A two-stage heterogeneous layered Ti-Al composite material and a method for preparing the same

Abstract

The application discloses a two-stage heterogeneous layered Ti-Al composite material and a preparation method thereof. The two-stage heterogeneous layered Ti-Al composite material comprises a titanium foil bottom layer, and at least one structural unit layer is sequentially solidified on the upper surface of the titanium foil bottom layer; the structural unit layer is formed by laminating and solidifying at least one coarse-grained aluminum foil layer, at least one fine-grained aluminum foil layer and a titanium foil surface layer; the coarse-grained aluminum foil and the fine-grained aluminum foil are alternately arranged; and the titanium foil surface layer is located at the uppermost layer of the structural unit layer. The preparation method of the two-stage heterogeneous layered Ti-Al composite material is as follows: on the basis of a friction stir fine-grained processing, fine-grained aluminum foils and coarse-grained aluminum foils and titanium foils are solidified and formed under low-temperature conditions by using an ultrasonic additive manufacturing technology; the two-stage heterogeneous layered structure has small residual stress, compact structure, quantitatively controllable thickness proportion of coarse-grained and fine-grained layers and titanium-aluminum layers, and tightly combined interfaces between layers; and the comprehensive mechanical properties of the alloy material can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of layered heterogeneous composite materials technology, specifically to a two-level heterogeneous layered Ti-Al composite material and its preparation method. Background Technology

[0002] Bimetallic layered composite materials possess excellent properties such as high strength, toughness, and impact resistance, making them one of the main candidate materials for key structures in aerospace equipment and automobiles. Layered Ti-Al composites combine the high strength, high stiffness, corrosion resistance, and good creep resistance of titanium with the low density, ease of processing, and low cost of aluminum, showing great application potential. However, the relatively low strength and damping of aluminum and its alloys are among the main problems that Ti-Al composites need to overcome to operate in extreme environments.

[0003] Aluminum alloys with ultrafine or even nanocrystalline structures can achieve high strength and good room-temperature damping properties, but their ductility and toughness decrease significantly. Currently, constructing coarse-fine grain heterogeneous structures is commonly used to address the strength-ductility inversion problem in metallic materials. For example, in a coarse-fine grain layered structure, fine grains provide high strength, while coarse grains provide high ductility. During material stress, the interface between the coarse and fine grain regions activates microscopic mechanisms such as back stress strengthening, work hardening, and crack passivation, resulting in better ductility and toughness than homogeneous fine grains, and higher strength than homogeneous coarse grains. However, existing research on coarse-fine grain layered structures only exists in single metals, such as aluminum alloys, and the current methods for designing coarse-fine grain layered structures rely on metal rolling technology and laser / arc additive manufacturing technology. Traditional metal rolling technology can obtain a mixed coarse-fine grain structure, but because its control method is a holistic approach, it is difficult to accurately control the volume fraction, grain size, and grain distribution of coarse-grained and fine-grained aluminum layers in layered composite materials. Laser / arc additive manufacturing technology can also achieve rapid preparation of multilayer metal structures, but the high temperature during the forming process can cause coarsening of small-sized grains and large residual stress, resulting in component segregation, coarse grains, and non-dense structure in the finished product, thus reducing the overall mechanical properties.

[0004] In summary, no effective process method has yet been proposed for introducing a coarse-fine grain layered structure into the aluminum phase of Ti-Al composites. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a two-level heterogeneous layered Ti-Al composite material and its preparation method.

[0006] The technical solution adopted in this invention is:

[0007] A two-level heterogeneous layered Ti-Al composite material includes a titanium foil bottom layer, and at least one structural unit layer is sequentially solidified on the upper surface of the titanium foil bottom layer. The structural unit layer is formed by stacking and solidifying at least one layer of coarse-grained aluminum foil, at least one layer of fine-grained aluminum foil, and a titanium foil surface layer. The coarse-grained aluminum foil and the fine-grained aluminum foil are alternately arranged, and the titanium foil surface layer is located at the top of the structural unit layer.

[0008] Furthermore, the fine-grained aluminum foil is obtained by wire cutting after a fine-graining treatment of aluminum plate raw material through friction stirring.

[0009] Furthermore, the thickness of the titanium foil bottom layer is 0.1–0.2 mm, the thickness of the titanium foil surface layer in the structural unit layer is 0.1–0.2 mm, the thickness of the fine-grained aluminum foil is 0.1–0.5 mm, and the thickness of the coarse-grained aluminum foil is 0.1–0.5 mm.

[0010] The above-mentioned method for preparing a two-level heterogeneous layered Ti-Al composite material includes the following steps:

[0011] 4.1) Pretreatment: Remove surface oil stains from titanium foil raw materials, aluminum foil raw materials and aluminum plate raw materials with acetone, wipe them clean with anhydrous ethanol, and let them air dry before use;

[0012] 4.2) Refining treatment: The pretreated aluminum plate raw material is fixed on the worktable of the friction stir welding machine, and the stirring tool head is started to perform friction stir processing to obtain a fine grain structure;

[0013] 4.3) Processing the bottom layer and unit layer materials for lamination: Cut the aluminum plate that has undergone fine grain treatment into the required size to obtain fine-grained aluminum foil; cut the pretreated titanium foil raw material and aluminum foil raw material into the required size to obtain titanium foil bottom layer, titanium foil top layer and coarse-grained aluminum foil respectively;

[0014] 4.4) Cleaning treatment: Clean the surfaces of the fine-grained aluminum foil, titanium foil bottom layer, titanium foil top layer and coarse-grained aluminum foil obtained in step 3) with anhydrous ethanol and then air dry;

[0015] 4.5) Simultaneous consolidation of titanium foil bottom layer and unit layer: First, place the cleaned titanium foil bottom layer on the worktable of the ultrasonic consolidation equipment, and then lay coarse-grained aluminum foil, fine-grained aluminum foil and titanium foil surface layer on it in sequence to form a consolidation unit. After preheating to a certain temperature, ultrasonic consolidation is started to obtain a two-level heterogeneous layered Ti-Al composite material with a structural unit layer.

[0016] The above-mentioned method for preparing a two-level heterogeneous layered Ti-Al composite material includes the following steps:

[0017] 5.1) Pretreatment: Remove surface oil stains from titanium foil raw materials, aluminum foil and aluminum plate raw materials with acetone, wipe them clean with anhydrous ethanol, and air dry them for later use;

[0018] 5.2) Refining treatment: The pretreated aluminum plate raw material is fixed on the worktable of the friction stir welding machine, and the stirring tool head is started to perform friction stir processing to obtain a fine grain structure;

[0019] 5.3) Processing the bottom layer and unit layer materials for lamination: Cut the aluminum plate that has undergone fine grain treatment into the required size to obtain fine-grained aluminum foil; cut the pretreated titanium foil raw material and aluminum foil raw material into the required size to obtain titanium foil bottom layer, unit layer titanium foil and coarse-grained aluminum foil respectively;

[0020] 5.4) Cleaning treatment: Clean the surfaces of the fine-grained aluminum foil, bottom titanium foil, unit layer titanium foil and coarse-grained aluminum foil obtained in step 3) with anhydrous ethanol and then air dry;

[0021] 5.5) Synchronous consolidation of titanium substrate and first unit layer: First, place the cleaned titanium substrate on the worktable of the ultrasonic consolidation equipment. Then, lay coarse-grained aluminum foil, fine-grained aluminum foil and unit layer titanium foil on it in a certain order to form a consolidation unit and fix it. After heating to a certain temperature, perform ultrasonic consolidation.

[0022] 5.6) Ultrasonic additive manufacturing: The second unit layer, the third unit layer, and so on, are sequentially welded on top of the solidified first unit layer to obtain a two-level heterogeneous layered Ti-Al composite material with n structural unit layers.

[0023] Furthermore, in the fine crystallization process, the length of the stirring needle is 0.5–5.5 mm, the root diameter of the stirring needle is 6–8 mm, and the tip diameter is 5–6 mm; the tilt angle of the stirring tool head is 0°, the indentation depth is 0.05–0.25 mm, the rotation speed is 400–1200 rpm, the travel speed of the stirring tool head is 15–180 mm / min, and the distance between the axes of the stirring tool heads of adjacent processing paths is the tip diameter of the stirring needle.

[0024] Furthermore, in the grain refinement step, a cooling circulating water system is used for auxiliary cooling during the friction stir processing, and argon is used as a protective atmosphere. This allows for better grain refinement, resulting in nanocrystals; the use of an argon protective atmosphere prevents oxidation of the foil surface.

[0025] Furthermore, the process parameters for ultrasonic consolidation are as follows: ultrasonic amplitude 28–35 μm, normal pressure 2000–2500 N, travel speed 20–25 mm / s, and preheating temperature 140–190 °C.

[0026] Furthermore, the ultrasonic welding electrode travels in a straight line from one end of the foil to the other, then welds back to the starting point in the opposite direction, performing two processing passes until all areas of the foil are solidified.

[0027] The beneficial effects of this invention are as follows: Given coarse-grained and fine-grained aluminum foils obtained beforehand, this invention uses ultrasonic welding to bond the coarse-grained and fine-grained aluminum foils together with titanium foil. Ultrasonic additive manufacturing technology can be completed at low temperatures or even room temperature, featuring minimal material deformation, stable microstructure, and high interfacial bonding strength. It avoids the problems of small-size grain coarsening and high residual stress caused by the high temperatures associated with existing diffusion welding and explosive welding processes. Compared to existing technologies, this invention has the following advantages:

[0028] (1) The present invention proposes a method for preparing a two-level heterogeneous layered Ti-Al composite material. Under the dual action of stirring and friction, the grains of the original coarse-grained aluminum material are refined. At room temperature, ultrafine-grained or even nano-grained structures with controllable grain size and uniform distribution can be obtained in aluminum and its alloys. This provides fine-grained aluminum components for the two-level heterogeneous layered Ti-Al composite material. The process is simple, energy-saving and environmentally friendly, with a wide range of raw materials and a high yield.

[0029] (2) The present invention proposes a method for preparing a two-level heterogeneous layered Ti-Al composite material. Based on the stirring friction fine grain treatment, ultrasonic additive manufacturing technology is used to complete the high-quality and rapid solidification of fine-grained aluminum foil and coarse-grained aluminum foil and titanium foil under low temperature conditions. This method overcomes the shortcomings of high temperature and high heat effect in preparing layered composite materials by diffusion bonding and explosive composite, such as grain coarsening, high process difficulty, high energy consumption and high cost. This technology is simple to operate, energy-saving and environmentally friendly, and has a high yield.

[0030] (3) The method for preparing a two-level heterogeneous layered Ti-Al composite material proposed in this invention can conveniently achieve the controllable preparation of layered Ti-Al composite materials with different specifications and properties by changing parameters such as the composition, layer thickness, number of stacked layers and stacking order of the original aluminum and titanium materials.

[0031] (4) The present invention proposes a method for preparing a two-level heterogeneous layered Ti-Al composite material. The prepared two-level heterogeneous layered structure has low residual stress, dense structure, and the ratio of coarse-fine grain layer and titanium-aluminum layer thickness can be quantitatively controlled. The interlayer interface is tightly bonded, which can effectively improve the comprehensive mechanical properties of the alloy material. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the two-stage heterogeneous layered titanium-aluminum composite material obtained in Example 1.

[0033] Figure 2This is a schematic diagram of the structure of the two-stage heterogeneous layered titanium-aluminum composite material obtained in Example 2.

[0034] Figure 3 The image shows the metallographic structure of the two-stage heterogeneous layered titanium-aluminum composite material obtained in Example 1.

[0035] Figure 4 The image shows the metallographic structure of the two-stage heterogeneous layered titanium-aluminum composite material obtained in Example 2.

[0036] Figure 5 This is a diagram of the interface structure of the two-stage heterogeneous layered titanium-aluminum composite material obtained in Example 2. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and a preferred embodiment.

[0038] Example 1

[0039] See Figure 1 This embodiment provides a two-level heterogeneous layered Ti-Al composite material A, including a titanium foil bottom layer 10. Three structural unit layers 20 are sequentially fixed on the upper surface of the titanium foil bottom layer 10. The structural unit layer 20 is formed by sequentially stacking and fixing a coarse-grained aluminum foil 21, a fine-grained aluminum foil 22, a coarse-grained aluminum foil 23, and a titanium foil surface layer 24. The titanium foil surface layer 24 is located at the top of the structural unit layer 20.

[0040] In this embodiment, the thickness of the titanium foil bottom layer 10 is 0.1 mm, the thickness of the titanium foil top layer 24 is 0.1 mm, the thickness of the fine-grained aluminum foil 22 is 0.25 mm, and the thickness of the coarse-grained aluminum foil 23 is 0.2 mm. In other embodiments, the thickness of the titanium foil bottom layer 10 may also be 0.1–0.2 mm, the thickness of the titanium foil top layer may also be 0.1–0.2 mm, the thickness of the fine-grained aluminum foil may also be 0.1–0.5 mm, and the thickness of the coarse-grained aluminum foil may also be 0.1–0.5 mm.

[0041] The preparation method of a two-level heterogeneous layered Ti-Al composite material A in Example 1 is as follows:

[0042] ① Take a rolled 6061 aluminum alloy sheet with a length × width × thickness of 150mm × 100mm × 6mm, a supplied titanium strip with a length × width × thickness of 600mm × 25mm × 0.1mm, and a supplied 1100 coarse-grained aluminum alloy strip with a length × width × thickness of 600mm × 25mm × 0.2mm. Remove the oil stains from the surface of the aluminum alloy sheet with acetone, wipe it clean with anhydrous ethanol, and let it air dry.

[0043] ② Fix the cleaned 6061 aluminum alloy sheet onto the worktable of the friction stir welding machine, with the clean surface of the sheet facing upwards. Place a 6061 aluminum alloy pad between the sheet and the worktable to prevent the aluminum sheet from overheating and connecting with the worktable.

[0044] ③ Install a stirring tool head with a shoulder diameter of 22mm and a stirring pin length of 4.8mm on a friction stir welding machine. Set the process parameters as follows: the stirring head rotates clockwise at 800rpm, the processing speed is 100mm / min, the downward pressure is 0.15mm, and the stirring head has no tilt angle. Then, use the friction stir welding equipment to process the aluminum plate in multiple passes to obtain 6061Al aluminum alloy plate with refined grains.

[0045] ④ The fine-grained 6061 aluminum alloy sheet after the above-mentioned friction stir treatment was cut using an electrical discharge wire cutting machine to obtain three pieces of fine-grained 6061 aluminum alloy foil with a size of 150mm×25mm×0.25mm; the above-mentioned titanium strip and 1100 coarse-grained aluminum alloy strip were cut using an electrical discharge wire cutting machine to obtain four pieces of titanium foil with a size of 150mm×25mm×0.1mm and six pieces of coarse-grained aluminum foil with a size of 150mm×25mm×0.1mm respectively;

[0046] ⑤ Clean the surfaces of the obtained fine-grained aluminum foil, titanium foil, and coarse-grained aluminum foil with anhydrous ethanol and then air dry them;

[0047] ⑥ Take the processed foil and stack it on the worktable of the ultrasonic consolidation equipment in the order of titanium foil 10, coarse-grained aluminum foil 21, fine-grained aluminum foil 22, coarse-grained aluminum foil 23, and titanium foil 24. Titanium foil 10 is the bottom layer, and a 6061 alloy pad is added between it and the worktable. The top titanium foil 24 and the bottom titanium foil 10 are clamped and fixed at both ends. Then, the worktable is preheated to 165°C so that the temperature of the foil is slightly higher than the recrystallization temperature of aluminum.

[0048] ⑦ Set the ultrasonic consolidation process parameters as follows: positive pressure 2000N, ultrasonic amplitude 28μm, consolidation speed 20mm / s. Then connect and form the three foil materials. During welding, the ultrasonic welding head moves 120mm along the length of the foil material and then welds back to the starting point in the opposite direction. That is, two processing passes are performed to complete the consolidation of the first structural unit layer 20, which includes 1100 coarse-grained aluminum foil, 6061 fine-grained aluminum foil, 1100 coarse-grained aluminum foil, and TA1 foil.

[0049] ⑧ The second and third groups of foils are successively welded onto the already solidified composite foil to obtain a two-level heterogeneous layered Ti-Al composite material A containing a heterogeneous aluminum layer with three structural unit layers 20 and a TA1 layer structure on the upper and lower surfaces.

[0050] The microstructure of the resulting two-level heterolayered Ti-Al composite material A is as follows: Figure 2 As shown, from Figure 2 As can be seen, the Ti-Al composite material B has good bonding between its layers, and there is no grain growth in the fine-grained layer; the mechanical properties of the composite material were measured by tensile test and are shown in Table 1.

[0051] Example 2

[0052] See Figure 2 This embodiment provides a two-level heterogeneous layered Ti-Al composite material B, including a titanium foil bottom layer 11. Three structural unit layers 30 are sequentially solidified on the upper surface of the titanium foil bottom layer 11. The structural unit layer 31 is formed by sequentially stacking and solidifying a coarse-grained aluminum foil 31, a fine-grained aluminum foil 32, and a titanium foil surface layer 33. The titanium foil surface layer 33 is located at the topmost layer of the structural unit layer 30.

[0053] The preparation method of a two-level heterogeneous layered Ti-Al composite material B in Example 2 is as follows:

[0054] ① Take a rolled 6061 aluminum alloy sheet with a length × width × thickness of 150mm × 100mm × 6mm, a supplied titanium strip with a length × width × thickness of 600mm × 25mm × 0.1mm, and a supplied 1100 coarse-grained aluminum alloy strip with a length × width × thickness of 600mm × 25mm × 0.2mm. Remove the oil stains from the surface of the aluminum alloy sheet with acetone, wipe it clean with anhydrous ethanol, and let it air dry.

[0055] ② Fix the cleaned 1060 aluminum alloy sheet onto the worktable of the friction stir welding machine, with the clean surface of the sheet facing upwards. Place a 6061 / 1060 aluminum alloy sheet between the sheet and the worktable to prevent the aluminum sheet from overheating and connecting with the worktable.

[0056] ③ Install a stirring tool head with a shoulder diameter of 22mm and a stirring pin length of 5.5mm on a friction stir welding machine. Set the process parameters as follows: the stirring head rotates clockwise at a speed of 600rpm, the processing speed is 150mm / min, the downward pressure is 0.1mm, and the stirring head has no tilt angle. Then, use the friction stir welding equipment to process the aluminum plate in multiple passes to obtain 1060Al plate with refined grains.

[0057] ④ The fine-grained 6061 aluminum alloy sheet after the above friction stir treatment was cut using an electrical discharge wire cutting machine to obtain three pieces of fine-grained 6061 aluminum alloy foil with dimensions of 150mm×25mm×0.25mm; the above-mentioned titanium strip and 1100 coarse-grained aluminum alloy strip were cut using an electrical discharge wire cutting machine to obtain four pieces of titanium foil with dimensions of 150mm×25mm×0.1mm and three pieces of coarse-grained aluminum foil with dimensions of 150mm×25mm×0.1mm respectively;

[0058] ⑤ Clean the surfaces of the obtained fine-grained aluminum foil, titanium foil, and coarse-grained aluminum foil with anhydrous ethanol and then air dry them;

[0059] ⑥ Take the processed foil and stack it on the worktable of the ultrasonic consolidation equipment in the order of titanium foil 11, coarse-grained aluminum foil 31, fine-grained aluminum foil 32, coarse-grained aluminum foil 33, and titanium foil 34. Titanium foil 11 is the bottom layer, and a 6061 alloy pad is added between it and the worktable. The top titanium foil 34 and the bottom titanium foil 11 are clamped and fixed at both ends. Then, the worktable is preheated to 170°C so that the temperature of the foil is slightly higher than the recrystallization temperature of aluminum.

[0060] ⑦ Set the ultrasonic consolidation process parameters as follows: positive pressure 2100N, ultrasonic amplitude 30μm, consolidation speed 22mm / s. Then connect the three foil materials to form a shape. During welding, the ultrasonic welding head moves 100mm along the length of the foil material and then welds back to the starting point in the opposite direction. That is, two processing passes are performed to complete the consolidation of the first group of composite foil materials.

[0061] ⑧ On the already solidified composite foil, the second and third groups of 1100-1060-TA1 foils are successively welded to obtain a two-level heterogeneous layered Ti-Al composite material containing 4 TA1 layers and 3 layers of fine-grained 1060-coarse-grained 1100 layered aluminum layers with TA1 layer structure on the upper and lower surfaces.

[0062] The microstructure of the two-level heterogeneous layered Ti-Al composite material B obtained in Example 2 is shown in the attached figure. Figure 4 As shown, the interface structure is as follows Figure 5 As shown, from Figure 4 and Figure 5 As can be seen, the Ti-Al composite material has good bonding between its layers, and no grain growth is observed in the fine-grained layer; the mechanical properties of the two-stage heterogeneous layered Ti-Al composite material B, measured by tensile testing, are shown in Table 1.

[0063] Comparative Example 1

[0064] A layered Ti-Al composite material C is prepared by the following method:

[0065] ① Take a titanium strip with a length × width × thickness of 600mm × 25mm × 0.1mm and a 1100 coarse-grained aluminum alloy strip with a length × width × thickness of 600mm × 25mm × 0.2mm. Remove the oil stains from the surface of the aluminum alloy sheet with acetone and wipe it clean with anhydrous ethanol. Let it air dry.

[0066] ② Place two titanium foils (150mm×25mm×0.1mm) and nine 6061 coarse-grained aluminum foils (150mm×25mm×0.1mm) on the worktable of the ultrasonic consolidation equipment in the order of titanium foil-coarse-grained aluminum foil-titanium foil; add a 6061 alloy pad between the bottom titanium foil and the worktable, and clamp and fix the ends of the top titanium foil and the bottom titanium foil. Then preheat the worktable to 165℃ so that the foil temperature is slightly higher than the recrystallization temperature of aluminum.

[0067] ③ The ultrasonic consolidation process parameters were set as follows: positive pressure 2000N, ultrasonic amplitude 28μm, and consolidation speed 20mm / s. Then, the three foil materials were connected and formed. During welding, the ultrasonic welding head traveled 120mm along the length of the foil material and then returned to the starting point in the opposite direction. That is, two processing steps were performed to complete the consolidation and forming of the foil material. The layered Ti-Al composite material C was obtained. The mechanical properties of the layered Ti-Al composite material C measured by tensile test are shown in Table 1.

[0068] Table 1 Quasi-static tensile properties of two-stage heterolayered Ti-Al composites

[0069]

[0070] As can be seen from Table 1, compared with composite materials that do not contain fine-grained aluminum layers, the composite material designed in this invention has significantly improved strength and little change in plasticity.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also within the protection scope of the present invention.

Claims

1. A two-level heterogeneous layered Ti-Al composite material, characterized in that, The device includes a titanium foil substrate, and at least one structural unit layer is sequentially bonded to the upper surface of the titanium foil substrate. The structural unit layer is formed by stacking and bonding at least one layer of coarse-grained aluminum foil, at least one layer of fine-grained aluminum foil, and a titanium foil surface layer. The coarse-grained aluminum foil and the fine-grained aluminum foil are alternately arranged, and the titanium foil surface layer is located at the top of the structural unit layer. The coarse-grained aluminum foil, the fine-grained aluminum foil, and the titanium foil are bonded together by an ultrasonic welding process. The fine-grained aluminum foil is obtained by wire cutting of aluminum plate raw material after a fine-graining treatment through stirring friction processing. In the fine crystallization process, the length of the stirring needle is 0.5–5.5 mm, the root diameter of the stirring needle is 6–8 mm, and the tip diameter is 5–6 mm; the tilt angle of the stirring tool head is 0°, the indentation depth is 0.05–0.25 mm, the rotation speed is 400–1200 rpm, the travel speed of the stirring tool head is 15–180 mm / min, and the distance between the axes of the stirring tool heads of adjacent processing paths is the tip diameter of the stirring needle; The process parameters for ultrasonic consolidation are: ultrasonic amplitude 28-35μm, normal pressure 2000-2500N, travel speed 20-25mm / s, and preheating temperature 140-190℃.

2. The two-level heterogeneous layered Ti-Al composite material according to claim 1, characterized in that, The thickness of the titanium foil bottom layer is 0.1–0.2 mm, the thickness of the titanium foil surface layer in the structural unit layer is 0.1–0.2 mm, the thickness of the fine-grained aluminum foil is 0.1–0.5 mm, and the thickness of the coarse-grained aluminum foil is 0.1–0.5 mm.

3. The method for preparing a two-level heterogeneous layered Ti-Al composite material as described in claim 1, characterized in that, Includes the following steps: 1) Pretreatment: Remove surface oil stains from titanium foil raw materials, aluminum foil raw materials and aluminum plate raw materials with acetone, wipe them clean with anhydrous ethanol, and let them air dry before use; 2) Refining treatment: The pretreated aluminum plate is fixed on the worktable of the friction stir welding machine, and the stirring tool head is started to perform friction stir processing to obtain a fine grain structure; 3) Processing the bottom layer and unit layer materials for lamination: Cut the aluminum plate that has undergone fine grain treatment into the required size to obtain fine-grained aluminum foil; cut the pretreated titanium foil raw material and aluminum foil raw material into the required size to obtain titanium foil bottom layer, titanium foil top layer and coarse-grained aluminum foil respectively; 4) Cleaning treatment: Clean the surfaces of the fine-grained aluminum foil, titanium foil bottom layer, titanium foil top layer and coarse-grained aluminum foil obtained in step 3) with anhydrous ethanol and then air dry; 5) Simultaneous consolidation of titanium foil bottom layer and unit layer: First, place the cleaned titanium foil bottom layer on the worktable of the ultrasonic consolidation equipment, and then lay coarse-grained aluminum foil, fine-grained aluminum foil and titanium foil surface layer on it in sequence to form a consolidation unit. After preheating to a certain temperature, ultrasonic consolidation is started to obtain a two-level heterogeneous layered TiAl composite material with a structural unit layer.

4. The method for preparing a two-level heterogeneous layered Ti-Al composite material according to claim 1, characterized in that, Includes the following steps: 1) Pretreatment: Remove surface oil stains from titanium foil raw materials, aluminum foil and aluminum plate raw materials with acetone, wipe them clean with anhydrous ethanol, and let them air dry before use; 2) Refining treatment: The pretreated aluminum plate is fixed on the worktable of the friction stir welding machine, and the stirring tool head is started to perform friction stir processing to obtain a fine grain structure; 3) Processing the bottom layer and unit layer materials for lamination: Cut the aluminum plate that has undergone fine grain treatment into the required size to obtain fine-grained aluminum foil; cut the pretreated titanium foil raw material and aluminum foil raw material into the required size to obtain titanium foil bottom layer, unit layer titanium foil and coarse-grained aluminum foil respectively; 4) Cleaning treatment: Clean the surfaces of the fine-grained aluminum foil, bottom titanium foil, unit layer titanium foil and coarse-grained aluminum foil obtained in step 3) with anhydrous ethanol and then air dry; 5) Synchronous consolidation of titanium substrate and first unit layer: First, place the cleaned titanium substrate on the worktable of the ultrasonic consolidation equipment. Then, lay coarse-grained aluminum foil, fine-grained aluminum foil and unit layer titanium foil on it in a certain order to form a consolidation unit and fix it. After heating to a certain temperature, perform ultrasonic consolidation. 6) Ultrasonic additive manufacturing: The second unit layer, the third unit layer, and so on, are sequentially welded on top of the solidified first unit layer until the nth unit layer is obtained, resulting in a two-level heterogeneous layered TiAl composite material with n structural unit layers.

5. The method for preparing a two-level heterogeneous layered Ti-Al composite material according to claim 1, characterized in that, In the fine crystallization process, a cooling circulating water system is used to assist cooling during the friction stirring process, and argon is used as a protective atmosphere.

6. The method for preparing a two-level heterogeneous layered Ti-Al composite material according to claim 1, characterized in that, The ultrasonic welding electrode travels in a straight line from one end of the foil to the other, then welds back to the starting point in the opposite direction, performing two processing steps until all areas of the foil are solidified.

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