A method for preparing titanium-aluminum composite thin plate

Abstract

The present invention discloses a method for preparing a titanium-aluminum composite thin plate, comprising: selecting a titanium plate and an aluminum plate; determining the area of the original titanium plate and aluminum plate based on the principle of constant volume according to the size of the desired composite plate; performing surface treatment on the titanium plate and the aluminum plate respectively; spreading aluminum powder on the surface of the treated titanium plate or aluminum plate, and then placing the corresponding aluminum plate or titanium plate; placing the sandwich structure in a vacuum heating furnace for heat preservation treatment; partially fusing the two plates by the heat generated by the spontaneous combustion of the aluminum powder, and holding the heat for a sufficient time to allow the atoms to diffuse with each other, thereby achieving a tight bond between the titanium plate and the aluminum plate; performing multiple asynchronous rolling on the tightly bonded titanium-aluminum composite plate, with the rolling reduction in subsequent passes gradually decreasing; annealing the composite blank to eliminate residual stress and work hardening, and remove surface oxides, thereby obtaining a titanium-aluminum composite plate with a small thickness and a large area, thereby improving processing quality and utilization rate, saving titanium with aluminum, and reducing costs.

Description

Technical Field

[0001] The invention belongs to the technical field of composite materials and relates to a method for preparing a titanium-aluminum composite thin plate. Background Art

[0002] Titanium and its alloys possess high specific strength, excellent heat resistance, corrosion resistance, and biocompatibility, resulting in significant applications in aerospace, automotive, and medical fields. Although titanium ranks tenth in the Earth's crust, its smelting technology remains challenging due to its high production costs. Consequently, the high cost of titanium and its alloys restricts their widespread use. Composite plates, using aluminum as the matrix and titanium as the reinforcement, can significantly reduce titanium usage, significantly lowering costs. Furthermore, composite plates offer the advantages of both, leveraging the low density and high thermal conductivity of aluminum with the high-temperature and corrosion resistance of titanium while achieving lightweight performance. However, due to the significant differences in mechanical properties between titanium and aluminum and the complex plastic processing of titanium, achieving deformation coordination during subsequent processing and synthesis is challenging, making industrial production difficult. Therefore, developing a process technology and equipment to manufacture high-quality titanium-aluminum composite plates suitable for industrial production is crucial.

[0003] Currently, the thickness of lightweight sheets is generally too thick to meet the needs of larger and thicker devices such as mobile phones, computer casings, and car wheels. It cannot meet the needs of higher requirements such as audio eardrums and magnetic shielding of signal transmitters. In addition, there is not much research in my country on ultra-thin lightweight sheets. For the preparation of ultra-thin sheets, it is difficult to obtain them using conventional extrusion methods or even explosive forming. Moreover, the crystal structure of titanium alloy is a close-packed hexagonal structure with only three slip systems, so it is difficult to undergo large-scale deformation at room temperature. During the hot rolling process, due to the excessive thinness of the sheet and the rapid cooling rate, it is difficult to ensure temperature control, resulting in cracks on the processed surface, side cracks, and plate misalignment during the rolling process. This leads to high scrap rate of the sheet, reduced utilization rate, and increased cost. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for preparing titanium-aluminum composite thin plates, which has small thickness and large area, improves processing quality and utilization rate, saves titanium with aluminum, reduces costs, and solves the problems existing in the prior art.

[0005] The technical solution adopted by the present invention is a method for preparing a titanium-aluminum composite thin plate, comprising the following steps:

[0006] Step 1. Select titanium plate and aluminum plate;

[0007] Step 2: Determine the area of the original titanium plate and aluminum plate according to the size of the required composite plate and the principle of constant volume; perform surface treatment on the titanium plate and aluminum plate respectively;

[0008] Step 3: Spread aluminum powder with a particle size of 800-1000 mesh on the surface of the treated titanium plate or aluminum plate, and then place the corresponding aluminum plate or titanium plate; place the sandwich structure consisting of the aluminum plate, aluminum powder, and titanium plate in a vacuum heating furnace for 3-5 hours of insulation treatment at a temperature of 550-580°C; the heat generated by the spontaneous combustion of the aluminum powder sandwiched between the titanium plate and the aluminum plate partially fuses the two plates, and the atoms diffuse into each other, so that the titanium plate and the aluminum plate are tightly bonded;

[0009] Step 4: performing multiple asynchronous rolling on the tightly bonded titanium-aluminum composite plate, with the rolling reduction of subsequent passes gradually decreasing;

[0010] Step 5: Anneal the composite blank completed in step 4 to eliminate residual stress and work hardening, and remove surface oxides.

[0011] Furthermore, in step 1, the aluminum plate is selected from one of grades 1100, 5083, 6061 or 7075, and the titanium plate is a pure titanium plate of α, β or α+β, or one of a series of titanium alloy plates.

[0012] Furthermore, in step 1, the thickness of the titanium plate is no more than 3 mm, and the thickness of the aluminum plate is 3-5 mm.

[0013] Furthermore, in step 2, the surface treatment of the titanium plate and the aluminum plate includes: sandblasting to remove surface oxide scale, alcohol cleaning and drying, and acetone ultrasonic cleaning to remove surface oil stains.

[0014] Furthermore, in step 3, the vacuum degree is not less than 10 -2 Pa.

[0015] Furthermore, in step 3, the aluminum powder is spread by spraying with a powder spray gun, randomly spreading by hand, or spreading row by row.

[0016] Furthermore, in step 4, the temperature of the asynchronous rolling is 400-420°C, the holding time is 15-20 min, the rolling speed is 5-10 mm / s, the rolling force is 200-300 MPa, the first rolling reduction rate is 50-60%, and 3-8 passes of hot rolling are continued according to the thickness of the composite plate, and the rolling reduction gradually decreases to 10-20%.

[0017] Furthermore, in step 4, after each asynchronous rolling pass, the composite blank is placed in a vacuum furnace and annealed at 350-380° C. for 0.5-1 h before the next asynchronous rolling pass.

[0018] Furthermore, in step 5, the composite blank completed in step 4 is annealed at 300-320° C. for 1-2 hours to eliminate residual stress and work hardening.

[0019] Furthermore, the thickness of the prepared titanium-aluminum composite thin plate is no more than 0.1 mm, and the width of the composite plate is 0.01 m to 1.5 m.

[0020] The beneficial effects of the present invention are:

[0021] This invention employs a specific method of local fusion, cleverly utilizing the exothermic reaction of aluminum powder to resolve the issues of poor weld strength and conventional rolling. It also utilizes interatomic diffusion and grain boundary sliding to compensate for the poor plastic deformation of titanium alloys. Furthermore, asynchronous rolling technology addresses the cracking problem associated with conventional rolling of heterogeneous materials. The ultra-thin composite plate produced by this invention is no thicker than 0.1 mm, boasts a large surface area, and maintains flatness, with no hollowing or edge cracking, thus improving its quality. The yield strength and tensile strength at room temperature reach 180 MPa and 210 MPa, respectively, with an elongation of 17.8%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1 is a flow chart of an embodiment of the present invention.

[0024] Figure 2 Schematic diagram of asynchronous rolling technology in an embodiment of the present invention; (a) is asynchronous rolling with the same diameter, (b) is rolling with different friction coefficients of the upper and lower rollers, and (c) is asynchronous rolling with different diameters.

[0025] Figure 3 These are SEM and EDS analysis images of the interface of the Ti / Al composite thin plate prepared in Example 1 of the present invention; (a) is the SEM of the interface of the Ti / Al composite thin plate, (b) is a local enlarged image of (a), (c) is a local enlarged image of (b), and (d) is the EDS analysis image of the interface of the Ti / Al composite thin plate. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0027] Example 1,

[0028] A method for preparing a titanium-aluminum composite thin plate, such as Figure 1 As shown, the following steps are included:

[0029] Step 1: Select raw materials. The composite sheet can be made of either pure metal or alloy, depending on performance requirements. For example, the aluminum sheet can be selected from 1100, 5083, 6061, and 7075. The titanium sheet is typically α-pure titanium, β-pure titanium, or α+β-pure titanium, or a titanium alloy. In this example, the titanium sheet is α-pure titanium, 3 mm thick; the aluminum sheet is 1100, 4 mm thick.

[0030] Step 2: Pretreatment: The dimensions of the original titanium and aluminum plates are determined based on the desired composite sheet size and the principle of volume invariance. These dimensions must also conform to the working dimensions of the rolling mill. The plates are then surface treated by sandblasting to remove surface oxide scale, alcohol cleaning and drying, and acetone ultrasonic cleaning to remove surface oil stains.

[0031] Step 3: Vacuum diffusion connection: Spread aluminum powder with a particle size of 900 mesh on the titanium plate selected in step 2, then put the aluminum plate on it and place them in a vacuum heating furnace (vacuum degree 10 -2 Pa) and kept at 560 ° C for 4 hours. The heat generated by the spontaneous combustion of aluminum powder sandwiched between the titanium plate and the aluminum plate is used to partially fuse the two. Then, the long-term heat preservation allows the atoms to diffuse with each other, thus achieving a relatively tight bond.

[0032] Step 4: Asynchronous rolling. The rolling process is as follows: Figure 2 As shown in the figure, the rolling temperature, rolling pressure, and rolling passes during the rolling process have a very important influence on the structure and organization of the plate. Therefore, the reasonable control of these parameters is the key to the process. If the heating temperature is too high, the grain size of the aluminum plate will grow abnormally and the grain size will coarsen, causing the mechanical properties of the composite material to deteriorate. It may also cause the titanium plate to spontaneously combust or strongly oxidize. If the heating temperature is too low, the plastic deformation performance of the titanium plate will not be improved, and cracks will easily form during the rolling process, which may cause the titanium plate to break.

[0033] In this embodiment, a rolling temperature of 410°C and a holding time of 18 minutes were selected. Furthermore, due to the poor plasticity of titanium in the composite material, deformation during rolling is difficult. If the rolling reduction is too small and fails to reach the critical reduction ratio, the plates will not recombine and will separate. Therefore, a higher reduction ratio is selected. Similarly, due to the poor plasticity, the rolling pressure cannot be too high, as excessive pressure can easily cause the material to neck and crack. Considering factors such as rolling temperature and time, and through practical exploration, a rolling speed of 8 mm / s, a rolling force of 250 MPa, and a rolling reduction ratio of 55% were used. One rolling pass was performed to obtain composite blank I.

[0034] Put the composite blank I into a vacuum furnace (vacuum degree not less than 10 -1 Annealing at 350°C for 1 hour in a 1000-gallon (Pa) chamber facilitates diffusion between the individual sheet atoms, increases the bonding strength between the sheets, and improves plastic deformation. Subsequently, annealed composite blank I was heated to 410°C for 15 minutes. After removal, it was rolled twice with a controlled reduction of 40% to obtain composite blank II.

[0035] Place the composite blank II into a vacuum furnace (vacuum degree not less than 10 -1 Annealing at 350°C for 1 hour in a 1000-degree Celsius (Pa) chamber facilitates diffusion between the individual sheet atoms, increases the bonding strength between the sheets, and improves plastic deformation. Subsequently, the annealed composite blank II was heated at 410°C for 15 minutes. After removal, three passes of rolling were performed with a controlled reduction of 30% to obtain composite blank III.

[0036] The 4th and 5th hot rolling passes can be continued according to the thickness requirement of the composite plate, but the rolling reduction of subsequent passes is gradually reduced to 20%, 10%, etc. Otherwise, edge cracking is likely to occur.

[0037] Step 5: Post-processing: The composite blank III completed in step 4 is annealed at 320°C for 2 hours to eliminate residual stress and work hardening. A fourth hot rolling pass is performed, and step 5 is repeated. A fifth hot rolling pass is then performed. Surface oxides are then removed by mechanical rough grinding, sandblasting, or chemical etching to obtain a titanium-aluminum composite plate.

[0038] The size of the titanium-aluminum composite plate produced in this embodiment is 300mm×2000mm×0.1mm, the thickness of the over-plating layer does not exceed 1 micron, the yield strength and tensile strength at room temperature reach 180MPa and 210MPa respectively, and the elongation reaches 17.8%. Interface SEM and EDS analysis, such as Figure 3As shown in (a); 0.2mm and 0.54mm in (a) represent the thickness changes of the aluminum plate and titanium plate after three rolling passes. Titanium has great strength, so the change is small; line1 in (c) represents the line scan along the interface, that is, the marked part is the path of the electronic scan; it can be seen from (d) that, in addition to the main alloying elements of titanium and aluminum, the others are small amounts of alloying elements contained in the material.

[0039] Example 2,

[0040] A method for preparing a titanium-aluminum composite thin plate comprises the following steps:

[0041] Step 1: Select a titanium plate and an aluminum plate. The aluminum plate is selected from grade 7075. The titanium plate is an α+β pure titanium plate. The thickness of the titanium plate is 2 mm, and the thickness of the aluminum plate is 3 mm.

[0042] Step 2: Pretreatment: Based on the desired composite sheet dimensions, the original titanium and aluminum sheet sizes are determined based on the principle of volume retention, which must also conform to the mill's operating dimensions. The sheets are then surface treated by sandblasting to remove surface scale, alcohol cleaning and drying, and acetone ultrasonic cleaning to remove surface oil stains.

[0043] Step 3, vacuum diffusion bonding: sprinkle aluminum powder with a particle size of 800 mesh on the titanium plate selected in step 2, then place the aluminum plate on it and place them in a vacuum heating furnace (vacuum degree 10 -3 The titanium plate and the aluminum plate are partially fused together by the heat generated by the spontaneous combustion of the aluminum powder sandwiched between the titanium plate and the aluminum plate. The long-term heat preservation allows the atoms to diffuse with each other, thus achieving a relatively tight bond.

[0044] Step 4, asynchronous rolling; select the rolling temperature at 400°C, the holding time at 20 min, the rolling speed at 5 mm / s, the rolling force at 200 MPa, the rolling reduction rate at 50%, and perform rolling once to obtain the composite blank I.

[0045] The composite blank I is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank I after annealing was annealed at 360°C for 0.8h in a heat treatment plant (Pa). The composite blank I was then taken out and rolled for two passes with a rolling reduction of 40% to obtain a composite blank II.

[0046] The composite blank II is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank II after annealing was annealed at 400°C for 15 min, and after being taken out, the rolling pressure was controlled to 30% for 3 passes to obtain the composite blank III.

[0047] The composite blank III is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank III was annealed at 400°C for 15 min and then taken out and rolled with a reduction of 25% for 4 passes to obtain the composite blank IV.

[0048] The composite blank IV was placed in a vacuum furnace (vacuum degree 10 -1 The composite blank IV after annealing was annealed at 400°C for 15 min, and after being taken out, the rolling reduction was controlled at 25% for 5 passes to obtain the composite blank V.

[0049] The composite blank V is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank V after annealing was annealed at 400°C for 15 min, and after being taken out, the rolling reduction was controlled at 25% for 6 passes to obtain the composite blank VI.

[0050] The composite blank VI is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank VI after annealing was heated to 400°C for 15 min, and after being taken out, the rolling pressure was controlled to be 25% and rolled for 7 times to obtain the composite blank VII.

[0051] The composite blank VII is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank VII was annealed at 360°C for 0.8 h in a vacuum oven (Pa). The annealed composite blank VII was then heated to 400°C for 15 min. After being taken out, the composite blank was rolled for 8 passes with a rolling reduction of 20% to obtain the composite blank VII.

[0052] Step 5: Post-processing: The composite blank VII completed in step 4 is annealed at 310°C for 1.5 hours to eliminate residual stress and work hardening. Surface oxides are then removed by mechanical rough grinding, sandblasting, or chemical etching to obtain a titanium-aluminum composite plate.

[0053] The size of the titanium-aluminum composite plate prepared in this embodiment is 200 mm×1000 mm×0.05 mm, and the tensile strength at room temperature is 203 MPa and the elongation is 15.1%.

[0054] Example 3,

[0055] A method for preparing a titanium-aluminum composite thin plate comprises the following steps:

[0056] Step 1: Select a titanium plate and an aluminum plate. The aluminum plate is selected from grade 6061. The titanium plate is a titanium alloy. The thickness of the titanium plate is 1 mm, and the thickness of the aluminum plate is 5 mm.

[0057] Step 2: Pretreatment: Based on the desired composite sheet dimensions, the original titanium and aluminum sheet sizes are determined based on the principle of volume retention, which must also conform to the mill's operating dimensions. The sheets are then surface treated by sandblasting to remove surface scale, alcohol cleaning and drying, and acetone ultrasonic cleaning to remove surface oil stains.

[0058] Step 3: Vacuum diffusion bonding: Sprinkle aluminum powder with a particle size of 1000 mesh on the aluminum plate selected in step 2, then place the titanium plate and place them in a vacuum heating furnace (vacuum degree 10 -5 The titanium plate and the aluminum plate are partially fused together by the heat generated by the spontaneous combustion of the aluminum powder sandwiched between them. Then, the long-term heat preservation allows the atoms to diffuse with each other, thus achieving a relatively tight bond.

[0059] Step 4, asynchronous rolling; select the rolling temperature at 420°C, the holding time at 15 min, the rolling speed at 10 mm / s, the rolling force at 300 MPa, the rolling reduction rate at 60%, and perform rolling once to obtain the composite blank I.

[0060] The composite blank I is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank I after annealing was annealed at 420°C for 15 min, and after being taken out, the rolling reduction was controlled to 40% for two passes to obtain the composite blank II.

[0061] The composite blank II is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank II after annealing was annealed at 420°C for 15 min, and after being taken out, the rolling reduction was controlled to 30% for 3 passes to obtain the composite blank III.

[0062] Repeat the above process three times to obtain composite blank VI.

[0063] The composite blank VI is placed in a vacuum furnace (vacuum degree 10 -1 The composite blank VI after annealing was annealed at 420°C for 15 min, and after being taken out, the rolling reduction was controlled to 20% for 7 passes to obtain the composite blank VII.

[0064] Step 5: Post-processing: The composite blank VII completed in step 4 is annealed at 300°C for 1 hour to eliminate residual stress and work hardening. Surface oxides are then removed by mechanical rough grinding, sandblasting, or chemical etching to obtain a titanium-aluminum composite plate.

[0065] Titanium and aluminum differ greatly in terms of crystal structure (aluminum is a face-centered cubic crystal structure, titanium is a close-packed hexagonal structure) and basic properties (aluminum has a melting point of over 600 degrees and good plasticity, while titanium has a melting point of over 1,000 degrees and poor plasticity and toughness). Ordinary rolling technology (applying the same load, the same rolling rate, and the same pressing wheel during rolling) is difficult to meet. If they are to be deformed synchronously, it is inevitable that one will meet the requirements, while the other will either crack or fail to deform; or, the composite plate requires a difference in thickness between the two materials. In the embodiment of the present invention, the thickness of the composite plate is relatively small, and asynchronous rolling is adopted. Asymmetrical rolling (AR) is used to deform the plate with uneven forces on the upper and lower parts, including three types, namely asynchronous rolling of the same diameter, rolling with different friction coefficients of the upper and lower rollers, and asynchronous rolling of different diameters, such as Figure 2 The characteristic of asynchronous rolling is the existence of a "rolling zone". When the reduction is the same, the plate grains are made finer and more uniform, and it is also conducive to the occurrence of dynamic recrystallization.

[0066] The particle size range of the aluminum powder sprinkled in the embodiment of the present invention is 800-1000 mesh (average particle size of about 10 microns). If the particle size is too small, the surface energy is too large and it is easy to spontaneously combust; if the particle size is too large, it may not burn at this heating temperature, and local high temperature will not be generated, thereby playing the role of spot welding; the local high temperature generated by spontaneous combustion in the heating furnace is instantly spot welded to the aluminum plate and the titanium plate, and the amount of aluminum powder sprinkled is 0.2-0.5 kg / m 2 If too much aluminum powder is sprinkled, the aluminum plate to be rolled may melt, or a brittle phase of titanium-aluminum compound may be generated, resulting in poor performance of the composite plate. If too little is sprinkled, there will be too few corresponding welding points, which is not conducive to subsequent rolling and also affects the bonding strength. Therefore, the aluminum powder is required to be randomly spread between the titanium plate and the aluminum plate to form spot welding.

[0067] The size of the titanium-aluminum composite plate prepared in this embodiment is 100 mm×3000 mm×0.03 mm, and the tensile strength at room temperature is 280 MPa and the elongation is 13.1%.

[0068] Comparative Example 1,

[0069] The same as steps 1-3 of Example 1, except that steps 4-5 are omitted; alternatively, the movement of the metal particles on the contact surface of the plates is intensified by heating, pressurizing, or the like, causing the metal particles to diffuse into each other's matrix. After the additional energy is removed, the mobility of the metal particles decreases due to the interaction between the particles and the decrease in temperature, resulting in some of the titanium particles that have moved into the aluminum matrix and some of the aluminum particles in the titanium matrix failing to return to their original substrates, thereby forming a diffusion layer at the contact interface to obtain a titanium-aluminum composite plate. The resulting plate has low strength, making it difficult to obtain a composite plate with a small thickness and a large area.

[0070] Comparative Example 2,

[0071] Titanium-aluminum composite plates are produced through explosive lamination. This involves using the high-pressure shock wave generated by the explosive detonation to cause the titanium and aluminum plates to collide at extremely high speeds. During this process, the substrates undergo plastic deformation, thus bonding together to form a composite plate. Due to the extremely large shock wave generated during the explosive lamination process, if the substrate is too thin, the impact of the shock wave will cause it to shatter, preventing the formation of a composite plate. Generally, the minimum thickness of the plates is 6mm, and specialized equipment is required, resulting in high costs.

[0072] Comparative Example 3,

[0073] Titanium-aluminum composite plates are prepared by solid-liquid casting and rolling; the maximum shear strength of the titanium-aluminum composite plates prepared by this technology reaches 108Mpa (the Ti / Al composite plates prepared by Yanshan University and others by casting and rolling have a tensile strength of 172.3MPa, due to the local appearance of TiAl3 hard and brittle phases at the interface); this technology first requires melting the aluminum material, pouring it on the titanium plate, and then rolling it after solidification, which requires additional smelting equipment. More importantly, it is easy to form a hard and brittle TiAl intermetallic compound phase at the bonding interface, affecting the strength and toughness of the composite plate.

[0074] Comparative Example 4,

[0075] Titanium-aluminum composite plates are produced through a rolling composite method; this involves using the rolling pressure of a rolling mill to induce severe plastic deformation in the metal sheets, thereby forming bonding points at the contact surfaces of the plates and producing a composite plate. For example, titanium and aluminum plates are homogenized and heat-treated, their surfaces cleaned, and then stacked. After the ends are welded, protective steel plates are stacked on top of each other. An anti-sticking layer (Al2O3 nanoparticles) is applied between the steel and composite plates, and multiple hot rolling passes are performed to produce ultra-thin titanium-aluminum composite plates. Their room-temperature tensile strength exceeds 200 MPa. This technique requires end welding and the addition of a steel protective sleeve, which requires greater rolling force. Consequently, the resulting sheet thickness is difficult to achieve below 0.1 mm.

[0076] The present embodiment cannot be used to apply alumina powder. Alumina powder is a ceramic powder with an extremely high melting point (above approximately 1800°C), making it difficult to achieve spot welding using the methods of the present embodiment. In the present embodiment, the aluminum powder can be applied using a powder spray gun, randomly sprinkled by hand, or spread row by row like wheat. The present embodiment utilizes the exothermic reaction after aluminum combustion to achieve localized spot welding without forming intermetallic compounds. This prevents subsequent rolling from creating "hard spots" that could affect deformation uniformity. Uniformity is irrelevant, as unevenness creates irregular welds, which facilitates the bonding of the composite plate. Furthermore, these localized welds are a transitional stage; true bonding is achieved through subsequent intensive rolling, atomic diffusion at high temperatures, and mechanical meshing (or metallurgical bonding).

[0077] Prior art 1 (CN 108296288 A) uses pulsed current to create arcs between nanoparticles and the plate to melt and weld. This method uses pulsed discharge welding to weld the nanoparticles at specific points, requiring a powerful pulse power supply. Otherwise, welding a single point in just a few seconds is difficult; in practical applications, both a pulse power supply and a pulse welding head are required. The present invention utilizes the exothermic reaction generated by the combustion of aluminum powder to achieve localized fusion, completing the process in a single pass, improving production efficiency and eliminating the need for point-by-point welding. Even if individual points are not welded, subsequent rolling and annealing at a specific temperature can achieve a high-quality bond.

[0078] Existing composite plates mostly use explosive welding and rolling technology, which has problems such as large plate thickness, the need for special occasions and protection, wavy interfaces, cold welds and cracks. The ultra-thin composite plate prepared in the embodiment of the present invention has a thickness of no more than 0.1mm and a large width (0.01m~1.5m, depending on the length of the rolling roller), that is, a large area. At the same time, it is technically difficult to ensure that the composite plate is uniform (flatness), has no hollows, and has no edge cracks. The embodiment of the present invention adopts a specific method of local fusion and cleverly utilizes the exothermic reaction of aluminum powder to solve the problem of poor bonding strength between cold welds and ordinary rolling. It further solves the problem of cracks that are prone to occur in ordinary rolling of heterogeneous materials through asynchronous rolling technology. The asynchronous rolling and the multi-pass control of rolling temperature and rolling amount are all obtained through a large number of experimental studies.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of protection of the present invention.

Claims

1. A method for preparing a titanium-aluminum composite thin plate, characterized in that: The following steps are involved: Step 1. Select titanium plate and aluminum plate; Step 2: Determine the size of the original titanium plate and aluminum plate according to the required size of the composite plate and the principle of constant volume; perform surface treatment on the titanium plate and aluminum plate respectively; Step 3: Spread aluminum powder with a particle size of 800-1000 mesh on the surface of the treated titanium plate or aluminum plate, and then place the corresponding aluminum plate or titanium plate; place the sandwich structure consisting of the aluminum plate, aluminum powder, and titanium plate in a vacuum heating furnace for 3-5 hours of insulation treatment at a temperature of 550-580°C; the heat generated by the spontaneous combustion of the aluminum powder sandwiched between the titanium plate and the aluminum plate partially fuses the two plates, and the atoms diffuse into each other, so that the titanium plate and the aluminum plate are tightly bonded; Step 4: performing multiple asynchronous rolling on the tightly bonded titanium-aluminum composite plate, with the rolling reduction of subsequent passes gradually decreasing; Step 5: Anneal the composite blank completed in step 4 to eliminate residual stress and work hardening, and remove surface oxides.

2. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: In step 1, the aluminum plate is selected from one of grades 1100, 5083, 6061 or 7075, and the titanium plate is a pure titanium plate of α, β or α+β, or one of a series of titanium alloy plates.

3. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: In step 1, the thickness of the titanium plate is no more than 3 mm, and the thickness of the aluminum plate is 3-5 mm.

4. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: In step 2, the surface treatment of the titanium plate and the aluminum plate includes: sandblasting to remove surface oxide scale, alcohol cleaning and drying, and acetone ultrasonic cleaning to remove surface oil stains.

5. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: In step 3, the vacuum degree is not less than 10 -2 Pa.

6. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: In step 3, the aluminum powder is spread by spraying with a powder spray gun, randomly spreading by hand, or spreading row by row.

7. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: In step 4, the temperature of the asynchronous rolling is 400-420° C., the holding time is 15-20 min, the rolling speed is 5-10 mm / s, the rolling force is 200-300 MPa, the first rolling reduction ratio is 50-60%, and 3-8 passes of hot rolling are continued according to the thickness of the composite plate, and the rolling reduction gradually decreases to 10-20%.

8. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: In the step 4, after each asynchronous rolling, the composite blank is placed in a vacuum furnace and annealed at 350-380° C. for 0.5-1 h before the next asynchronous rolling.

9. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: In step 5, the composite blank completed in step 4 is annealed at 300-320° C. for 1-2 hours to eliminate residual stress and work hardening.

10. The method for preparing a titanium-aluminum composite thin plate according to claim 1, characterized in that: The thickness of the prepared titanium-aluminum composite thin plate is no more than 0.1 mm, and the width of the composite plate is 0.01 m to 1.5 m.

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