on the surface. The polished alloy is ultrasonically cleaned with anhydrous ethanol at a frequency of 20kHz for 15 minutes, and blown dry with a nitrogen gun to obtain the treated DD10 single crystal high-temperature alloy base material;

[0041] Step 2: Prepare the intermediate layer and clamp the intermediate layer and the DD10 single crystal high-temperature alloy base material in a sandwich structure of "base material-intermediate layer-base material";

[0042] The process of preparing the intermediate layer includes the following steps:

[0043] Step 1: According to the atomic ratio of the elements NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 Weigh metal element particles Ni, Co, Cr, W, Mo, Ta, Ge, Re, Hf, and La with a purity greater than 99.99 wt%, clean the surface with a dilute sulfuric acid solution, and then ultrasonically clean them in an alcohol solution;

[0044] Step 2, Melting: The cleaned raw materials are loaded into a medium frequency induction melting furnace. The mechanical pump and Roots pump are started in sequence to create a vacuum environment. High-purity argon gas is then filled in as a protective atmosphere to maintain dynamic pressure balance. The medium frequency power supply is activated for gradient heating. During the heating process, electromagnetic stirring combined with flux covering technology is used to perform slag removal and refining treatment to eliminate non-metallic inclusions and complete the alloying melting process. The above process is repeated three times, and the alloy is poured into a mold and cooled to obtain alloy bars with consistent specifications. The melting temperature is 1300°C.

[0045] Step 3, Strip Spinning: The alloy rod is encapsulated in a high-purity quartz tube and fixed vertically to the center of the induction coil of a single-roll strip spinning machine. After the vacuum system is interlocked and activated, high-purity argon gas is filled for protection. Medium-frequency induction heating is applied to the alloy to 150°C above the liquidus. The melt is then pressurized and sprayed onto the surface of a rapidly rotating copper roller, where it rapidly solidifies to form an amorphous foil intermediate layer with a thickness of 65μm. The required process parameters are: beryllium copper diameter of 400mm, copper roller speed of 1800rpm, cooling rate greater than 106°C / sec; nozzle width of 12mm, diameter of 1.5mm; distance between the nozzle and the copper roller surface of 0.5mm; and argon injection pressure of 45kPa.

[0046] Step 3: Vacuum diffusion welding furnace cavity modification: Figure 1 As shown, a magnetic field generator is embedded in the inner wall of the vacuum diffusion welding furnace to facilitate the application of the magnetic field. The alternating magnetic field is selected as the applied magnetic field type. The direction of the magnetic field is perpendicular to the surface to be welded, and the magnetic field strength is debugged. For the magnetic-assisted transient liquid phase diffusion welding test, the magnetic field strength needs to be strictly controlled to ensure that the magnetic field strength is maintained between 0.1-0.5T and the alternating frequency is 30HZ to avoid deterioration of the joint performance caused by magnetic field strength imbalance.

[0047] Step 4: Place the "base material-intermediate layer-base material" structure in step 2 in the vacuum diffusion welding furnace modified in step 3 for transient liquid phase diffusion welding;

[0048] During the welding process, the magnetic field application process needs to be carried out simultaneously with heating, and the magnetic field intensity gradient is applied at the same time; during the heating process, in the first section, the vacuum diffusion welding furnace is heated from room temperature to 500°C at a rate of 10°C / min, and kept at 500°C for 10 minutes. It is worth noting that the magnetic field is applied while the temperature rises to 300°C. In the second section, the temperature is raised to 900°C at a rate of 10°C / min, and kept at 900°C for 10 minutes. In the third section, the temperature is raised to the welding temperature of 1175°C at a rate of 10°C / min. In the fourth section, the welding temperature is kept at 1175°C for 1 hour, and a pressure of 5MPa is applied for insulation and pressure maintenance. At the end of insulation and pressure maintenance, the pressure is unloaded first, and the weldment cools with the furnace. When the temperature of the vacuum diffusion welding furnace drops to 300°C, the magnetic field generator is turned off. When the temperature of the vacuum diffusion welding furnace drops to room temperature, the welding is completed. The vacuum degree during the entire welding process is always no higher than , the welded parts of DD10 single crystal high temperature alloy are obtained, and the microstructure of the joint is as follows Figure 2 As shown; the mechanical properties of the welded joint of this embodiment were tested using an INSTRON3382 electronic universal material testing machine, and the shear strength of the joint can reach 857MPa.

[0049] Example 2

[0050] This embodiment uses NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 As an intermediate layer, a magnetic field is applied to assist in transient liquid phase diffusion welding of nickel-based single crystal high-temperature alloy DD10, wherein the process of preparing the intermediate layer includes the following steps:

[0051] Step 1: According to the atomic ratio of the elements NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 Weigh metal element particles Ni, Co, Cr, W, Mo, Ta, Ge, Re, Hf, and La with a purity greater than 99.99 wt%, clean the surface with a dilute sulfuric acid solution, and then ultrasonically clean them in an alcohol solution;

[0052] Step 2, Melting: The cleaned raw materials are loaded into a medium frequency induction melting furnace. The mechanical pump and Roots pump are started in sequence to create a vacuum environment. High-purity argon gas is then filled in as a protective atmosphere to maintain dynamic pressure balance. The medium frequency power supply is activated for gradient heating. During the heating process, electromagnetic stirring combined with flux covering technology is used to perform slag removal and refining treatment to eliminate non-metallic inclusions and complete the alloying melting process. The above process is repeated three times, and the alloy is poured into a mold and cooled to obtain alloy bars with consistent specifications. The melting temperature is 1300°C.

[0053] Step 3, strip spinning: encapsulate the alloy rod in a high-purity quartz tube, fix it vertically in the center of the induction coil of the single-roll strip spinning machine, interlock and start the vacuum system, fill it with high-purity argon protection, medium-frequency induction heating to 150°C above the alloy liquidus, pressurize and spray the melt onto the surface of the rapidly rotating copper roller, and rapidly cool and solidify to form an amorphous foil intermediate layer with a thickness of 50 μm; the remaining steps are the same as Example 1.

[0054] The mechanical properties of the welded joint of this embodiment were tested using an INSTRON 3382 electronic universal material testing machine, and the shear strength of the joint can reach 845 MPa.

[0055] Example 3

[0056] This embodiment uses NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 As an intermediate layer, a magnetic field is applied to assist in transient liquid phase diffusion welding of nickel-based single crystal high-temperature alloy DD10, wherein the process of preparing the intermediate layer includes the following steps:

[0057] Step 1: According to the atomic ratio of the elements NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 Weigh metal element particles Ni, Co, Cr, W, Mo, Ta, Ge, Re, Hf, and La with a purity greater than 99.99 wt%, clean the surface with a dilute sulfuric acid solution, and then ultrasonically clean them in an alcohol solution;

[0058] Step 2, Melting: The cleaned raw materials are loaded into a medium frequency induction melting furnace. The mechanical pump and Roots pump are started in sequence to create a vacuum environment. High-purity argon gas is then filled in as a protective atmosphere to maintain dynamic pressure balance. The medium frequency power supply is activated for gradient heating. During the heating process, electromagnetic stirring combined with flux covering technology is used to perform slag removal and refining treatment to eliminate non-metallic inclusions and complete the alloying melting process. The above process is repeated three times, and the alloy is poured into a mold and cooled to obtain alloy bars with consistent specifications. The melting temperature is 1300°C.

[0059] Step 3, strip spinning: encapsulate the alloy rod in a high-purity quartz tube, fix it vertically in the center of the induction coil of the single-roll strip spinning machine, interlock and start the vacuum system, fill it with high-purity argon protection, and perform medium-frequency induction heating to 150°C above the liquidus of the alloy. Pressurize the melt and spray it onto the surface of the rapidly rotating copper roller. Rapidly cool and solidify it to form an amorphous foil intermediate layer with a thickness of 80 μm. The remaining steps are the same as in Example 1.

[0060] The mechanical properties of the welded joint of this embodiment were tested using an INSTRON 3382 electronic universal material testing machine, and the shear strength of the joint can reach 847 MPa.

[0061] Comparative Example 1

[0062] This comparative example uses NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 As the intermediate layer, the nickel-based single crystal high-temperature alloy DD10 is used for instantaneous liquid phase diffusion bonding. The specific steps are as follows:

[0063] Step 1 and step 2 are the same as in Example 1;

[0064] Step 3: Place the "parent material-intermediate layer-parent material" structure in step 2 in a vacuum diffusion welding furnace without a magnetic field generator for transient liquid phase diffusion welding; in the heating process, in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 500°C at a rate of 10°C / min, and kept at 500°C for 10 minutes. It is worth noting that a magnetic field is applied while the temperature is rising to 300°C. In the second stage, the temperature is raised to 900°C at a rate of 10°C / min, and kept at 900°C for 10 minutes. In the third stage, the temperature is raised to 1300°C at a rate of 10°C / min. In the fourth stage, the temperature is kept at 1300°C for 4 hours, and a pressure of 5MPa is applied for heat preservation and pressure maintenance. At the end of the heat preservation and pressure maintenance, the pressure is unloaded, and the weldment is cooled to room temperature with the furnace, and the welding is completed. The vacuum degree during the entire welding process is always no higher than , the welded parts of DD10 single crystal high temperature alloy are obtained, and the microstructure of the joint is as follows Figure 3 shown.

[0065] The mechanical properties of the welded joints of this comparative example were tested using an INSTRON 3382 electronic universal material testing machine, and the shear strength of the joints could reach 798 MPa.

[0066] Comparative Example 2

[0067] This comparative example uses BNi-2 foil as the intermediate layer to achieve transient liquid phase diffusion bonding of nickel-based single crystal high-temperature alloy DD10. The specific steps are as follows:

[0068] Step 1 is the same as in Example 1;

[0069] Step 2: Clamp the BNi-2 foil intermediate layer and the DD10 single crystal high-temperature alloy base material in a sandwich structure of "base material-intermediate layer-base material";

[0070] Step 3: Place the "parent material-intermediate layer-parent material" structure in step 2 in a vacuum diffusion welding furnace without a magnetic field generator for transient liquid phase diffusion welding; during the heating process, in the first stage, the vacuum diffusion welding furnace is heated from room temperature to 500°C at a rate of 10°C / min, and kept at 500°C for 10 minutes; in the second stage, the temperature is increased to 900°C at a rate of 10°C / min, and kept at 900°C for 10 minutes; in the third stage, the temperature is increased to the welding temperature of 1200°C at a rate of 10°C / min; in the fourth stage, the temperature is kept at 1200°C for 4 hours, and a pressure of 5MPa is applied for heat preservation and pressure maintenance; at the end of the heat preservation and pressure maintenance, the pressure is unloaded, and the weldment is cooled to room temperature with the furnace, and the welding is completed. The vacuum degree during the entire welding process is always no higher than , DD10 single crystal high temperature alloy welded parts are obtained, and the microstructure of the joint is as follows Figure 4 shown.

[0071] The mechanical properties of the welded joints of this comparative example were tested using an INSTRON 3382 electronic universal material testing machine, and the shear strength of the joints could reach 694 MPa.

[0072] Combine Figure 2 、 Figure 3 、 Figure 4 It can be seen that the microstructure of the joint of the transient liquid phase diffusion welding connection of the nickel-based single crystal high-temperature alloy DD10 based on electromagnetic field assistance and intermediate layer design in Example 1 is as follows: Figure 2As shown, it shows that even at lower temperatures, there is no white hard and brittle phase in the welded joint, that is, the joints are all isothermally solidified, and at the same time, the time required for welding is reduced, and the efficiency is improved. The mechanical properties of the welded joint of Example 1 were tested using an INSTRON3382 electronic universal material testing machine. The shear strength of the joint of Example 1 can reach 857MPa; Comparative Example 1 is a transient liquid phase diffusion connection of nickel-based single crystal high-temperature alloy DD10 based on an intermediate layer design. Even if the corresponding welding temperature and holding time are increased, the synergistic effect based on electromagnetic field assistance and intermediate layer design can only be replicated to a certain extent. The microstructure of the resulting joint is as follows Figure 3 As shown in the figure, it can be seen that without the assistance of a magnetic field, when the welding temperature and holding time are increased, a small amount of white hard and brittle phase appears in the joint, that is, a non-isothermal solidification area appears. At this time, the mechanical properties of the joint are reduced to 798MPa. In comparative example 2, commercially available BNi-2 is used to perform transient liquid phase diffusion bonding on nickel-based single crystal high-temperature alloy DD10 at 1200℃. The microstructure of the joint is as follows: Figure 4 As shown, from Figure 4 It can be clearly seen that when using traditional intermediate layer for transient liquid phase diffusion welding, even if the temperature is appropriately increased, the brittle phase in the joint cannot be completely eliminated, that is, there is always a non-isothermal solidification area, which is easy to induce crack initiation. At this time, the joint performance is low, only 694MPa.

[0073] 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.

[0074] 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.

[0075] 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 DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field, characterized in that: The following steps are involved: Step 1: Prepare the intermediate layer; the atomic ratio of the intermediate layer is NiCo 22 Cr 20 W 10 Mo7Ta5Ge5Re2Hf 0.8 La 0.2 ; Step 2: Embed a magnetic field generator into the inner wall of the vacuum diffusion welding furnace; Step 3: Transient liquid phase diffusion welding: The middle layer of step 1 is placed between the upper and lower layers of DD10 single crystal high temperature alloy base material, and placed in the vacuum diffusion welding furnace of step 2 for transient liquid phase diffusion welding. During the welding process, an alternating magnetic field is applied in a direction perpendicular to the surface to be welded, and heating and applying the magnetic field are carried out simultaneously, finally obtaining a welded part of DD10 single crystal high temperature alloy.

2. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field assist according to claim 1, characterized in that: The process of preparing the intermediate layer described in step one is to weigh metal element particles Ni, Co, Cr, W, Mo, Ta, Ge, Re, Hf, and La with a purity greater than 99.99 wt% according to the atomic ratio of the elements, put them into a smelting furnace after cleaning, and smelt them to obtain alloy rods. Thereafter, the alloy melt is spun on a single-roller strip spinning machine using alloy melt spinning technology to prepare an amorphous foil intermediate layer.

3. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field as claimed in claim 2, characterized in that: The thickness of the amorphous foil middle layer is 50 μm-80 μm.

4. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field as claimed in claim 2, characterized in that: The smelting temperature is 1300°C.

5. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field assist according to claim 2, characterized in that: The process of preparing the amorphous foil intermediate layer using the alloy melt spinning technology is as follows: the alloy rod is encapsulated in a quartz tube, fixed vertically to the center of the induction coil of a single-roller spinning machine, heated to 150°C above the liquidus line of the alloy rod under the protection of a vacuum and argon atmosphere, and the melt is pressurized and sprayed onto the surface of the copper roller to solidify to form the amorphous foil intermediate layer.

6. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field assist according to claim 1, characterized in that: The intensity of the magnetic field applied in step 3 is 0.1T-0.5T, and the magnetic field intensity gradient increases, and the alternating frequency is 30HZ.

7. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field assist according to claim 1, characterized in that: The heating process described in step three adopts a segmented heating method. In the first section, the vacuum diffusion welding furnace is heated from room temperature to 500°C at a rate of 10°C / min, and kept at 500°C for 10 minutes. When the temperature is raised to 300°C, a magnetic field is applied. In the second section, the temperature is raised to 900°C at a rate of 10°C / min, and kept at 900°C for 10 minutes. In the third section, the temperature is raised to the welding temperature of 1175°C at a rate of 10°C / min. In the fourth section, the welding temperature is kept at 1175°C for 1 hour, and a pressure of 5 MPa is applied for heat and pressure maintenance.

8. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field as claimed in claim 7, characterized in that: In the transient liquid phase diffusion welding process, when the heat preservation and pressure holding are finished, the pressure is first unloaded, and the weldment is cooled along with the furnace. When the temperature of the vacuum diffusion welding furnace drops to 300°C, the magnetic field generator is turned off. When the temperature of the vacuum diffusion welding furnace drops to room temperature, the welding is completed.

9. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and magnetic field assistance according to claim 1, characterized in that: Before the transient liquid phase diffusion welding in step 3, the DD10 single crystal high temperature alloy was polished with 400#, 600#, 1000#, 1500#, and 2000# sandpaper in sequence. After polishing, it was mechanically polished with a polishing liquid and ultrasonically cleaned in anhydrous ethanol.

10. The DD10 single crystal high temperature alloy connection method based on an intermediate layer and a magnetic field assist according to claim 1, characterized in that: The vacuum degree of the vacuum diffusion welding furnace described in step 3 .

Images