Vacuum diffusion bonding method for nickel-based superalloy and MoNbTaW series refractory alloy

Abstract

The invention discloses a vacuum diffusion bonding method for a nickel-based superalloy and MoNbTaW series refractory alloy, and aims to solve the problem that the quality of a welding joint is affected due to the fact that the welding joint of the nickel-based superalloy and the MoNbTaW series refractory alloy can generate a Cr-rich brittle phase. The vacuum diffusion method comprises the following steps: 1, polishing the nickel-based high-temperature alloy and the MoNbTaW series refractory alloy; secondly, nickel sulfate, nickel chloride, nickel borate, sulfuric acid, lauryl sodium sulfate and water are mixed, an electroplating solution is obtained, the nickel-based superalloy is electroplated, an electroplated nickel grain layer is obtained, and the MoNbTaW series refractory alloy and the nickel-based superalloy are jointed; thirdly, the to-be-welded part is placed in a vacuum diffusion furnace; and 4, performing vacuum diffusion bonding. According to the method, the electronickelling grain layer is used, connection is conducted at the relatively low temperature and the relatively low pressure, only interdiffusion of the electronickelling grain layer and refractory alloy in a small range exists on a connector interface, a Cr-rich brittle phase is not generated, and cracks are prevented from being generated in the connector.

Description

Technical Field

[0001] The invention belongs to the field of metal connection, and in particular relates to a method for vacuum diffusion connection of a nickel-based high-temperature alloy and a MoNbTaW series refractory alloy. Background Art

[0002] Nickel-based superalloys have high thermal strength due to the comprehensive strengthening of elements such as Cr, Co, W, and Ti. They can be used for a long time at temperatures below 900°C and are often used to manufacture hot end parts of aerospace engines and gas turbines, such as combustion chambers, turbine blades, and other parts. MoNbTaW-based refractory alloys have the characteristics of high melting point, high strength, and corrosion resistance, and are suitable for engineering applications in high temperature and corrosive environments. Therefore, achieving high-quality connection between nickel-based superalloys and MoNbTaW-based refractory alloys is of great significance to the development of aviation, aerospace, and energy industries.

[0003] Previously, Meng Xianlin and others from Northwestern Polytechnical University used Cu, Ni, and Cu / Ni / Cu foils as intermediate layers (Meng Xianlin, Hu Rui, Tang Bin, et al. Effect of intermediate layer on interface structure of Ni-Cr-W high temperature alloy diffusion bonding [J]. Materials Science and Technology, 2013, 21(3):41-48.), and welded nickel-based alloy (Ni-Cr-W alloy) using vacuum diffusion bonding technology at 950°C, 30MPa, and 45min. The effects of different intermediate layers on the vacuum diffusion bonding effect of the nickel-based alloy were compared and analyzed. When metal Ni foil was used as the intermediate layer, the diffusion interface was well connected and no obvious reaction layer existed. Suzumura et al. conducted diffusion welding of A286 nickel-based alloy (SUZUMURAA, ONZAWA T, TAMURA H. Solid-state diffusion weldability of high temperature alloy A286 and hastelloy X [J]. Transactions of the Japan Welding Society, 1983, 14: 26-32.), and found that when no intermediate layer was added, the brittle phase at the interface affected the mechanical properties of the joint. When pure metal Ni foil was used as the intermediate layer, the Ti-containing intermediate phase disappeared, which improved the mechanical properties of the diffusion welding joint. Pouranvari M et al. used transient liquid phase bonding technology to study the effect of welding temperature on the microstructure of the GTD-111 alloy / Ni-Si-B intermediate layer (Pouranvari M, Ekrami A, Kokabi AH. Effect of bonding temperature on microstructure development during TLP bonding of anickel base superalloy [J]. Journal of Alloys and Compounds. 2009; 469 (1-2), 270-275.). At low welding temperatures (1000℃ and 1050℃), the microstructure of the non-uniform solidification zone is controlled by B diffusion, and a large amount of chromium-rich carbon borides can be observed in the diffusion-affected zone. At high welding temperatures (1080℃), the dissolution and diffusion of alloying elements Ti and Cr have a more obvious effect on the microstructure of the joint.

[0004] In summary, there are few publicly reported methods for connecting nickel-based high-temperature alloys with MoNbTaW-based refractory alloys, and there are also some problems. In particular, brittle intermetallic compounds are prone to appear in the diffusion zone, which seriously limits the mechanical properties of the joint. After welding, brittle fracture is the main cause, and a strong joint cannot be obtained. When connecting, it is necessary to comprehensively consider factors such as welding process parameters, intermediate layer composition and thickness, and post-weld heat treatment. The current research on diffusion connection between MoNbTaW-based refractory alloys and nickel-based high-temperature alloys is very imperfect. Therefore, it is urgent to develop a new connection method that can achieve high-quality connection between nickel-based high-temperature alloys and MoNbTaW-based refractory alloys, and have high enough strength to meet service requirements. Summary of the invention

[0005] The present invention provides a method for vacuum diffusion joining of a nickel-based high-temperature alloy and a MoNbTaW series refractory alloy in order to solve the problems that in the existing method for joining a nickel-based high-temperature alloy and a MoNbTaW series refractory alloy, a Cr-rich brittle phase will be generated in the welded joint, resulting in extremely low strength of the obtained welded joint, and even prone to brittle fracture after welding, resulting in poor joint quality, and the like.

[0006] The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy of the present invention is implemented by the following steps:

[0007] 1. The surfaces of the nickel-based high-temperature alloy and the MoNbTaW series refractory alloy to be welded are polished and ultrasonically cleaned to obtain the cleaned nickel-based high-temperature alloy and the MoNbTaW series refractory alloy;

[0008] 2. Mix nickel sulfate, nickel chloride, boric acid, sulfuric acid, sodium dodecyl sulfate and distilled water to obtain an electroplating solution, use an electrolytic Ni block as an anode and a cleaned nickel-based high-temperature alloy as a cathode for electroplating to obtain a nickel-based high-temperature alloy with an electroplated nickel grain layer attached to the welded surface, join the MoNbTaW series refractory alloy and the nickel-based high-temperature alloy with the electroplated nickel grain layer attached, apply clamping pressure, and obtain an assembly to be welded;

[0009] 3. Place the assembly to be welded in a high-temperature vacuum diffusion furnace and evacuate to the working vacuum degree;

[0010] 4. Heating, applying working pressure, controlling the connection temperature to 900-1300°C for diffusion welding, cooling to room temperature, and completing vacuum diffusion bonding of the nickel-based high-temperature alloy and the MoNbTaW-based refractory alloy;

[0011] The electroplating solution in step 2 has a nickel sulfate concentration of 100-300 g / L, a sulfuric acid concentration of 20-50 g / L, a boric acid concentration of 10-50 g / L, a nickel chloride concentration of 10-50 g / L, and a sodium dodecyl sulfate concentration of 0.05-0.15 g / L.

[0012] The present invention proposes a method for connecting a nickel-based high-temperature alloy and a MoNbTaW series refractory alloy. The method uses an electroplated nickel grain layer to perform connection at a relatively low temperature and a relatively small pressure. During the high-temperature connection diffusion process, the electroplated nickel grain layer effectively separates the nickel-based high-temperature alloy from the MoNbTaW series refractory alloy. Only a small range of mutual diffusion between the electroplated nickel grain layer and the MoNbTaW series refractory alloy exists at the joint interface, and no Cr-rich brittle phase is generated, thereby avoiding the generation of cracks inside the joint.

[0013] Compared with the existing nickel-based high-temperature alloy and MoNbTaW series refractory alloy connection technology, the vacuum diffusion welding method of the nickel-based high-temperature alloy and MoNbTaW series refractory alloy of the present invention has high joint strength. Since the formation of Cr-rich brittle phase is avoided in the joint, the joint strength is significantly improved. The use of electroplated nickel grain layer can make the welding temperature relatively low, which can minimize the damage caused by high temperature to the performance of the alloy base material.

[0014] The vacuum diffusion bonding method of the present invention is simple and easy to operate, enriches the types of bonding technologies for nickel-based high-temperature alloys and MoNbTaW-based refractory alloys, and has broad application prospects and great practical value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a low-magnification backscattered electron photograph of the interface structure of the GH4099 alloy / MoNbTaW refractory alloy joint obtained under the conditions of 1050°C / 20min / 20MPa using a 20μm electroplated nickel grain layer in Example 1;

[0016] Figure 2 This is a high-magnification backscattered electron photograph of the interface structure of the GH4099 alloy / MoNbTaW refractory alloy joint obtained under the conditions of 1050°C / 20min / 20MPa using a 20μm electroplated nickel grain layer in Example 1;

[0017] Figure 3 The backscattered electron photo and energy spectrum scanning photo of the GH4099 alloy / MoNbTaW refractory alloy joint obtained at 1050°C / 20min / 20MPa using a 20μm electroplated nickel grain layer in Example 1. DETAILED DESCRIPTION

[0018] Specific implementation method 1: The vacuum diffusion bonding method of the nickel-based high-temperature alloy and the MoNbTaW-based refractory alloy in this implementation method is implemented according to the following steps:

[0019] 1. The surfaces of the nickel-based high-temperature alloy and the MoNbTaW series refractory alloy to be welded are polished and ultrasonically cleaned to obtain the cleaned nickel-based high-temperature alloy and the MoNbTaW series refractory alloy;

[0020] 2. Mix nickel sulfate, nickel chloride, boric acid, sulfuric acid, sodium dodecyl sulfate and distilled water to obtain an electroplating solution, use an electrolytic Ni block as an anode and a cleaned nickel-based high-temperature alloy as a cathode for electroplating to obtain a nickel-based high-temperature alloy with an electroplated nickel grain layer attached to the welded surface, join the MoNbTaW series refractory alloy and the nickel-based high-temperature alloy with the electroplated nickel grain layer attached, apply clamping pressure, and obtain an assembly to be welded;

[0021] 3. Place the assembly to be welded in a high-temperature vacuum diffusion furnace and evacuate to the working vacuum degree;

[0022] 4. Heating, applying working pressure, controlling the connection temperature to 900-1300°C for diffusion welding, cooling to room temperature, and completing vacuum diffusion bonding of the nickel-based high-temperature alloy and the MoNbTaW-based refractory alloy;

[0023] The electroplating solution in step 2 has a nickel sulfate concentration of 100-300 g / L, a sulfuric acid concentration of 20-50 g / L, a boric acid concentration of 10-50 g / L, a nickel chloride concentration of 10-50 g / L, and a sodium dodecyl sulfate concentration of 0.05-0.15 g / L.

[0024] This embodiment adopts the method of vacuum diffusion of electroplated nickel grain layer to connect nickel-based high-temperature alloy and MoNbTaW series refractory alloy. It is not affected by the shape and size of the parent material and has a wide range of applications. While reducing the connection temperature, it can avoid the formation of Cr-rich brittle phase in the joint.

[0025] Specific implementation method 2: The difference between this implementation method and specific implementation method 1 is that the nickel-based high-temperature alloy described in step 1 is GH nickel-based high-temperature alloy containing Cr element, K nickel-based casting high-temperature alloy, powder metallurgy nickel-based high-temperature alloy, Inconel alloy or Monel alloy.

[0026] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that the MoNbTaW-based refractory alloy in step one also contains one or more elements of Hf, Ti, and Si.

[0027] Specific implementation method four: The difference between this implementation method and specific implementation methods one to three is that in step one, 400#, 800#, 1200#, 1500#, 2000# and 3000# silicon carbide water-abrasive paper is used in sequence to grind the surfaces of the nickel-based high-temperature alloy and MoNbTaW refractory alloy to be welded.

[0028] Specific embodiment 5: This embodiment is different from specific embodiments 1 to 4 in that in step 2, the plating solution temperature is 45°C to 65°C, the magnetic stirring speed is 250r / min to 380r / min, and the current density of the direct current is 2A / dm 2 ~5A / dm 2 The electroplating treatment is carried out under the conditions of , and the electroplating treatment time is 20min to 90min.

[0029] Specific implementation method 6: The difference between this implementation method and any one of specific implementation methods 1 to 5 is that the thickness of the electroplated nickel grain layer in step 2 is 5 to 200 μm.

[0030] Specific implementation method 7: This implementation method is different from the specific implementation methods 1 to 6 in that the working vacuum degree in step 3 is better than 5×10 -3 Pa.

[0031] Specific implementation eight: This implementation is different from any one of specific implementations one to seven in that the heating rate in step four is controlled to be 5° C. / min to 25° C. / min.

[0032] Specific embodiment 9: This embodiment is different from specific embodiments 1 to 8 in that in step 4, diffusion welding is performed at a connection temperature of 900 to 1300° C. and the temperature is kept for 30 to 120 minutes.

[0033] Specific embodiment ten: This embodiment is different from any one of specific embodiments one to nine in that the cooling rate in step four is 2° C. / min to 10° C. / min.

[0034] Embodiment 1: The vacuum diffusion bonding method of the nickel-based high-temperature alloy and the MoNbTaW-based refractory alloy in this embodiment is implemented according to the following steps:

[0035] 1. Mechanically grinding and polishing the surfaces of the GH4099 alloy and the MoNbTaW refractory alloy (12Mo-25Nb-32Ta-31W wt.%) to be welded, respectively. The mechanical grinding is performed by using 400#, 800#, 1500#, 2000# and 3000# SiC water-abrasive sandpaper in sequence. The welded parts after grinding are ultrasonically cleaned in anhydrous ethanol for 5 minutes to obtain the cleaned nickel-based high-temperature alloy and MoNbTaW refractory alloy.

[0036] 2. Mix nickel sulfate, nickel chloride, boric acid, sulfuric acid, sodium dodecyl sulfate and distilled water to obtain an electroplating solution. Use the electrolytic Ni block as the anode and the cleaned nickel-based high-temperature alloy as the cathode. When the electroplating solution temperature is 55°C, the magnetic stirring speed is 300r / min and the DC current density is 3A / dm 2Electroplating treatment is performed under the conditions of , to obtain a nickel-based high-temperature alloy with an electroplated nickel grain layer attached to the surface to be welded, the MoNbTaW series refractory alloy and the nickel-based high-temperature alloy with an electroplated nickel grain layer with a thickness of 20 μm are joined, and clamping pressure is applied to obtain an assembly to be welded;

[0037] 3. Place the assembly to be welded in a high-temperature vacuum diffusion furnace and evacuate to the working vacuum degree, which should be better than 5×10 -3 MPa;

[0038] Fourth, control the heating rate to 10℃ / min, apply a working pressure of 20MPa, control the connection temperature to 1050℃, keep it warm for 20min for diffusion welding, control the cooling rate to 5℃ / min, cool it down to room temperature, and complete the vacuum diffusion connection between the nickel-based high-temperature alloy and the MoNbTaW series refractory alloy;

[0039] The nickel sulfate concentration in the electroplating solution described in step 2 is 180 g / L, the concentration of 98% concentrated sulfuric acid is 40 g / L, the concentration of boric acid is 15 g / L, the concentration of nickel chloride is 50 g / L, and the concentration of sodium dodecyl sulfate is 0.1 g / L.

[0040] In this example, the low-magnification and high-magnification backscattered electron photographs of the interface structure of the GH4099 alloy / MoNbTaW refractory alloy joint obtained using a 50 μm electroplated nickel grain layer at 1050°C / 20 min / 20 MPa are shown in Figure 2. Figure 1 and Figure 2 shown.

[0041] The electroplated nickel grain layer added inside the joint during welding blocks the diffusion of Cr in the GH4099 alloy, reduces the damage to the parent material properties caused by high temperature environment, and reduces the diffusion degree of Cr. Figure 3 It can be seen that the electroplated nickel grain layer effectively separates the nickel-based high-temperature alloy from the MoNbTaW refractory alloy. It is found that there is only a small range of mutual diffusion between the electroplated nickel grain layer and the MoNbTaW refractory alloy at the joint interface, and no Cr-rich brittle phase is generated, which avoids the generation of cracks inside the joint and better guarantees the mechanical properties of the welded joint.

Claims

1. A method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy, characterized in that The vacuum diffusion connection method is implemented according to the following steps:

1. The surfaces of the nickel-based high-temperature alloy and the MoNbTaW series refractory alloy to be welded are polished and ultrasonically cleaned to obtain the cleaned nickel-based high-temperature alloy and the MoNbTaW series refractory alloy; 2. Mix nickel sulfate, nickel chloride, boric acid, sulfuric acid, sodium dodecyl sulfate and distilled water to obtain an electroplating solution, use an electrolytic Ni block as an anode and a cleaned nickel-based high-temperature alloy as a cathode for electroplating to obtain a nickel-based high-temperature alloy with an electroplated nickel grain layer attached to the welded surface, join the MoNbTaW series refractory alloy and the nickel-based high-temperature alloy with the electroplated nickel grain layer attached, apply clamping pressure, and obtain an assembly to be welded; 3. Place the assembly to be welded in a high-temperature vacuum diffusion furnace and evacuate to the working vacuum degree; 4. Heating, applying working pressure, controlling the connection temperature to 900-1300°C for diffusion welding, cooling to room temperature, and completing vacuum diffusion bonding of the nickel-based high-temperature alloy and the MoNbTaW-based refractory alloy; The electroplating solution in step 2 has a nickel sulfate concentration of 100-300 g / L, a sulfuric acid concentration of 20-50 g / L, a boric acid concentration of 10-50 g / L, a nickel chloride concentration of 10-50 g / L, and a sodium dodecyl sulfate concentration of 0.05-0.15 g / L.

2. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that The nickel-based high-temperature alloy described in step 1 is a GH nickel-based high-temperature alloy containing Cr, a K nickel-based casting high-temperature alloy, a powder metallurgy nickel-based high-temperature alloy, an Inconel alloy or a Monel alloy.

3. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that In step 1, the MoNbTaW-based refractory alloy further contains one or more elements of Hf, Ti, and Si.

4. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that In step 1, 400#, 800#, 1200#, 1500#, 2000# and 3000# silicon carbide water-abrasive paper are used in sequence to grind the surfaces of the nickel-based high-temperature alloy and MoNbTaW-based refractory alloy to be welded.

5. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that In step 2, the plating solution temperature is 45°C to 65°C, the magnetic stirring speed is 250r / min to 380r / min, and the DC current density is 2A / dm 2 ~5A / dm 2 The electroplating treatment is carried out under the conditions of , and the electroplating treatment time is 20min to 90min.

6. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that The thickness of the electroplated nickel grain layer in step 2 is 5 to 200 μm.

7. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that The working vacuum degree in step 3 is better than 5×10 -3 Pa.

8. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that In step 4, the heating rate is controlled to be 5°C / min to 25°C / min.

9. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that In step 4, diffusion welding is performed at a connection temperature of 900 to 1300° C. for 30 to 120 minutes.

10. The method for vacuum diffusion bonding of a nickel-based high-temperature alloy and a MoNbTaW-based refractory alloy according to claim 1, characterized in that The cooling rate in step 4 is 2°C / min to 10°C / min.

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