A method for preparing TiAl-Ti2AlNb laminated plate

Abstract

The present invention discloses a method for preparing a TiAl-Ti2AlNb laminated plate, comprising the following steps: S1: subjecting a TiAl alloy sheet and a Ti2AlNb alloy sheet assembled in a sheath to a high-temperature vacuum treatment, wherein the vacuum degree must reach 5×10 ‑3 Pa or less; wherein, the two thin plates are cross-stacked from top to bottom, and it is necessary to ensure that the top and bottom thin plates are both TiAl thin plates; S2: the jacketed sample after high-temperature vacuum treatment is heated to 1200°C-1280°C with the furnace, kept warm at this temperature for 1h~2h, then taken out and rolled on the rolling mill, the rolling speed is 5m / min~6m / min, the reduction between passes is 15%~18%, the return to the furnace and insulation time between passes is 10min~15min, the total deformation of rolling is 50%~75%, and the last pass of rolling is cooled with the furnace / air cooled to room temperature; S3: the jacketed sample after rolling treatment is unjacketed and stress-relief annealed. The preparation method provided by the present invention simplifies the preparation process, shortens the preparation cycle, and reduces production costs without affecting the formability of the plate.

Description

Technical Field

[0001] The invention belongs to the technical field of metal layered composite material preparation, and specifically relates to a method for preparing a TiAl-Ti2AlNb laminated plate. Background Art

[0002] With the rapid advancement of my country's aviation and aerospace industries, the requirements for high-temperature structural materials have been put forward as "stronger, stiffer, more heat-resistant and lighter". As a representative of the new generation of lightweight metal structural materials, TiAl alloy has a relatively low density (3.9-4.2g / cm 3 ), high specific strength and specific elastic modulus, low diffusion coefficient, excellent oxidation resistance and other characteristics, it has important application prospects in the preparation of aircraft skin, rudder, tail nozzle expansion adjustment plate and other thermal protection system components. However, due to the intrinsic brittleness of intermetallic compounds, TiAl alloy sheets are very easy to crack after damage. In order to solve the problem of low fracture toughness of TiAl alloy, it is proposed to prepare a laminated composite material (Metallic-Intermetallic-Laminate composite, MIL) by stacking a toughening material in the middle of TiAl alloy. The density of Ti2AlNb alloy is 5.0-5.8g / cm 3 , the service temperature is 650℃-750℃, which is second only to the service temperature of TiAl alloy (700℃-900℃). At the same time, it has excellent fracture toughness, impact toughness, fatigue resistance and other advantages, and is the most potential toughening material. Therefore, the preparation of TiAl-Ti2AlNb laminated plates is expected to make up for the poor toughness of TiAl alloy plates and improve their safety as hot end structural materials.

[0003] At present, there are some studies on the preparation of TiAl-Ti2AlNb composite plates, mainly including foil hot pressing method (CN110202867A), which generates TiAl and Ti2AlNb in situ by foil metallurgy vacuum hot pressing, but the multilayer composite plate generated by this method has more interface holes due to the Kirkendall effect, and the size of the composite plate is limited by practical problems such as equipment size and parameters. In addition, there are also many reports on the diffusion welding method to obtain TiAl-Ti2AlNb composite materials, mainly through cutting patterns, surface treatment, making assembly parts, welding and other steps, but due to the characteristics of low diffusion coefficient of intermetallic compounds, brittle compounds will be produced at the interface of heterogeneous joints, which will have an adverse effect on the connection interface and require long-term heat treatment to eliminate. For this reason, the method of jacket rolling is used to perform thermomechanical deformation on the TiAl-Ti2AlNb heterogeneous diffusion connection joint, which eliminates the interface brittle compounds and improves the joint strength at the same time. However, this method has a complex process and high cost, and the diffusion welding temperature is high and the time is long, which increases the preparation cycle and energy consumption. According to current patent inquiries and domestic and foreign literature reports, there is no physical picture of TiAl-based composite material published.

[0004] In summary, a method for preparing TiAl-Ti2AlNb layered composites in large quantities with simple process is urgently needed. Therefore, the present application designs a low-cost TiAl-Ti2AlNb laminated rolled plate based on hot jacket rolling. Summary of the invention

[0005] The purpose of the present invention is to prepare TiAl-Ti2AlNb layered composites, solve key problems such as interface holes, cracks, and formation of interface brittle compounds, simplify the preparation process, shorten the preparation cycle, and reduce production costs without affecting the formability of the sheet.

[0006] To achieve the above object, the present invention specifically provides a method for preparing a TiAl-Ti2AlNb laminated plate, comprising the following steps:

[0007] Step 1: The TiAl alloy sheet and Ti2AlNb alloy sheet assembled in the package are subjected to high temperature vacuum treatment, and the vacuum degree needs to reach 5×10 -3 Pa or less; wherein the TiAl alloy sheet and the Ti2AlNb alloy sheet are stacked crosswise from top to bottom, and it is necessary to ensure that the top layer and the bottom layer are both TiAl sheets;

[0008] Step 2: The wrapped sample after high-temperature vacuum treatment is heated to 1200°C-1280°C in the furnace, kept at this temperature for 1h-2h, and then taken out and rolled on the rolling mill. The rolling speed is 5m / min-6m / min, the reduction between passes is 15%-18%, the return and insulation time between passes is 10min-15min, the total deformation of rolling is 50%-75%, and the last rolling pass is cooled in the furnace / air-cooled to room temperature;

[0009] Step 3: After rolling, the jacketed sample is de-jacketed and subjected to stress relief annealing to obtain a TiAl-Ti2AlNb laminate.

[0010] As a further illustration of the present invention, the method further comprises, before performing step 1:

[0011] The cut TiAl alloy thin plates and Ti2AlNb alloy thin plates were ground to remove cutting marks and finely ground to 800 mesh;

[0012] The finely ground TiAl alloy sheets and Ti2AlNb alloy sheets are cleaned with 5vol.%-10vol.% HF to remove surface oxides, and completely immersed for 10s-30s until no bubbles are generated on the surface of the sheets; rinse with clean water for 1-2min, then use alcohol for ultrasonic cleaning for 5-10min, and blow dry for later use.

[0013] As a further description of the present invention, the package includes upper and lower covers and a middle frame, and the package material is 304 stainless steel.

[0014] As a further illustration of the present invention, the thickness of the upper and lower covers of the package is 5 mm, and the length and width are 25-30 mm larger than the sample size respectively. The thickness of the middle frame of the package is consistent with the sample thickness, the length and width are consistent with the upper and lower covers, and a 2 mm wide exhaust hole is left at the tail.

[0015] As a further illustration of the present invention, in step 1, the process of assembling the TiAl alloy sheet and the Ti2AlNb alloy sheet in the sheath specifically includes:

[0016] The TiAl alloy thin plate and the Ti2AlNb alloy thin plate are stacked crosswise from top to bottom, and both the top and bottom thin plates must be TiAl thin plates;

[0017] Yttrium oxide coating is applied to the outer layer of the stacked thin plates. After the coating is completely dry, a layer of tantalum foil is wrapped around the stacked thin plates. The whole is then placed inside a sheath and welded. During welding, a stainless steel pipe is connected to the tail of the sheath.

[0018] As a further illustration of the present invention, the high temperature vacuum treatment process in step 1 specifically includes:

[0019] The vacuum reached 5×10 -3 Pa, heating was started to rise to 200℃-300℃, and vacuum was drawn again to 5×10 -3 Pa; then continue to heat up to 500℃-600℃ and keep warm, and evacuate once more to 5×10 -3 Pa; finally, the temperature was raised to 800℃-850℃ and kept warm, and the vacuum was once again evacuated to 5×10 -3 Pa.

[0020] As a further illustration of the present invention, the vacuum degree in the staged heating and vacuuming process in step 1 cannot be less than 1×10 -2 Pa.

[0021] As a further illustration of the present invention, the stress relief annealing process in step 3 specifically includes:

[0022] The TiAl-Ti2AlNb laminated plate obtained after removing the sheath is kept at 800°C-850°C for 6 hours, and a pressure of 10-15KN is applied to level the plate, and then the plate is cooled to room temperature with the furnace to obtain a TiAl-Ti2AlNb laminated plate.

[0023] As a further illustration of the present invention, the specific composition of the TiAl alloy is Ti-43Al-4Nb-Mo-0.1Bat.%, and the specific composition of the Ti2AlNb alloy is Ti-22Al-25Nb at.%.

[0024] As a further illustration of the present invention, when the thin plates are stacked in step 1, the TiAl / Ti2AlNb layer thickness ratio ranges from 1.2 to 3.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] 1. The present invention adopts a vacuum jacket rolling method, omitting the step of vacuum diffusion welding, and successfully prepares TiAl-Ti2AlNb laminated rolled plates. Due to the extremely narrow range of vacuum diffusion welding parameters, the formation of interface brittle compounds is inevitable, and the formation of brittle compounds limits the relative sliding of TiAl and Ti2AlNb alloys during the initial deformation of rolling. The huge difference in the deformation capacity of TiAl and Ti2AlNb leads to stress concentration at the welding interface, which causes cracks in the interface and penetrates the TiAl alloy. While omitting the step of vacuum diffusion welding, the present invention also performs high-temperature vacuum jacketing, which greatly ensures the coordination of TiAl and Ti2AlNb alloys in the initial deformation stage, and ensures that the interface does not oxidize under high-temperature deformation. The high-temperature vacuum jacket rolling method allows the interface elements to diffuse fully under the action of thermal coupling, and no interface brittle compounds are formed. At the same time, the interface is well bonded, and no holes generated by the foil hot pressing method appear. The subsequent complex heat treatment process is avoided to eliminate interface defects, which fully saves labor costs, reduces the energy loss of equipment, shortens the preparation cycle, and reduces manufacturing costs. At the same time, the size of the board is not limited by the equipment, which further increases the possibility of industrial application.

[0027] 2. The present invention realizes the combination between dissimilar metallic compounds and successfully prepares a multilayer TiAl-Ti2AlNb layered composite. Based on the complexity of the TiAl alloy and Ti2AlNb alloy structure, the matrix and interface structure of the two alloys can be regulated by subsequent heat treatment methods to give full play to the advantages of the two alloys and further improve the mechanical properties of the TiAl-Ti2AlNb layered composite.

[0028] 3. The design concept of the present invention is based on the shell nacre structure, with the outer TiAl layer as a hard and brittle layer that is also resistant to high temperatures, and the inner Ti2AlNb layer as a tough layer. The multi-layer structure design hinders the rapid expansion of cracks in the TiAl layer, thereby improving the strength and toughness of the plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The figure is a schematic diagram of the assembled vacuum jacketed rolled piece in the present invention, wherein only three layers of TiAl-Ti2AlNb layered composite are shown, but the present invention is not limited thereto;

[0030] Figure 2 The actual pictures of TiAl-Ti2AlNb laminated rolled plates obtained by the present invention, wherein (a) has 3 layers, (b) has 5 layers, and (c) has 7 layers;

[0031] Figure 3 for Figure 2 BSE-SEM images of TiAl-Ti2AlNb laminated rolled plates with different numbers of layers. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The present invention provides a method for preparing a TiAl-Ti2AlNb laminated plate, comprising the following steps:

[0034] S1: material preparation, cutting a number of TiAl alloy thin plates and Ti2AlNb alloy thin plates by wire cutting, grinding off the wire cutting marks on a grinder, and fine grinding to 800 mesh.

[0035] S2: Surface treatment: clean the obtained TiAl and Ti2AlNb alloy sheets with 5vol.%-10vol.% HF to remove surface oxides, and completely soak for 10s-30s until no bubbles are generated on the surface of the sheet. Rinse with water for 1-2min, then use alcohol for ultrasonic cleaning for 5-10min, and blow dry with a hair dryer for later use.

[0036] S3: Preparation of the package, which includes upper and lower covers and a middle frame, and the package material is 304 stainless steel.

[0037] S4: Assemble, stack the TiAl alloy sheet and the Ti2AlNb alloy sheet crosswise from top to bottom, and ensure that the top and bottom sheets are both TiAl sheets; apply yttrium oxide coating on the outermost layer, and wrap a layer of tantalum foil after the coating is completely dry. After assembly, place it inside the 304 stainless steel sheath and weld it. When welding, connect a stainless steel tube to the tail of the sheath.

[0038] S5: Vacuum treatment: the welded samples are subjected to high-temperature vacuum treatment, and the vacuum degree reaches 5×10 -3 Below Pa.

[0039] S6: High temperature rolling, the sample is heated to 1200°C-1280°C with the furnace, kept at this temperature for 1h~2h, then taken out and rolled on the rolling mill, the rolling speed is 5m / min~6m / min, the reduction between passes is 15%~18%, the return to the furnace and holding time between passes is 10min~15min, the total deformation of rolling is 50%~75%, and the last rolling pass is completed. Cool with the furnace / air cool to room temperature.

[0040] S7: Mechanically remove the sheath, and use a mechanical processing method to remove the sheath of the TiAl-Ti2AlNb laminated rolled plate cooled to room temperature in S6.

[0041] S8: stress relief annealing, the TiAl-Ti2AlNb laminated rolled plate taken out in S7 is kept at 800°C to 850°C for 6 hours, and a pressure of 10-15KN is applied to level the rolled plate, and then cooled to room temperature with the furnace.

[0042] Further, in S1, the TiAl alloy uses the third generation β-γ type TiAl alloy with strong deformation ability, and the specific composition is Ti-43Al-4Nb-Mo-0.1B (at.%), and the Ti2AlNb synthesis is divided into Ti-22Al-25Nb (at.%), and the thickness is 1-3mm respectively. Because Ti2AlNb is very easy to deform at high temperature, and TiAl alloy is not easy to deform. After a large number of experimental explorations, the present application found that when the layer thickness ratio is less than 1.2, the Ti2AlNb alloy bears the main deformation, and the larger deformation causes the Ti2AlNb alloy to produce wrinkles. When the layer thickness ratio is greater than 3, the Ti2AlNb alloy is too thin, and the ability to increase the fracture toughness of the TiAl / Ti2AlNb layered composite as a toughness layer is significantly reduced, so the TiAl / Ti2AlNb layer thickness ratio is preferably 1.2-3.

[0043] Furthermore, in step S3, the thickness of the upper and lower covers is 5mm, and the length and width are 25-30mm larger than the sample size, respectively. The thickness of the middle frame of the package must be consistent with the thickness of the sample, and the length and width are consistent with the upper and lower covers, and a 2mm wide exhaust hole is left at the tail. Furthermore, in step S4, a stainless steel pipe with a length of 0.5m is connected to the tail of the package, and the welding port is aligned with the reserved 2mm opening.

[0044] Furthermore, in step S5, the vacuum is evacuated to 5×10 -3 Pa, heating was started to rise to 200℃-300℃, and vacuum was drawn again to 5×10 -3 Pa, then continue to heat up to 500℃-600℃, and then evacuate to 5×10 -3 Pa; finally, the temperature was raised to 800℃-850℃ and kept warm, and the vacuum was once again evacuated to 5×10 -3 Pa. After reaching the target vacuum degree, leave 5-10cm of steel tube length and seal the tube. It is worth noting that the vacuum degree in this staged heating and vacuuming process must not be less than 1×10 -2 Pa, otherwise the TiAl / Ti2AlNb interface is easily oxidized, causing cracking and failure of the composite interface.

[0045] The following is explained in conjunction with specific embodiments:

[0046] Example 1

[0047] This embodiment is a method for preparing a three-layer TiAl-Ti2AlNb layered composite material, which is specifically carried out according to the following steps:

[0048] Step 1, preparation of TiAl and Ti2AlNb alloy sheets:

[0049] Several TiAl alloy sheets and Ti2AlNb alloy sheets were cut by wire cutting, and the wire cutting marks were removed on a grinder and finely ground to 800 mesh; the chemical composition of the TiAl alloy blank was: Ti-43Al-4Nb-1Mo-0.2B (at.%), and the size of the TiAl alloy sheet was 30×50×3mm 3 The chemical composition of the Ti2AlNb alloy blank is: Ti-22Al-25Nb (at.%), and the size of the Ti2AlNb alloy sheet is 30×50×2mm 3 The TiAl and Ti2AlNb alloy sheets are cut from forged billets;

[0050] Step 2, surface treatment of TiAl and Ti2AlNb alloy sheets:

[0051] Clean the obtained TiAl and Ti2AlNb alloy sheets with 5vol.%-10vol.% HF to remove surface oxides, and soak them completely for 10s-30s until no bubbles are generated on the surface of the sheet. Rinse with water for 1-2min, then use alcohol for ultrasonic cleaning for 5-10min, and blow dry with a hair dryer for later use;

[0052] Step 3, package preparation:

[0053] The package assembly includes upper and lower covers, a middle frame, and a stainless steel pipe. The package material is 304 stainless steel. The dimensions of the upper and lower covers are 80×65×5mm. 3 , the outer ring size of the middle frame is 80×65×10mm 3 , the inner ring size is 40×55×10mm 3 , and process 4 R2 chamfers, leaving a 2mm hole in the center of the frame; the stainless steel tube is 0.5mm long, 10mm outer diameter, 2mm wall thickness, and one end is threaded;

[0054] Step 4, Assembly:

[0055] The TiAl-Ti2AlNb-TiAl sheets are assembled in stacking order, and yttrium oxide coating is applied on the outer TiAl alloy. After the coating is completely dry, a layer of tantalum foil is wrapped around the outer side of the TiAl-Ti2AlNb laminated composite. After wrapping, it is placed inside a 304 stainless steel sheath and welded. During welding, a stainless steel pipe is connected to the 2mm hole reserved in the sheath.

[0056] Step 5, vacuum treatment:

[0057] Vacuum treatment: the welded samples are subjected to high temperature vacuum treatment, and the vacuum degree reaches 5×10 -3 Pa or less; the specific steps are: vacuuming to 5×10 -3 Pa, heating was started to rise to 200℃ and then vacuum was evacuated to 5×10 -3 Pa, then continue to heat up to 500℃ and keep warm, and evacuate once more to 5×10 -3 Pa; finally, the temperature was raised to 800℃ and kept warm, and the vacuum was once again evacuated to 5×10 -3 Pa. After reaching the target vacuum degree, leave 5-10cm of steel tube length and seal the tube;

[0058] Step 6, high temperature rolling:

[0059] The sample was heated to 1250°C in the furnace, kept at this temperature for 2 hours, and then taken out and rolled on the rolling mill. The rolling speed was 5m / min, the reduction between passes was 15%, the return to the furnace and holding time between passes was 15min, the total deformation of rolling was 60%, and the last rolling pass was air-cooled to room temperature.

[0060] Step 7, machining to remove the sleeve:

[0061] The sheath of the TiAl-Ti2AlNb laminated plate cooled to room temperature is removed by mechanical processing;

[0062] Step 8, stress relief annealing:

[0063] The taken-out TiAl-Ti2AlNb laminated rolled plate was kept at 900°C for 6h, and a pressure of 15KN was applied to level the rolled plate, and then cooled to room temperature with the furnace.

[0064] Example 2

[0065] This embodiment is a method for preparing a 5-layer TiAl-Ti2AlNb layered composite material. The 5 layers are stacked in the order of TiAl-Ti2AlNb-TiAl-Ti2AlNb-TiAl, and the size of the TiAl alloy sheet is 30×50×2 mm. 3 , the size of Ti2AlNb alloy sheet is 30×50×1mm 3 .

[0066] Example 3

[0067] This embodiment is a method for preparing a 7-layer TiAl-Ti2AlNb layered composite material. The 7 layers are stacked in the order of TiAl-Ti2AlNb-TiAl-Ti2AlNb-TiAl-Ti2AlNb-TiAl, and the size of the TiAl alloy sheet is 30×50×1.3 mm. 3 , the size of Ti2AlNb alloy sheet is 30×50×1mm 3 .

[0068] The specific preparation process of the above-mentioned embodiments 2 and 3 is the same as that of embodiment 1 except for the above-mentioned stacking sequence and the specific number of stacked layers.

[0069] Figure 2 The actual picture of the TiAl-Ti2AlNb laminated rolled plate obtained by the present invention, wherein (a) is 3 layers, (b) is 5 layers, and (c) is 7 layers. It can be seen from the figure that the laminated plate prepared by the present invention has a high surface quality and has no defects such as cracks; the size of the laminated plate can be increased with the size of the initial plate and is not limited to the size shown in the figure.

[0070] Figure 3 for Figure 2 BSE-SEM images of TiAl-Ti2AlNb laminated rolled plates with different numbers of layers. It can be seen from the figure that the TiAl-Ti2AlNb interface is well bonded, without defects such as holes and cracks, and no AlNb2 brittle compounds are produced on the interface (brittle compounds often appear in laminated materials prepared by diffusion welding. The presence of this brittle phase will reduce the interface bonding force and deteriorate the mechanical properties of the material.)

[0071] It should be noted that, in this article, terms such as "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0072] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a TiAl-Ti2AlNb laminated plate, characterized in that: The following steps are involved: Step 1: The TiAl alloy sheet and Ti2AlNb alloy sheet assembled in the package are subjected to high temperature vacuum treatment, and the vacuum degree needs to reach 5×10 -3 Pa or less; wherein the TiAl alloy sheet and the Ti2AlNb alloy sheet are stacked crosswise from top to bottom, and it is necessary to ensure that the top layer and the bottom layer are both TiAl sheets; The high temperature vacuum treatment process specifically includes: vacuuming to 5×10 -3 Pa, heating was started to rise to 200℃-300℃, and vacuum was drawn again to 5×10 -3 Pa; then continue to heat up to 500℃-600℃ and keep warm, and evacuate once more to 5×10 -3 Pa; finally, the temperature was raised to 800℃-850℃ and kept warm, and the vacuum was once again evacuated to 5×10 -3 Pa; Step 2: The wrapped sample after high-temperature vacuum treatment is heated to 1200°C-1280°C with the furnace, kept at this temperature for 1h-2h, and then taken out and rolled on the rolling mill. The rolling speed is 5m / min-6m / min, the reduction between passes is 15%-18%, the return to the furnace and insulation time between passes is 10min-15min, the total deformation of rolling is 50%-75%, and the last rolling pass is cooled with the furnace or air-cooled to room temperature; Step 3: After rolling, the jacketed sample is de-jacketed and subjected to stress relief annealing to obtain a TiAl-Ti2AlNb laminate.

2. The method for preparing the TiAl-Ti2AlNb laminated plate according to claim 1, characterized in that: Before performing step 1, the method further comprises: The cut TiAl alloy thin plates and Ti2AlNb alloy thin plates were ground to remove cutting marks and finely ground to 800 mesh; The finely ground TiAl alloy sheets and Ti2AlNb alloy sheets are cleaned with 5vol.%-10vol.% HF to remove surface oxides, and completely immersed for 10s-30s until no bubbles are generated on the surface of the sheets; rinse with clean water for 1-2min, then use alcohol for ultrasonic cleaning for 5-10min, and blow dry for later use.

3. The method for preparing the TiAl-Ti2AlNb laminated plate according to claim 1, characterized in that: The package comprises an upper cover, a lower cover and a middle frame, and the package is made of 304 stainless steel.

4. The method for preparing the TiAl-Ti2AlNb laminated plate according to claim 3, characterized in that: The thickness of the upper and lower covers of the package is 5 mm, and the length and width are 25-30 mm larger than the sample size. The thickness of the middle frame of the package is consistent with the thickness of the sample, and the length and width are consistent with the upper and lower covers, and a 2 mm wide exhaust hole is left at the tail.

5. The method for preparing the TiAl-Ti2AlNb laminated plate according to claim 1, characterized in that: In step 1, the process of assembling the TiAl alloy sheet and the Ti2AlNb alloy sheet in the sheath specifically includes: The TiAl alloy thin plate and the Ti2AlNb alloy thin plate are stacked crosswise from top to bottom, and both the top and bottom thin plates must be TiAl thin plates; Yttrium oxide coating is applied to the outer layer of the stacked thin plates. After the coating is completely dry, a layer of tantalum foil is wrapped around the stacked thin plates. The whole is then placed inside a sheath and welded. During welding, a stainless steel pipe is connected to the tail of the sheath.

6. The method for preparing the TiAl-Ti2AlNb laminated plate according to claim 1, characterized in that: The vacuum degree in the staged heating and vacuuming process in step 1 cannot be less than 1×10 -2 Pa.

7. The method for preparing the TiAl-Ti2AlNb laminated plate according to claim 1, characterized in that: The stress relief annealing process in step 3 specifically includes: The TiAl-Ti2AlNb laminated plate obtained after removing the sheath is kept at 800°C-850°C for 6 hours, and a pressure of 10-15KN is applied to level the plate, and then the plate is cooled to room temperature with the furnace to obtain a TiAl-Ti2AlNb laminated plate.

8. The method for preparing the TiAl-Ti2AlNb laminated plate according to claim 1, characterized in that: The specific composition of the TiAl alloy is Ti-43Al-4Nb-Mo-0.1Bat.%, and the specific composition of the Ti2AlNb alloy is Ti-22Al-25Nbat.%.

9. The method for preparing the TiAl-Ti2AlNb laminated plate according to claim 1, characterized in that: When the thin plates are stacked in step 1, the TiAl / Ti2AlNb layer thickness ratio ranges from 1.2 to 3.

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