Method for connecting TC4 titanium alloy and TiAl alloy

Abstract

The invention relates to a connecting method of a titanium-based metal material, and discloses a method for connecting a TC4 titanium alloy and a TiAl alloy material, and the method comprises the following steps: S1, placing a TiCoCuNiV alloy foil between the TC4 titanium alloy and the TiAl alloy for assembling to obtain a to-be-connected piece; and S2, the to-be-connected piece is subjected to vacuum hot pressing treatment. The method can effectively improve the shearing strength of the alloy connecting joint and the overall structural stability.

Description

Technical Field

[0001] The invention relates to a method for connecting titanium-based metal materials, and in particular to a method for connecting TC4 titanium alloy and TiAl alloy. Background Art

[0002] TC4 titanium alloy is widely used in aerospace, shipbuilding, automotive and medical industries due to its low density, high specific strength, good crack propagation resistance and corrosion resistance. TiAl alloy has high specific modulus and specific strength, excellent oxidation resistance and creep resistance, making it the most promising lightweight high-temperature structural material, mainly used in the aerospace field, such as engine low-pressure turbine blades, aircraft skins, combustion chamber nozzles, etc. In order to give full play to the excellent performance of the two alloys, connecting TC4 titanium alloy and TiAl alloy to make composite components can save costs and increase application flexibility.

[0003] Direct connection of TC4 titanium alloy and TiAl alloy will produce a large amount of brittle B2 phase and α2-Ti3Al phase intermetallic compounds in the joint, which is not conducive to improving the strength of the joint. The two materials have obvious differences in physical properties, especially the difference in linear expansion coefficient, which will produce large residual stress in the joint and affect the strength of the interface. In the prior art, an intermediate layer alloy is used to connect TC4 titanium alloy and TiAl alloy, but the strength of the joint between TC4 titanium alloy and TiAl alloy needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to overcome the problem in the prior art that the strength of the connection joint between TC4 titanium alloy and TiAl alloy needs to be improved, and to provide a method for connecting TC4 titanium alloy and TiAl alloy, which can effectively improve the shear strength of the alloy connection and improve the overall structural stability.

[0005] In order to achieve the above object, the present invention provides a method for connecting TC4 titanium alloy and TiAl alloy, the method comprising the following steps: S1, placing a TiCoCuNiV alloy foil between a TC4 titanium alloy and a TiAl alloy and assembling them to obtain a part to be connected; S2. Performing vacuum hot pressing treatment on the parts to be connected.

[0006] Preferably, in the step S1, the atomic ratio of titanium, cobalt, copper, nickel and vanadium in the TiCoCuNiV alloy foil is 1.1-1.3:1: 0.9-1.1:0.9-1.1:0.7-0.9.

[0007] Further preferably, the atomic ratio of titanium, cobalt, copper, nickel and vanadium in the TiCoCuNiV alloy foil is 1.15-1.25:1:0.95-1.05:0.95-1.05:0.75-0.85.

[0008] Preferably, in the TiCoCuNiV alloy foil, the atomic percentage of titanium is 20-26At%, the atomic percentage of copper is 18-22At%, the atomic percentage of nickel is 18-22At%, and the atomic percentage of vanadium is 14-18At%.

[0009] Preferably, the preparation method of the TiCoCuNiV alloy foil comprises: placing copper, nickel, cobalt, titanium and vanadium metals in a container in sequence, and then performing vacuum arc melting to obtain a TiCoCuNiV alloy ingot; cutting and polishing the TiCoCuNiV alloy ingot to obtain a TiCoCuNiV alloy foil.

[0010] Preferably, the TiCoCuNiV alloy foil has a thickness of 40-60 μm.

[0011] Preferably, the method further comprises: before placing the TiCoCuNiV alloy foil between the TC4 titanium alloy and the TiAl alloy samples, cutting the TC4 titanium alloy and the TiAl alloy into connection samples.

[0012] Preferably, the vacuum hot pressing step comprises: applying a connection pressure of 5-15 MPa to the parts to be connected, and controlling the vacuum degree to be less than or equal to 2.5×10 -3 Pa, heat to the second temperature T2 and keep for 10-30 minutes, then heat to the third temperature T3 and keep for 30-90 minutes.

[0013] Further preferably, the step of vacuum hot pressing comprises: applying a connection pressure of 5-15 MPa to the parts to be connected, and controlling the vacuum degree to be less than or equal to 2.5×10 -3 Pa, first heats to the first temperature T1 at a first heating rate, then heats to the second temperature T2 at a second heating rate and holds for 10-30 min, and finally heats to the third temperature T3 at a third heating rate and holds for 30-90 min. The first heating rate is lower than the third heating rate, the third heating rate is lower than the second heating rate, the first temperature T1 is lower than the second temperature T2, and the second temperature T2 is lower than the third temperature T3.

[0014] More preferably, the method further comprises: cooling the product obtained by the vacuum hot pressing treatment to a fourth temperature T4 at a cooling rate of 2-6°C / min, and then cooling the product, wherein the fourth temperature T4 is higher than the second temperature T2.

[0015] Further preferably, the first temperature T1 is 320-380°C, the second temperature T2 is 650-720°C, the third temperature T3 is 870-960°C, the fourth temperature T4 is 720-750°C, the first heating rate is 2-8°C / min, the second heating rate is 12-18°C / min, and the third heating rate is 8-12°C / min.

[0016] Through the above technical scheme, the method for connecting TC4 titanium alloy and TiAl alloy provided by the present invention adopts TiCoCuNiV alloy foil as the intermediate layer, which can make the elements at the joint more inclined to be mixed and distributed to increase its uniformity, reduce the content of intermetallic compounds that may appear on the interface, and effectively improve the shear strength of the connection joint between TC4 titanium alloy and TiAl alloy.

[0017] In addition, TiCoCuNiV has a high content of Ti and V elements, which shows good matching with the base material, thereby promoting the mutual diffusion between elements and further improving the overall structural stability of the connection joint. By adjusting the hot pressing connection process parameters such as foil thickness, heating rate and holding time, the connection temperature and applied pressure can be effectively reduced, and the deformation of the base material can be reduced while reducing the energy consumption during the alloy connection process. Moreover, the TiCoCuNiV alloy foil used does not contain precious metal elements and has a low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the assembly structure of the parts to be connected in a specific embodiment of the present invention; Figure 2 is the backscattered microstructure morphology of the alloy obtained in Example 1; Figure 3 It is a schematic diagram of a connector shearing die in a specific implementation manner. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] As mentioned above, the present invention provides a method for connecting TC4 titanium alloy and TiAl alloy, the method comprising the following steps: S1, placing a TiCoCuNiV alloy foil between a TC4 titanium alloy and a TiAl alloy and assembling them to obtain a part to be connected; S2. Performing vacuum hot pressing treatment on the parts to be connected.

[0021] According to the present invention, the nominal composition of TC4 titanium alloy is Ti-6Al-4V; the nominal composition of TiAl alloy sample is Ti-43Al-9V-0.2Y. TiCoCuNiV alloy foil is a foil formed by an alloy containing five metal elements: titanium, cobalt, copper, nickel and vanadium.

[0022] The inventors found during the research process that the use of TiCoCuNiV alloy foil to connect TC4 titanium alloy and TiAl alloy can effectively improve the shear strength of the connection joint and the overall structural stability. In addition, the TiCoCuNiV alloy foil used does not contain precious metal elements and has a low cost.

[0023] Preferably, in the step S1, the atomic ratio of titanium, cobalt, copper, nickel and vanadium in the TiCoCuNiV alloy foil is 1.1-1.3:1:0.9-1.1:0.9-1.1:0.7-0.9. The atomic ratio of cobalt to titanium may be 1:1.1, 1:1.12, 1:1.14, 1:1.16, 1:1.18, 1:1.2, 1:1.22, 1:1.24, 1:1.26, 1:1.28, 1:1.3, or any value in the range formed by these ratios; the atomic ratio of cobalt to copper may be 1:0.9, 1:0.92, 1:0.94, 1:0.96, 1:0.98, 1:1.0, 1:1.02, 1:1.04, 1:1.06, 1:0.08, 1:1.1, or any value in the range formed by these ratios. The atomic ratio of titanium to nickel can be 1:0.9, 1:0.92, 1:0.94, 1:0.96, 1:0.98, 1:1.0, 1:1.02, 1:1.04, 1:1.06, 1:0.08, 1:1.1, or any value in the range formed by these ratios; the atomic ratio of titanium to vanadium can be 1:0.7, 1:0.72, 1:0.74, 1:0.76, 1:0.78, 1:0.8, 1:0.82, 1:0.84, 1:0.86, 1:0.88, 1:0.9, or any value in the range formed by these ratios. The study found that controlling the atomic ratio of cobalt, copper, nickel, titanium and vanadium in the TiCoCuNiV alloy foil within the above range can further improve the maximum shear force of the connection joint of the TC4 titanium alloy and TiAl alloy samples. From the perspective of further improving the shear strength of the connection joint between TC4 titanium alloy and TiAl alloy, it is further preferred that the atomic ratio of titanium, cobalt, copper, nickel and vanadium in the TiCoCuNiV alloy foil is 1.15-1.25:1:0.95-1.05:0.95-1.05:0.75-0.85.

[0024] In order to further improve the shear strength of the connection joint between the TC4 titanium alloy and the TiAl alloy sample, preferably, in the TiCoCuNiV alloy foil, the atomic percentage content of titanium is 22-26At%, and can be 22At%, 22.5At%, 23At%, 23.5At%, 24At%, 24.5At%, 25At%, 25.5At%, 26At%, or any value within the range formed by these values; the atomic percentage content of copper is 18-22At%, and can be 18At%, 19At%, 20At%, 21At%, 22.5At%, 23.5At%, 24At%, 24.5At%, 25At%, 25.5At%, 26At%, or any value within the range formed by these values; At%, 22At%, or any value in the ranges formed by these values; the atomic percentage content of nickel is 18-22At%, can be 18At%, 19At%, 20At%, 21At%, 22At%, or any value in the ranges formed by these values; the atomic percentage content of vanadium is 14-18At%, can be 14At%, 14.5At%, 15At%, 15.5At%, 16At%, 16.5At%, 17At%, 17.5At%, 18At%, or any value in the ranges formed by these values.

[0025] The TiCoCuNiV alloy foil can be prepared by cutting the TiCoCuNiV molten alloy, or by rolling the TiCoCuNiV molten alloy. Preferably, the method for preparing the TiCoCuNiV alloy foil comprises: placing copper, nickel, cobalt, titanium and vanadium metals in a container in sequence, and then performing vacuum arc melting to obtain a TiCoCuNiV alloy ingot; cutting and polishing the TiCoCuNiV alloy ingot to obtain a TiCoCuNiV alloy foil. The alloy foil prepared by the above method has a more uniform thickness, and can accurately control the thickness of the connecting piece while simplifying the steps, thereby further improving the shear strength of the connection joint between the TC4 titanium alloy and the TiAl alloy.

[0026] According to the present invention, copper, nickel, cobalt, titanium and vanadium metals can be metal particles. The container can be any feasible container. As a specific embodiment of the present invention, the container is a crucible. The order in which copper, nickel, cobalt, titanium and vanadium metals are placed in the container is based on the melting point of the metal materials. The metal material with a low melting point is placed at the bottom of the container, and then other metal materials are placed in the order of increasing melting points, and the metal material with the highest melting point is placed at the top.

[0027] Preferably, the method further comprises: before placing the TiCoCuNiV alloy foil between the TC4 titanium alloy and the TiAl alloy, cleaning the TiCoCuNiV alloy foil, which can further improve the connection effect between the TC4 titanium alloy and the TiAl alloy. The cleaning can be carried out by any feasible cleaning method in the prior art, such as cleaning, ultrasonic cleaning, etc. Ultrasonic cleaning is preferred. The cleaning solution used can be selected from at least one of ethanol, acetone and water, preferably ethanol.

[0028] According to the present invention, in order to make the raw materials mixed more uniformly and further improve the shear strength of the connection joint between TC4 titanium alloy and TiAl alloy, the current of vacuum arc melting is 280-310A, the voltage is 380V, and the arc is maintained at 40-60S. After each melting of the alloy, the alloy is cooled and then turned over for melting, and this is repeated more than 5 times.

[0029] Preferably, the thickness of the TiCoCuNiV alloy foil is 40-60 μm, which can be 40 μm, 44 μm, 48 μm, 52 μm, 56 μm, 60 μm, or any value within the range formed by these values. Controlling the thickness of the TiCoCuNiV alloy foil within the above range can further improve the shear strength of the connection joint between the TC4 titanium alloy and the TiAl alloy.

[0030] Preferably, the method further comprises: before placing the TiCoCuNiV alloy foil between the TC4 titanium alloy and the TiAl alloy sample, cutting the TC4 titanium alloy block and the TiAl alloy block. The contact effect between the TC4 titanium alloy sample, the TiAl alloy sample and the TiCoCuNiV alloy foil can be improved, thereby further improving the shear strength of the connection joint between the TC4 titanium alloy and the TiAl alloy. The parallelism of the upper and lower surfaces of the cut sample is less than or equal to 0.02 mm, and the surface roughness of the TiCoCuNiV alloy foil is Ra0.2-0.4. By controlling the roughness and parallelism of the TC4 titanium alloy and the TiAl alloy before connection, the size of the composite component obtained after connection can be effectively controlled, and there is no need to further process the component after connection, thereby ensuring the accuracy of the composite component while simplifying the processing technology.

[0031] Preferably, the method further comprises: grinding and polishing the cut sample, which can further improve the contact effect between the TC4 titanium alloy sample, the TiAl alloy sample and the TiCoCuNiV alloy foil. Further preferably, the polished sample is cleaned.

[0032] According to the present invention, polishing can be performed in any feasible manner. As a specific embodiment of the present invention, polishing is performed by mechanical polishing with diamond abrasive paste, and cleaning is performed by ultrasonic cleaning. Preferably, the solvent used for cleaning is ethanol.

[0033] Preferably, the sandpaper used for grinding is 360-3000# SiC sandpaper. The grinding process includes: grinding the surfaces to be welded of the TC4 titanium alloy and TiAl alloy samples in turn with 360-3000# SiC sandpaper step by step. The contact effect between the TC4 titanium alloy sample, the TiAl alloy sample and the TiCoCuNiV alloy foil can be improved, thereby further improving the shear strength of the connection between the TC4 titanium alloy and the TiAl alloy sample.

[0034] In order to further improve the shear strength of the connection between the TC4 titanium alloy and the TiAl alloy sample, preferably, before the cutting, the TC4 titanium alloy is cold rolled and annealed. Further preferably, the annealing conditions include: a temperature of 750-930°C and a time of 1-2.5h. More preferably, the annealing conditions include: a temperature of 780-900°C and a time of 1.5-2h.

[0035] Preferably, the cutting process includes: the size of the TC4 titanium alloy sample after cutting is 28-32mm×18-22mm×4-6mm, and the size of the TiAl alloy sample after cutting is 18-22mm×14-16mm×3-4mm. As a specific embodiment of the present invention, the TC4 titanium alloy is cut into a size of 30mm×20mm×5mm using an electric spark wire cutting machine, and the TiAl alloy is cut into a size of 20mm×15mm×3mm using a cutting machine.

[0036] Preferably, the method further comprises: after cleaning, using a hair dryer to dry the surface.

[0037] Preferably, the vacuum hot pressing step comprises: applying a connection pressure of 5-15 MPa to the parts to be connected, and controlling the vacuum degree to be less than or equal to 2.5×10 -3 Pa, heated to the second temperature T2 and maintained for 10-30 minutes, and then heated to the third temperature T3 and maintained for 30-90 minutes. The vacuum hot pressing treatment by the above method can effectively increase the contact degree of the connecting parts, and can further improve the shear strength of the connection between the TC4 titanium alloy and the TiAl alloy sample. Considering that the shear strength of the connection between the TC4 titanium alloy and the TiAl alloy sample can be further improved, it is further preferred that the step of vacuum hot pressing treatment includes: applying a connection pressure of 5-15MPa to the parts to be connected, and controlling the vacuum degree to be less than or equal to 2.5×10 -3Pa, first heat to the first temperature T1 at the first heating rate, then heat to the second temperature T2 at the second heating rate and keep it for 10-30min, and finally heat to the third temperature T3 at the third heating rate or even keep it for 30-90min. The first heating rate is lower than the third heating rate, the second heating rate is lower than the second heating rate, the first temperature T1 is lower than the second temperature T2, and the second temperature T2 is lower than the third temperature T3.

[0038] Preferably, the method further comprises: cooling the product obtained by the vacuum hot pressing treatment to a fourth temperature T4 at a cooling rate of 2-6°C / min and then directly cooling the product, wherein the fourth temperature T4 is higher than the second temperature T2. Studies have shown that the shear strength of the connection joint of the TC4 titanium alloy and TiAl alloy samples obtained by the above method is higher. From the perspective of being able to further improve the shear strength of the connection joint between the TC4 titanium alloy and the TiAl alloy sample, it is further preferred that the first temperature T1 is 320-380°C, which can be 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, or any value in the range formed by these temperatures; the second temperature T2 is 650-720°C, which can be 650°C, 660°C, 670°C, 680°C, 690°C, 700°C, 710°C, 720°C, or any value in the range formed by these temperatures; the third temperature T3 is 870-960°C, which can be 870°C, 890°C, 910°C, 920°C, 940°C, 960°C, or any value in the range formed by these temperatures. any value between the ranges formed by these temperatures; the fourth temperature T4 is 720-760°C, which can be 720°C, 730°C, 740°C, 750°C, 760°C, or any value between the ranges formed by these temperatures; the first heating rate is 2-8°C / min, which can be 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, or any value between the ranges formed by these values; the second heating rate is 12-18°C / min, which can be 12°C / min, 13°C / min, 14°C / min, 15°C / min, 16°C / min, 17°C / min, 18°C / min, or any value between the ranges formed by these values.

[0039] Preferably, the heating rate to the third temperature T3 is 8-12° C. / min, and the cooling rate to the fourth temperature T4 is 2-6° C. / min.

[0040] From the viewpoint of being able to further improve the shear strength of the connection joint between the TC4 titanium alloy and the TiAl alloy samples, it is further preferred that the third temperature T3 is 930-960°C.

[0041] In order to further improve the shear strength of the connection joint between the TC4 titanium alloy and the TiAl alloy samples, preferably, the connection pressure is 10-15 MPa.

[0042] According to a particularly preferred embodiment of the present invention, a method for connecting TC4 titanium alloy and TiAl alloy is provided, comprising the following steps: S1, annealing the cold-rolled TC4 titanium alloy at 890° C. for 1.5 h, then cutting it into alloy sample blocks, grinding, polishing, ultrasonically cleaning and drying the surface to be welded to obtain a TC4 titanium alloy block to be welded; The TiAl alloy after blank forging is cut into alloy blocks, and the surfaces to be connected are ground, polished, ultrasonically cleaned and dried to obtain TiAl alloy blocks to be welded; S2, the mass of titanium, cobalt, copper, nickel and vanadium is calculated according to the atomic ratio of 1.1-1.3:1: 0.9-1.1:0.9-1.1:0.7-0.9, the bulk metal raw material is calculated and weighed according to the total mass of 400g ingot, the purity of the metal raw material is 99.99%, the smelting raw material is placed in a crucible in order of melting point, and smelted in a vacuum induction arc furnace, the current of vacuum arc melting is 280-310A, the voltage is 380V, and the arc is maintained at 40-60S, and the alloy is turned over and smelted after being cooled after each smelting alloy is melted, and the smelting is repeated for more than 5 times to make a TiCoCuNiV alloy ingot with uniform composition; The TiCoCuNiV alloy ingot is cut into thin sheets with a thickness of 0.3-0.5 mm, and is mechanically polished to a thickness of 40-60 μm. The surface is ultrasonically cleaned and blown dry. The obtained TiCoCuNiV alloy foil is placed between the TC4 titanium alloy and the TiAl alloy and placed in a graphite mold for assembly to obtain a part to be connected; S3. Place the parts to be connected in a vacuum hot pressing sintering furnace, apply a connection pressure of 5-15MPa to the sample to be welded, and wait until the vacuum degree in the furnace drops to 2.5×10 -3 Pa, heating to 320-380°C at a heating rate of 2-8°C / min, then heating to 650-720°C at a heating rate of 12-18°C / min, and keeping at this temperature for 10-30min, then heating to 870-960°C at a rate of 8-12°C / min, keeping for 30-90min, and performing hot pressing connection; S4. After the connection is completed, first cool down to 720-760℃ at a rate of 2-6℃ / min, then cool to room temperature with the furnace and unload the pressure to take out the alloy.

[0043] The method for connecting TC4 titanium alloy and TiAl alloy provided by the present invention adopts TiCoCuNiV alloy foil as an intermediate layer, and designs and changes the atomic ratio of elements in the intermediate layer so that the elements at the joint tend to be more mixedly distributed to increase their uniformity, reduce the content of intermetallic compounds that may appear on the interface, and can effectively improve the shear strength of the connection joint between TC4 titanium alloy and TiAl alloy.

[0044] The content of Ti and V elements in the intermediate layer is relatively high and shows good matching with the base material, thereby promoting the mutual diffusion between the elements and improving the overall structural stability of the connection joint.

[0045] By adjusting the hot pressing connection process parameters such as foil thickness, heating rate and holding time, the connection temperature and applied pressure can be effectively reduced, thereby reducing energy consumption during alloy connection and reducing deformation of the parent material. By controlling the roughness and parallelism of the TC4 titanium alloy and TiAl alloy samples before connection, the size of the composite component obtained after connection can be effectively controlled, and the component does not need to be further processed after connection, which ensures the accuracy of the composite component and simplifies the processing technology. In addition, the TiCoCuNiV alloy foil used does not contain precious metal elements and has a low cost.

[0046] The present invention will be described in detail below through examples. In the following examples, the raw materials of titanium, cobalt, copper, nickel, vanadium, iron and aluminum are high-purity metal particles of Zhongnuo New Materials, and the purity of the raw materials is 99.99%.

[0047] Preparation Example 1 Titanium, cobalt, copper, nickel and vanadium are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain TiCoCuNiV ingot-1. Among them, the atomic percentage of Ti is 24%, the atomic percentage of Co is 20%, the atomic percentage of Cu is 20%, the atomic percentage of Ni is 20%, and the atomic percentage of V is 16%.

[0048] Preparation Example 2 Titanium, cobalt, copper, nickel and vanadium are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain TiCoCuNiV ingot-2; Among them, the atomic percentage of Ti is 23%, the atomic percentage of Co is 20%, the atomic percentage of Cu is 19%, the atomic percentage of Ni is 21%, and the atomic percentage of V is 17%.

[0049] Preparation Example 3 Titanium, cobalt, copper, nickel and vanadium are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain TiCoCuNiV ingot-3; Among them, the atomic percentage of Ti is 25%, the atomic percentage of Co is 20%, the atomic percentage of Cu is 21%, the atomic percentage of Ni is 19%, and the atomic percentage of V is 15%.

[0050] Preparation Example 4 Titanium, cobalt, copper, nickel and vanadium are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain TiCoCuNiV ingot-4; Among them, the atomic percentage of Ti is 22%, the atomic percentage of Co is 20%, the atomic percentage of Cu is 18%, the atomic percentage of Ni is 22%, and the atomic percentage of V is 18%.

[0051] Preparation Example 5 Titanium, cobalt, copper, nickel and vanadium are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain TiCoCuNiV ingot-5; Among them, the atomic percentage of Ti is 26%, the atomic percentage of Co is 20%, the atomic percentage of Cu is 22%, the atomic percentage of Ni is 18%, and the atomic percentage of V is 14%.

[0052] Preparation Example 6 Titanium, cobalt, copper and nickel are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain a TiCoCuNi ingot. Among them, the atomic percentage of Ti is 23.8%, the atomic percentage of Co is 25.4%, the atomic percentage of Cu is 25.4%, and the atomic percentage of Ni is 25.4%.

[0053] Preparation Example 7 Titanium, cobalt, copper and vanadium are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain a TiCoCuV ingot. Among them, the atomic percentage of Ti is 30%, the atomic percentage of Co is 25%, the atomic percentage of Cu is 25%, and the atomic percentage of V is 20%.

[0054] Preparation Example 8 Titanium, cobalt, nickel and vanadium are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain a TiCoNiV ingot. Among them, the atomic percentage of Ti is 30%, the atomic percentage of Co is 25%, the atomic percentage of Ni is 25%, and the atomic percentage of V is 20%.

[0055] Preparation Example 9 Titanium, cobalt, copper, nickel and iron are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain a TiCoCuNiFe ingot. Among them, the atomic percentage of Ti is 23%, the atomic percentage of Co is 20%, the atomic percentage of Cu is 20%, the atomic percentage of Ni is 20%, and the atomic percentage of Fe is 17%.

[0056] Preparation Example 10 Cobalt, nickel and iron are placed in a crucible in order from low to high melting points, and then placed in a vacuum induction arc furnace for smelting. After each smelting, the alloy is cooled and then turned over for smelting. The smelting is repeated 5 times to obtain a CoNiFe ingot. Among them, the atomic percentage of Co is 28%, the atomic percentage of Ni is 45%, and the atomic percentage of Fe is 27%.

[0057] Example 1 S1. First, anneal the cold-rolled TC4 titanium alloy at 890°C for 2h, and then cut it into alloy blocks of 30mm×20mm×5mm; cut the TiAl alloy into alloy blocks of 20mm×15mm×3mm; grind the surface to be welded step by step with 360-2000# SiC sandpaper, mechanically polish it with water-soluble diamond grinding paste, and ultrasonically clean it in anhydrous ethanol for 10min and then blow dry the surface to obtain the TC4 titanium alloy sample block and the TiAl alloy sample block to be connected; S2. Cut the TiCoCuNiV alloy ingot-1 into 0.3mm thick slices, and grind and polish them step by step with 360-2000# SiC sandpaper into 50μm (±5μm) thick foils with surface roughness ≤Ra0.4 and parallelism of upper and lower surfaces ≤0.02mm. Then place the foil between the TC4 titanium alloy block and the TiAl alloy block (see Figure 1 ), put it into the graphite mold for assembly to obtain the parts to be connected; S3. Place the parts to be connected in a vacuum hot pressing sintering furnace, apply a pressure of 5MPa to the sample to be welded, and wait until the vacuum degree in the furnace drops to 2.5×10 -3 Pa, heat to 350℃ at a heating rate of 5℃ / min, then heat to 700℃ at a heating rate of 15℃ / min, keep at 700℃ for 20min, then heat to 870℃ at a rate of 10℃ / min, keep for 60min, and then connect; S4. After the connection is completed, the temperature is lowered to 720°C at a rate of 5°C / min, then cooled to room temperature with the furnace and the pressure is unloaded to take out the alloy.

[0058] The interface structure of the TC4 titanium alloy and the TiAl alloy prepared in Example 1 was observed using a scanning electron microscope, and the Figure 2 .pass Figure 2 It can be seen from the interface microstructure that the interface structure of the connection between TiCoCuNiV alloy and TiAl alloy and TC4 titanium alloy is uniform, the weld is flat, and there are no obvious welding defects. The diffusion zone on one side of TiCoCuNiV alloy and TiAl alloy can be divided into three connection layers. The first layer is mainly the β / B2 phase formed by the diffusion of elements in TiCoCuNiV alloy into TiAl alloy. The second layer is dark gray and consists of Al(Cu,Ni)Ti phase, and the light gray connection layer is Al(Co,Ni)2Ti phase.

[0059] from Figure 2 It can be seen that the bonding area between TiCoCuNiV alloy and TC4 consists of two connection layers. It can be observed that the connection layer on the side of TC4 titanium alloy is thicker, consisting of long torn α-Ti phase and large β-Ti phase, belonging to Widmanstatten structure. This is because the Co, Cu, and Ni elements in the TiCoCuNiV alloy diffuse into TC4, reducing the β phase transformation temperature of TC4, promoting the growth of α-Ti and β-Ti, and making the β grains at the interface coarsening. Through the analysis of the organizational interface between TC4 and TiCoCuNiV intermediate layer, the interface layer is mainly composed of Ti-rich intermetallic compounds and a small amount of Ti2Ni phase. In the entire joint area, the intermediate layer of TiCoCuNiV alloy is mainly composed of face-centered cubic phase and body-centered cubic phase. The face-centered cubic phase includes bright white Cu-rich phase and light gray (Ni,Ti)-rich face-centered cubic phase, and the body-centered cubic phase is mainly dark gray body-centered cubic matrix phase. The TiCoCuNiV alloy intermediate layer exists in the form of solid solution.

[0060] Example 2 The alloys are connected in accordance with the method of Example 1, except that step S3 includes: placing the parts to be connected in a vacuum hot pressing sintering furnace, applying a pressure of 5 MPa to the sample to be welded, and waiting for the vacuum degree in the furnace to drop to 2.5×10 -3Pa, heat to 350°C at a heating rate of 5°C / min, then heat to 700°C at a heating rate of 15°C / min, keep at 700°C for 20min, then heat to 900°C at a rate of 10°C / min, keep for 60min, and connect.

[0061] Example 3 The alloys are connected in accordance with the method of Example 1, except that step S3 includes: placing the parts to be connected in a vacuum hot pressing sintering furnace, applying a pressure of 5 MPa to the sample to be welded, and waiting for the vacuum degree in the furnace to drop to 2.5×10 -3 Pa, heat to 350°C at a heating rate of 5°C / min, then heat to 700°C at a heating rate of 15°C / min, keep at 700°C for 20min, then heat to 930°C at a rate of 10°C / min, keep for 60min, and connect.

[0062] Example 4 The alloys are connected in accordance with the method of Example 1, except that step S3 includes: placing the parts to be connected in a vacuum hot pressing sintering furnace, applying a pressure of 5 MPa to the sample to be welded, and waiting for the vacuum degree in the furnace to drop to 2.5×10 -3 Pa, heat to 350°C at a heating rate of 5°C / min, then heat to 700°C at a heating rate of 15°C / min, keep at 700°C for 20min, then heat to 960°C at a rate of 10°C / min, keep for 60min, and connect.

[0063] Example 5 The alloys are connected in accordance with the method of Example 1, except that step S3 comprises: placing the parts to be connected in a vacuum hot pressing sintering furnace, applying a pressure of 10 MPa to the sample to be welded, and waiting for the vacuum degree in the furnace to drop to 2.5×10 -3 Pa, heat to 350°C at a heating rate of 5°C / min, then heat to 700°C at a heating rate of 15°C / min, keep at 700°C for 20min, then heat to 960°C at a rate of 10°C / min, keep for 60min, and connect.

[0064] Example 6 The alloys are connected in accordance with the method of Example 1, except that step S3 includes: placing the parts to be connected in a vacuum hot pressing sintering furnace, applying a pressure of 15 MPa to the sample to be welded, and waiting for the vacuum degree in the furnace to drop to 2.5×10 -3 Pa, heat to 350°C at a heating rate of 5°C / min, then heat to 700°C at a heating rate of 15°C / min, keep at 700°C for 20min, then heat to 960°C at a rate of 10°C / min, keep for 60min, and connect.

[0065] Example 7 The alloys are connected in accordance with the method of Example 5, except that step S3 includes: placing the parts to be connected in a vacuum hot pressing sintering furnace, applying a pressure of 10 MPa to the sample to be welded, and waiting for the vacuum degree in the furnace to drop to 2.5×10 -3 Pa, heat to 650°C at a heating rate of 5°C / min, keep at 650°C for 20min, then heat to 960°C at a rate of 10°C / min, keep for 60min, and then connect.

[0066] Example 8 The alloys are connected according to the method of Example 5, except that step S3 includes: the holding time after heating to 960° C. is 30 minutes.

[0067] Example 9 The alloys are connected according to the method of Example 5, except that step S3 includes: the holding time after heating to 960° C. is 90 minutes.

[0068] Example 10 The alloys were connected according to the method of Example 5, except that in step S2, the foil was polished to a thickness of 30 μm (±5 μm).

[0069] Embodiment 11 The alloys were connected according to the method of Example 5, except that in step S2, the foil was polished to a thickness of 40 μm (±5 μm).

[0070] Example 12 The alloys were connected according to the method of Example 5, except that in step S2, the foil was polished to a thickness of 60 μm (±5 μm).

[0071] Example 13 The alloys were connected according to the method of Example 5, except that in step S2, the foil was polished to a thickness of 70 μm (±5 μm).

[0072] Embodiment 14 The alloys were connected according to the method of Example 5, except that the TiCoCuNiV alloy ingot-1 was replaced by TiCoCuNiV alloy ingot-2.

[0073] Embodiment 15 The alloys were connected according to the method of Example 5, except that TiCoCuNiV alloy ingot-1 was replaced by TiCoCuNiV alloy ingot-3.

[0074] Example 16 The alloys were connected according to the method of Example 5, except that TiCoCuNiV alloy ingot-1 was replaced by TiCoCuNiV alloy ingot-4.

[0075] Embodiment 17 The alloys were connected according to the method of Example 5, except that TiCoCuNiV alloy ingot-1 was replaced by TiCoCuNiV alloy ingot-5.

[0076] Embodiment 18 The alloys are connected according to the method of Example 1, except that step S4 includes: after the connection is completed, the temperature is lowered to 690° C. at a rate of 5° C. / min, then cooled to room temperature in the furnace and the pressure is unloaded to take out the alloy.

[0077] Comparative Example 1 The alloys were connected according to the method of Example 1, except that the TiCoCuNiV alloy ingot-1 was replaced by a TiCoCuNi ingot.

[0078] Comparative Example 2 The alloys were connected in the same manner as in Example 1, except that the TiCoCuNiV alloy ingot-1 was replaced by a TiCoCuV ingot.

[0079] Comparative Example 3 The alloys were connected according to the method of Example 1, except that the TiCoCuNiV alloy ingot-1 was replaced by the TiCoNiV ingot.

[0080] Comparative Example 4 The alloys were connected in accordance with the method of Example 1, except that the TiCoCuNiV alloy ingot-1 was replaced by a TiCoCuNiFe ingot.

[0081] Comparative Example 5 The alloys were connected in accordance with the method of Example 1, except that the TiCoCuNiV alloy ingot-1 was replaced by a CoNiFe ingot.

[0082] Test Case The connecting test pieces in the above embodiments and comparative examples were tested for shear strength using a mold (see Figure 3 ), the testing instrument is INSTRON5969 electronic universal material testing machine, the loading speed is 0.5.mm / min, and the results are shown in Table 1.

[0083] Table 1

[0084] It can be seen from the results in Table 1 that the shear strength of the embodiments is greater than that of the comparative examples, indicating that the method provided by the present invention for connecting TC4 titanium alloy and TiAl alloy can effectively improve the shear strength of the connection joint and facilitate subsequent applications.

[0085] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for connecting TC4 titanium alloy and TiAl alloy, characterized in that: The method comprises the following steps: S1, placing a TiCoCuNiV alloy foil between a TC4 titanium alloy and a TiAl alloy for assembly to obtain a part to be connected; S2. Performing vacuum hot pressing treatment on the parts to be connected.

2. The method according to claim 1, characterized in that In the step S1, the atomic ratio of titanium, cobalt, copper, nickel and vanadium in the TiCoCuNiV alloy foil is 1.1-1.3:1:0.9-1.1:0.9-1.1:0.7-0.

9.

3. The method according to claim 2, characterized in that The atomic ratio of titanium, cobalt, copper, nickel and vanadium in the TiCoCuNiV alloy foil is 1.15-1.25:1:0.95-1.05:0.95-1.05:0.75-0.

85.

4. The method according to any one of claims 1 to 3, characterized in that The preparation method of the TiCoCuNiV alloy foil comprises: placing copper, nickel, cobalt, titanium and vanadium metals in a container in sequence, and then performing vacuum arc melting to obtain a TiCoCuNiV alloy ingot; and cutting and polishing the TiCoCuNiV alloy ingot to obtain a TiCoCuNiV alloy foil.

5. The method according to any one of claims 1 to 3, characterized in that: The method further comprises: before placing the TiCoCuNiV alloy foil between the TC4 titanium alloy and the TiAl alloy, cutting the TC4 titanium alloy and the TiAl alloy into connection samples.

6. The method according to any one of claims 1 to 3, characterized in that: The thickness of the TiCoCuNiV alloy foil is 40-60 μm.

7. The method according to any one of claims 1 to 3, characterized in that The vacuum hot pressing treatment step includes: applying a connection pressure of 5-15 MPa to the parts to be connected, and controlling the vacuum degree to be less than or equal to 2.5×10 -3 Pa, heat to the second temperature T2 and keep for 10-30 minutes, then heat to the third temperature T3 and keep for 30-90 minutes.

8. The method according to claim 7, characterized in that The vacuum hot pressing treatment step includes: applying a connection pressure of 5-15 MPa to the parts to be connected, and controlling the vacuum degree to be less than or equal to 2.5×10 -3 Pa, firstly heats to a first temperature T1 at a first heating rate, then heats to a second temperature T2 at a second heating rate and holds for 10-30 min, and finally heats to a third temperature T3 at a third heating rate and holds for 30-90 min, wherein the first heating rate is lower than the third heating rate, the third heating rate is lower than the second heating rate, the first temperature T1 is lower than the second temperature T2, and the second temperature T2 is lower than the third temperature T3.

9. The method according to claim 8, characterized in that The method further includes: cooling the product obtained by the vacuum hot pressing treatment to a fourth temperature T4 at a cooling rate of 2-6°C / min and then cooling it in the furnace, wherein the fourth temperature T4 is higher than the second temperature T2.

10. The method according to claim 9, characterized in that The first temperature T1 is 320-380°C, the second temperature T2 is 650-720°C, the third temperature T3 is 870-960°C, the fourth temperature T4 is 720-750°C, the first heating rate is 2-8°C / min, the second heating rate is 12-18°C / min, and the third heating rate is 8-12°C / min.

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