A method for brazing titanium alloys to nickel-based superalloys using a composite interlayer
By preparing an Nb/Cu composite interlayer and using TiZrCuNi powder solder and Au-Ni solder, the problem of intermetallic compound formation during the brazing of titanium alloys and nickel-based superalloys was solved, achieving a high-strength and reliable connection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2025-06-20
- Publication Date
- 2026-08-04
AI Technical Summary
During the brazing process between titanium alloys and nickel-based superalloys, a large number of intermetallic compounds are generated, resulting in joints that are brittle, prone to fracture, and have poor impact resistance and mechanical properties.
A composite intermediate layer was prepared by thermoplastic deformation using immiscible Nb and Cu elements to block inter-element interactions and avoid the formation of intermetallic compounds. TiZrCuNi powder solder and Au-Ni solder were then used for brazing.
After holding at a brazing temperature of 960℃ for 20 minutes, the room temperature shear strength of the joint reached 272.3MPa, achieving a reliable connection between titanium alloy and nickel-based superalloy, with no intermetallic compounds in the joint.
Smart Images
Figure CN120516111B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for brazing titanium alloys and nickel-based superalloys. Background Technology
[0002] With the rapid development of the aviation industry, the design of hypersonic aircraft has placed increasingly higher demands on the performance of aero-engines. The thrust-to-weight ratio (thrust per unit weight of an aircraft) is a crucial comprehensive indicator for evaluating the engine's technical level and operational capability, directly impacting flight performance such as maximum speed, rate of climb, and lift limit. Significant advancements in aero-engine thrust-to-weight ratio often lead to the emergence of a new generation of hypersonic aircraft. Besides advanced design technologies, improving the thrust-to-weight ratio of aero-engines strongly depends on the development of advanced materials and manufacturing technologies. Structural components of engines urgently require new materials that are heat-resistant, have high specific strength, high specific modulus, are oxidation-resistant, and flame-retardant. In recent years, titanium alloys, as a lightweight structural material widely used in the aerospace field, have advantages such as low density, high specific strength, and good corrosion resistance. However, their maximum operating temperature is only around 600℃. When the operating temperature rises further, the thermal strength and thermal stability of titanium alloys become difficult to match, and their oxidation resistance decreases sharply, limiting their use in high-temperature components of aero-engines. Compared to titanium alloys, nickel-based superalloys incorporate a large number of strengthening elements, resulting in superior high-temperature strength, stiffness, oxidation resistance, and excellent fatigue resistance. They are widely used in heat-resistant components of various rocket engines, space shuttles, and other aircraft, and are now commonly used structural materials in high-temperature engine components. However, the high density of nickel-based superalloys limits the improvement of engine thrust-to-weight ratio. Achieving a reliable connection between titanium alloys and nickel-based superalloys could overcome the difficulties in forming and processing, while also leveraging the advantages of both materials, thus broadening their application range. Therefore, achieving a reliable connection between titanium alloys and nickel-based superalloys has significant engineering implications.
[0003] Currently, active brazing is the preferred method for joining ceramics and metals due to its simple operation and wide adaptability to joint size and shape. However, there are few reports on brazing titanium alloys and nickel alloys, mainly because a large number of intermetallic compounds are generated during the brazing process of dissimilar metals, resulting in brittle joints that are prone to fracture, have poor impact resistance, and poor mechanical properties. Therefore, it is necessary to study and solve the problem of intermetallic compound generation during the brazing process. Summary of the Invention
[0004] The present invention aims to solve the technical problem that the current brazing process of titanium alloys and nickel alloys produces a large number of intermetallic compounds, resulting in poor mechanical properties, and provides a method for brazing titanium alloys and nickel-based high-temperature alloys using a composite intermediate layer.
[0005] The method of brazing titanium alloy and nickel-based superalloy using a composite intermediate layer according to the present invention is carried out according to the following steps:
[0006] I. Preparation of Nb / Cu composite interlayer:
[0007] ① Polish the surfaces of both Nb and Cu sheets sequentially with 600#, 1000#, 2000#, 3000#, and 5000# grit sandpaper to remove the oxide layer until the surface is shiny;
[0008] ② Immerse both the polished Nb and Cu sheets in acetone for ultrasonic cleaning, then rinse with anhydrous ethanol and dry.
[0009] ③ The dried Nb and Cu sheets are bonded together and then placed in a thermal simulation testing machine at 600℃~1000℃ and a strain rate of 0.1s. -1 ~10s -1 Under certain conditions, high-temperature compression was performed with a compression amount of 60%~90%, followed by air cooling to room temperature to obtain the Nb / Cu composite intermediate layer;
[0010] 2. Polish the surfaces of the base titanium alloy and the base nickel-based superalloy to be welded with 200#, 400#, 600# and 800# metallographic sandpaper in sequence until the surface is bright; immerse the polished titanium alloy and nickel-based superalloy in acetone for ultrasonic cleaning, and then rinse and dry with anhydrous ethanol.
[0011] 3. The two base materials after the above treatment, TiZrCuNi powder solder, Au-Ni solder and Nb / Cu composite intermediate layer are stacked and assembled in the form of titanium alloy-TiZrCuNi-Nb / Cu composite intermediate layer-AuNi-nickel-based high temperature alloy, with Nb in the composite intermediate layer located on one side of TiZrCuNi powder solder.
[0012] 4. Place the above-mentioned brazing assembly in a vacuum brazing furnace, with the titanium alloy at the top. Place a pressure block on top of the titanium alloy to ensure close contact between the base material and the brazing filler metal during the brazing process. Then, evacuate the furnace, raise the temperature to 300℃~310℃ and hold for 10min~15min, then raise the temperature to 800℃~810℃, then raise the temperature to the connection temperature of 960℃~980℃ and hold for 5min~20min, then lower the temperature to 300℃~310℃. Finally, turn off the power and let the furnace cool to room temperature, thus completing the brazing of the titanium alloy and the nickel-based high-temperature alloy.
[0013] This invention uses immiscible Nb and Cu elements and obtains an Nb / Cu composite metal interlayer through thermoplastic deformation bonding. Nb and Cu have no solubility in the phase diagram and no intermetallic compounds are formed. The prepared composite metal interlayer is sandwiched between two brazing fillers to prevent inter-element interactions and reduce the formation of intermetallic compounds. The resulting joint has no intermetallic compounds and can achieve a room temperature shear strength of 272.3 MPa after holding at a brazing temperature of 960°C for 20 minutes. Attached Figure Description
[0014] Figure 1 This is a schematic diagram of the assembly of the sample to be welded in step three of Experiment 1;
[0015] Figure 2 To obtain the microstructure of the joint for Experiment 3;
[0016] Figure 3 The fracture morphology of the joint was obtained for Experiment 3. Detailed Implementation
[0017] Specific Implementation Method 1: This implementation method is a method for brazing titanium alloy and nickel-based high-temperature alloy using a composite intermediate layer, specifically carried out according to the following steps:
[0018] I. Preparation of Nb / Cu composite interlayer:
[0019] ① Polish the surfaces of both Nb and Cu sheets sequentially with 600#, 1000#, 2000#, 3000#, and 5000# grit sandpaper to remove the oxide layer until the surface is shiny;
[0020] ② Immerse both the polished Nb and Cu sheets in acetone for ultrasonic cleaning, then rinse with anhydrous ethanol and dry.
[0021] ③ The dried Nb and Cu sheets are bonded together and then placed in a thermal simulation testing machine at 600℃~1000℃ and a strain rate of 0.1s. -1 ~10s -1 Under certain conditions, high-temperature compression was performed with a compression amount of 60%~90%, followed by air cooling to room temperature to obtain the Nb / Cu composite intermediate layer;
[0022] 2. Polish the surfaces of the base titanium alloy and the base nickel-based superalloy to be welded with 200#, 400#, 600# and 800# metallographic sandpaper in sequence until the surface is bright; immerse the polished titanium alloy and nickel-based superalloy in acetone for ultrasonic cleaning, and then rinse and dry with anhydrous ethanol.
[0023] 3. The two base materials after the above treatment, TiZrCuNi powder solder, Au-Ni solder and Nb / Cu composite intermediate layer are stacked and assembled in the form of titanium alloy-TiZrCuNi-Nb / Cu composite intermediate layer-AuNi-nickel-based high temperature alloy, with Nb in the composite intermediate layer located on one side of TiZrCuNi powder solder.
[0024] 4. Place the above-mentioned brazing assembly in a vacuum brazing furnace, with the titanium alloy at the top. Place a pressure block on top of the titanium alloy to ensure close contact between the base material and the brazing filler metal during the brazing process. Then, evacuate the furnace, raise the temperature to 300℃~310℃ and hold for 10min~15min, then raise the temperature to 800℃~810℃, then raise the temperature to the connection temperature of 960℃~980℃ and hold for 5min~20min, then lower the temperature to 300℃~310℃. Finally, turn off the power and let the furnace cool to room temperature, thus completing the brazing of the titanium alloy and the nickel-based high-temperature alloy.
[0025] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the thickness of the Nb sheet in step one is 0.3 mm, and the thickness of the Cu sheet is 1 mm. Everything else is the same as in Specific Implementation Method One.
[0026] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that: in step 1, ②, both the polished Nb and Cu sheets are immersed in acetone and ultrasonically cleaned for 15 minutes. Everything else is the same as in Specific Implementation Method 1 or 2.
[0027] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: in step one ③, the dried Nb sheet and Cu sheet are bonded together and then placed in a thermal simulation testing machine at 800℃ and a strain rate of 5s. -1 Under certain conditions, high-temperature compression was performed with a compression amount of 70%, followed by air cooling to room temperature to obtain the Nb / Cu composite intermediate layer. Other aspects are the same as in any of the specific embodiments one to three.
[0028] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that the titanium alloy used as the base material in step two is TA15. Everything else is the same as in Specific Implementation Method Four.
[0029] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Five in that the base material nickel-based superalloy mentioned in step two is K4648. Everything else is the same as in Specific Implementation Method Five.
[0030] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that: in step two, both the polished titanium alloy and the nickel-based superalloy are immersed in acetone for ultrasonic cleaning for 15 minutes, and then rinsed and dried with anhydrous ethanol. Everything else is the same as in Specific Implementation Method Six.
[0031] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Seven in that the pressure provided by the pressing block in step four is 1×10⁻⁶. 3 Pa. Everything else is the same as in Specific Implementation Method Seven.
[0032] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that: in step four, a vacuum is drawn to 1.0 × 10⁻⁶. -3 Pa. Everything else is the same as in specific implementation method eight.
[0033] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Nine in that: in step four, the temperature is raised to 300°C and held for 10 minutes, then raised to 800°C, then raised to the connection temperature of 960°C and held for 20 minutes, then lowered to 300°C, and finally the power is turned off and the furnace is cooled to room temperature, thus completing the brazing of the titanium alloy and the nickel-based superalloy. Everything else is the same as in Specific Implementation Method Nine.
[0034] The invention was verified using the following experiments:
[0035] Experiment 1: This experiment demonstrates a method for brazing titanium alloy and nickel-based superalloy using a composite interlayer, specifically carried out according to the following steps:
[0036] I. Preparation of Nb / Cu composite interlayer:
[0037] ① The surfaces of both Nb and Cu sheets are polished sequentially with 600#, 1000#, 2000#, 3000#, and 5000# grit sandpaper to remove the oxide layer until the surface is shiny; the thickness of the Nb sheet is 0.3 mm and the thickness of the Cu sheet is 1 mm.
[0038] ② Immerse both the polished Nb and Cu sheets in acetone and ultrasonically clean for 15 minutes, then rinse with anhydrous ethanol and dry.
[0039] ③ The dried Nb and Cu sheets are bonded together and then placed in a Gleeble 1500 thermal simulation test chamber at 800°C and a strain rate of 5 s. -1 Under certain conditions, high-temperature compression was performed with a compression amount of 70%, followed by air cooling to room temperature to obtain the Nb / Cu composite intermediate layer;
[0040] 2. Polish the surfaces to be welded of the base titanium alloy TA15 and the base nickel-based superalloy K4648 with 200#, 400#, 600# and 800# metallographic sandpaper until they are bright. After polishing, immerse the titanium alloy and nickel-based superalloy in acetone for ultrasonic cleaning for 15 minutes, then rinse and dry with anhydrous ethanol.
[0041] 3. The two pre-treated base materials, TiZrCuNi powder solder, Au-Ni solder, and Nb / Cu composite interlayer are stacked and assembled in the form of TA15-TiZrCuNi-Nb / Cu composite interlayer-AuNi-K4648 (e.g., Figure 1 As shown), the Nb in the composite intermediate layer is located on one side of the TiZrCuNi powder solder;
[0042] 4. Place the above-mentioned brazing assembly in a vacuum brazing furnace, with the titanium alloy at the top. Place a pressure block above the titanium alloy to ensure close contact between the base material and the brazing filler metal during the brazing process. The pressure provided by the pressure block is 1×10⁻⁶. 3 Pa, then evacuated to 1.0 × 10 Pa. -3 Pa, then heat to 300℃ at a heating rate of 10℃ / min and hold for 10min, then heat to 800℃ at a heating rate of 10℃ / min, then heat to the connection temperature of 960℃ at a heating rate of 5℃ / min and hold for 5min, then cool to 300℃ at a cooling rate of 5℃ / min, and finally turn off the power and let the furnace cool to room temperature, thus completing the brazing of titanium alloy and nickel-based superalloy.
[0043] Experiment 2: This experiment differs from Experiment 1 in that, in step four, the temperature is increased to the connection temperature of 960℃ at a rate of 5℃ / min and held for 10 minutes. Everything else is the same as Experiment 1.
[0044] Experiment 3: This experiment differs from Experiment 1 in that in step four, the temperature is increased to the connection temperature of 960℃ at a rate of 5℃ / min and held for 20 minutes. Everything else is the same as Experiment 1.
[0045] The mechanical properties of the joint were evaluated using tensile shear strength. The joint strengths obtained under different brazing temperatures, brazing filler metal compositions and holding times are shown in Table 1 below. When the joint was held at a brazing temperature of 960℃ for 20 minutes (Experiment 3), the room temperature shear strength reached 272.3 MPa.
[0046] Table 1. Room temperature shear strength of the joint
[0047]
[0048] Figure 2To obtain the microstructure of the joint for Experiment 3, Figure (a) shows the overall morphology of the joint, Figure (b) shows the weld morphology on the TA15 side, and Figure (c) shows the weld morphology on the K4648 side. As shown in Figure (a), the joint is dense and free of defects such as pores or cracks. In Figure (b), it can be observed that the weld on the TA15 side is mainly composed of black needle-like phase A and dark gray phase B. From Figure (c), it can be found that the weld on the K4648 side is mainly composed of a eutectic structure formed by gray phase C, black phase D, and white phase E, as well as dark gray phase F.
[0049] right Figure 2 EDS analysis was performed at each point in (b) and (c), and the results are shown in Table 2. Figure 2 In (b), the black phase A has a higher content of Ti and Al elements, suggesting it is an α-Ti phase. Compared to phase A, the dark gray phase B has a higher content of Zr and Nb elements. Since both Zr and Nb are β-Ti stable elements, it is speculated that this phase is a β-Ti phase. Through the analysis of… Figure 2 Analysis of the elemental composition at each point in (c) confirms that phase C is a (Au,Cu,Ni) solid solution phase, the black phase D in the eutectic structure is a Ni-rich solid solution phase, and the white phase E is an Au-rich solid solution phase. The interface layer F near the K4648 side can be identified as a (Ni,Cr) solid solution phase, containing small amounts of Au and Cu elements. Therefore, the entire joint structure can be determined as TA15 / α-Ti / β-Ti / Nb-Cu / (Au,Cu,Ni) solid solution / (Ni,Cr) solid solution / K4648, with no intermetallic compounds formed within the joint.
[0050] Table 2 Figure 2 Energy dispersive spectral analysis results at various points (at.%)
[0051]
[0052] Figure 3 To obtain the fracture morphology of the joint in Experiment 3, the results show that the Nb / Cu composite metal interlayer of the present invention was successfully used to join TA15 titanium alloy and K4648 nickel-based superalloy.
Claims
1. A method for brazing titanium alloy and nickel-based superalloy using a composite interlayer, characterized in that... The method for brazing titanium alloys and nickel-based superalloys using a composite interlayer is carried out according to the following steps: I. Preparation of Nb / Cu composite intermediate layer: ① Polish the surfaces of both Nb and Cu sheets sequentially with 600#, 1000#, 2000#, 3000#, and 5000# grit sandpaper to remove the oxide layer until the surface is shiny; The thickness of the Nb sheet is 0.3 mm, and the thickness of the Cu sheet is 1 mm. ② Immerse both the polished Nb and Cu sheets in acetone for ultrasonic cleaning, then rinse with anhydrous ethanol and dry. ③ The dried Nb and Cu sheets are bonded together and then placed in a thermal simulation testing machine at 600℃~1000℃ and a strain rate of 0.1s. -1 ~10s -1 Under certain conditions, high-temperature compression was performed with a compression amount of 60%~90%, followed by air cooling to room temperature to obtain the Nb / Cu composite intermediate layer; 2. Polish the surfaces of the base titanium alloy and the base nickel-based superalloy to be welded with 200#, 400#, 600# and 800# metallographic sandpaper in sequence until the surface is bright; immerse the polished titanium alloy and nickel-based superalloy in acetone for ultrasonic cleaning, and then rinse and dry with anhydrous ethanol. The base material titanium alloy is TA15; the base material nickel-based high-temperature alloy is K4648; 3. The above-treated titanium alloy, nickel-based superalloy, TiZrCuNi powder solder, Au-Ni solder and Nb / Cu composite intermediate layer are stacked and assembled in the form of titanium alloy-TiZrCuNi-Nb / Cu composite intermediate layer-AuNi-nickel-based superalloy, with Nb in the composite intermediate layer located on the TiZrCuNi powder solder side.
4. Place the above-mentioned stacked assembly in a vacuum brazing furnace, with the titanium alloy at the top. Place a pressure block on top of the titanium alloy to ensure close contact between the base material and the brazing filler metal during the brazing process. Then, evacuate the furnace, raise the temperature to 300℃~310℃ and hold for 10min~15min, then raise the temperature to 800℃~810℃, then raise the temperature to the connection temperature of 960℃~980℃ and hold for 5min~20min, then lower the temperature to 300℃~310℃. Finally, turn off the power and let the furnace cool to room temperature, thus completing the brazing of the titanium alloy and the nickel-based high-temperature alloy.
2. The method for brazing titanium alloy and nickel-based superalloy using a composite interlayer according to claim 1, characterized in that... In step 1②, both the polished Nb and Cu sheets are immersed in acetone and ultrasonically cleaned for 15 minutes.
3. The method for brazing titanium alloy and nickel-based superalloy using a composite interlayer according to claim 1, characterized in that... In step 1, section 3, the dried Nb and Cu sheets are bonded together and then placed in a thermal simulation testing machine at 800°C and a strain rate of 5 s. -1 Under certain conditions, high-temperature compression was performed with a compression amount of 70%, followed by air cooling to room temperature to obtain the Nb / Cu composite intermediate layer.
4. The method for brazing titanium alloy and nickel-based superalloy using a composite interlayer according to claim 1, characterized in that... In step two, both the polished titanium alloy and the nickel-based superalloy are immersed in acetone for ultrasonic cleaning for 15 minutes, and then rinsed and dried with anhydrous ethanol.
5. The method for brazing titanium alloy and nickel-based superalloy using a composite interlayer according to claim 1, characterized in that... The pressure provided by the pressure block in step four is 1×10. 3 Pa.
6. The method for brazing titanium alloy and nickel-based superalloy using a composite interlayer according to claim 1, characterized in that... In step four, a vacuum is drawn to 1.0 × 10⁻⁶. -3 Pa.
7. The method for brazing titanium alloy and nickel-based superalloy using a composite interlayer according to claim 1, characterized in that... In step four, the temperature is raised to 300℃ and held for 10 minutes, then raised to 800℃, then raised to the connection temperature of 960℃ and held for 20 minutes, then lowered to 300℃, and finally the power is turned off and the furnace is cooled to room temperature, thus completing the brazing of the titanium alloy and the nickel-based high-temperature alloy.