Reliable Ti65 high-temperature titanium alloy low-temperature diffusion bonding method

Abstract

The invention discloses a reliable Ti65 high-temperature titanium alloy low-temperature diffusion bonding method, and belongs to the technical field of titanium alloy diffusion bonding. The method aims at solving the problem that the temperature needed by diffusion bonding of the Ti65 high-temperature titanium alloy is too high. The method comprises the following steps: 1, pretreating a titanium alloy plate; 2, hydrotreating the titanium alloy plate; 3, depositing a coating; 4, diffusion bonding; and 5, dehydrogenation treatment. According to the method focused on thermal hydrogen treatment, the hydrogen escape phenomenon in the diffusion bonding process is inhibited through magnetron sputtering, and the diffusion bonding temperature of the titanium alloy is reduced through hydrogen-induced plasticity, hydrogen reduction of the phase change temperature of the titanium alloy and hydrogen-promoted phase change. According to the method provided by the invention, the diffusion bonding temperature can be reduced by utilizing hydrogen to the greatest extent in the diffusion bonding process, and a dehydrogenation technology is used after the bonding is finished, so that the structure is reduced, the influences of hydrogen embrittlement and the like caused by hydride in the titanium alloy are avoided, and the diffusion bonding temperature is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of titanium alloy diffusion bonding technology, specifically relating to a technical method for reducing the diffusion bonding temperature of near-α type titanium alloy Ti65 through thermal hydrogen treatment. Background Technology

[0002] Titanium and its alloys possess excellent corrosion resistance and mechanical properties, making them highly promising for applications in structural components. Ti65 titanium alloy, a near-alpha type titanium alloy, combines high-temperature strength, low density, and good creep resistance, allowing it to operate for extended periods at approximately 650°C. It is a candidate material for high-temperature components such as integral bladed disks (Blisks) for engines. Currently, integral bladed disks typically employ welding or diffusion bonding methods to connect the disk and blades. These joints require not only high strength but also excellent thermal stability and operational reliability.

[0003] Diffusion bonding (DB) has proven effective in producing high-quality joints in joining similar or dissimilar titanium alloys, holding significant value in high-precision applications. However, for near-α titanium alloys like Ti65, which have high β-transformation temperatures, extremely low β-phase content, small α-phase diffusion coefficients, and poor high-temperature creep properties, obtaining reliable diffusion-bonded joints typically requires higher processing temperatures. This can easily lead to severe grain growth and microstructure coarsening, resulting in degradation of both the joint and the base material properties. Existing research has shown that prolonged DB at higher temperatures can nearly double the grain size, significantly weakening the overall joint performance. Therefore, there is an urgent need to develop low-temperature diffusion bonding technologies suitable for Ti65.

[0004] Studies have shown that hydrogen promotes α→β H Phase transformation can significantly increase the β-phase content and plasticity at high temperatures, facilitate pore closure during diffusion bonding, and significantly improve atomic diffusion rate by altering the formation and migration energies of lattice defects. However, for near-α titanium alloys, hydrogen-induced phase transformations are mostly confined to the vicinity of grain boundaries, occurring only within a very small volume fraction range, and the interface remains continuous with β phases. H The phase is difficult to form, thus its promoting effect on diffusion bonding is limited. Achieving β at the diffusion bonding interface... H The enrichment and continuous distribution of the phase requires a sufficiently high hydrogen concentration in the interfacial region.

[0005] Therefore, how can we achieve continuous β-coated titanium alloys at the diffusion bonding interface through methods such as thermal hydrogen treatment while maintaining the overall microstructure stability of the near-α titanium alloy? H Phase enrichment, clarifying the mechanism by which hydrogen-induced phase transformation and lattice defect evolution promote low-temperature diffusion bonding behavior, and thus achieving low-temperature high-strength diffusion bonding of near-α titanium alloys such as Ti65, remains an important technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to solve the problem of excessively high temperatures required for diffusion bonding of Ti65 high-temperature titanium alloys, and to provide a reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloys.

[0007] This invention focuses on a method for thermal hydrogen treatment. It suppresses hydrogen escape during the diffusion bonding process through magnetron sputtering and utilizes hydrogen plasticity, hydrogen-induced phase transformation temperature reduction, and hydrogen-driven phase transformation to lower the diffusion bonding temperature of titanium alloys. The method provided by this invention maximizes the use of hydrogen to reduce the diffusion bonding temperature during the diffusion bonding process and employs dehydrogenation technology after bonding to reduce the microstructure, avoiding hydrogen embrittlement caused by hydrides in the titanium alloy, thus significantly reducing the diffusion bonding temperature.

[0008] A reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy is specifically carried out according to the following steps:

[0009] I. Pretreatment of titanium alloy plates:

[0010] The titanium alloy plate is cut, polished, cleaned and dried according to the size requirements to obtain the pre-treated titanium alloy plate.

[0011] II. Hydrogenation treatment of titanium alloy plates:

[0012] The pretreated titanium alloy plate is placed in a vacuum furnace and hydrogenated in a hydrogen atmosphere. The temperature, hydrogen pressure and hydrogenation time are controlled to obtain a hydrogenated titanium alloy plate with a certain hydrogen content.

[0013] III. Coating Deposition:

[0014] A thin aluminum-titanium film was deposited on the surface of a titanium alloy plate by magnetron sputtering to prevent hydrogen escape caused by heating during subsequent diffusion bonding, thus obtaining a titanium alloy plate with a thin aluminum-titanium film deposited on the surface.

[0015] IV. Diffusion Connection:

[0016] Two titanium alloy plates with aluminum-titanium thin films deposited on their surfaces are diffused together at a predetermined temperature to obtain a diffused-bonded titanium alloy plate.

[0017] V. Dehydrogenation treatment:

[0018] The aluminum-titanium thin film on the surface of the diffusion-bonded titanium alloy plate is polished off, and then heat-treated under vacuum to remove hydrogen to a safe hydrogen content, thus obtaining a high-performance Ti65 high-temperature titanium alloy component.

[0019] The present invention has the following beneficial effects:

[0020] This invention proposes a low-temperature diffusion bonding technology for Ti65 high-temperature titanium alloys based on thermal hydrogen-induced phase transformation and synergistic magnetron sputtering hydrogen barrier. A composite method of "thermal hydrogen pretreatment + vacuum confinement + precise pressure" is employed to achieve close atomic contact at the Ti65 titanium alloy interface and rapid diffusion at a low temperature of 750℃. The thermal hydrogen treatment induces an α→β phase transformation in the Ti65 alloy, reducing the atomic diffusion activation energy. Furthermore, the magnetron sputtered Al-Ti film provides both hydrogen escape barrier and oxidation protection. The vacuum environment eliminates interfacial contamination, resulting in a porous, high-bonding diffusion bond joint. This invention also offers the following advantages:

[0021] (1) The present invention utilizes a vacuum hot pressing sintering furnace to achieve full vacuum protection during the connection process, effectively solving the problem of easy oxidation of Ti65 titanium alloy at high temperature and easy formation of brittle oxide layer at the interface; at the same time, it greatly reduces the diffusion connection temperature, which greatly reduces the consumption of raw materials and production costs.

[0022] (2) Based on the low temperature and high pressure diffusion bonding process, the axial pressure of 25MPa when bonding Ti65 titanium alloy interfaces makes the gap between the contact interfaces approach zero; while achieving low temperature bonding, it avoids the coarsening of matrix grains caused by high temperature, and refines the structure through hydrogen-induced phase transformation, thereby improving the comprehensive mechanical properties of Ti65 titanium alloy components to a certain extent.

[0023] (3) This invention can symmetrically combine multiple groups of Ti65 samples for simultaneous diffusion bonding, and achieve batch joint preparation in a single vacuum heating and pressurization process. At the same time, the equipment (vacuum furnace, magnetron sputtering instrument) used in the core preparation method based on thermal hydrogen treatment and magnetron sputtering are all conventional equipment in the field of material processing, and no special customized device is required. The chemical reagents used are only environmentally friendly cleaning agents such as anhydrous ethanol, which solves the problems of large investment, complex process and low production efficiency of existing Ti65 titanium alloy high temperature bonding technology. It has the advantages of strong process controllability, convenient operation and good adaptability to batch production. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the hot hydrogen treatment of Ti65 high-temperature titanium alloy in Example 1;

[0025] Figure 2 This is a schematic diagram of magnetron sputtering of titanium alloy after thermal hydrogen treatment in Example 1;

[0026] Figure 3 This is a schematic diagram of diffusion connection in Example 1;

[0027] Figure 4The images show the microstructures of the original Ti65 high-temperature titanium alloy and the Ti65 high-temperature titanium alloy after hydrogen treatment. (a) is the microstructure of the original Ti65 high-temperature titanium alloy, (b) is the microstructure of the hydride titanium alloy plate with a hydrogen content of 0.3 wt.% obtained in Example 1, (c) is the microstructure of the hydride titanium alloy plate with a hydrogen content of 0.4 wt.% obtained in Example 2, and (d) is the microstructure of the hydride titanium alloy plate with a hydrogen content of 0.5 wt.% obtained in Example 3.

[0028] Figure 5 The images show the weld seams after hydrogen diffusion bonding of the samples. (a) is the weld seam morphology of the original Ti65 high-temperature titanium alloy in Comparative Example 1, (b) is the weld seam morphology of the titanium alloy plate with hydrogen content of 0.3 wt.% in Example 1, (c) is the weld seam morphology of the titanium alloy plate with hydrogen content of 0.4 wt.% in Example 2, and (d) is the weld seam morphology of the titanium alloy plate with hydrogen content of 0.5 wt.% in Example 3.

[0029] Figure 6 The shear strength of the Ti65 high-temperature titanium alloy components obtained in Examples 1-3 and Comparative Examples 1-4 is given. Detailed Implementation

[0030] Specific Implementation Method 1: This implementation method is a reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy, which is specifically completed according to the following steps:

[0031] I. Pretreatment of titanium alloy plates:

[0032] The titanium alloy plate is cut, polished, cleaned and dried according to the size requirements to obtain the pre-treated titanium alloy plate.

[0033] II. Hydrogenation treatment of titanium alloy plates:

[0034] The pretreated titanium alloy plate is placed in a vacuum furnace and hydrogenated in a hydrogen atmosphere. The temperature, hydrogen pressure and hydrogenation time are controlled to obtain a hydrogenated titanium alloy plate with a certain hydrogen content.

[0035] III. Coating Deposition:

[0036] A thin aluminum-titanium film was deposited on the surface of a titanium alloy plate by magnetron sputtering to prevent hydrogen escape caused by heating during subsequent diffusion bonding, thus obtaining a titanium alloy plate with a thin aluminum-titanium film deposited on the surface.

[0037] IV. Diffusion Connection:

[0038] Two titanium alloy plates with aluminum-titanium thin films deposited on their surfaces are diffused together at a predetermined temperature to obtain a diffused-bonded titanium alloy plate.

[0039] V. Dehydrogenation treatment:

[0040] The aluminum-titanium thin film on the surface of the diffusion-bonded titanium alloy plate is polished off, and then heat-treated under vacuum to remove hydrogen to a safe hydrogen content, thus obtaining a high-performance Ti65 high-temperature titanium alloy component.

[0041] The core innovation of this implementation method lies in the following: thermal hydrogen treatment causes the Ti65 titanium alloy to undergo an α→β phase transformation, reducing the atomic diffusion activation energy and achieving low-temperature bonding at 750℃; the magnetron sputtered Al-Ti film simultaneously plays a dual role of "preventing hydrogen escape" and "preventing oxidation"; the vacuum environment and precise dehydrogenation process work together to avoid thermal deformation and oxidation, and eliminate the negative impact of residual hydrogen on mechanical properties, ultimately obtaining a dense and firmly bonded joint.

[0042] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in the following ways: The grinding method described in Step One is to use 1000# SiC sandpaper to grind in the same direction, ensuring that the surface roughness Ra of the titanium alloy plate is ≤1.6μm and there is no obvious deformation; the cleaning method described in Step One is to use anhydrous ethanol as the cleaning agent and ultrasonically clean for 10-15 minutes; the cutting size of the titanium alloy plate in Step One is 30mm×30mm×1mm, and the cut surface is burr-free. Other steps are the same as in Specific Implementation Method One.

[0043] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that: in step two, the pretreated titanium alloy plate is placed in a vacuum furnace, and then the vacuum level inside the furnace is evacuated to 5×10⁻⁶. -4 Below Pa, the temperature is increased to the hydrogenation temperature of 750°C at a rate of 15°C / min. High-purity hydrogen gas is introduced, and the hydrogen pressure is controlled at 0.1MPa~0.5MPa. Hydrogenation is carried out at 750°C for 30 minutes, and then cooled to room temperature in the furnace to obtain a hydrogenated titanium alloy plate with a hydrogen content of 0.1wt.%~0.5wt.%. Other steps are the same as in specific implementation method one or two.

[0044] This embodiment describes a method for determining hydrogen absorption during the hydrogenation process. To minimize experimental error, the mass difference before and after hydrogenation is measured using a high-precision balance (accuracy 0.01 mg) to determine the hydrogen absorption of the sample; three samples are prepared as replicates for each set of experimental parameters.

[0045] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that the magnetron sputtering technology described in step three uses a dual-target system. The target materials are a titanium target and an aluminum target with a purity of 99.9%, and the target material specifications are a diameter of 50mm × a thickness of 5mm; the vacuum chamber needs to be evacuated to 7 × 10⁻⁶ m³ / h before sputtering. -4The working gas is argon with a purity of 99.999%, the argon flow rate is 100 sccm, and the working pressure is maintained at 0.3 Pa. Other steps are the same as in specific implementation methods one to three.

[0046] In this embodiment, the target material is driven by a pulsed DC power supply.

[0047] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the deposition parameters of the aluminum-titanium thin film described in step three are: pulsed DC power supply frequency of 50kHz, reverse time of 4μs, titanium target power of 150W, aluminum target power of 120W, deposition time of 120s, and film thickness of approximately 500nm. Other steps are the same as in Specific Implementation Methods One to Four.

[0048] Specific Implementation Method Six: The difference between this implementation method and Specific Implementation Methods One to Five is that the diffusion bonding method described in step four is as follows: the titanium alloy plate after surface deposition of aluminum-titanium thin film is placed in a vacuum furnace, and then the vacuum furnace is evacuated to 6×10⁻⁶. -3 Pa, then heat from room temperature to 750°C at a heating rate of 10°C / min, hold at that temperature for 5 minutes, then apply a pressure of 25 MPa, hold at that temperature and pressure for 40 minutes, and then cool to below 100°C at a cooling rate of 6°C / min. The other steps are the same as in specific embodiments one to five.

[0049] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One through Six in that: In step four, the surfaces of the two titanium alloy plates with deposited aluminum-titanium films are lightly sanded with 1500# SiC sandpaper to remove the oxide film generated by the high-temperature hydrogenation treatment. Then, they are ultrasonically cleaned with anhydrous ethanol for 10 minutes and dried. Next, the two titanium alloy plates with deposited aluminum-titanium films are assembled using a butt-joint assembly method, and diffusion bonding is performed at a predetermined temperature to obtain the diffusion-bonded titanium alloy plates. Other steps are the same as in Specific Implementation Methods One through Six.

[0050] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One through Seven in that: in step five, the aluminum-titanium film on the surface of the diffused titanium alloy plate is polished off to ensure complete exposure of the titanium alloy before placing it in a vacuum tube furnace, and the vacuum tube furnace is evacuated to 5×10⁻⁶. -4 Below Pa, the temperature is increased to 700℃ at a heating rate of 10℃ / min, held for 120min, and dehydrogenated until the hydrogen content is reduced to below 0.005wt.% to obtain a high-performance Ti65 high-temperature titanium alloy component. Other steps are the same as in specific embodiments one to seven.

[0051] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the titanium alloy plate mentioned in step one is a Ti65 high-temperature titanium alloy with a thickness of 1 mm. The other steps are the same as in Specific Implementation Methods One to Eight.

[0052] The Ti65 high-temperature titanium alloy described in this embodiment was originally rolled and then subjected to low-temperature annealing, and was provided by China Western Titanium Industry Co., Ltd.

[0053] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One through Nine in that: the diffusion connection process described in step four involves real-time monitoring of the sample temperature using thermocouples inside the furnace, with temperature fluctuations controlled within ±5℃; the clamps used for connection are made of high-temperature resistant ceramic material to prevent high-temperature adhesion to the titanium alloy plate. Other steps are the same as in Specific Implementation Methods One through Nine.

[0054] The beneficial effects of the present invention are verified using the following embodiments:

[0055] Example 1: This example proposes a method for preparing low-temperature diffusion bonding of Ti65 titanium alloy with thermal hydrogen treatment assistance. The purpose is to solve the problems of high diffusion bonding temperature, insufficient joint strength, hydrogen escape and surface oxidation of existing Ti65 titanium alloys. Through the synergistic process of "thermal hydrogen-induced phase transformation + magnetron sputtering hydrogen blocking + vacuum diffusion bonding", a high-performance joint can be prepared at a low temperature of 750℃.

[0056] This embodiment provides a reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy, characterized in that the method is specifically completed according to the following steps:

[0057] I. Pretreatment of titanium alloy plates:

[0058] Ti65 titanium alloy sheet (original state: rolled + low temperature annealed, thickness 1mm) was wire-cut into 30mm×30mm×1mm square samples. The sample surface was then polished in the same direction with 1000# SiC sandpaper to remove rolling oxide scale and machining marks until the surface roughness Ra≤1.6μm. Subsequently, the Ti65 titanium alloy sheet was ultrasonically cleaned in anhydrous ethanol for 10min to remove surface oil and wear debris. Finally, it was dried in a 60℃ forced-air drying oven to obtain the pretreated titanium alloy sheet.

[0059] II. Hydrogenation treatment of titanium alloy plates:

[0060] like Figure 1 As shown, the pretreated titanium alloy plate is placed in a vacuum furnace. After closing the furnace door, the vacuum pump is started to evacuate the furnace to a vacuum level of 5 × 10⁻⁶. -4Below Pa, the temperature is increased to the hydrogenation temperature of 750°C at a rate of 15°C / min, high-purity hydrogen is introduced, and the hydrogen pressure is controlled at 0.28MPa; hydrogenation is carried out at 750°C for 30 min, and then cooled to room temperature with the furnace to obtain a hydrogenated titanium alloy plate with a hydrogen content of 0.3wt.%.

[0061] III. Coating Deposition:

[0062] like Figure 2 As shown, a dual-target magnetron sputtering system was used, with titanium and aluminum targets of 99.9% purity (50 mm in diameter and 5 mm in thickness) and a target spacing of 80 mm. The titanium hydride alloy plate was fixed on the sample stage, and after the vacuum chamber was closed, a vacuum of 7 × 10⁻⁶ was evacuated. -4 The pressure was below Pa; 99.999% pure argon gas was introduced as the working gas, and the argon gas flow rate was adjusted to 100 sccm to maintain the working pressure of the vacuum chamber at 0.3 Pa; the target material was driven by a pulsed DC power supply at a frequency of 50 kHz and a reverse time of 4 μs. The titanium target power was set to 150 W, the aluminum target power was set to 120 W, and the deposition time was 120 s to form an Al-Ti composite film with a thickness of about 500 nm on the non-bonded surface of the sample; after deposition, the sample was naturally cooled to room temperature and taken out for use, resulting in a titanium alloy plate with an aluminum-titanium film deposited on the surface;

[0063] In step three, the titanium and aluminum targets were pre-sputtered for 30 seconds before deposition to remove the oxide layer on the target surface.

[0064] IV. Diffusion connection (e.g.) Figure 3 (as shown)

[0065] ① Use 1500# SiC sandpaper to lightly grind the surfaces of the two titanium alloy plates with aluminum-titanium films deposited on their surfaces to remove the trace oxide layer generated during the high-temperature hydrogenation process. Then, use anhydrous ethanol for ultrasonic cleaning for 10 minutes and dry them. Next, use a butt-fitting assembly method to assemble the two titanium alloy plates with aluminum-titanium films deposited on their surfaces (placed with the mating surfaces facing each other and the non-matting surfaces facing outwards, and fix them with high-temperature resistant ceramic clamps) to obtain the assembled titanium alloy plates.

[0066] ② Place the assembled titanium alloy plate into the vacuum furnace, and then evacuate the furnace to a vacuum level of 6×10. -3 Pa, then heat from room temperature to 750℃ at a heating rate of 10℃ / min, hold for 5min, then apply axial pressure of 25MPa through the hydraulic system, hold for 40min, and then cool to below 100℃ at a cooling rate of 6℃ / min.

[0067] During the diffusion bonding process described in step four, the sample temperature is monitored in real time by thermocouples inside the furnace, and the temperature fluctuation is controlled within ±5℃ to ensure process stability.

[0068] V. Dehydrogenation treatment:

[0069] The aluminum-titanium film on the surface of the diffusion-bonded titanium alloy plate is polished off to ensure complete exposure of the titanium alloy. Then, it is placed in a vacuum tube furnace, and the furnace is evacuated to 5×10⁻⁶ ppm. -4 Below Pa, the temperature is increased to 700℃ at a heating rate of 10℃ / min, held for 120min, and dehydrogenated until the hydrogen content is reduced to below 0.005wt.%. The mixture is then cooled to room temperature in the furnace. The Ti65 titanium alloy connecting joint has no risk of hydrogen embrittlement, resulting in a high-performance Ti65 high-temperature titanium alloy component (denoted as 0.3wt.%H).

[0070] In step five, during the 700℃ holding stage, the vacuum level inside the furnace needs to be continuously monitored to ensure it is not lower than 5×10⁻⁶. -4 Pa, to avoid sample oxidation during dehydrogenation.

[0071] Example 2: The difference between this example and Example 1 is that in step two, the pretreated titanium alloy plate is placed in a vacuum furnace, the furnace door is closed, and the vacuum pump is started to evacuate the vacuum level inside the furnace to 5×10⁻⁶. -4 Below Pa, the temperature is increased to the hydrogenation temperature of 750°C at a rate of 15°C / min. High-purity hydrogen gas is introduced, and the hydrogen pressure is controlled at 0.37 MPa. Hydrogenation is carried out at 750°C for 30 min, and then cooled to room temperature with the furnace to obtain a hydrogenated titanium alloy plate with a hydrogen content of 0.4 wt.%. The high-performance Ti65 high-temperature titanium alloy component obtained in step five is denoted as 0.4 wt.%H. Other steps and parameters are the same as in Example 1.

[0072] Example 3: The difference between this example and Example 1 is that in step two, the pretreated titanium alloy plate is placed in a vacuum furnace, the furnace door is closed, and the vacuum pump is started to evacuate the vacuum level inside the furnace to 5×10⁻⁶. -4 Below Pa, the temperature is increased to the hydrogenation temperature of 750°C at a rate of 15°C / min. High-purity hydrogen gas is introduced, and the hydrogen pressure is controlled at 0.49 MPa. Hydrogenation is carried out at 750°C for 30 min, and then cooled to room temperature in the furnace to obtain a hydrogenated titanium alloy plate with a hydrogen content of 0.5 wt.%. The high-performance Ti65 high-temperature titanium alloy component obtained in step five is denoted as 0.5 wt.%H. Other steps and parameters are the same as in Example 1.

[0073] Referring to Example 1: The conventional joining method for Ti65 high-temperature titanium alloy without H is completed according to the following steps:

[0074] I. Pretreatment of titanium alloy plates:

[0075] Ti65 high-temperature titanium alloy sheet (original state: rolled + low-temperature annealed, thickness 1mm, provided by China Western Titanium Industry Co., Ltd.) was wire-cut into 30mm×30mm×1mm square samples. The sample surface was then polished in the same direction with 1000# SiC sandpaper to remove rolling oxide scale and machining marks until the surface roughness Ra≤1.6μm. Subsequently, the Ti65 titanium alloy sheet was ultrasonically cleaned in anhydrous ethanol for 10min to remove surface oil and wear debris. Finally, it was dried in a 60℃ forced-air drying oven to obtain the pretreated titanium alloy sheet.

[0076] II. Diffusion Connection:

[0077] ① The two pre-treated titanium alloy plates are assembled using a butt-fitting assembly method (placed with the mating surfaces facing each other and the non-matting surfaces facing outwards, and fixed with high-temperature resistant ceramic clamps) to obtain the assembled titanium alloy plates.

[0078] ② Place the assembled titanium alloy plate into the vacuum furnace, and then evacuate the furnace to a vacuum level of 6×10. -3 Pa, then heat from room temperature to 750℃ at a heating rate of 10℃ / min (conventional H-free diffusion bonding usually requires a high temperature above 900℃ to achieve a welding rate of over 90%), hold at that temperature for 5 min, then apply an axial pressure of 25MPa through a hydraulic system, hold at that temperature and pressure for 40 min, and then cool to below 100℃ at a cooling rate of 6℃ / min to obtain a Ti65 high-temperature titanium alloy component (denoted as H-free).

[0079] During the diffusion bonding process described in step two, the sample temperature is monitored in real time by thermocouples inside the furnace, and the temperature fluctuation is controlled within ±5℃ to ensure process stability.

[0080] Referring to Example 2: The joining method for Ti65 high-temperature titanium alloy is specifically completed according to the following steps:

[0081] I. Pretreatment of titanium alloy plates:

[0082] Ti65 titanium alloy sheet (original state: rolled + low temperature annealed, thickness 1mm) was wire-cut into 30mm×30mm×1mm square samples. The sample surface was then polished in the same direction with 1000# SiC sandpaper to remove rolling oxide scale and machining marks until the surface roughness Ra≤1.6μm. Subsequently, the Ti65 titanium alloy sheet was ultrasonically cleaned in anhydrous ethanol for 10min to remove surface oil and wear debris. Finally, it was dried in a 60℃ forced-air drying oven to obtain the pretreated titanium alloy sheet.

[0083] II. Hydrogenation treatment of titanium alloy plates:

[0084] The pretreated titanium alloy plate was placed in a vacuum furnace. After closing the furnace door, the vacuum pump was started to evacuate the furnace to a vacuum level of 5 × 10⁻⁶. -4 Below Pa, the temperature is increased to the hydrogenation temperature of 750°C at a rate of 15°C / min, high-purity hydrogen is introduced, the hydrogen pressure is controlled at 0.28MPa, and hydrogenation is carried out at 750°C for 30min. The furnace is then cooled to room temperature to obtain a hydrogenated titanium alloy plate with a hydrogen content of 0.3wt.%.

[0085] III. Diffusion Connection:

[0086] ① Lightly grind the surfaces of two titanium hydride alloy plates with a hydrogen content of 0.3 wt.% using 1500# SiC sandpaper, then ultrasonically clean them with anhydrous ethanol for 10 minutes and dry them; then assemble the two titanium hydride alloy plates with a hydrogen content of 0.3 wt.% using a butt joint assembly method (place them with the mating surfaces facing each other and the non-matting surfaces facing outwards, and fix them with high-temperature resistant ceramic clamps) to obtain the assembled titanium alloy plates;

[0087] ② Place the assembled titanium alloy plate into the vacuum furnace, and then evacuate the furnace to a vacuum level of 6×10. -3 Pa, then heat from room temperature to 750℃ at a heating rate of 10℃ / min, hold for 5min, then apply axial pressure of 25MPa through a hydraulic system, hold for 40min, and then cool to below 100℃ at a cooling rate of 6℃ / min to obtain Ti65 high-temperature titanium alloy component (denoted as 0.3wt.%H without Ti-Al film).

[0088] During the diffusion bonding process described in step three, the sample temperature is monitored in real time by thermocouples inside the furnace, and the temperature fluctuation is controlled within ±5℃ to ensure process stability.

[0089] Comparative Example 3: The difference between this comparative example and Comparative Example 2 is that in step two, the pretreated titanium alloy plate is placed in a vacuum furnace, the furnace door is closed, and the vacuum pump is started to evacuate the vacuum level inside the furnace to 5 × 10⁻⁶. -4 Below Pa, the temperature was increased to the hydrogenation temperature of 750°C at a rate of 15°C / min. High-purity hydrogen gas was introduced, and the hydrogen pressure was controlled at 0.37 MPa. Hydrogenation was carried out at 750°C for 30 min, and then cooled to room temperature with the furnace to obtain a hydrogenated titanium alloy plate with a hydrogen content of 0.4 wt.%. The Ti65 high-temperature titanium alloy component obtained in step three is denoted as 0.4 wt.%H without Ti-Al film. Other steps and parameters are the same as those in Comparative Example 2.

[0090] Comparative Example 4: The difference between this comparative example and Comparative Example 2 is that in step two, the pretreated titanium alloy plate is placed in a vacuum furnace, the furnace door is closed, and the vacuum pump is started to evacuate the vacuum level inside the furnace to 5 × 10⁻⁶. -4Below Pa, the temperature was increased to the hydrogenation temperature of 750°C at a rate of 15°C / min. High-purity hydrogen gas was introduced, and the hydrogen pressure was controlled at 0.49 MPa. Hydrogenation was carried out at 750°C for 30 min, and then cooled to room temperature with the furnace to obtain a hydrogenated titanium alloy plate with a hydrogen content of 0.5 wt.%. The Ti65 high-temperature titanium alloy component obtained in step three is denoted as 0.5 wt.%H without Ti-Al film. Other steps and parameters are the same as those in Comparative Example 2.

[0091] Microstructure analysis: The dehydrogenated connector was cut along the cross-section, and after inlaying, grinding and polishing, it was etched for 15s using Keller's reagent (HF:HNO3:H2O=1:3:16, volume ratio). The interface bonding state was observed using a ZEISS-Gemini560 scanning electron microscope.

[0092] Figure 4 The images show the microstructures of the original Ti65 high-temperature titanium alloy and the Ti65 high-temperature titanium alloy after hydrogen treatment. (a) is the microstructure of the original Ti65 high-temperature titanium alloy, (b) is the microstructure of the hydride titanium alloy plate with a hydrogen content of 0.3 wt.% obtained in Example 1, (c) is the microstructure of the hydride titanium alloy plate with a hydrogen content of 0.4 wt.% obtained in Example 2, and (d) is the microstructure of the hydride titanium alloy plate with a hydrogen content of 0.5 wt.% obtained in Example 3.

[0093] from Figure 4 It can be seen that with the increase of hydrogen content, β phase precipitates at the equiaxed α phase grain boundary. Moreover, the presence of hydrogen greatly reduces the critical precipitation rate of martensite, causing martensite to precipitate within the equiaxed α phase.

[0094] Figure 5 The images show the weld seams after hydrogen diffusion bonding of the samples. (a) is the weld seam morphology of the original Ti65 high-temperature titanium alloy in Comparative Example 1, (b) is the weld seam morphology of the titanium alloy plate with hydrogen content of 0.3 wt.% in Example 1, (c) is the weld seam morphology of the titanium alloy plate with hydrogen content of 0.4 wt.% in Example 2, and (d) is the weld seam morphology of the titanium alloy plate with hydrogen content of 0.5 wt.% in Example 3.

[0095] from Figure 5 It can be seen that with the increase of hydrogen content, the weld bonding rate of Ti65 high-temperature titanium alloy welds first increases and then decreases. The figure shows that the optimal hydrogen content for promoting the diffusion bonding process is 0.4 wt.%.

[0096] Figure 6 The shear strength of the Ti65 high-temperature titanium alloy components obtained in Examples 1-3 and Comparative Examples 1-4;

[0097] from Figure 6It can be seen that the shear strength of Ti65 high-temperature titanium alloy components first increases and then decreases with increasing hydrogen content. The shear strength of the magnetron sputtering process including TiAl film is generally higher than that without TiAl film, demonstrating the significant meaning and role of magnetron sputtering in preventing hydrogen leakage for diffusion bonding.

[0098] In summary, this invention achieves high-performance diffusion bonding at a low temperature of 750℃ by inducing phase transformation in Ti65 titanium alloy through thermal hydrogen treatment, combined with magnetron sputtering hydrogen inhibition and precise hydrogen removal processes. Experiments demonstrate that this method effectively suppresses surface oxidation and hydrogen escape, resulting in dense and firmly bonded joints. It also boasts advantages such as simple process, low cost, and high efficiency, making it suitable for mass production of Ti65 titanium alloy components in the aerospace field.

Claims

1. A reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy, characterized in that... The method is specifically implemented according to the following steps: I. Pretreatment of titanium alloy plates: The titanium alloy plate is cut, polished, cleaned and dried according to the size requirements to obtain the pre-treated titanium alloy plate. II. Hydrogenation treatment of titanium alloy plates: The pretreated titanium alloy plate is placed in a vacuum furnace and hydrogenated in a hydrogen atmosphere. The temperature, hydrogen pressure and hydrogenation time are controlled to obtain a hydrogenated titanium alloy plate with a certain hydrogen content. III. Coating Deposition: A thin film of aluminum-titanium was deposited on the surface of a titanium alloy plate by magnetron sputtering to prevent hydrogen escape caused by temperature rise during subsequent diffusion bonding, thus obtaining a titanium alloy plate with a thin film of aluminum-titanium on the surface. IV. Diffusion Connection: Two titanium alloy plates with aluminum-titanium thin films deposited on their surfaces are diffused together at a predetermined temperature to obtain a diffused titanium alloy plate. V. Dehydrogenation treatment: The aluminum-titanium thin film on the surface of the diffusion-bonded titanium alloy plate is polished off, and then heat-treated under vacuum to remove hydrogen to a safe hydrogen content, thus obtaining a high-performance Ti65 high-temperature titanium alloy component.

2. The reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... The grinding method described in step one is as follows: use 1000# SiC sandpaper to grind in the same direction to ensure that the surface roughness Ra of the titanium alloy plate is ≤1.6μm and there is no obvious deformation; the cleaning method described in step one is as follows: use anhydrous ethanol as the cleaning agent and ultrasonically clean for 10min~15min; the cutting size of the titanium alloy plate in step one is 30mm×30mm×1mm, and the cut surface is free of burrs.

3. The reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... In step two, the pretreated titanium alloy plate is placed in a vacuum furnace, and then the vacuum level inside the furnace is evacuated to 5×10⁻⁶. -4 Below Pa, the temperature is increased to the hydrogenation temperature of 750°C at a rate of 15°C / min. High-purity hydrogen gas is introduced and the hydrogen pressure is controlled at 0.1MPa~0.5MPa. Hydrogenation is carried out at 750°C for 30 minutes, and then cooled to room temperature with the furnace to obtain a hydrogenated titanium alloy plate with a hydrogen content of 0.1wt.%~0.5wt.%.

4. The reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... The magnetron sputtering technology described in step three employs a dual-target system, using titanium and aluminum targets with a purity of 99.9%, and target specifications of 50mm in diameter × 5mm in thickness; the vacuum chamber needs to be evacuated to 7 × 10⁻⁶ before sputtering. -4 Below Pa, the working gas is argon with a purity of 99.999%, the argon flow rate is 100 sccm, and the working pressure is maintained at 0.3 Pa.

5. A reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... The deposition parameters of the aluminum-titanium thin film described in step three are as follows: pulsed DC power supply frequency of 50kHz, reverse time of 4μs, titanium target power of 150W, aluminum target power of 120W, deposition time of 120s, and film thickness of approximately 500nm.

6. A reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... The diffusion bonding method described in step four is as follows: A titanium alloy plate with a thin aluminum-titanium film deposited on its surface is placed in a vacuum furnace, and then the vacuum furnace is evacuated to a vacuum level of 6 × 10⁻⁶. -3 Pa, then heat from room temperature to 750℃ at a heating rate of 10℃ / min, hold for 5min, then apply a pressure of 25MPa, hold for 40min, and then cool to below 100℃ at a cooling rate of 6℃ / min.

7. A reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... In step four, the surfaces of the two titanium alloy plates with deposited aluminum-titanium films on their surfaces are lightly sanded with 1500# SiC sandpaper to remove the oxide film generated by the high-temperature hydrogenation treatment. Then, the plates are ultrasonically cleaned with anhydrous ethanol for 10 minutes and dried. The two titanium alloy plates with deposited aluminum-titanium films on their surfaces are then assembled using a butt joint assembly method and diffusion connection is performed at a predetermined temperature to obtain the diffusion-connected titanium alloy plates.

8. A reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... In step five, the aluminum-titanium film on the surface of the diffusion-bonded titanium alloy plate is polished off to ensure that the titanium alloy is completely exposed. Then, it is placed in a vacuum tube furnace, and the vacuum tube furnace is evacuated to 5×10⁻⁶. -4 Below Pa, the temperature is increased to 700℃ at a heating rate of 10℃ / min, held for 120min, and dehydrogenated until the hydrogen content is reduced to below 0.005wt.% to obtain high-performance Ti65 high-temperature titanium alloy components.

9. A reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... The titanium alloy plate mentioned in step one is Ti65 high-temperature titanium alloy with a thickness of 1mm.

10. A reliable low-temperature diffusion bonding method for Ti65 high-temperature titanium alloy according to claim 1, characterized in that... The diffusion bonding process described in step four involves real-time monitoring of the sample temperature using thermocouples inside the furnace, with temperature fluctuations controlled within ±5℃. The clamps used for bonding are made of high-temperature resistant ceramic material to prevent high-temperature adhesion to the titanium alloy plate.

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