A composite foil material and its preparation method, and a flexible display screen support backplate.

Abstract

This invention belongs to the field of flexible display screen technology, and specifically relates to a composite foil material and its preparation method, as well as a flexible display screen support backplate. The composite foil material of this invention includes a first region and a second region, which are distributed on a plane perpendicular to the thickness direction of the foil material. The plane perpendicular to the thickness direction includes a first direction and a second direction that are perpendicular to each other. Along the first or second direction, the second region is arranged in a cyclical pattern at least once. The material of the first region includes a metallic material (selected from at least one stainless steel, titanium alloy, or copper alloy). The material of the second region includes an aluminum-based composite material reinforced with particles or fibers. The composite foil material provided by this invention simultaneously possesses high strength, high elastic modulus, high thermal conductivity, low density, and high elongation to meet the requirements of repeated bending of the screen, and achieves the goals of overall weight reduction and thinning.

Description

Technical Field

[0001] This invention belongs to the field of flexible display screen technology, and specifically relates to a composite foil material and its preparation method, and a flexible display screen support backplate. Background Technology

[0002] With the rapid development and increasingly fierce competition in the 3C electronics industry, the lightweighting, ultra-thinning and high-performance of products such as mobile phones, computers and wearable electronic devices are the future development trends. Taking foldable phones as an example, in order to make them lighter and thinner, the weight reduction of components is calculated in "grams". Among them, the screen is one of the most critical and important components of foldable phones, and weight reduction and thinning are urgent. The support plate on the back of the mobile phone display screen plays a supporting role for the flexible screen, which puts forward high performance requirements for the materials: (1) The support material is required to have comprehensive performance of high strength (strong resistance to drop deformation), high elastic modulus (good stiffness), and high thermal conductivity (heat dissipation); (2) The bending area of ​​the support material has high elongation (good ductility) to meet the requirements of repeated bending of the screen for hundreds of thousands of times; (3) The material density is as low as possible and the thickness is as thin as possible (below 0.2mm) to achieve the goal of overall weight reduction and thinning.

[0003] Currently, most flexible screen support plates for 3C products use titanium alloys, stainless steel, and carbon fiber materials. Stainless steel and titanium alloys have high elongation, which can meet the requirements of repeated bending of the screen, but the materials are heavy and have poor thermal conductivity, which limits their applications. Carbon fiber materials are difficult to thin further after reaching a certain thickness due to complex manufacturing processes, and carbon fiber materials also have problems such as anisotropy of properties and poor thermal conductivity. In other words, existing aluminum-based composite materials cannot simultaneously meet the performance requirements of being ultra-thin, ultra-light, ultra-strong, and repeatedly bendable. Summary of the Invention

[0004] The purpose of this invention is to provide a composite foil material and its preparation method, as well as a flexible display screen support backplate. The composite foil material provided by this invention possesses comprehensive properties including high strength (strong resistance to drop deformation), high elastic modulus (good stiffness), and high thermal conductivity (heat dissipation), as well as low material density and high elongation (good ductility). The composite foil material has the lowest possible density and the thinnest possible thickness (below 0.2mm), meeting the requirements of being ultra-thin, ultra-light, ultra-strong, and repeatedly bendable. It can meet the requirements of hundreds of thousands of repeated bending cycles for the screen and helps achieve the goals of overall weight reduction and thinning.

[0005] The first aspect of the present invention provides a composite foil material, the composite foil material including a first region and a second region, the first region and the second region being distributed on a plane perpendicular to the thickness direction of the composite foil material; The plane perpendicular to the thickness direction of the composite foil includes a first direction and a second direction, which are perpendicular to each other; along the first direction or the second direction, the first region and the second region are arranged in a cycle at least once in the order of second region, first region, second region; The material of the first region includes metallic materials; the material of the second region includes aluminum-based composite materials. The metallic material is selected from at least one of stainless steel, titanium alloy, and copper alloy; The aluminum-based composite material is an aluminum-based composite material reinforced with particles or fibers.

[0006] In some alternative embodiments, the metal material is selected from at least one of stainless steel and titanium alloy; for example, the metal material may be selected from 630 stainless steel or TC4 titanium alloy.

[0007] In some alternative embodiments, the elongation of the metallic material is 8%-18%, the yield strength is 800-1000 MPa, and the elastic modulus is 100-200 GPa. The first region of this invention uses a specific metal material whose elongation, strength and modulus can meet the requirements for support and bending. At the same time, it is used only in the first region and will not affect the ultra-thin and ultra-light performance of the composite foil.

[0008] In some optional embodiments, the aluminum-based composite material has an elastic modulus of 170-230 GPa, a yield strength of 350-550 MPa, and a density of 2.7-3.0 g / cm³. 3 .

[0009] In some alternative embodiments, the aluminum-based composite material includes aluminum-based metal powder and reinforcement; The aluminum-based metal powder is selected from at least one of aluminum powder and aluminum alloy powder; The present invention does not specifically limit the aluminum alloy powder, and the aluminum alloy powder includes, but is not limited to, 2009 aluminum alloy, 2014 aluminum alloy, 5026 aluminum alloy, 5052 aluminum alloy, 6061 aluminum alloy, 6063 aluminum alloy, 7055 aluminum alloy, and 7075 aluminum alloy.

[0010] In some alternative embodiments, the reinforcing body is selected from at least one of Al2O3, SiC, Si, AlN, B4C, SiO2, TiB2, TiBW, graphene, carbon nanotubes, and carbon fibers; The volume content of the reinforcement in the aluminum matrix composite material is 30-70%.

[0011] The 30-70 vol.% particle-reinforced Al-based composite material in the edge areas on both sides has high strength, high modulus, high thermal conductivity, and low density, which can meet the structural performance requirements of the screen support plate.

[0012] Particle-reinforced aluminum matrix composites are lightweight, high-performance materials. By controlling the type and amount of reinforcing particles in the second region, the composite material can achieve a low density (density < 3.0 g / cm³). 3 It possesses excellent comprehensive properties such as high elastic modulus (>130GPa), high strength, and high thermal conductivity, enabling it to meet the requirements of ultra-lightweight, ultra-thin, and ultra-strong performance when used in 3C electronic products.

[0013] In some optional embodiments, the thickness of the composite foil is 0.08-0.2 mm; The width of the first region is 5-35mm; The width of the second region can be adjusted according to the actual situation. The present invention does not impose a specific limitation. In some optional embodiments, the width of the first region is 35-100mm. In some alternative implementations, a metal fusion region is further included between the first region and the second region, the metal fusion region including single planar fusion or toothed interlocking structure fusion.

[0014] In some alternative implementations, the cross-sectional shape of a single tooth of the toothed interlocking structure includes, but is not limited to, a triangle, a rectangle, a trapezoid, or an arc.

[0015] In some alternative embodiments, the metal fusion region further includes a transition metal material; the transition metal material includes at least one of aluminum, copper, nickel, chromium, and aluminum alloys.

[0016] A second aspect of the present invention provides a method for preparing a composite foil, comprising the following steps: One side of a metal material sheet is bonded to an aluminum-based composite material sheet, and the other side of the metal material sheet is bonded to another aluminum-based composite material sheet. The sheet is arranged in the order of aluminum-based composite material sheet, metal material sheet, and aluminum-based composite material sheet at least once and placed in a hot isostatic pressing sleeve to obtain a product to be pressed. At least one product to be pressed is subjected to hot isostatic pressing, mechanical thinning, and post-treatment to obtain the composite foil. The composite foil material is obtained by having a first direction and a second direction on a plane perpendicular to its thickness direction, the first direction and the second direction being perpendicular to each other; along the first direction or the second direction, the composite foil material is arranged in a cycle of aluminum-based composite material, metal material, and aluminum-based composite material at least once; Alternatively, one side of the metal material sheet is bonded to aluminum-based composite powder, and the other side of the metal material sheet is bonded to aluminum-based composite powder. The metal material sheet and aluminum-based composite powder are arranged in a hot isostatic pressing sleeve in the order of aluminum-based composite powder, metal material sheet and aluminum-based composite powder at least once to obtain the product to be pressed. At least one product to be pressed is subjected to hot isostatic pressing, mechanical thinning and post-treatment to obtain the composite foil. The composite foil is obtained by having a first direction and a second direction on a plane perpendicular to the thickness direction, the first direction and the second direction being perpendicular to each other; along the first direction or the second direction, the composite foil is arranged in the order of aluminum-based composite material, metal material, and aluminum-based composite material at least once in a cycle.

[0017] In some optional embodiments, the hot isostatic pressing (HIP) temperature is 420-600°C, the HIP pressure is 80-130 MPa, and the HIP holding time is 1-5 h. The vacuum degree during hot isostatic pressing is less than 1×10⁻⁶. -2 Pa.

[0018] In some alternative implementations, mechanical thinning includes, but is not limited to, wire cutting, laser cutting, and diamond wire cutting.

[0019] In some optional embodiments, the surface of the metal material sheet that is bonded to the aluminum-based composite material sheet or aluminum-based composite powder has a planar structure or a serrated structure; In some optional embodiments, the surface of the aluminum-based composite material sheet that is bonded to the metal material sheet has a planar structure or a toothed structure, and is bonded to the surface of the metal material sheet in a planar or toothed manner.

[0020] In some optional embodiments, prior to the bonding step, a surface treatment step is included on the surface of the metal material sheet that will be bonded to the aluminum-based composite material sheet or aluminum-based composite powder. In some optional embodiments, the surface treatment includes one or more combinations of chemical etching, mechanical polishing, sandblasting, shot peening, and metal plating. In some optional embodiments, prior to the bonding step, a surface treatment step is included on the surface of the aluminum-based composite material sheet that will be bonded to the metal material sheet. In some alternative embodiments, the surface treatment includes one or more combinations of chemical etching, mechanical polishing, sandblasting, shot peening, and metal plating.

[0021] In some optional embodiments, after the step of bonding one side of the metal material sheet to the aluminum-based composite powder, a transition metal material is further filled between the aluminum-based composite material sheet and the metal material sheet. In some optional embodiments, the transition metal material includes at least one of aluminum, copper, nickel, chromium, and aluminum alloys.

[0022] In some optional embodiments, the method for preparing the aluminum-based composite material sheet includes: Aluminum-based metal powder and reinforcement are ground and mixed, and then subjected to cold isostatic pressing and subsequent hot isostatic pressing to obtain the aluminum-based composite material sheet. In some alternative embodiments, the grinding and mixing includes ball milling; The ball milling process involves a ball milling speed of 130-150 rpm, a ball milling time of 10-40 h, and a ball-to-material ratio of (0.3-10):1. The pressure of the cold isostatic pressing is 80-180MPa, and the holding time of the cold isostatic pressing is 10-60min; The temperature of the post-heat isostatic pressing is 420-600℃, the pressure of the post-heat isostatic pressing is 80-130MPa, and the holding time of the post-heat isostatic pressing is 1-5h.

[0023] The vacuum degree during the post-hot isostatic pressing is less than 1×10⁻⁶. -2 Pa; In some alternative embodiments, the aluminum-based composite powder is prepared by grinding and mixing aluminum-based metal powder and reinforcing agents; In some alternative embodiments, the grinding and mixing includes ball milling; The ball milling speed for the ball milling mixture is 130~150 rpm, the ball milling time is 10-40 h, and the ball-to-material ratio is (0.3-10):1.

[0024] A third aspect of the present invention provides a flexible display screen support backplate, the flexible display screen support backplate comprising the above-described composite foil or the composite foil prepared by the above-described preparation method.

[0025] In some alternative implementations, the composite foil is used in the flexible display screens of foldable phones and foldable computers, and can also be used in the flexible display screens of 3C products such as tablet computers and wearable electronic devices.

[0026] In some optional embodiments, the composite foil is used to fabricate an ultra-thin flexible display screen support backplate for use in the flexible display screens of foldable phones and foldable computers, and can also be used in the flexible display screens of 3C products. These 3C products include, but are not limited to, computers, tablets, mobile phones, and wearable electronic devices.

[0027] Compared with the prior art, the present invention has the following beneficial effects: 1. The composite foil of this invention is composed of a particle-reinforced aluminum matrix composite material in the edge regions on both sides and a metal material in the middle region. The particle- or fiber-reinforced aluminum matrix composite material in the edge regions possesses high strength, high modulus, high thermal conductivity, and low density, meeting the structural performance requirements of the screen support plate while significantly reducing weight. The metal material (stainless steel, carbon steel, titanium, copper alloy) in the middle region has high elongation, meeting the requirements for etching and repeated bending of the support plate. By combining the particle-reinforced aluminum matrix composite material with the metal material in the middle region, and by removing a large amount of this material during subsequent support plate processing, the weight of the screen support plate is almost not increased. Therefore, the novel composite foil of this invention can simultaneously meet the requirements for structural support and bending of the screen, while also possessing high thermal conductivity and lightweight properties, achieving the performance requirements of ultra-thin, ultra-light, ultra-strong, and repeatedly bendable composite foil.

[0028] 2. The composite foil of the present invention has a narrow metal width of 5-35mm in the middle, and a large amount of it will be removed during the subsequent etching process of the support plate, so it will hardly increase the weight of the screen support plate.

[0029] 3. The composite foil of this invention uses a lightweight aluminum-based composite material (reinforcing body volume content 30-70%) for the two side regions (second region); wherein the reinforcing body is composed of one or more of Al2O3, SiC, Si, AlN, B4C, SiO2, TiB2, TiBW, graphene, carbon nanotubes, carbon fibers, etc. (not limited to these). The middle region utilizes the high elongation of the metal for precision etching and is repeatedly bent for use due to its high strength and high modulus. The two side regions utilize the high modulus, high strength, and high thermal conductivity of the material to provide support and heat dissipation for the flexible screen. The combination of the two materials further combines low density, high strength, high modulus, good elongation, and comprehensive performance such as support and heat dissipation for the flexible screen.

[0030] 4. In the composite foil preparation method provided by this invention, the 30-70 vol.% particle-reinforced Al-based composite material on both sides of the composite foil exhibits high strength and hardness but low elongation. Preparing foils thinner than 0.2 mm using traditional rolling and calendering processes is extremely difficult, as the material is prone to cracking. This is especially true when the particle content reaches 45% or more, as the material's low plasticity (elongation typically below 1%) makes material thinning virtually impossible during rolling. This invention employs mechanical thinning, a first-time application in the preparation of high-content particle-reinforced aluminum-based composite foils, enabling efficient thinning of foils thinner than 0.2 mm.

[0031] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 Example 1 provides a process flow diagram for the preparation of a composite foil; Figure 2 Example 7 provides a process flow diagram for the preparation of a composite foil; Figure 3 A schematic diagram of a novel aluminum-based composite foil prepared by hot isostatic pressing (HIP). Figure (a) is a schematic diagram of the novel aluminum-based composite foil prepared by hot isostatic pressing with a triangular transition layer in Example 1; Figure (b) is a schematic diagram of the novel aluminum-based composite foil prepared by hot isostatic pressing with a rectangular transition layer in Example 1; Figure (c) is a schematic diagram of the novel aluminum-based composite foil prepared by hot isostatic pressing with a straight transition layer in Example 1; and Figure (d) is a schematic diagram of the novel aluminum-based composite foil prepared by hot isostatic pressing with a powder-filled configuration on both sides of the middle region in Example 7. Figure 4 Images of three different aluminum-based composite materials; Among them, Figure (a) shows the triangular configuration of the transition layer in Example 1, Figure (b) shows the rectangular configuration of the transition layer in Example 1, and Figure (c) shows the straight configuration of the transition layer in Example 1; Figure 5 This is a diagram showing the actual thickness measurement of the composite foil prepared in Example 3; Figure 6 SEM images of both sides of the composite foil prepared in Example 5. Detailed Implementation

[0034] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0035] It should be understood that the terminology used herein is for the purpose of describing particular exemplary embodiments only and is not intended to be limiting. Unless the context clearly indicates otherwise, the singular forms “a,” “an,” and “described” as used herein may also include the plural forms. The terms “comprising,” “including,” “containing,” and “having” are inclusive and therefore indicate the presence of the stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein are not construed as requiring them to be performed in a particular order described or illustrated unless the order of performance is explicitly indicated. It should also be understood that additional or alternative steps may be used.

[0036] In the description of the embodiments of this invention, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this invention, "multiple" means two or more, unless otherwise explicitly defined.

[0037] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0038] In the description of the embodiments of this invention, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0039] In the description of the embodiments of the present invention, the term "multiple" refers to two or more (including two), similarly, "multiple groups" refers to two or more (including two groups), and "multiple pieces" refers to two or more (including two pieces).

[0040] In the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0041] Combination Figure 3 and Figure 4 The present invention provides a composite foil material, the composite foil material including a first region 1 and a second region 2, the first region 1 and the second region 2 being distributed on a plane perpendicular to the thickness direction of the foil material; The plane perpendicular to the thickness direction of the foil includes a first direction and a second direction, which are perpendicular to each other; along the first direction or the second direction, the first region and the second region are arranged in a cycle at least once in the order of second region 2, first region 1, and second region 2; the material of the first region 1 includes a metallic material; the material of the second region 2 includes an aluminum-based composite material; the metallic material is selected from at least one of stainless steel, titanium alloy, and copper alloy; the aluminum-based composite material is an aluminum-based composite material reinforced with particles or fibers.

[0042] In some alternative embodiments, the metallic material is selected from at least one of 630 stainless steel and TC4 titanium alloy; In some optional embodiments, the aluminum-based composite material includes aluminum-based metal powder and a reinforcing agent; the aluminum-based metal powder is selected from at least one of aluminum powder and aluminum alloy powder; the reinforcing agent is selected from at least one of Al2O3, SiC, Si, AlN, B4C, SiO2, TiB2, TiBW, graphene, carbon nanotubes, and carbon fibers; the volume content of the reinforcing agent in the aluminum-based composite material is 30-70%.

[0043] In some optional embodiments, the thickness of the composite foil is 0.08-0.2 mm; The width of the first region is 5-35mm; In some alternative implementations, a metal fusion region is further included between the first region and the second region, such as... Figure 3 As shown, the metal fusion region includes single-planar fusion or toothed interlocking structure fusion; In some alternative implementations, such as Figure 3As shown, the cross-sectional shape of a single tooth in the toothed interlocking structure includes a triangle, rectangle, trapezoid, or arc. In some optional embodiments, the metal fusion region further includes a transition metal material; the transition metal material includes at least one of aluminum, copper, nickel, chromium, and 6013Al aluminum alloy.

[0044] In some optional embodiments, the physical image of the composite foil provided by the present invention is as follows: Figure 4 As shown.

[0045] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or through existing methods; unless otherwise specified, the amounts of experimental reagents used are the amounts used in conventional experimental operations; unless otherwise specified, the experimental methods are conventional methods. It should be further noted that the following descriptions are merely exemplary and not intended to limit the specific scope of the invention. Moreover, the comparative examples below are selected to compare with the technical solutions of the present invention to demonstrate the advancement of the present invention, and do not necessarily represent prior art in this technical field.

[0046] Example 1 This embodiment provides a method for preparing a composite foil (composite foil including aluminum-based composite material and 630 stainless steel), the process flow diagram is as follows. Figure 1 As shown, the specific steps include the following: The aluminum-based composite material contains 50 vol.% silicon carbide (SiCp) reinforcing phase with a median particle size of 10 μm, and the aluminum alloy powder is 6013Al powder with a median particle size of 30 μm. The SiCp powder and 6013Al alloy powder were ball-milled at 150 rpm for 12 hours at a ball-to-powder ratio of 1:1. The mixed powder was sieved and then placed into a cold isostatic pressing (CIP) rubber sheath for 30 minutes at a pressure of 200 MPa. The CIP billet was then vacuum-degassed in a pit-type resistance furnace, with the vacuum level required to be less than 10 kJ / m² at the end of the degassed process. -2 Pa; The vacuum-degassed and sealed billet was subjected to hot isostatic pressing (HIP) sintering at a temperature of 520℃, a pressure of 80MPa, and a holding time of 2h. The HIP billet was then machined using diamond tools to remove the aluminum cladding on the surface of the billet, yielding a 50 vol.% SiCp / 6013Al composite billet with both sides.

[0047] The 50 vol.% SiCp / 6013Al aluminum-based composite material and 630 stainless steel prepared in the previous step were machined to form a triangular structure with 2 mm on each side and an included angle of 45° on the contact surface with the 630 stainless steel. After machining, the surface oxide layer was removed by mechanical wire polishing. Then, the two materials were assembled into the same package in the order of 50 vol.% SiCp / 6013Al + 630 stainless steel + 50 vol.% SiCp / 6013Al (see schematic diagram). Figure 3 As shown in Figure (a), a layer of 6013Al aluminum powder with a median particle size of 5 μm is uniformly spread between 50 vol.% SiCp / 6013Al and 630 stainless steel (the aluminum powder promotes interfacial bonding during sintering). The billet is degassed under vacuum in a pit-type resistance furnace, and the vacuum level is required to be less than 10 at the end of the degassed process. -2 Pa; The vacuum-degassed and sealed billet is subjected to hot isostatic pressing (HIP) sintering at a temperature of 580℃, a pressure of 80MPa, and a holding time of 2h. After removing the aluminum cladding, the billet is obtained. After the prepared ingot is processed to the specified size, it is thinned by diamond wire cutting to obtain a foil with a thickness ≤0.2mm. The foil is then subjected to heat treatment (including solution treatment and aging treatment), thermal tension leveling, and polishing to obtain the composite foil (see actual image). Figure 4 (Figure (a)). Solution treatment temperature 520℃, solution treatment time 1h, aging treatment temperature 180℃, aging treatment time 10h. On a plane perpendicular to the thickness direction of the composite foil, 50vol.%SiCp / 6013Al, 630 stainless steel, and 50vol.%SiCp / 6013Al are arranged sequentially along the first direction.

[0048] The composite foil, after heat treatment, has a tensile strength ≥500 MPa, a yield strength ≥450 MPa, and an elongation ≥1% for both sides made of 50 vol.% SiCp / 6013Al. The middle layer of 630 stainless steel has a tensile strength ≥1100 MPa, a yield strength ≥950 MPa, and an elongation ≥10%. The interfacial strength between the 50 vol.% SiCp / 6013Al and stainless steel is ≥190 MPa (tensile strength, yield strength, and elongation are tested according to the test methods in GB / T 288.1-2021, and the interfacial strength is tested according to the tensile strength test method in GB / T 288.1-2021).

[0049] Example 2 This embodiment provides a method for preparing a composite foil (composite foil including aluminum-based composite material and 630 stainless steel), comprising the following steps: The aluminum matrix composite material contains 50 vol.% SiCp reinforcing phase with a median SiCp particle size of 10 μm, and the aluminum alloy powder is 6013Al powder with a median particle size of 30 μm. The SiCp powder and 6013Al alloy powder were ball-milled at 150 rpm for 12 hours at a ball-to-powder ratio of 1:1. The mixed powder was sieved and then placed into a cold isostatic pressing (CIP) rubber sheath for 30 minutes at a pressure of 200 MPa. The CIP billet was then vacuum-degassed in a pit-type resistance furnace, with the vacuum level required to be less than 10 kJ / min at the end of the degassed process. -2 Pa; The vacuum-degassed and sealed billet was subjected to hot isostatic pressing (HIP) sintering at a temperature of 520℃, a pressure of 80MPa, and a holding time of 2h. The HIP billet was then machined using diamond tools to remove the aluminum cladding on the surface of the billet, yielding a 50 vol.% SiCp / 6013Al composite billet with both sides.

[0050] The 50 vol.% SiCp / 6013Al aluminum-based composite material and 630 stainless steel prepared in the previous step were machined to form a rectangular shape with 2 mm on each side of the contact surface with the 630 stainless steel. After machining, the 50 vol.% SiCp / 6013Al aluminum-based composite material was immersed in a 5% sodium hydroxide solution for 3 minutes to remove the surface oxide layer; the stainless steel was fully immersed in 10% hydrofluoric acid for 5 minutes. Then, the two materials were assembled into the same package in the order of 50 vol.% SiCp / 6013Al + 630 stainless steel + 50 vol.% SiCp / 6013Al (see schematic diagram). Figure 3 As shown in Figure (b), a layer of 6013Al aluminum powder with a median particle size of 5 μm was uniformly spread between 50 vol.% SiCp / 6013Al and 630 stainless steel (the aluminum powder promotes interfacial bonding during sintering). The billet was vacuum degassed in a pit-type resistance furnace. The vacuum degree was required to be less than 10 at the end of the vacuum degassed process. -2 Pa; The vacuum-degassed and sealed billet is subjected to hot isostatic pressing (HIP) sintering at a temperature of 580℃, a pressure of 80MPa, and a holding time of 2h. After removing the aluminum cladding, the billet is obtained. After the prepared ingot is processed to the specified size, it is thinned by diamond wire cutting to obtain a foil with a thickness ≤0.2mm. The foil is then subjected to heat treatment (including solution treatment and aging treatment), thermal tension leveling, and polishing to obtain the composite foil (see actual image). Figure 4(b) In the figure, the solution treatment temperature is 520℃, the solution treatment time is 1h, the aging treatment temperature is 180℃, and the aging treatment time is 10h. On the plane perpendicular to the thickness direction of the composite foil, the foils are arranged sequentially along the first direction as 50vol.%SiCp / 6013Al, 630 stainless steel, and 50vol.%SiCp / 6013Al.

[0051] After heat treatment, the composite foil with 50 vol.% SiCp / 6013Al on both sides has a tensile strength ≥500 MPa, a yield strength ≥450 MPa, and an elongation ≥1%. The 630 stainless steel in the middle has a tensile strength ≥1100 MPa, a yield strength ≥950 MPa, and an elongation ≥10%. The interfacial strength between the 50 vol.% SiCp / 6013Al and stainless steel is ≥175 MPa.

[0052] Example 3 This embodiment provides a method for preparing a composite foil (composite foil including aluminum-based composite material and 630 stainless steel), comprising the following steps: The SiCp reinforcing phase in the aluminum matrix composite material contains 30 vol.%, with a median SiCp particle size of 10 μm. The aluminum alloy powder is 6013Al powder with a median particle size of 30 μm. The SiCp powder and 6013Al alloy powder were ball-milled at 150 rpm for 12 hours at a ball-to-powder ratio of 1:1. The mixed powder was sieved and then placed into a cold isostatic pressing (CIP) rubber sheath for 30 minutes at a pressure of 200 MPa. The CIP billet was then vacuum-degassed in a pit-type resistance furnace, with the vacuum level required to be less than 10 kJ / m² at the end of the degassed process. -2 Pa; The vacuum-degassed and sealed billet was subjected to hot isostatic pressing (HIP) sintering at a temperature of 520℃, a pressure of 80MPa, and a holding time of 2h. The HIP billet was then machined using diamond tools to remove the aluminum cladding from the billet surface, yielding a 30 vol.% SiCp / 6013Al composite billet with both sides.

[0053] The 30 vol.% SiCp / 6013Al aluminum-based composite material prepared in the previous step was precision milled to obtain a bulk material with a surface roughness Ra < 0.8 μm in contact with 630 stainless steel. The 30 vol.% SiCp / 6013Al aluminum-based composite material was immersed in a 2% sodium hydroxide solution for 5 min to remove the surface oxide layer; the stainless steel was fully immersed in a 10% hydrofluoric acid solution for 5 min. Then, the two materials were assembled in the same package according to the following sequence: 30 vol.% SiCp / 6013Al + 630 stainless steel + 30 vol.% SiCp / 6013Al (see schematic diagram). Figure 3As shown in Figure (c), a layer of 6013Al aluminum powder with a median particle size of 5 μm is uniformly spread between 30 vol.% SiCp / 6013Al and 630 stainless steel (the aluminum powder promotes interfacial bonding during sintering). The billet is degassed under vacuum in a pit-type resistance furnace, and the vacuum level is required to be less than 10 at the end of the degassed process. -2 Pa; The vacuum-degassed and sealed billet is subjected to hot isostatic pressing (HIP) sintering at a temperature of 560℃, a pressure of 80MPa, and a holding time of 2h. After removing the cladding, the billet is obtained. After processing the prepared ingot to the specified dimensions, wire cutting is performed to thin it to obtain a foil with a thickness ≤0.2mm. Subsequently, the foil undergoes heat treatment (including solution treatment and aging treatment), thermal tension leveling, and polishing to obtain the composite foil (see actual image). Figure 4 (Figure (c)) Solution treatment temperature 540℃, solution treatment time 1h, aging treatment temperature 180℃, aging treatment time 10h. On a plane perpendicular to the thickness direction of the composite foil, 30vol.%SiCp / 6013Al, 630 stainless steel, and 30vol.%SiCp / 6013Al are arranged sequentially along the first direction.

[0054] After heat treatment, the composite foil consists of 30 vol.% SiCp / 6013Al on both sides with a tensile strength ≥480 MPa, a yield strength ≥400 MPa, and an elongation ≥2.5%. The middle section is made of 630 stainless steel with a tensile strength ≥1100 MPa, a yield strength ≥950 MPa, and an elongation ≥10%. The interfacial strength between the 30 vol.% SiCp / 6013Al and 630 stainless steel is ≥175 MPa.

[0055] Example 4 This embodiment provides a method for preparing a composite foil (composite foil including aluminum-based composite material and 630 stainless steel), comprising the following steps: The aluminum matrix composite material contains 70 vol.% SiCp reinforcing phase with a median SiCp particle size of 10 μm, and the aluminum alloy powder is 7075Al powder with a median particle size of 30 μm. The SiCp powder and 7075Al alloy powder were ball-milled at 150 rpm for 12 hours at a ball-to-powder ratio of 1:1. The mixed powder was sieved and then placed into a cold isostatic pressing (CIP) rubber sheath for 30 minutes at a pressure of 200 MPa. The CIP billet was then vacuum-degassed in a pit-type resistance furnace, with the vacuum level required to be less than 10 kJ / m² at the end of the degassed process. -2Pa; The vacuum-degassed and sealed billet was subjected to hot isostatic pressing (HIP) sintering at a temperature of 520℃, a pressure of 80MPa, and a holding time of 2h. The HIP billet was then machined using diamond tools to remove the aluminum cladding from the billet surface, yielding a 70 vol.% SiCp / 7075Al composite billet with both sides.

[0056] The 70 vol.% SiCp / 7075Al aluminum-based composite material prepared in the previous step was precision milled to obtain a bulk material with a surface roughness Ra < 0.8 μm in contact with 630 stainless steel. The 70 vol.% SiCp / 7075Al aluminum-based composite material was immersed in a 2% sodium hydroxide solution for 3 min to remove the surface oxide layer; the stainless steel was then fully immersed in a 10% hydrofluoric acid solution for 5 min. The two materials were then assembled in the same package according to the following sequence: 70 vol.% SiCp / 7075Al + 630 stainless steel + 70 vol.% SiCp / 7075Al. A layer of 6013Al aluminum powder with a median particle size of 5 μm was uniformly spread between the 70 vol.% SiCp / 7075Al and the 630 stainless steel (the aluminum powder promotes interfacial bonding during sintering). The billet was then vacuum degassed in a pit-type resistance furnace, with the vacuum level required to be less than 10⁻² Pa at the end of the vacuum degassed process. The vacuum-degassed and sealed billet was then subjected to hot isostatic pressing (HIP) sintering at a temperature of 500℃, a pressure of 80 MPa, and a holding time of 2 hours. After removing the package, the billet was obtained. After processing the prepared ingot to the specified dimensions, it is thinned by diamond wire cutting to obtain a foil with a thickness ≤0.2mm. The foil is then subjected to heat treatment (including solution treatment and aging treatment), thermal tension leveling, and polishing to obtain a composite foil. The solution treatment temperature is 470℃, and the solution treatment time is 1 hour; the aging treatment temperature is 120℃, and the aging treatment time is 10 hours. On a plane perpendicular to the thickness direction of the composite foil, the foil is arranged sequentially along the first direction in the order of 70 vol.% SiCp / 7075Al, 630 stainless steel, and 70 vol.% SiCp / 7075Al.

[0057] The composite foil, after heat treatment, has a tensile strength ≥600 MPa, a yield strength ≥550 MPa, and an elongation ≥0.5% for both sides made of 70 vol.% SiCp / 7075Al. The middle layer of 630 stainless steel has a tensile strength ≥1100 MPa, a yield strength ≥950 MPa, and an elongation ≥10%. The interfacial strength between the 70 vol.% SiCp / 6013Al and 630 stainless steel is ≥165 MPa.

[0058] Example 5 This embodiment provides a method for preparing a composite foil (composite foil including aluminum-based composite material and TC4 titanium alloy), comprising the following steps: The aluminum matrix composite material contains 50 vol.% SiCp reinforcing phase with a median SiCp particle size of 10 μm, and the aluminum alloy powder is 6013Al powder with a median particle size of 20 μm. First, the SiCp reinforcement is dried, then the 6013Al alloy matrix powder is added, and the mixture is ball-milled at 150 rpm for 12 hours at a ball-to-powder ratio of 1:1. The mixed powder is then sieved and placed into a cold isostatic pressing (CIP) rubber sheath for 30 minutes at a pressure of 200 MPa. The CIP billet is then vacuum-degassed in a pit-type resistance furnace, with the vacuum level required to be less than 10 kJ / m² at the end of the degassed process. -2 Pa; The vacuum-degassed and sealed billet was subjected to hot isostatic pressing (HIP) sintering at a temperature of 500℃, a pressure of 80MPa, and a holding time of 2h. The HIP billet was then machined using diamond tools to remove the aluminum cladding from the billet surface, yielding a 50 vol.% SiCp / 6013Al composite billet with both sides.

[0059] The 50 vol.% SiCp / 6013Al aluminum-based composite material prepared in the previous step was precision milled to obtain a bulk material with a surface roughness Ra < 0.8 μm at contact with the TC4 titanium alloy. The 50 vol.% SiCp / 6013Al aluminum-based composite material was immersed in a 2% sodium hydroxide solution at above 90°C for 3 minutes to remove the surface oxide layer; the TC4 titanium alloy was fully immersed in hydrofluoric acid at above 90°C for 5 minutes. Then, the two materials were assembled in the same package according to the order 50 vol.% SiCp / 6013Al + TC4 titanium alloy + 50 vol.% SiCp / 6013Al. A layer of copper powder with a median particle size of 10 μm was uniformly spread between the 50 vol.% SiCp / 6013Al and TC4 (copper powder promotes interfacial bonding during sintering). The billet was vacuum degassed in a pit-type resistance furnace, and the vacuum degree was required to be less than 10 at the end of the vacuum degassed process. -2 Pa; The vacuum-degassed and sealed billet is subjected to hot isostatic pressing (HIP) sintering at a temperature of 580℃, a pressure of 80MPa, and a holding time of 2h. After removing the cladding, the billet is obtained. After processing the prepared ingot to the specified dimensions, it is thinned by laser cutting to obtain a foil with a thickness ≤0.2mm. Subsequently, the foil undergoes heat treatment (including solution treatment and aging treatment), thermal tension leveling, and polishing to obtain a composite foil. The solution treatment temperature is 520℃, and the solution treatment time is 1 hour; the aging treatment temperature is 180℃, and the aging treatment time is 10 hours. On a plane perpendicular to the thickness direction of the composite foil, the foil is arranged sequentially along the first direction in the order of 50 vol.% SiCp / 6013Al, TC4 titanium alloy, and 50 vol.% SiCp / 6013Al.

[0060] After heat treatment, the composite foil with 50 vol.% SiCp / 6013Al on both sides has a tensile strength ≥ 500 MPa, a yield strength ≥ 450 MPa, and an elongation ≥ 1%. The TC4 in the middle has a tensile strength ≥ 950 MPa, a yield strength ≥ 850 MPa, and an elongation ≥ 10%. The interfacial strength between the 50 vol.% SiCp / 6013Al and TC4 composite is ≥ 175 MPa.

[0061] Example 6 This embodiment provides a method for preparing a composite foil (composite foil including aluminum-based composite material and TC4 titanium alloy), comprising the following steps: The aluminum matrix composite material contains 50 vol.% SiCp reinforcing phase with a median SiCp particle size of 10 μm, and the aluminum alloy powder is 6013Al powder with a median particle size of 20 μm. First, the SiCp reinforcement is dried, then the 6013Al alloy matrix powder is added, and the mixture is ball-milled at 150 rpm for 12 hours at a ball-to-powder ratio of 1:1. The mixed powder is then sieved and placed into a cold isostatic pressing (CIP) rubber sheath for 30 minutes at a pressure of 200 MPa. The CIP billet is then vacuum-degassed in a pit-type resistance furnace, with the vacuum level required to be less than 10 kJ / m² at the end of the degassed process. -2 Pa; The vacuum-degassed and sealed billet was subjected to hot isostatic pressing (HIP) sintering at a temperature of 500℃, a pressure of 80MPa, and a holding time of 2h. The HIP billet was then machined using diamond tools to remove the aluminum cladding from the billet surface, yielding a 50 vol.% SiCp / 6013Al composite billet with both sides.

[0062] The 50 vol.% SiCp / 6013Al aluminum-based composite material prepared in the previous step was precision milled to obtain a block with a surface roughness Ra < 0.8 μm at the contact surface with the TC4 titanium alloy. Then, nickel plating with a thickness of 15 μm was performed on the milled surface of the aluminum-based composite material. Subsequently, the two materials were assembled in the same package according to the following sequence: 50 vol.% SiCp / 6013Al + TC4 titanium alloy + 50 vol.% SiCp / 6013Al. The ingot was then vacuum degassed in a pit-type resistance furnace. The vacuum level at the end of the vacuum degassed process was required to be less than 10. -2 Pa; The vacuum-degassed and sealed billet is subjected to hot isostatic pressing (HIP) sintering at a temperature of 420℃, a pressure of 120MPa, and a holding time of 2h. After removing the cladding, the billet is obtained. After processing the prepared ingot to the specified dimensions, it is thinned by diamond wire cutting to obtain a foil with a thickness ≤0.2mm. The foil is then subjected to heat treatment (including solution treatment and aging treatment), thermal tension leveling, and polishing to obtain a composite foil. The solution treatment temperature is 520℃, and the solution treatment time is 1 hour; the aging treatment temperature is 180℃, and the aging treatment time is 10 hours. On a plane perpendicular to the thickness direction of the composite foil, the foil is arranged sequentially along the first direction in the order of 50 vol.% SiCp / 6013Al, TC4 titanium alloy, and 50 vol.% SiCp / 6013Al.

[0063] After heat treatment, the composite foil with 50 vol.% SiCp / 6013Al on both sides has a tensile strength ≥500 MPa, a yield strength ≥450 MPa, and an elongation ≥1%. The TC4 in the middle has a tensile strength ≥950 MPa, a yield strength ≥850 MPa, and an elongation ≥10%. The interfacial strength between the 50 vol.% SiCp / 6013Al and TC4 composite is ≥160 MPa.

[0064] Example 7 This embodiment provides a method for preparing a composite foil (composite foil comprising aluminum-based composite powder and TC4 titanium alloy), the process flow diagram of which is shown below. Figure 2 As shown, the specific steps include the following: The aluminum matrix composite powder contains 50 vol.% SiCp reinforcing phase with a median SiCp particle size of 10 μm and 6013Al powder with a median aluminum alloy particle size of 20 μm. First, the SiCp reinforcement was dried, then the 6013Al alloy matrix powder was added, and the mixture was ball-milled at 150 rpm for 12 hours with a ball-to-powder ratio of 1:1 to obtain the aluminum matrix composite powder (a mixture of 50 vol.% SiCp and 6013Al).

[0065] The intermediate interlayer material, TC4 titanium alloy, was precision milled to achieve a surface roughness Ra < 0.8 μm for contact with the aluminum-based composite powder. After removing the oxide film from the titanium alloy surface through mechanical wire polishing, it was placed in the middle of the casing. The sides were filled with a 50 vol.% SiCp / 6013Al mixed powder, and the powder was compacted (see schematic diagram). Figure 3 (As shown in Figure (d)). After sealing, the sheath is vacuum degassed in a pit-type resistance furnace. The vacuum level is required to be less than 10 at the end of the vacuum degassed process. -2 Pa; The vacuum-degassed and sealed billet is subjected to hot isostatic pressing (HIP) sintering at a temperature of 560℃, a pressure of 80MPa, and a holding time of 2h. After removing the cladding, the billet is obtained. After processing the prepared ingot to the specified dimensions, it is thinned by diamond wire cutting to obtain a foil with a thickness ≤0.2mm. The foil is then subjected to heat treatment (including solution treatment and aging treatment), thermal tension leveling, and polishing to obtain a composite foil. The solution treatment temperature is 520℃, and the solution treatment time is 1 hour; the aging treatment temperature is 180℃, and the aging treatment time is 10 hours. On a plane perpendicular to the thickness direction of the composite foil, the foil is arranged sequentially along the first direction in the order of 50 vol.% SiCp / 6013Al, TC4 titanium alloy, and 50 vol.% SiCp / 6013Al.

[0066] After heat treatment, the composite foil with 50 vol.% SiCp / 6013Al on both sides has a tensile strength ≥500 MPa, a yield strength ≥450 MPa, and an elongation ≥1%. The TC4 in the middle has a tensile strength ≥950 MPa, a yield strength ≥850 MPa, and an elongation ≥10%. The interfacial strength between the 50 vol.% SiCp / 6013Al and TC4 composite is ≥170 MPa.

[0067] Comparative Example 1 This comparative example provides a composite foil material that differs from Example 1 in that it uses only a 50 vol.% SiCp / 6013Al composite material ingot. Its preparation method includes the following steps: The aluminum-based composite material contains 50 vol.% SiCp reinforcing phase with a median SiCp particle size of 10 μm and 6013Al alloy powder with a median aluminum alloy particle size of 30 μm. The SiCp powder and 6013Al alloy powder were ball-milled at 150 rpm for 12 hours at a ball-to-powder ratio of 1:1. The mixed powder was sieved and then placed into a cold isostatic pressing (CIP) rubber sheath for 30 minutes at a pressure of 200 MPa. The CIP billet was then vacuum-degassed in a pit-type resistance furnace, with a vacuum level of less than 10⁻² Pa at the end of the degassed process. Finally, the vacuum-degassed and sealed billet was hot isostatically pressed at 520°C for 2 hours at a pressure of 80 MPa. The hot isostatic pressing billet was machined using diamond tools to remove the aluminum cladding on the surface of the billet, thus obtaining the 50 vol.% SiCp / 6013Al composite billet.

[0068] After processing the prepared ingot to the specified dimensions, it was thinned by diamond wire cutting to obtain a foil with a thickness ≤0.2mm. The foil was then subjected to heat treatment (including solution treatment and aging treatment), thermal tension leveling, and polishing to obtain a composite foil. The solution treatment temperature was 520℃, and the solution treatment time was 1h. The aging treatment temperature was 180℃, and the aging treatment time was 10h. The obtained material (50 vol.% SiCp / 6013Al) after heat treatment had a tensile strength ≥500 MPa, a yield strength ≥450 MPa, and an elongation ≥1%. This composite foil did not meet the requirement of high elongation in the middle region, and fracture occurred when the middle region was bent during subsequent use.

[0069] Test Example 1 The composite foils prepared in Examples 1-7 are shown in Table 1, with the metal material in the middle region as the first region and the aluminum-based composite material on both sides of the first region as the second region. The dimensions of the composite foils prepared in Examples 1-7 and Comparative Example 1 are shown in Table 2. The material properties of the first and second regions of the composite foils prepared in Examples 1-7 and Comparative Example 1 are shown in Table 2.

[0070] Table 1 Dimensions of composite foils in Examples 1-7

[0071] Table 2 Material properties of Region 1 and Region 2

[0072] Test Example 2 The composite foils prepared in Examples 1-7 and Comparative Example 1 were subjected to room temperature tensile tests (including tensile strength, yield strength, and elongation), elastic modulus tests, average bulk density tests, and repeated bending performance tests. The room temperature tensile test method followed GB / T 228.1-2021, the elastic modulus test method followed GB / T 22315-2008, and the average bulk density test method followed GB / T 1423-1996. The average bulk density of 630 stainless steel was 7.8 g / cm³. 3 The average bulk density of TC4 titanium alloy is 4.5 g / cm³. 3 The composite foil of this invention has ultra-lightweight properties. The repeated bending performance test method involves conducting 200,000 bending cycles at room temperature using a bending machine to verify its repeated bending performance. No breakage after the test indicates a pass, proving good bending performance; breakage indicates poor bending performance. The test results are shown in Table 3.

[0073] Table 3

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A composite foil material, characterized in that, The composite foil includes a first region and a second region, which are distributed on a plane perpendicular to the thickness direction of the composite foil. The plane perpendicular to the thickness direction of the composite foil includes a first direction and a second direction, which are perpendicular to each other; along the first direction or the second direction, the first region and the second region are arranged in a cycle at least once in the order of second region, first region, second region; The material of the first region includes metallic materials; the material of the second region includes aluminum-based composite materials. The metallic material is selected from at least one of stainless steel, titanium alloy, and copper alloy; The aluminum-based composite material is an aluminum-based composite material reinforced with particles or fibers.

2. The composite foil material according to claim 1, characterized in that, The elongation of the metal material is 8%-18%, the yield strength is 800-1000 MPa, and the elastic modulus is 100-200 GPa. And / or, the aluminum-based composite material has an elastic modulus of 170-230 GPa, a yield strength of 350-550 MPa, and a density of 2.7-3.0 g / cm³. 3 ; Preferably, the metal material is selected from at least one of stainless steel and titanium alloy; And / or, the aluminum-based composite material includes aluminum-based metal powder and reinforcement; The aluminum-based metal powder is selected from at least one of aluminum powder and aluminum alloy powder; The reinforcing agent is selected from at least one of Al2O3, SiC, Si, AlN, B4C, SiO2, TiB2, TiBW, graphene, carbon nanotubes, and carbon fibers; The volume content of the reinforcement in the aluminum matrix composite material is 30-70%.

3. The composite foil material according to claim 1, characterized in that, The thickness of the composite foil is 0.08-0.2 mm; The width of the first region is 5-35mm; And / or, the first region and the second region further include a metal fusion region, which includes single planar fusion or toothed interlocking structure fusion; Optionally, the cross-sectional shape of a single tooth in the toothed interlocking structure may include a triangle, a rectangle, a trapezoid, or an arc.

4. The composite foil material according to claim 1, characterized in that, The metal fusion zone also includes transition metal materials; The transition metal material includes at least one of aluminum, copper, nickel, chromium, and aluminum alloys.

5. A method for preparing the composite foil according to any one of claims 1-4, characterized in that, Includes the following steps: One side of a metal material sheet is bonded to an aluminum-based composite material sheet, and the other side of the metal material sheet is bonded to another aluminum-based composite material sheet. The sheet is arranged in the order of aluminum-based composite material sheet, metal material sheet, and aluminum-based composite material sheet at least once and placed in a hot isostatic pressing sleeve to obtain a product to be pressed. At least one product to be pressed is subjected to hot isostatic pressing, mechanical thinning, and post-treatment to obtain the composite foil. Alternatively, one side of the metal material sheet is bonded to aluminum-based composite powder, and the other side of the metal material sheet is bonded to aluminum-based composite powder. The metal material sheet and aluminum-based composite powder are arranged in a hot isostatic pressing sleeve in the order of aluminum-based composite powder, metal material sheet, and aluminum-based composite powder at least once to obtain the product to be pressed. At least one product to be pressed is subjected to hot isostatic pressing, mechanical thinning, and post-treatment to obtain the composite foil.

6. The method for preparing the composite foil according to claim 5, characterized in that, The hot isostatic pressing (HIP) temperature is 420-600℃, the hot isostatic pressing pressure is 80-130MPa, and the hot isostatic pressing holding time is 1-5h. The vacuum degree during hot isostatic pressing is less than 1×10⁻⁶. -2 Pa.

7. The method for preparing the composite foil according to claim 5, characterized in that, The surface of the metal material plate that is bonded to the aluminum-based composite material plate or aluminum-based composite material powder has a planar structure or a toothed structure. Preferably, the surface of the aluminum-based composite material sheet that is bonded to the metal material sheet has a planar structure or a toothed structure, and is bonded to the surface of the metal material sheet in a planar or toothed manner.

8. The method for preparing the composite foil according to any one of claims 5-7, characterized in that, Before the bonding step, the method further includes a surface treatment step on the surface of the metal material plate that is to be bonded to the aluminum-based composite material plate or aluminum-based composite material powder. Optionally, the surface treatment includes one or more combinations of chemical etching, mechanical polishing, sandblasting, shot peening, and metal plating. And / or, prior to the bonding step, the method further includes a surface treatment step on the surface of the aluminum-based composite material sheet that will be bonded to the metal material sheet; Optionally, the surface treatment includes one or more combinations of chemical etching, mechanical polishing, sandblasting, shot peening, and metal plating.

9. The method for preparing the composite foil according to any one of claims 5-8, characterized in that, The post-processing steps include heat treatment and leveling. Optionally, the heat treatment includes a solution treatment and an aging treatment performed sequentially. Optionally, the solution treatment temperature is 505-535℃, and the solution treatment time is 1-2 hours; The aging treatment temperature is 165-195℃, and the aging treatment time is 8-12h.

10. A flexible display screen support backplate, characterized in that, The flexible display screen support backplate comprises the composite foil as described in any one of claims 1-4 or the composite foil prepared by the preparation method described in any one of claims 5-9.

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