Interlayer alloy for diffusion bonding of Ti2AlNb-based alloy and welding method
By designing the intermediate layer alloy and vacuum gradient hot pressing treatment process for Ti2AlNb alloy, the problem of poor weldability of Ti2AlNb alloy is solved, and a high-strength, high-plastic and stable welded joint is obtained, with better performance than the prior art.
Patent Information
- Application Number
- CN202510334440.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-20
- Publication Date
- 2025-05-27
AI Technical Summary
The weldability of Ti2AlNb alloy is poor, and traditional fusion welding methods are difficult to effectively apply, resulting in defects such as cracks and pores of welded joints. In the existing diffusion connection technology, the addition of the intermediate layer will produce a brittle phase or lead to uneven joint structure, making it difficult to obtain a welded joint with excellent performance and stable performance.
An intermediate layer alloy for diffusion connection of Ti2AlNb-based alloy was designed and prepared, with a composition of 34% to 68% Ti, 10% to 20% Al, 10% to 20% Nb, 12% to 26% Zr, 0~1% Ta, a thickness of 30~40μm, and a vacuum gradient hot pressing treatment process was used for welding.
Through this intermediate layer alloy and process, a Ti2AlNb-based alloy diffusion connection joint without obvious defects and uniform structure was obtained. The joint has excellent plasticity while maintaining high tensile strength. The elongation after break reaches 7.86% or above, the shear strength is greater than 685MPa, and its performance is better than the prior art.
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Abstract
Description
Technical Field
[0001] The present invention relates to the field of intermetallic compound welding, and in particular to a method for welding Ti 2 Intermediate layer alloy for diffusion bonding of AlNb-based alloys and welding method. Background Art
[0002] Ti 2 AlNb alloy is an intermetallic compound material based on an ordered orthorhombic structure O phase, which has the characteristics of high room temperature / high temperature strength and good oxidation resistance. 2 The room temperature plasticity and fracture toughness of AlNb alloy are significantly better than those of traditional Ti-Al alloys. 2 AlNb alloys have great application potential in the aerospace field. The intrinsic brittleness of intermetallic compounds makes Ti 2 AlNb alloys have poor weldability, and conventional fusion welding methods are difficult to effectively apply to Ti 2 AlNb alloy, welding problem has become one of the main difficulties in its practical application. Diffusion bonding as a solid-state welding technology can effectively avoid defects such as cracks and pores that may occur during fusion welding, and obtain welded joints with uniform structure and good performance. 2 Diffusion bonding of AlNb alloys is expected to solve the problem of poor weldability and promote the development of Ti 2 The application of AlNb-based alloys is of great significance. In recent years, many scholars have conducted some research on Ti 2 Wang et al. used Ti-Ni based amorphous strips as the intermediate layer to bond Ti-22Al-25Nb alloys in the paper "Effect of Nb content in Ti-Ni-Nb brazing alloys on the microstructure and mechanical properties of Ti-22Al-25Nb alloy brazed joints". 2 AlNb alloys were diffused and bonded, and Nb was found to be generated at the joint. 3 Al, Ti 2 Ni and τ 3 The same brittle phase causes the joint to fracture during deformation. Huang et al. 2In the paper “Simultaneously enhancing strength-ductility synergy in the TiAlNb vacuum diffusion-bonded joints for superior mechanical performance”, a Ti100-xMox intermediate layer alloy was used for diffusion bonding. The addition of the surface intermediate layer can effectively improve the strength of the joint, but at the same time, a brittle intermetallic compound phase will be generated at the joint surface, causing brittle fracture of the joint. 2 In the paper "AlNb diffusion bonding joint via heterogeneous high-entropy interface design", Al-Nb-Hf-Ta-Ti high entropy alloy was used as the intermediate layer to successfully obtain a defect-free joint. However, due to the large difference in the structure between the intermediate layer and the matrix, it is difficult to achieve coordinated deformation during the deformation process, and stress concentration is formed at the connection surface, resulting in premature fracture of the joint, which limits the further improvement of the joint performance.
[0003] Currently, most of the 2 The diffusion bonding of AlNb alloys all adds an intermediate layer alloy. A suitable intermediate layer can effectively improve the connection quality of the joint and enhance its mechanical properties. However, the addition of the existing intermediate layer will produce a brittle phase or cause uneven joint structure, making it difficult to obtain an excellent and stable Ti 2 AlNb alloy diffusion bonding joint. And higher temperature and pressure in the alloy diffusion bonding process are conducive to the bonding of the bonding interface, but too high temperature will cause irreversible deterioration of the alloy matrix structure and reduce the joint performance. At the same time, too high temperature and pressure will cause obvious macroscopic deformation of the sample. In the prior art, when a single layer of pure metal or alloy is used as an intermediate layer, the diffusion bonding temperature can be effectively reduced, but the overall performance of the joint is not high, and it is difficult to obtain a diffusion bonding joint with excellent performance and stability. When using a multi-layer metal foil as an intermediate layer, due to the large number of intermediate layers, the overall mechanical properties of the alloy are not evenly distributed, and strength fluctuations occur in different joint areas, affecting the bearing capacity of the entire joint.
[0004] Therefore, in order to further improve Ti 2 The comprehensive performance and connection stability of AlNb diffusion bonding joints urgently require the development of new intermediate layer alloys and corresponding diffusion bonding processes to obtain high-quality Ti 2 AlNb alloy welded joints. Summary of the invention
[0005] In view of this, the object of the present invention is to provide a method for2 Intermediate layer alloy for diffusion bonding of AlNb-based alloys and welding method.
[0006] The objective of the present invention is achieved through the following technical solutions:
[0007] <First aspect>
[0008] The present invention provides a method for Ti 2 The intermediate layer alloy of AlNb-based alloy diffusion bonding, wherein the intermediate layer alloy composition is 34% to 68% Ti, 10% to 20% Al, 10% to 20% Nb, 12% to 26% Zr, and 0 to 1% Ta in atomic percentage;
[0009] The thickness of the intermediate layer alloy is 30-40 μm.
[0010] As an embodiment, the alloy composition of the intermediate layer is 34% to 68% Ti, 10% to 20% Al, 10% to 20% Nb, and 12% to 26% Zr.
[0011] In some embodiments, the intermediate layer alloy is: Ti 58 Al 13 Nb 14 Zr 15 、Ti 44 Al 18 Nb 18 Zr 20 、Ti 68 Al 10 Nb 10 Zr 12 、Ti 34 Al 20 Nb 20 Zr 26 or Ti 64 Al 10 Nb 12 Zr 14 .
[0012] As an embodiment, the intermediate layer alloy composition further includes 34% to 68% Ti, 10% to 20% Al, 10% to 20% Nb, 12% to 26% Zr, and 0.2 to 1% Ta.
[0013] In some embodiments, the intermediate layer alloy is: Ti 57.8 Al 13 Nb 14 Zr 15 Ta 0.2 or Ti 57 Al 13 Nb 14 Zr 15 Ta1 .
[0014] <Second Aspect>
[0015] The present invention provides a method for Ti 2 The preparation method of the intermediate layer alloy for AlNb-based alloy diffusion bonding comprises the following steps: weighing raw materials according to the alloy components, then vacuum melting the raw materials to obtain a uniform alloy ingot, and then cutting and thinning the alloy ingot to obtain an intermediate layer alloy with a thickness of 30 to 40 μm.
[0016] As an embodiment, the purity of each element in the raw material is not less than 99.5wt.%
[0017] As an embodiment, the vacuum degree during vacuum melting is not less than 5×10 -3 Pa.
[0018] In some embodiments, the vacuum melting is performed using a non-consumable vacuum arc furnace.
[0019] As an implementation scheme, the vacuum melting has a melting current of 250 to 400 A and a melting time of 1 to 2 minutes.
[0020] As an embodiment, the raw material is a bulk metal material, and the raw material is first polished, cleaned and dried before being weighed.
[0021] As an embodiment, during the smelting process, Al in the raw materials is placed in the lower layer, Ti and Zr are placed in the middle layer, and the remaining raw materials are placed in the upper layer.
[0022] As an embodiment, before the smelting, a Ti ingot is additionally placed in the intermediate layer smelting furnace for melting to remove oxygen in the furnace.
[0023] As an embodiment, before the smelting, the additional Ti ingot is smelted at a current of 250-400A for a time of 1-2 minutes.
[0024] As an embodiment, the cutting is: using a wire cutting machine to cut the intermediate layer alloy ingot.
[0025] As an embodiment, the thickness of the alloy ingot obtained by cutting is 250-350 μm.
[0026] In some embodiments, the thickness of the cut alloy ingot is 300 μm.
[0027] As an embodiment, the thinning treatment is: sandpapers of different specifications are selected in sequence from coarse to fine to grind the surface of the cut alloy ingot.
[0028] In some embodiments, the cut alloy ingot is polished with 180#, 200#, 500#, 800#, 1000#, and 2000# SiC sandpaper in sequence.
[0029] <Third Aspect>
[0030] The present invention provides the above-mentioned intermediate layer alloy for Ti 2 The method for diffusion welding of AlNb-based alloy comprises the steps of: 2 The surfaces of the AlNb-based alloy to be connected are processed into mirror surfaces with a roughness Ra of 0.1 to 0.5 μm, and then the intermediate layer alloy is placed between two Ti 2 The surfaces of the AlNb-based alloy to be connected are in contact with each other to form an assembly block, and then a vacuum gradient hot pressing process is performed. The gradient hot pressing process includes six stages, wherein:
[0031] After heating to the first temperature in the first stage, the first period of time is maintained, the first temperature is 280-320°C, and the first period of time is 13-17 minutes;
[0032] The second stage is heated to the second temperature, and then the pre-tightening pressure is applied and maintained for the second period of time. The second temperature is 580-620°C, the pre-tightening pressure is 2.5-3.5MPa, and the second period of time is 13-17min.
[0033] In the third stage, the axial pressure is increased to the third stage temperature, and then the axial pressure is kept at the pressure level 1, and the temperature of the third stage is 940-980°C, the pressure level 1 is 20-60 MPa, and the third stage time is 25-35 minutes.
[0034] In the fourth stage, the sample is heated to the fourth temperature, and then the axial pressure is increased to pressure 2 and maintained for the fourth time. The fourth temperature is at α 2 +B2 two-phase region, and the phase transition temperature is 10-40°C lower than that of B2 / α2+B2, and the pressure is higher than that of Ti 2 The yield strength of the AlNb-based alloy at the fourth temperature is 10-20 MPa lower, and the fourth time is 2.5-3.5 min;
[0035] In the fifth stage, the heating is stopped until the temperature drops to the fifth stage temperature, and then the heat preservation is started, and the pressure is reduced to pressure three, and the heat preservation and pressure preservation time is the fifth stage. The pressure three is 20-60MPa, the fifth stage temperature is 940-980℃, and the fifth stage time is 25-35min;
[0036] The sixth stage is to unload the pressure and cool the sample to room temperature in the furnace to complete the Ti 2 Diffusion bonding process of AlNb alloy.
[0037] As an embodiment, the heating rate in the method is 4 to 12°C / min.
[0038] As an embodiment, the temperature is increased to the first stage temperature at a rate of 8-12°C / min.
[0039] As an embodiment, the temperature is increased to the second stage temperature at a rate of 8-12°C / min.
[0040] As an embodiment, the temperature is increased to the third stage temperature at a rate of 4-6°C / min.
[0041] As an embodiment, the temperature is increased to the fourth stage temperature at a rate of 8-12°C / min.
[0042] As an implementation scheme, in the second stage, the pressure increase time is 3 to 5 seconds.
[0043] In some embodiments, in the second stage, the pressure increasing rate is 50 MPa / min.
[0044] As an implementation scheme, in the third stage, the pressure increase time is 20 to 70 seconds.
[0045] In some embodiments, in the third stage, the pressure increasing rate is 50 MPa / min.
[0046] As an implementation scheme, in the fourth stage, the boost time is 54 to 108 seconds.
[0047] In some embodiments, in the fourth stage, the pressure increasing rate is 100 MPa / min.
[0048] As an implementation scheme, in the fifth stage, the pressure reduction time is 54 to 108 seconds.
[0049] In some embodiments, in the fifth stage, the pressure reduction rate is 100 MPa / min.
[0050] As an implementation scheme, in the fifth stage, the cooling time is 80 to 180 seconds.
[0051] In some embodiments, in the fifth stage, the cooling rate is 30° C. / min.
[0052] As an embodiment, the temperature of the fourth stage is 1020-1050°C, and the pressure is 150-200 MPa.
[0053] As an embodiment, the vacuum degree of the vacuum gradient heat treatment is not less than 5×10 -3 Pa.
[0054] In some embodiments, the vacuum degree of the vacuum gradient heat treatment is 5×10 -3 Pa.
[0055] As an embodiment, the surfaces to be connected are first rough-polished and then fine-polished.
[0056] In some embodiments, the surfaces to be connected are firstly rough-polished using SiC sandpaper and then fine-polished using diamond suspension.
[0057] As an embodiment, the surfaces to be connected are firstly subjected to ultrasonic cleaning and drying treatment before the assembly blocks are assembled.
[0058] In some embodiments, the ultrasonic cleaning is to clean the Ti with the surface to be connected. 2 The AlNb-based alloy was placed in anhydrous ethanol and subjected to ultrasonic treatment.
[0059] In some embodiments, the drying process is: using a drying oven to dry the sample at a temperature of 200° C. for 15 minutes.
[0060] <Fourth Aspect>
[0061] A kind of adding middle layer Ti 2 AlNb-based alloy welded joints are composed of the above-mentioned intermediate layer alloy and the Ti 2 It is formed by diffusion of AlNb-based alloy.
[0062] Compared with the prior art, the present invention has the following beneficial effects:
[0063] 1) Through component screening, we designed and prepared a suitable 2 High strength and high toughness TiAlNbZr (Ta) high entropy alloy intermediate layer for AlNb alloy diffusion bonding, the main elements of the intermediate layer alloy are 2 AlNb alloy is the same, Zr and Ta elements in Ti 2 AlNb exists in the form of solid solution in the alloy. 2 Diffusion bonding of AlNb alloys can avoid the formation of harmful phases and obtain joints with uniform structure.
[0064] 2) The present invention introduces a short-time high temperature and high pressure process without causing alloy structure deterioration and obvious deformation of the sample. The short-time high temperature and high pressure is used to promote the bonding of the connection interface and accelerate the healing of the holes at the interface. The conventional diffusion bonding process is combined with the short-time high temperature and high pressure process to achieve Ti 2 Compared with the conventional diffusion process, the present invention can not only obtain higher quality Ti 2AlNb alloy diffusion bonding joints can shorten process time and improve efficiency.
[0065] 3) Ti obtained by the intermediate layer alloy and diffusion bonding process provided by the present invention 2 AlNb alloy joints have excellent performance. The joints have excellent plasticity while maintaining high tensile strength. The elongation after fracture reaches 7.86% and above, and the highest reaches 10.25%, which fully demonstrates the performance of Ti 2 AlNb alloy diffusion bonding joints have excellent comprehensive performance in strength and plasticity. At the same time, the connection process provided by the present invention can obtain a TiNb alloy with a shear strength greater than 685MPa (even >720MPa). 2 AlNb alloy joints are currently Ti 2 AlNb alloy diffusion bonded joints have the highest shear strength. BRIEF DESCRIPTION OF THE DRAWINGS
[0066] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:
[0067] Figure 1 Ti in the present invention 2 The clamping method of the assembly block formed by the AlNb-based alloy and the intermediate layer alloy during diffusion bonding;
[0068] Figure 2 The Ti with intermediate layer obtained in Example 1 of the present invention 2 Microstructure of AlNb-based alloy joints;
[0069] Figure 3 The Ti without intermediate layer obtained in Comparative Example 1 of the present invention 2 Microstructure of AlNb-based alloy joints. DETAILED DESCRIPTION
[0070] The present invention is described in detail below in conjunction with embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, some adjustments and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.
[0071] The raw materials used in this specific embodiment are obtained from commercial channels, including:
[0072] Ti 2 The AlNb alloy composition is Ti-22Al-23Nb-1Mo-1Zr (at.%);
[0073] The purity of titanium is 99.5wt.%, the purity of aluminum is 99.9wt.%, the purity of niobium is 99.9wt.%, the purity of zirconium is 99.9wt.%, and the purity of tantalum is 99.9wt.%.
[0074] This specific embodiment provides a Ti 2 The welding method of AlNb-based alloy comprises the following steps:
[0075] S1. Preparation of intermediate layer alloy Ti a Al b Nb c Zr d Ta e , where the subscripts a, b, c, d and e in the alloy expression represent the atomic ratio of the corresponding components, respectively, and satisfy a is 34 to 68, b is 10 to 20, c is 10 to 20, d is 12 to 26, e is 0 to 1, and a+b+c+d+e=100;
[0076] The thickness of the intermediate layer alloy is 30-40 μm, and the roughness Ra is 0.1-0.5 μm.
[0077] S2、Ti 2 The AlNb-based alloy surface to be connected is processed to obtain a surface to be connected with a roughness Ra of 0.1 to 0.5 μm;
[0078] S3, such as Figure 1 As shown, the intermediate layer alloy is placed between two Ti 2 An assembly block is formed between the surfaces of the AlNb-based alloy to be connected, and LRA-15 boron nitride solder stop coating is sprayed on the side of the assembly block;
[0079] S4. Performing gradient hot pressing treatment on the assembly block.
[0080] Further, the gradient hot pressing treatment is performed as follows:
[0081] In the first stage, heating to the first temperature at the first heating speed and then maintaining it for the first period of time, the first temperature is 280-320°C, the first heating speed is 8-12°C / min, and the first period of time is 13-16min;
[0082] In the second stage, the second temperature is heated to the second temperature at the second heating speed, a pre-tightening pressure is applied, and the second time is maintained. The second temperature is 590-620°C, the second heating speed is 8-10°C / min, the pre-tightening pressure is 2.5-3.5MPa, the pressure increase rate is 50MPa / min, and the second time is 14-17min.
[0083] In the third stage, the temperature is heated to the third stage temperature at the third stage heating speed, and the axial pressure is increased to pressure one, and the temperature and pressure are kept for the third stage. The temperature of the third stage is 940-980°C, the heating speed of the third stage is 4-6°C / min, the pressure one is 20-60MPa, the pressure increase rate is 50MPa / min, and the third stage time is 25-33min.
[0084] In the fourth stage, the sample is heated to the fourth temperature at the fourth heating rate, the axial pressure is increased to pressure 2 and maintained for the fourth time, and the fourth temperature is at α 2 +B2 two-phase region, and the ratio B2 / α 2 +B2 phase transition temperature is 10-40℃ lower, the heating rate of the fourth stage is 10-12℃ / min, and the pressure is higher than that of Ti 2 The yield strength of the AlNb-based alloy at the fourth temperature is 10-20 MPa lower, the pressure increase rate is 100 MPa / min, and the fourth time is 2-3.5 min;
[0085] In the fifth stage, the heating is stopped and the pressure is reduced to pressure three. After the sample is cooled to the fifth stage temperature, the temperature and pressure are kept for the fifth period. The pressure three is 20-60MPa, the pressure reduction rate is 100MPa / min, the fifth stage temperature is 940-980℃, the cooling rate is 30℃ / min, and the fifth period is 25-35min.
[0086] In the sixth stage, the pressure is unloaded and the sample is cooled to room temperature in the furnace to complete the Ti 2 Diffusion bonding process of AlNb alloy.
[0087] It should be noted that Ti 2 The phase transition temperature of AlNb-based alloys is affected by the alloy composition, and the yield strength is affected by the alloy composition and the alloy hot working state. The selection of the fourth stage heating temperature and pressure is related to the Ti used. 2 The Ti used in the present invention is related to AlNb alloy. 2 B2 / α of AlNb alloy 2 +B2 phase transition temperature is about 1060℃, so the fourth stage heating temperature is selected to be 1020~1050℃. The selection of pressure 2 is related to the yield strength of the alloy at the heating temperature. 2 The yield strength of the AlNb alloy at the fourth stage heating temperature is 160-210 MPa, so the second pressure is selected to be 150-200 MPa.
[0088] Example 1
[0089] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2The welding method of AlNb-based alloy comprises the following steps:
[0090] The intermediate layer alloy composition used in this embodiment is: Ti 58 Al 13 Nb 14 Zr 15 .
[0091] S1. Mixing the ingredients according to the intermediate layer alloy composition and preparing the intermediate layer alloy.
[0092] First, the raw materials are polished, cleaned and dried. A grinding wheel is used to polish to remove the surface oxide film, and anhydrous ethanol is used for ultrasonic cleaning for 5 minutes. A drying cabinet is used for drying at a temperature of 200°C for 10 minutes, and then the raw materials are weighed; the prepared raw materials are then smelted in a non-consumable vacuum arc furnace; then the obtained ingot is cut and thinned, and a wire cutting machine is used to cut the intermediate layer alloy ingot. The thickness of the cut alloy is about 300μm, and then 180#, 200#, 500#, 800#, 1000#, and 2000# SiC sandpapers are used to polish the intermediate layer alloy cut by wire cutting in turn, and finally an intermediate layer alloy with a thickness of about 30μm is obtained.
[0093] Specifically, arc melting is carried out in a non-consumable vacuum arc furnace, and Al (lower layer), Ti and Zr (middle layer), and Nb (upper layer) are placed in the groove of the furnace plate from bottom to top.
[0094] Further specific melting steps include vacuuming, filling with argon, melting Ti ingots, and melting the alloy. The vacuum degree of vacuuming is required to reach 5×10 -3 Pa or more, the purpose of melting Ti ingot is to consume free oxygen in the furnace, the melting current of Ti ingot is 250-400A, the time is 1-2min (300A, 1min in this embodiment), the current of melting alloy is 250-400A, the time is 1-2min (350A, 1.5min in this embodiment), after the alloy is cooled, it is turned over, and the melting is repeated 4-6 times (5 times in this embodiment) to ensure uniform alloy composition;
[0095] S2. Processing Ti 2 AlNb-based alloy surface to be connected.
[0096] First, Ti 2 The AlNb-based alloy is wire-cut to remove a surface layer with a thickness of at least 0.5 mm to obtain a surface to be connected; and then the obtained surface to be connected is polished.
[0097] The polishing treatment is specifically as follows: using SiC sandpaper, using 180#, 200#, 500#, 800#, 1000#, and 2000# sandpaper in sequence to rough-polish the surface to be connected, using 0.5μm diamond suspension for fine-polishing when the surface is semi-mirror, and completing polishing when the connecting surface has a mirror effect (roughness Ra=0.1~0.5μm), and finally performing ultrasonic cleaning (ultrasonic cleaning in anhydrous ethanol for 10 minutes) and drying treatment (treatment in a drying oven at 200°C for 15 minutes) on the sample to obtain a treated surface to be connected.
[0098] S3. Assemble the assembly blocks.
[0099] The intermediate layer alloy is placed between two Ti 2 AlNb-based alloys are placed between them, and the upper and lower surfaces of the intermediate layer alloy are in contact with the two surfaces to be connected respectively; then LRA-15 boron nitride coating is sprayed on the sides around it, and it is loaded into the matching fixture of the vacuum diffusion furnace.
[0100] S4. Performing gradient heat treatment on the assembly block.
[0101] Place the assembly block in a vacuum diffusion furnace and evacuate to 5 × 10 -3 After Pa, a gradient heat treatment is performed. In this embodiment, the gradient heat treatment process is:
[0102] In the first stage, the sample was heated to 300°C at a heating rate of 10°C / min and then maintained for 15 min;
[0103] In the second stage, the sample was heated to 600°C at a heating rate of 10°C / min, and then a preload pressure of about 3MPa was applied (the pressure increase rate was 50MPa / min), and the temperature and pressure were maintained for 15min.
[0104] In the third stage, the connection was heated to 960°C at a heating rate of 5°C / min, and then the connection pressure was increased to 60MPa (the pressure increase rate was 50MPa / min), and the temperature and pressure were maintained for 30 minutes;
[0105] In the fourth stage, the sample was heated to 1020°C at 10°C / min, and then the axial pressure was increased to 200 MPa (pressurization rate was 100 MPa / min), and the temperature and pressure were maintained for 3 min;
[0106] In the fifth stage, the heating is stopped (at a rate of 30°C / min) until the temperature drops to 960°C, and then the temperature is kept constant. The pressure is reduced to 60MPa (at a rate of 100MPa / min), and the temperature and pressure are kept constant for 30 minutes.
[0107] The sixth stage is to unload the pressure and cool the sample to room temperature in the furnace to complete the Ti 2 Diffusion bonding process of AlNb alloy.
[0108] Example 2
[0109] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0110] In the gradient hot pressing process, the third stage is to heat to 940℃ at a heating rate of 5℃ / min, and at the same time increase the connection pressure to 20MPa, and keep it warm and pressurized for 30min; the fifth stage is to stop heating and reduce the pressure to 20MPa, and keep it warm and pressurized for 30min after the sample is cooled to 940℃; the process parameters of other stages remain unchanged.
[0111] Example 3
[0112] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0113] In the gradient hot pressing process, in the fourth stage, the sample was heated to 1050°C at 10°C / min, and the axial pressure was increased to 150 MPa and maintained for 2 min; the process parameters of other stages remained unchanged.
[0114] Example 4
[0115] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0116] In the gradient hot pressing process, in the fourth stage, the sample was heated to 1040°C at 10°C / min, and the axial pressure was increased to 180 MPa and maintained for 2 min; the process parameters of other stages remained unchanged.
[0117] Example 5
[0118] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0119] In the gradient hot pressing process, the third stage is to heat the sample to 950°C at a heating rate of 5°C / min, and at the same time increase the connection pressure to 40MPa, and keep it warm and pressurized for 30 minutes; the fourth stage is to heat the sample to 1030°C at 10°C / min, increase the axial pressure to 190MPa and maintain it for 3 minutes; the fifth stage is to stop heating and reduce the pressure to 40MPa, and keep the sample warm and pressurized for 30 minutes after cooling to 950°C; the process parameters of other stages remain unchanged.
[0120] Example 6
[0121] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0122] In the gradient hot pressing process, the heating temperature of the first stage is 280°C, the first heating rate is 12°C / min, and the first period is 13min; the heating temperature of the second stage is 620°C, the second heating rate is 8°C / min, the preload pressure is 2.5MPa, and the second period is 17min; the heating rate of the third stage is 4°C / min, and the third period is 25min; the heating rate of the fourth stage is 12°C / min, and the fourth period is 3.5min; the process parameters of other stages remain unchanged.
[0123] The shear strength of the joint in this embodiment was tested using a microcomputer-controlled electronic universal testing machine CMT 5105 and was found to be 708 MPa.
[0124] Example 7
[0125] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0126] In the gradient hot pressing process, the heating temperature of the first stage is 320°C, the first heating rate is 8°C / min, and the first period is 16min; the heating temperature of the second stage is 590°C, the second heating rate is 9°C / min, the preload pressure is 3.5MPa, and the second period is 14min; the heating rate of the third stage is 6°C / min, and the third period is 33min; the heating rate of the fourth stage is 11°C / min, and the fourth period is 2.5min; the process parameters of other stages remain unchanged.
[0127] The shear strength of the joint in this embodiment was tested using a microcomputer-controlled electronic universal testing machine CMT 5105 and was found to be 718 MPa.
[0128] Example 8
[0129] This embodiment provides a Ti-Al-Nb-Zr-Ta intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0130] The intermediate layer alloy composition used in this embodiment is: Ti 57.8 Al 13 Nb 14 Zr 15 Ta 0.2 ;
[0131] During arc melting in a non-consumable vacuum arc furnace, Al (lower layer), Ti and Zr (middle layer), Nb and Ta (upper layer) are placed in the groove of the furnace plate from bottom to top.
[0132] Example 9
[0133] This embodiment provides a Ti-Al-Nb-Zr-Ta intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0134] The intermediate layer alloy composition used in this embodiment is: Ti 57 Al 13 Nb 14 Zr 15 Ta 1 ;
[0135] During arc melting in a non-consumable vacuum arc furnace, Al, Ti, Zr, Nb and Ta are placed in the groove of the furnace plate from bottom to top.
[0136] Example 10
[0137] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0138] The intermediate layer alloy composition used in this embodiment is: Ti 44 Al 18 Nb 18 Zr 20 , thickness is 35μm.
[0139] The shear strength of the joint in this embodiment was tested using a microcomputer-controlled electronic universal testing machine CMT 5105 and was found to be 725 MPa.
[0140] Embodiment 11
[0141] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0142] The intermediate layer alloy composition used in this embodiment is: Ti 68 Al 10 Nb 10 Zr 12 , thickness is 40μm.
[0143] The shear strength of the joint in this embodiment was tested using a microcomputer-controlled electronic universal testing machine CMT 5105 and was found to be 698 MPa.
[0144] Example 12
[0145] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0146] The intermediate layer alloy composition used in this embodiment is: Ti 34 Al 20 Nb 20 Zr 26 , thickness is 30μm.
[0147] The shear strength of the joint in this embodiment was tested using a microcomputer-controlled electronic universal testing machine CMT 5105 and was found to be 711 MPa.
[0148] Embodiment 13
[0149] This embodiment provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0150] The intermediate layer alloy composition used in this embodiment is: Ti 64 Al 10 Nb 12 Zr 14 , thickness is 40μm;
[0151] In the gradient hot pressing process, the third stage is to heat to 980℃ at a heating rate of 5℃ / min, and at the same time increase the connection pressure to 40MPa, and keep it warm and pressurized for 30min; the fifth stage is to stop heating and reduce the pressure to 40MPa, and keep it warm and pressurized for 30min after the sample is cooled to 980℃; the process parameters of other stages remain unchanged.
[0152] Comparative Example 1
[0153] In this comparative example, a Ti without adding an intermediate layer alloy is provided. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0154] Step S1 is not included;
[0155] In step S3, the two surfaces to be connected are brought into contact with each other to form an assembly block, and other parameters remain unchanged.
[0156] Comparative Example 2
[0157] This comparative example provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0158] The fourth and fifth stages of the gradient hot pressing process are omitted;
[0159] In the third stage of this comparative example, the temperature is heated to 960°C at a heating rate of 5°C / min, and the connection pressure is increased to 60MPa, and the temperature is maintained for 80 minutes. The temperature maintenance time of the third stage in this comparative example is set to 80 minutes because the total time required for the temperature maintenance from the third stage to the fifth stage in Example 1 is 73.8 minutes. To ensure the reliability of the data, the time of the third stage in Comparative Example 1 is greater than the total time of the third to fifth stages in Example 1.
[0160] Comparative Example 3
[0161] This comparative example provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0162] The intermediate layer alloy composition used in this embodiment is: Ti 72 Al 8 Nb 8 Zr 14 .
[0163] Comparative Example 4
[0164] This comparative example provides a Ti-Al-Nb-Zr intermediate layer. 2 The welding method of AlNb-based alloy has the same steps as those of Example 1, except that:
[0165] The intermediate layer alloy composition used in this embodiment is: Ti 30 Al 22 Nb 18 Zr30 .
[0166] Performance testing:
[0167] The above-mentioned examples and comparative examples were subjected to tissue morphology testing.
[0168] Figure 2 This is the microstructure of the Ti2AlNb alloy weld joint with the intermediate layer added in Example 1. It can be seen that there are no obvious welding defects at the weld joint, and an excellent metallurgical bond is achieved between the intermediate layer and the matrix alloy.
[0169] Figure 3 The microstructure of the Ti2AlNb alloy welded joint without adding an intermediate layer in Comparative Example 1 is as follows. Compared with Example 1, when no intermediate layer is used, most areas of the joint achieve metallurgical bonding, but unwelded voids exist in some areas.
[0170] The uniaxial tensile test of the welded joint was carried out using a universal material testing machine Z20 at a tensile rate of 1×10 -3 / s; the joint shear strength test was carried out using a microcomputer-controlled electronic universal testing machine CMT 5105, and the pressure head descending speed was 0.2mm / min. Table 1 shows the mechanical property test results of the above-mentioned embodiment and comparative example samples.
[0171] Table 1 Mechanical properties of welded joints
[0172] Maximum tensile strength / MPa Elongation after break / % Shear strength / MPa Example 1 989 8.12 721 Example 2 970 7.86 697 Example 3 992 9.16 726 Example 4 996 8.46 718 Example 5 976 9.05 715 Example 8 968 10.25 691 Example 9 963 8.61 685 Example 13 978 8.23 705 Comparative Example 1 972 3.1 681 Comparative Example 2 963 5.3 672 Comparative Example 3 810 2.5 586 Comparative Example 4 791 2.6 561
[0173] It can be seen that the present invention designs and prepares the intermediate layer alloy, and introduces a short-time high-temperature and high-pressure process based on the conventional diffusion bonding process, which promotes the bonding of the connection interface, accelerates the healing of the holes at the interface, and obtains a Ti with no obvious defects and uniform structure. 2 AlNb-based alloy diffusion bonding joint. TiNb-based alloy diffusion bonding joint obtained by using the intermediate layer and diffusion bonding process provided by the present invention 2 AlNb alloy diffusion bonded joints have excellent mechanical properties, and their elongation and shear strength are higher than the relevant data in current research results.
[0174] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.
Claims
1. An intermediate layer alloy for diffusion bonding of Ti2AlNb-based alloys, characterized in that: In terms of atomic percentage, the intermediate layer alloy composition is 34% to 68% Ti, 10% to 20% Al, 10% to 20% Nb, 12% to 26% Zr, and 0 to 1% Ta. The thickness of the intermediate layer alloy is 30 to 40 μm.
2. The method for preparing the intermediate layer alloy according to claim 1, characterized in that: The raw materials are weighed according to the alloy composition, and then the raw materials are vacuum-melted to obtain a uniform alloy ingot, and then the alloy ingot is cut and thinned to obtain an intermediate layer alloy with a thickness of 30 to 40 μm.
3. The method for preparing the intermediate layer alloy according to claim 2, characterized in that: During the smelting process, Al in the raw materials is placed in the lower layer, Ti and Zr are placed in the middle layer, and the remaining raw materials are placed in the upper layer.
4. The method for preparing the intermediate layer alloy according to claim 2, characterized in that: Prior to the smelting, the Ti ingot in the pre-placed smelting furnace is melted to remove oxygen in the furnace.
5. The method for welding Ti2AlNb-based alloy using the intermediate layer alloy according to claim 1, characterized in that: The method comprises the steps of: processing the surfaces to be connected of the Ti2AlNb-based alloy into mirror surfaces with a roughness Ra of 0.1 to 0.5 μm, placing the intermediate layer alloy between the surfaces to be connected of the two Ti2AlNb-based alloys and contacting each other to form an assembly block, and then performing a vacuum gradient hot pressing process, wherein the gradient hot pressing process comprises six stages, wherein: In the first stage, the temperature is heated to the first temperature and maintained for the first period of time. The first temperature is 280-320°C and the first period of time is 13-17 minutes. The second stage is heated to the second temperature, and then the pre-tightening pressure is applied and maintained for the second period of time. The second temperature is 580-620°C, the pre-tightening pressure is 2.5-3.5MPa, and the second period of time is 13-17min. In the third stage, the axial pressure is increased to the third stage temperature, and then the axial pressure is kept at the pressure level 1, and the temperature of the third stage is 940-980°C, the pressure level 1 is 20-60 MPa, and the third stage time is 25-35 minutes. In the fourth stage, the sample is heated to the fourth stage temperature, and then the axial pressure is increased to pressure 2 and maintained for the fourth stage. The fourth stage temperature is in the α2+B2 two-phase region and is 10-40°C lower than the B2 / α2+B2 phase transition temperature. Pressure 2 is 10-20MPa lower than the yield strength of the Ti2AlNb-based alloy at the fourth stage temperature. The fourth stage time is 2.5-3.5min. In the fifth stage, stop heating until the temperature drops to the fifth stage temperature, then start heat preservation and reduce the pressure to pressure three. After the sample cools to the fifth stage temperature, keep the temperature and pressure for the fifth period. The pressure three is 20-60MPa, the fifth stage temperature is 940-980℃, and the fifth period is 25-35min. In the sixth stage, the pressure is unloaded and the sample is cooled to room temperature in the furnace to complete the diffusion bonding process of the Ti2AlNb alloy.
6. The method according to claim 5, characterized in that The temperature of the fourth stage is 1020-1050° C., and the pressure is 150-200 MPa.
7. The method according to claim 5, characterized in that The vacuum degree of the vacuum gradient heat treatment is not less than 5×10 -3 Pa.
8. The method according to claim 5, characterized in that In the method, the heating rate is 4-12°C / min.
9. The method according to claim 5, characterized in that The surfaces to be connected are first rough-polished and then fine-polished.
10. A Ti2AlNb-based alloy welded joint with an added intermediate layer, characterized in that: The intermediate layer alloy is diffused with the Ti2AlNb-based alloys on both sides.