A material for joining single crystal superalloys and polycrystalline superalloys and methods of making and using the same

Abstract

The application discloses a material for connecting single-crystal superalloy and polycrystal superalloy and a preparation and use method thereof, and the material comprises low-melting-point Ni-Ti alloy powder and high-melting-point Ni-based alloy powder. The material can realize rapid high-performance connection of the single-crystal superalloy and the polycrystal superalloy. The application belongs to the technical field of alloy material connection.

Description

Technical Field

[0001] This invention belongs to the field of alloy material joining technology, specifically relating to a material for joining single-crystal superalloys and polycrystalline superalloys, and its preparation and use methods. Background Technology

[0002] Aero engines are a symbol of modern powerful nations and a key element in great power competition, hailed as the "crown jewel" of modern industry. To develop advanced aero engines with high thrust-to-weight ratios, modern aero engines increasingly adopt integral bladed disk (IBD) structures, abandoning the traditional split-disk tenon joint structure. The lightweight design of IBD can reduce weight by 20%-30%, while effectively reducing heat transfer drag and heat transfer interfaces, thus improving the thermal efficiency of the aero engine. The materials used for turbine disks and blades typically differ significantly in properties. With the increasing thrust-to-weight ratio of aero engines, the high-temperature performance requirements for blade materials are becoming increasingly stringent, leading to the era of single-crystal superalloys for turbine blades. Advanced aero engine turbine disk materials typically employ polycrystalline superalloys such as powder metallurgy, wrought superalloys, and cast superalloys. Therefore, achieving high-performance bonding between single-crystal and polycrystalline superalloys to manufacture integral turbine disks has become a crucial technology urgently needed for the development of new advanced aero engines.

[0003] Currently, the main methods for joining single-crystal / polycrystalline superalloys include fusion welding, brazing, linear friction welding, and transient liquid-phase diffusion bonding. All of these methods have limitations. Common fusion welding methods for nickel-based superalloys include electron beam welding and laser welding. Since the Al+Ti content in nickel-based superalloys is typically greater than 6 wt.%, solidification cracks inevitably appear at the joint during fusion welding. Both brazing and transient liquid-phase diffusion bonding of superalloys use Si and B as melting point reducing elements to prepare the joining materials. After joining, the joint is prone to residual brittle compounds of Si and B, resulting in extremely poor joint performance (below 50%). Although prolonged heat treatment can eliminate these brittle compounds, this leads to severe grain growth in the polycrystalline superalloy base material, causing a sharp deterioration in its mechanical properties. Therefore, traditional brazing and transient liquid-phase diffusion bonding are not suitable for joining single-crystal and polycrystalline superalloys. In linear friction welding of single-crystal and polycrystalline superalloys, the significant difference in their high-temperature strength makes it difficult for single-crystal superalloys to undergo plastic deformation, while allowing easy transfer of the friction surface in polycrystalline superalloys, leading to defects such as oxide inclusions and microcracks. Furthermore, linear friction welding of single-crystal / polycrystalline superalloys can easily generate residual stress in the joint due to the mismatch in the thermal expansion coefficients of the dissimilar alloys. Therefore, linear friction welding is not a suitable process for joining single-crystal / polycrystalline superalloys. Summary of the Invention

[0004] To address the high-performance bonding problem between single-crystal and polycrystalline superalloys in the manufacturing of integral turbine disks for high-performance aero-engines, this invention proposes a material for bonding single-crystal and polycrystalline superalloys, as well as its preparation and application methods.

[0005] This invention provides a material for connecting single-crystal superalloys and polycrystalline superalloys, the material comprising low-melting-point Ni-Ti alloy powder and high-melting-point Ni-based alloy powder.

[0006] As an embodiment of the present invention, the chemical composition of the low-melting-point Ni-Ti alloy is: Ti

[0007] 25.0~45.0 wt.%, the remainder being Ni.

[0008] As an embodiment of the present invention, the chemical composition of the high-melting-point Ni-based alloy powder is: Cr 5.0~20.0 wt.%, Co 5.0~15.0 wt.%, Mo 5.0~10.0 wt.%, W 5.0~10.0 wt.%, with the remainder being Ni.

[0009] As an embodiment of the present invention, the low-melting-point Ni-Ti alloy powder has a particle size of no more than 100 μm and a melting point of no more than 1200 °C; the high-melting-point Ni-based alloy powder has a particle size of no more than 100 μm and a melting point of no less than the solution heat treatment temperature of nickel-based single crystal high-temperature alloy.

[0010] As an embodiment of the present invention, in the material, the volume ratio of low-melting-point Ni-Ti alloy powder to high-melting-point Ni-based alloy powder is 1~4:1; the material is spherical and / or near-spherical alloy powder with an average particle size ranging from 5 to 106 μm.

[0011] As an embodiment of the present invention, the single-crystal superalloy is a nickel-based single-crystal superalloy prepared by directional solidification process;

[0012] The polycrystalline high-temperature alloy is a powder high-temperature alloy prepared by hot isostatic pressing.

[0013] The second aspect of the present invention provides a method for preparing the material described in the first aspect, the method comprising: the material being prepared by an electrode induction melting gas atomization powdering method or a plasma rotating electrode powdering method, wherein the low-melting-point Ni-Ti alloy powder and the high-melting-point Ni-based alloy powder are mixed in a planetary ball mill for 60-120 min at a rotation speed of 200-240 r / min to obtain the material.

[0014] A third aspect of the present invention provides a method for joining single-crystal superalloys and polycrystalline superalloys using the material described in the first aspect or the material prepared by the method described in the second aspect, the method comprising:

[0015] S1: Cleaning the surfaces of the single-crystal and polycrystalline high-temperature alloys to be joined: Use 400#, 600#, 800#, 1000#, 1200#, 1500#, and 2000# sandpaper sequentially to polish the surfaces of the single-crystal and polycrystalline high-temperature alloys to be joined; then, immerse them completely in acetone and ultrasonically clean for 10-20 minutes; after cleaning, remove them and place them in a vacuum drying oven to dry at a temperature of 50-80℃ for 20-40 minutes; after cleaning, the surfaces to be joined should be free of oil and oxide residue.

[0016] S2: Pre-applied connecting material: Mix the connecting material with an organic solvent to form a paste, and apply it evenly to the surfaces of the single-crystal high-temperature alloy and the polycrystalline high-temperature alloy to be connected. The thickness of the applied connecting material is about 0.2-0.4 mm.

[0017] S3: Assembly of the parts to be connected: Place the monocrystalline high-temperature alloy and polycrystalline high-temperature alloy parts to be connected, after applying an appropriate amount of connecting material, into a special connecting fixture;

[0018] S4: Connection: A vacuum brazing furnace is used for connection, and continuous pressure is applied. When the vacuum degree inside the furnace reaches 5×10 -3 Start heating at Pa, with a heating rate of 10~15℃ / min, and heat to a temperature lower than the solution heat treatment temperature of the polycrystalline high-temperature alloy. Hold at this temperature for 30~120 minutes, then furnace cool down.

[0019] As an embodiment of the present invention, in step S2, the organic solvent is selected from terpineol and / or alcohol.

[0020] In one embodiment of the present invention, in step S4, the temperature of the connection is 1100℃~1200℃, and the heat preservation time is 30~120min.

[0021] The above-mentioned technical solution provided by this invention brings at least the following beneficial effects:

[0022] (1) The present invention uses a mixture of low-melting-point Ni-Ti alloy powder and high-melting-point Ni alloy powder as the connecting material for single-crystal high-temperature alloys and polycrystalline high-temperature alloys. It does not contain melting-reducing elements such as Si and B. The connecting layer does not contain Si- and B-rich brittle compounds or eutectic structures, and it does not require long-term heat preservation and diffusion to achieve composition homogenization.

[0023] (2) The connecting material of the present invention is formed by mixing two alloy powders. The homogenization process of the joint is a rapid diffusion mechanism with a large diffusion area and short diffusion distance, which can greatly accelerate the dynamics of the connection process.

[0024] (3) The connection between the single-crystal high-temperature alloy and the polycrystalline high-temperature alloy of the present invention can be completed under the conditions of lower connection temperature and very short connection time, thereby greatly reducing the impact of the connection process on the polycrystalline high-temperature alloy base material;

[0025] (4) After the single-crystal high-temperature alloy and polycrystalline high-temperature alloy connecting materials of the present invention are connected, a polycrystalline high-temperature alloy connecting layer with the same composition and microstructure as the base material can be formed, thereby obtaining a high-performance connecting joint of single-crystal high-temperature alloy and polycrystalline high-temperature alloy such as powder high-temperature alloy, wrought high-temperature alloy and cast high-temperature alloy. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is an assembly diagram of a connecting material and a connecting method for single-crystal and polycrystalline high-temperature alloys.

[0028] Figure 2 This is a schematic diagram of a connection material and connection method for single-crystal high-temperature alloys and polycrystalline high-temperature alloys, wherein 1 is a single-crystal high-temperature alloy, 2 is Ni-Cr-Co-Mo-W alloy powder, 3 is Ni-Ti alloy powder, 4 is FGH96, and 5 is liquid phase;

[0029] Figure 3 The images show the microstructure of the bonding layer and the substrate of the single-crystal and polycrystalline high-temperature alloy bonding materials and bonding methods in Example 1.

[0030] Figure 4 The images show the microstructure of the bonding layer and the substrate of the single-crystal and polycrystalline high-temperature alloy bonding materials and bonding methods in Example 2.

[0031] Figure 5 The images show the microstructure of the bonding layer and the substrate of the single-crystal high-temperature alloy and polycrystalline high-temperature alloy bonding materials and bonding methods in Example 3.

[0032] Figure 6 The room temperature tensile strength of the connecting layer in Example 4 is the connecting material and connecting method for single-crystal and polycrystalline high-temperature alloys.

[0033] Figure 7 The high-temperature tensile strength of the connecting layer at 650°C is given by the connecting material and connecting method of the single-crystal high-temperature alloy and the polycrystalline high-temperature alloy in Example 4. Detailed Implementation

[0034] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0035] This invention addresses the high-performance bonding problem between single-crystal and polycrystalline superalloys in the manufacturing of integral turbine bladed disks. The invention proposes a bonding material and method for single-crystal and polycrystalline superalloys. The bonding material is a fully heat-treated nickel-based single-crystal superalloy prepared by directional solidification, with the directional solidification direction of the single-crystal superalloy being the

[001] direction. The polycrystalline superalloy is a powder superalloy prepared by hot isostatic pressing. The raw materials for preparing the bonding material in this invention are not limited to low-melting-point Ni-Ti alloy powder or high-melting-point Ni-based alloy powder; low-melting-point Ni-Ti alloy foil or high-melting-point Ni-based alloy foil can also be used.

[0036] The principle of the connecting materials and methods for single-crystal and polycrystalline high-temperature alloys is as follows: Figure 3 As shown, a bonding material is formed using a mixture of Ni-Ti alloy powder and Ni-Cr-Co-Mo-W alloy powder. The bonding is achieved by heating in a vacuum brazing furnace under a certain pressure. During the bonding process, the Ni-Ti alloy powder melts to form a liquid phase, which forms a dense solid-liquid hybrid bonding layer with the solid Ni-Cr-Co-Mo-W alloy powder. Bonding is achieved through solid-liquid interdiffusion between the liquid phase and the high-melting-point component particles and the base material. Further isothermal diffusion homogenization yields a high-temperature alloy bonding layer with a composition and structure nearly identical to the polycrystalline high-temperature alloy base material, achieving high-performance bonding between single-crystal and polycrystalline high-temperature alloys. This invention can also be used for bonding single-crystal high-temperature alloys to other polycrystalline high-temperature alloys, such as wrought and cast high-temperature alloys.

[0037] Example 1

[0038] This embodiment describes a material and its application method for connecting single-crystal superalloys and polycrystalline superalloys. The nickel-based single-crystal superalloy used is DD5, and the polycrystalline superalloy is FGH96. Electrical discharge machining (EDM) is employed to fabricate materials with dimensions of 10×10×2mm on both the DD5 single-crystal superalloy base material and the FGH96 polycrystalline superalloy. 3 The block components to be connected are assembled as follows: Figure 1 As shown.

[0039] The chemical composition of the Ni-Ti alloy powder used in this embodiment is: Ti 25.0~45.0 wt.%, the remainder being Ni, and the particle size of the Ni-Ti alloy powder is no greater than 106 μm. The chemical composition of the Ni-Cr-Co-Mo-W alloy powder is: Cr 5.0~20.0 wt.%, Co 5.0~15.0 wt.%, Mo 5.0~10.0 wt.%, W 5.0~10.0 wt.%, the remainder being Ni, and the particle size of all Ni-Cr-Co-Mo-W alloy powders is no greater than 106 μm, and its melting temperature is higher than 1300℃.

[0040] The specific process of this embodiment includes the following steps:

[0041] Step 1: Use 400#, 600#, 800#, 1000#, 1200#, 1500#, and 2000# sandpaper to polish the surfaces of the nickel-based single-crystal high-temperature alloy and the polycrystalline high-temperature alloy to be joined in sequence;

[0042] Step 2: Immerse the polished parts to be connected completely in acetone and ultrasonically clean for 10 minutes. After cleaning, remove them from the acetone and place them in a vacuum drying oven to dry at a temperature of 50-80℃ for 20-40 minutes.

[0043] Step 3: Set the volume ratio of Ni-Ti alloy powder to Ni-Cr-Co-Mo-W alloy powder to 1:1, and weigh out appropriate amounts of Ni-Ti alloy powder and Ni-Cr-Co-Mo-W alloy powder, wherein the mass fraction of Ni-Cr-Co-Mo-W alloy powder in the connecting material is 60% and the mass fraction of Ni-Cr-Co-Mo-W alloy powder in the connecting material is 40%.

[0044] Step 4: Use a planetary ball mill to mix the weighed connecting material for 60-120 minutes, setting the speed to 240 r / min;

[0045] Step 5: Add organic solvent to the well-mixed connecting material and stir until it becomes a paste. Place the paste between the DD5 single crystal high-temperature alloy and the FGH96 polycrystalline high-temperature alloy base material to be connected, and fix it with a clamp.

[0046] Step 6: Place the prepared parts to be connected into the vacuum brazing furnace, and use a mechanical pump and a diffusion pump to evacuate the brazing furnace until the vacuum level reaches 5×10⁻⁶. -3 At a temperature of Pa, heating begins at a rate of 15°C / min, reaching 1150°C. After holding at this temperature for 30 minutes, the furnace is cooled down at a rate of approximately 5-10°C / min. Once the furnace temperature has dropped to room temperature, the DD5 single-crystal high-temperature alloy and the FGH96 connector are removed.

[0047] The DD5 single-crystal high-temperature alloy and FGH96 connector obtained in step 6 were cut along the axial section. The section was mechanically polished with sandpaper, followed by electropolishing and electrolytic etching. The electropolishing solution consisted of 20 vol.% concentrated sulfuric acid and 80 vol.% methanol, with parameters of 20-30V and 20s. The electrolytic etching solution consisted of 150mL phosphoric acid, 10mL concentrated sulfuric acid, and 15g CrO3, with parameters of 3-5V and 2-3s. The microstructure of the connecting layer and the substrate was observed using a scanning electron microscope. Figure 3 As shown, the bonding layer has a polycrystalline structure, resulting in a polycrystalline high-temperature alloy bonding layer with a composition and structure similar to the base material.

[0048] Example 2

[0049] This embodiment describes a material and its application method for connecting single-crystal superalloys and polycrystalline superalloys. The nickel-based single-crystal superalloy used is DD5, and the polycrystalline superalloy is FGH96. Electrical discharge machining (EDM) is employed to fabricate materials with dimensions of 10×10×2mm on both the DD5 single-crystal superalloy base material and the FGH96 polycrystalline superalloy. 3 The block to be connected.

[0050] The chemical composition of the Ni-Ti alloy powder used in this embodiment is: Ti 25.0~45.0 wt.%, the remainder being Ni, and the particle size of the Ni-Ti alloy powder is no greater than 106 μm. The chemical composition of the Ni-Cr-Co-Mo-W alloy powder is: Cr 5.0~20.0 wt.%, Co 5.0~15.0 wt.%, Mo 5.0~10.0 wt.%, W 5.0~10.0 wt.%, the remainder being Ni, and the particle size of all Ni-Cr-Co-Mo-W alloy powders is no greater than 106 μm, and its melting temperature is higher than 1300℃.

[0051] The specific process of this embodiment includes the following steps:

[0052] Step 1: Use 400#, 600#, 800#, 1000#, 1200#, 1500#, and 2000# sandpaper to polish the surfaces of the nickel-based single-crystal high-temperature alloy and the polycrystalline high-temperature alloy to be joined in sequence;

[0053] Step 2: Immerse the polished parts to be connected completely in acetone and ultrasonically clean for 10 minutes. After cleaning, remove them from the acetone and place them in a vacuum drying oven to dry at a temperature of 50-80℃ for 20-40 minutes.

[0054] Step 3: Set the volume ratio of Ni-Ti alloy powder to Ni-Cr-Co-Mo-W alloy powder to 1:1, and weigh out appropriate amounts of Ni-Ti alloy powder and Ni-Cr-Co-Mo-W alloy powder, wherein the mass fraction of Ni-Cr-Co-Mo-W alloy powder in the connecting material is 60% and the mass fraction of Ni-Cr-Co-Mo-W alloy powder in the connecting material is 40%.

[0055] Step 4: Use a planetary ball mill to mix the weighed connecting material for 60-120 minutes, setting the speed to 240 r / min;

[0056] Step 5: Add organic solvent to the well-mixed connecting material and stir until it becomes a paste. Place the paste between the DD5 single crystal high-temperature alloy and the FGH96 polycrystalline high-temperature alloy base material to be connected, and fix it with a clamp.

[0057] Step 6: Place the prepared parts to be connected into the vacuum brazing furnace, and use a mechanical pump and a diffusion pump to evacuate the brazing furnace until the vacuum level reaches 5×10⁻⁶. -3 At a temperature of Pa, heating begins at a rate of 15°C / min, reaching 1150°C. After holding at this temperature for 60 minutes, the furnace is cooled down at a rate of approximately 5-10°C / min. Once the furnace temperature has dropped to room temperature, the DD5 single-crystal high-temperature alloy and FGH96 connectors are removed.

[0058] The DD5 single-crystal high-temperature alloy and FGH96 connector obtained in step 6 were cut along the axial section. After mechanically grinding and polishing the section with sandpaper, electropolishing and electrolytic etching were performed sequentially. The electropolishing solution consisted of 20 vol.% concentrated sulfuric acid and 80 vol.% methanol, with parameters of 20-30V and 20s. The electrolytic etching solution consisted of 150mL phosphoric acid, 10mL concentrated sulfuric acid, and 15g CrO3, with parameters of 3-5V and 2-3s. The microstructure of the connector layer and the substrate was observed using a scanning electron microscope. Figure 4 As shown, the bonding layer has a polycrystalline structure, resulting in a polycrystalline high-temperature alloy bonding layer with a composition and structure similar to the base material.

[0059] Example 3

[0060] This embodiment describes a material and its application method for connecting single-crystal superalloys and polycrystalline superalloys. The nickel-based single-crystal superalloy used is DD5, and the polycrystalline superalloy is FGH96. Electrical discharge machining (EDM) is employed to fabricate materials with dimensions of 10×10×2mm on both the DD5 single-crystal superalloy base material and the FGH96 polycrystalline superalloy. 3 The block to be connected.

[0061] The chemical composition of the Ni-Ti alloy powder used in this embodiment is: Ti 25.0~45.0 wt.%, the remainder being Ni, and the particle size of the Ni-Ti alloy powder is no greater than 106 μm. The chemical composition of the Ni-Cr-Co-Mo-W alloy powder is: Cr 5.0~20.0 wt.%, Co 5.0~15.0 wt.%, Mo 5.0~10.0 wt.%, W 5.0~10.0 wt.%, the remainder being Ni, and the particle size of all Ni-Cr-Co-Mo-W alloy powders is no greater than 106 μm, and its melting temperature is higher than 1300℃.

[0062] The specific process of this embodiment includes the following steps:

[0063] Step 1: Use 400#, 600#, 800#, 1000#, 1200#, 1500#, and 2000# sandpaper to polish the surfaces of the nickel-based single-crystal high-temperature alloy and the polycrystalline high-temperature alloy to be joined in sequence;

[0064] Step 2: Immerse the polished parts to be connected completely in acetone and ultrasonically clean for 10 minutes. After cleaning, remove them from the acetone and place them in a vacuum drying oven to dry at a temperature of 50-80℃ for 20-40 minutes.

[0065] Step 3: Set the volume ratio of Ni-Ti alloy powder to Ni-Cr-Co-Mo-W alloy powder to 1:1, and weigh out appropriate amounts of Ni-Ti alloy powder and Ni-Cr-Co-Mo-W alloy powder, wherein the mass fraction of Ni-Cr-Co-Mo-W alloy powder in the connecting material is 60% and the mass fraction of Ni-Cr-Co-Mo-W alloy powder in the connecting material is 40%.

[0066] Step 4: Use a planetary ball mill to mix the weighed connecting material for 60-120 minutes, setting the speed to 240 r / min;

[0067] Step 5: Add organic solvent to the well-mixed connecting material and stir until it becomes a paste. Place the paste between the DD5 single crystal high-temperature alloy and the FGH96 polycrystalline high-temperature alloy base material to be connected, and fix it with a clamp.

[0068] Step 6: Place the prepared parts to be connected into the vacuum brazing furnace, and use a mechanical pump and a diffusion pump to evacuate the brazing furnace until the vacuum level reaches 5×10⁻⁶. -3 At a temperature of Pa, heating begins at a rate of 15°C / min, reaching 1150°C. After holding at this temperature for 120 minutes, the furnace is cooled down at a rate of approximately 5-10°C / min. Once the furnace temperature has dropped to room temperature, the DD5 single-crystal high-temperature alloy and the FGH96 connector are removed.

[0069] The DD5 single-crystal high-temperature alloy and FGH96 connector obtained in step 6 were cut along the axial section. The section was mechanically polished with sandpaper, followed by electropolishing and electrolytic etching. The electropolishing solution consisted of 20 vol.% concentrated sulfuric acid and 80 vol.% methanol, with parameters of 20-30V and 20s. The electrolytic etching solution consisted of 150mL phosphoric acid, 10mL concentrated sulfuric acid, and 15g CrO3, with parameters of 3-5V and 2-3s. The microstructure of the connecting layer and the substrate was observed using a scanning electron microscope. Figure 5 As shown, the bonding layer has a polycrystalline structure, resulting in a polycrystalline high-temperature alloy bonding layer with a composition and structure similar to the base material.

[0070] Example 4

[0071] This embodiment describes a material and its application method for connecting single-crystal superalloys and polycrystalline superalloys. The nickel-based single-crystal superalloy used is DD5, and the polycrystalline superalloy is FGH96. Electrical discharge machining (EDM) is used to fabricate materials with dimensions of 10×10×10mm on both the DD5 single-crystal superalloy base material and the FGH96 polycrystalline superalloy. 3 The block to be connected.

[0072] The chemical composition of the Ni-Ti alloy powder used in this embodiment is: Ti 25.0~45.0 wt.%, the remainder being Ni, and the particle size of the Ni-Ti alloy powder is no greater than 106 μm. The chemical composition of the Ni-Cr-Co-Mo-W alloy powder is: Cr 5.0~20.0 wt.%, Co 5.0~15.0 wt.%, Mo 5.0~10.0 wt.%, W 5.0~10.0 wt.%, the remainder being Ni, and the particle size of all Ni-Cr-Co-Mo-W alloy powders is no greater than 106 μm, and its melting temperature is higher than 1300℃.

[0073] The specific process of the embodiment includes the following steps:

[0074] Step 1: Use 400#, 600#, 800#, 1000#, 1200#, 1500#, and 2000# sandpaper to polish the surfaces of the nickel-based single-crystal high-temperature alloy and the polycrystalline high-temperature alloy to be joined in sequence;

[0075] Step 2: Immerse the polished parts to be connected completely in acetone and ultrasonically clean for 10 minutes. After cleaning, remove them from the acetone and place them in a vacuum drying oven to dry at a temperature of 50-80℃ for 20-40 minutes.

[0076] Step 3: Set the volume ratio of Ni-Ti alloy powder to Ni-Cr-Co-Mo-W alloy powder to 1:1, and weigh out appropriate amounts of Ni-Ti alloy powder and Ni-Cr-Co-Mo-W alloy powder, wherein the mass fraction of Ni-Cr-Co-Mo-W alloy powder in the connecting material is 60% and the mass fraction of Ni-Cr-Co-Mo-W alloy powder in the connecting material is 40%.

[0077] Step 4: Use a planetary ball mill to mix the weighed connecting material for 60-120 minutes, setting the speed to 240 r / min;

[0078] Step 5: Add organic solvent to the well-mixed connecting material and stir until it becomes a paste. Place the paste between the DD5 single crystal high-temperature alloy and the FGH96 polycrystalline high-temperature alloy base material to be connected, and fix it with a clamp.

[0079] Step 6: Place the prepared parts to be connected into the vacuum brazing furnace, and use a mechanical pump and a diffusion pump to evacuate the brazing furnace until the vacuum level reaches 5×10⁻⁶. -3 At a temperature of Pa, heating begins at a rate of 15℃ / min, reaching 1150℃. The temperature is then held for 30min, 60min, and 120min respectively, followed by furnace cooling at a rate of approximately 5~10℃ / min. Once the furnace temperature has dropped to room temperature, the DD5 single-crystal high-temperature alloy and FGH96 connectors are removed.

[0080] The DD5 single-crystal superalloy and FGH96 connector obtained in step 6 were processed into standard tensile test samples and subjected to tensile tests at room temperature and 650°C. The test results are as follows: Figure 6 , Figure 7 As shown, the room temperature and high temperature tensile strengths of the DD5 single-crystal superalloy and the FGH96 connector can reach 787.07 MPa and 881.47 MPa, respectively. This indicates that the method of the present invention achieves high-performance bonding between single-crystal superalloys and polycrystalline superalloys.

[0081] The bonding material proposed in this invention for single-crystal and polycrystalline superalloys is a mixture of low-melting-point Ni-Ti alloy powder or foil and high-melting-point Ni-Cr-Co-Mo-W alloy powder or foil, free of melting point degrading elements such as Si and B. The bonding layer does not contain brittle Si and B-rich compounds or eutectic structures. This method significantly improves bonding kinetics and avoids the impact of the bonding process on the microstructure of the base material. After bonding, a polycrystalline superalloy bonding layer is formed, effectively improving the mechanical properties of the bonding layer and solving the problem of rapid, high-performance bonding between single-crystal and powder superalloys. This invention can also be used for bonding single-crystal superalloys with other polycrystalline superalloys, such as wrought and cast superalloys.

[0082] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A material for connecting single-crystal superalloys and polycrystalline superalloys, characterized in that, The materials include low-melting-point Ni-Ti alloy powder and high-melting-point Ni-based alloy powder; The chemical composition of the low-melting-point Ni-Ti alloy is: Ti 25.0~45.0 wt.%, the remainder being Ni; The chemical composition of the high-melting-point Ni-based alloy powder is: Cr 5.0~20.0 wt.%, Co 5.0~15.0 wt.%, Mo 5.0~10.0 wt.%, W 5.0~10.0 wt.%, with the remainder being Ni.

2. The material according to claim 1, characterized in that, The low-melting-point Ni-Ti alloy powder has a particle size of no more than 100 μm and a melting point of no more than 1200 °C; the high-melting-point Ni-based alloy powder has a particle size of no more than 100 μm and a melting point of no less than the solution heat treatment temperature of nickel-based single-crystal high-temperature alloys.

3. The material according to claim 1, characterized in that, In the material, the volume ratio of low-melting-point Ni-Ti alloy powder to high-melting-point Ni-based alloy powder is 1~4:1; the material is spherical and / or near-spherical alloy powder with an average particle size ranging from 5 to 106 μm.

4. The material according to claim 1, characterized in that, The single-crystal superalloy is a nickel-based single-crystal superalloy prepared by directional solidification process; The polycrystalline high-temperature alloy is a powder high-temperature alloy prepared by hot isostatic pressing.

5. A method for preparing the material according to any one of claims 1 to 4, characterized in that, The method includes: the material is prepared by electrode induction melting gas atomization powder preparation method or plasma rotating electrode powder preparation method, wherein the low melting point Ni-Ti alloy powder and the high melting point Ni-based alloy powder are mixed in a planetary ball mill for 60-120 min at a rotation speed of 200-240 r / min to obtain the material.

6. A method for joining single-crystal superalloys and polycrystalline superalloys using the material described in any one of claims 1 to 4 or the material prepared by the method described in claim 5, characterized in that, The method includes: S1: Cleaning the surfaces of the single-crystal and polycrystalline high-temperature alloys to be joined: Use 400#, 600#, 800#, 1000#, 1200#, 1500#, and 2000# sandpaper sequentially to polish the surfaces of the single-crystal and polycrystalline high-temperature alloys to be joined; then, immerse them completely in acetone and ultrasonically clean for 10-20 minutes; after cleaning, remove them and place them in a vacuum drying oven to dry at a temperature of 50-80℃ for 20-40 minutes; after cleaning, the surfaces to be joined should be free of oil and oxide residue. S2: Pre-applied connecting material: Mix the connecting material with an organic solvent to form a paste, and apply it evenly to the surfaces of the single-crystal high-temperature alloy and the polycrystalline high-temperature alloy to be connected. The thickness of the applied connecting material is 0.2-0.4 mm. S3: Assembly of the parts to be connected: Place the monocrystalline high-temperature alloy and polycrystalline high-temperature alloy parts to be connected, after applying an appropriate amount of connecting material, into a special connecting fixture; S4: Connection: A vacuum brazing furnace is used for connection, and continuous pressure is applied. When the vacuum degree inside the furnace reaches 5×10 -3 Start heating at Pa, with a heating rate of 10~15℃ / min, and heat to a temperature lower than the solution heat treatment temperature of the polycrystalline high-temperature alloy. Hold at this temperature for 30~120 minutes, then furnace cool down.

7. The method according to claim 6, characterized in that, In step S2, the organic solvent is selected from terpineol and / or alcohol.

8. The method according to claim 6, characterized in that, In step S4, the temperature of the connection is 1100℃~1200℃, and the heat preservation time is 30~120min.

Images