A gradient interface aluminum alloy layered composite material, its preparation method and application

Abstract

This invention relates to the field of metal matrix composites, specifically to a gradient interface aluminum alloy layered composite material, its preparation method, and its application. The gradient interface aluminum alloy layered composite material includes at least one soft aluminum alloy layer and at least one hard aluminum alloy layer. The soft aluminum alloy layer has a softening region with a microhardness lower than that of the soft aluminum alloy matrix immediately adjacent to the gradient transition zone. The interface region between the soft and hard aluminum alloy layers exhibits a gradient transition zone with variations in alloying elements, microhardness, and microstructure. This invention constructs a gradient structure with variations in composition, hardness, and microstructure in situ at the heterogeneous interface region, while simultaneously forming a softening region within the soft aluminum alloy layer immediately adjacent to the gradient transition zone. This effectively coordinates deformation between heterogeneous layers, significantly improves interfacial bonding strength, and achieves a synergistic improvement in material strength and plasticity.

Description

Technical Field

[0001] This invention relates to the field of metal matrix composites, specifically to a gradient interface aluminum alloy layered composite material, its preparation method, and its application. Background Technology

[0002] The improvement of aluminum alloy strength is often accompanied by a significant decrease in plasticity. Existing methods for preparing layered composite materials (such as rolling composite and cumulative rolling) suffer from a mismatch in physical and mechanical properties between heterogeneous layers, leading to stress concentration at the interface. This results in weak interfacial bonding, which becomes a channel for preferential crack initiation and propagation, ultimately causing early delamination failure of the material under strain far below theoretical values. Although existing technologies attempt to improve the interface through subsequent heat treatment, such treatments are mostly limited to eliminating residual stress or promoting atomic interdiffusion to achieve metallurgical bonding. Essentially, this involves "passively healing" existing defects or relying on the mechanical mixing effect brought about by large deformation, lacking the ability to actively design the evolution of the microstructure in the interfacial region. Therefore, how to avoid dependence on large deformation and instead improve the strength, plasticity, and interfacial bonding strength of composite materials simultaneously through the active design of interfacial gradient structures remains a pressing technical challenge in this field. Summary of the Invention

[0003] This invention provides a gradient interface aluminum alloy layered composite material, its preparation method, and its application, in order to solve the problems of existing layered aluminum alloy composite materials, which rely on large deformation to achieve interface mixing and lack active design of interface structure, resulting in difficulty in synergistic improvement of strength and plasticity and easy occurrence of early delamination failure.

[0004] In a first aspect, the present invention provides a gradient interface aluminum alloy layered composite material, comprising at least one soft aluminum alloy layer and at least one hard aluminum alloy layer, wherein the interface region between the soft aluminum alloy layer and the hard aluminum alloy layer has a gradient transition region exhibiting changes in alloying elements, microhardness and microstructure; wherein the soft aluminum alloy layer has a softening region in the region immediately adjacent to the gradient transition region, wherein the microhardness is lower than that of the soft aluminum alloy layer matrix. The gradient transition region has the following characteristics: The concentration of alloying elements in the hard aluminum alloy layer decreases from the concentration in the soft aluminum alloy layer. The microhardness value in the gradient transition zone increases from the soft aluminum alloy layer to the hard aluminum alloy layer. The size of the intermetallic compound reinforcing phase in the gradient transition region is less than 20 nm; as an example, the size of the intermetallic compound reinforcing phase is 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 19 nm, or within any of the above values ​​(e.g., 5~15 nm, 10~19 nm).

[0005] In one optional implementation, the width of the gradient transition region is 50~100μm; as an example, the width of the gradient transition region is 50μm, 55μm, 60μm, 65μm, 70μm, 75μm, 80μm, 85μm, 90μm, 95μm, 100μm, or within any of the above values ​​(e.g., 55~80μm, 70~100μm). And / or, the center of the softened region is located within a range of 0 to 100 μm from the boundary of the gradient transition region. For example, the softened region may be 0 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, 100 μm from the boundary of the gradient transition region, or within any of the above values ​​(e.g., 25 to 75 μm).

[0006] In one optional embodiment, the soft aluminum alloy layer and the hard aluminum alloy layer in the gradient interface aluminum alloy layered composite material are arranged in alternating layers, and the overall layered structure includes any one of a double-layer structure, a three-layer symmetrical sandwich structure, or a multi-layer alternating layered structure.

[0007] In one optional embodiment, the three-layer symmetrical sandwich structure includes a stacked arrangement of "soft aluminum alloy layer / hard aluminum alloy layer / soft aluminum alloy layer".

[0008] In one optional embodiment, the soft aluminum alloy includes 1xxx series industrial pure aluminum (e.g., 1060, 1050, 1100), 6xxx series aluminum alloys (e.g., 6063, 6082, 6061), etc., but is not limited thereto; And / or, the hard aluminum alloy includes 2xxx series aluminum alloys (e.g., 2024), 7xxx series aluminum alloys (e.g., 7075, 7050), etc., but is not limited thereto.

[0009] In one optional embodiment, the alloying element includes, but is not limited to, at least one of Zn, Mg, Ti, Cu, and Fe; And / or, the nanoscale intermetallic compound reinforcing phase includes, but is not limited to, the MgZn2 phase.

[0010] In a second aspect, the present invention also provides a method for preparing a gradient interface aluminum alloy layered composite material as described in the first aspect, comprising the following steps: Pretreatment is performed on the bonding surface between soft aluminum alloy sheet and hard aluminum alloy sheet. The pre-treated boards are stacked and assembled according to a preset layered structure to obtain a laminated assembly. Solid-state diffusion bonding treatment is applied to the laminated assembly; Gradient interface heat treatment is performed on the laminated billet after solid diffusion bonding treatment.

[0011] Through the combined action of the above steps, particularly the synergistic effect of solid-state diffusion bonding and gradient interface heat treatment, the microstructure of the heterogeneous interface region can be actively controlled. The mechanism is as follows: solid-state diffusion bonding first achieves initial atomic-level metallurgical bonding between layers, providing a clean interface channel for subsequent element diffusion; based on this, gradient interface heat treatment utilizes the chemical potential difference between hard and soft components as a driving force, driving alloying elements (such as Zn and Mg) in the hard aluminum alloy layer to diffuse directionally into the soft aluminum alloy layer by controlling the heat treatment temperature and time. This process requires the following thermodynamic and kinetic conditions: on the one hand, the temperature must be high enough to provide the activation energy required for element diffusion; on the other hand, the rapid coarsening temperature range of the existing strengthening phase (such as η-phase MgZn2) in the hard aluminum alloy must be avoided, while simultaneously suppressing abnormal grain growth in the soft aluminum alloy matrix. Within the selected temperature-time window, solute atoms diffusing into the soft aluminum alloy layer can reach critical supersaturation, thereby uniformly precipitating nanoscale intermetallic compound strengthening phases in situ on the soft aluminum alloy layer side near the interface, ultimately forming a gradient transition region with variations in composition, hardness, and microstructure.

[0012] In one alternative embodiment, the solid-state diffusion bonding process is carried out at a temperature T1 lower than the solidus temperature of the hard aluminum alloy; optionally, T1 is 490~510°C; as an example, T1 is 490°C, 495°C, 500°C, 505°C, 510°C, or within any range of the above values ​​(e.g., 495°C~505°C). And / or, the pressure P1 of the solid diffusion bonding process is 13~17MPa; as an example, P1 is 13MPa, 14MPa, 15MPa, 16MPa, 17MPa, or within any of the above values ​​(e.g., 14MPa~16MPa). And / or, the solid-state diffusion bonding process time t1 is 1.5~2.5h; as an example, t1 is 1.5h, 1.8h, 2.0h, 2.2h, 2.5h, or within any of the above values ​​(e.g., 1.8h~2.2h). And / or, the heating rate of the solid-state diffusion bonding process is 5~15℃ / min; as an example, the heating rate is 5℃ / min, 8℃ / min, 10℃ / min, 12℃ / min, 15℃ / min, or within any range of the above values ​​(e.g., 8~12℃ / min, 9~11℃ / min).

[0013] In one optional embodiment, the temperature T2 of the gradient interface heat treatment is ≤ T1; optionally, T2 is 470°C to 530°C; as an example, T2 is 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, or within any range of the above values ​​(e.g., 470°C to 530°C, 490°C to 510°C). And / or, the time t2 of the gradient interface heat treatment is 0.5h to 2h; as an example, t2 is 0.5h, 0.8h, 1.0h, 1.2h, 1.5h, 1.8h, 2.0h, or within any of the above values ​​(e.g., 0.5h to 2h, 50min to 70min).

[0014] In one alternative implementation, the solid-state diffusion bonding process is performed under vacuum or inert gas protection. And / or, the gradient interface heat treatment is performed in an inert atmosphere and / or air; And / or, the pretreatment includes precision machining of the mating surfaces to a mirror finish and cleaning to remove contaminants.

[0015] In this invention, it should be noted that the microhardness of the same aluminum alloy matrix material can vary depending on the heat treatment process conditions it undergoes.

[0016] Thirdly, the present invention also provides an aluminum alloy component comprising the gradient interface aluminum alloy layered composite material described in the first aspect, or the gradient interface aluminum alloy layered composite material prepared by the preparation method of the gradient interface aluminum alloy layered composite material described in the second aspect.

[0017] As an example, in automobiles, the aluminum alloy component can be an engine block, cylinder head, wheel, or other automotive parts, but is not limited to these; in aircraft, the aluminum alloy component can be an aircraft fuselage, wings, engine, or other parts, but is not limited to these; in electronic products, the aluminum alloy component can be a mobile phone casing, motherboard heat sink, or other components, but is not limited to these. Fourthly, the present invention also provides a terminal product comprising the aluminum alloy component described in the third aspect.

[0018] As an example, the terminal product may be a car, an airplane, an electronic product (such as a mobile phone, a computer, etc.), but is not limited to these.

[0019] The technical solution of this invention has the following advantages: 1. The gradient interface aluminum alloy layered composite material provided by this invention eliminates the abrupt performance change zone present in traditional heterogeneous interfaces by setting a gradient transition region between the soft aluminum alloy layer and the hard aluminum alloy layer, exhibiting a decreasing distribution of alloy element concentration, an increasing distribution of microhardness, and an intermetallic compound reinforcing phase size of less than 20 nm. Furthermore, a softening zone with a microhardness lower than that of the soft layer matrix is ​​set in the region immediately adjacent to the gradient transition region within the soft layer. This effectively mitigates the stress concentration caused by deformation mismatch between heterogeneous layers, preventing the interface from becoming a weak point for crack initiation and propagation. This gradient structure can stimulate heterogeneous deformation-induced (HDI) strengthening mechanisms, enabling the composite material to achieve significantly improved yield strength and tensile strength while maintaining high plasticity. It fundamentally solves the technical problems of existing layered composite materials, which rely on large deformation for interface mixing and lack proactive interface structure design, leading to difficulties in synergistic improvement of strength and plasticity and a tendency for early delamination failure.

[0020] 2. The method for preparing gradient interface layered aluminum alloy composite materials provided by this invention employs a process route combining solid-state diffusion bonding and gradient interface heat treatment. By controlling the heat treatment temperature and time window, the reinforcing elements in the hard aluminum alloy layer are actively driven to diffuse directionally towards the soft aluminum alloy layer. This results in a decreasing concentration of alloying elements from the hard aluminum alloy layer towards the soft aluminum alloy layer, and an in-situ gradient transition region is formed in the interface area where the microhardness increases from the soft layer to the hard layer. Simultaneously, a softening region is formed in the soft layer adjacent to the gradient transition region, and the size of the intermetallic compound reinforcing phase in the gradient transition region is less than 20 nm. This method not only achieves a significant leap in the comprehensive mechanical properties of the composite material but also provides a general technical path for developing high-performance gradient composite materials for other multilayer metal systems (such as Al / Mg, Al / Ti, Cu / Fe, etc.). Attached Figure Description

[0021] 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.

[0022] Figure 1 This is a schematic diagram of the solid-state diffusion bonding process in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the structure of the composite material after solid-state diffusion bonding treatment in Embodiment 1 of the present invention; Figure 3 This is a three-dimensional mapping diagram of the nano-indentation hardness of the interface region of the aluminum alloy layered composite material in Comparative Example 1 of the present invention. Figure 4This is a three-dimensional mapping diagram of the nano-indentation hardness of the interface region of the aluminum alloy layered composite material of Comparative Example 2 of the present invention. Figure 5 This is a three-dimensional mapping diagram of the nano-indentation hardness of the interface region of the aluminum alloy layered composite material in Embodiment 1 of the present invention; Figure 6 This is a bright-field transmission electron microscope (TEM) image of the interface region of the aluminum alloy layered composite material of Comparative Example 1 of the present invention. Figure 7 This is a bright-field transmission electron microscope (TEM) image of the interface region of the aluminum alloy layered composite material of Comparative Example 2 of the present invention. Figure 8 This is a bright-field transmission electron microscope (TEM) image of the interface region of the aluminum alloy layered composite material in Embodiment 1 of the present invention; Figure 9 The results are EDS energy dispersive spectroscopy line scans of the aluminum alloy layered composite material of Example 1 of this invention. Detailed Implementation

[0023] The following embodiments are provided to better understand the present invention, but the following embodiments do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the scope of protection of the present invention.

[0024] Unless otherwise specified, all experimental steps or conditions in the examples were performed according to conventional experimental procedures and conditions in the art. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0025] Example 1 This embodiment provides a method for preparing a gradient interface aluminum alloy layered composite material, the specific steps of which are as follows: (1) Pretreatment: 1.0mm thick 1060 industrial pure aluminum plate and 1.5mm thick 7075-T6 aluminum alloy plate were selected. The plates were cut into 100mm×100mm square pieces, and the mating surfaces were mechanically polished to a mirror finish. Then, they were ultrasonically cleaned in anhydrous ethanol for 15 minutes and dried. (2) Stacking assembly: Stack the layers in the order of “1060 / 7075 / 1060” to obtain the stacked assembly; (3) Solid-state diffusion bonding: The laminated assembly is placed in a vacuum hot press furnace and evacuated to a vacuum level of 1×10⁻⁶. -3 After Pa, the temperature is increased to 500℃ (T1) at 10℃ / min, an axial pressure of 15MPa (P1) is applied, and the temperature is maintained at this state for 2h (t1), followed by furnace cooling; the process diagram of solid-state diffusion bonding treatment is shown below.Figure 1 As shown, the structural schematic of the composite material after solid-state diffusion bonding treatment is as follows. Figure 2 As shown; (4) Gradient interface heat treatment: The laminated billet after solid diffusion bonding is placed in an air circulation furnace and held at 500℃ (T2) for 60 min (t2), and then taken out and air cooled to room temperature.

[0026] Testing revealed that the composite material prepared in this embodiment had a straight interface and good bonding. EDS energy dispersive spectroscopy analysis showed that the middle layer was 7075-T6 aluminum alloy, and the two sides were 1060 industrial pure aluminum. From the interface between the 7075-T6 aluminum alloy sides towards the interior of the 1060 alloy, the concentrations of Zn and Mg elements decreased. Figure 9 Nanoindentation testing revealed that the microhardness values ​​within the gradient transition region increased progressively from layer 1060 to layer 7075. A softened region with a microhardness lower than that of the 1060 layer matrix existed immediately adjacent to the gradient transition region within layer 1060; the center of this softened region was approximately 50 μm from the boundary of the gradient transition region. A gradient transition region with a width of approximately 80 μm existed at the interface. Figure 5 The size of the intermetallic compound strengthening phase in the gradient transition region is less than 20 nm, while the original coarse second phase on the 7075 side partially dissolves and its size is refined. Figure 8 Tensile tests showed that its yield strength was 102 MPa, tensile strength was 223 MPa, elongation after fracture was 21.7%, and the strength-ductility product reached 4.84 GPa·s.

[0027] Example 2 This embodiment provides a method for preparing a gradient interface aluminum alloy layered composite material. The difference between this method and Example 1 is that the gradient interface heat treatment temperature in step (4) is adjusted to 480℃, the holding time is extended to 90min, and other conditions are the same as in Example 1.

[0028] Testing revealed that the composite material prepared in this embodiment exhibited good interfacial bonding. The concentrations of Zn and Mg elements decreased progressively towards the 1060 layer from the bonding interface inwards. The microhardness value within the gradient transition region increased progressively from the 1060 layer towards the 7075 layer. A softening region with a microhardness lower than that of the 1060 layer matrix existed immediately adjacent to the gradient transition region within the 1060 layer; the center of this softening region was approximately 40 μm from the boundary of the gradient transition region. The gradient transition region was approximately 60 μm wide, and the size of the intermetallic compound reinforcing phase within it was less than 20 nm. Tensile testing showed a yield strength of 98 MPa, a tensile strength of 210 MPa, an elongation after fracture of 20.0%, and a strength-ductility product of 4.20 GPa·s.

[0029] Example 3 This embodiment provides a method for preparing a gradient interface aluminum alloy layered composite material. The difference between this method and Example 1 is that the gradient interface heat treatment temperature in step (4) is adjusted to 520℃, the holding time is shortened to 45min, and other conditions are the same as in Example 1.

[0030] Testing revealed that the composite material prepared in this embodiment exhibited good interfacial bonding. The concentrations of Zn and Mg elements decreased progressively towards the 1060 layer from the bonding interface inwards. The microhardness value within the gradient transition region increased progressively from the 1060 layer towards the 7075 layer. A softening region with a microhardness lower than that of the 1060 layer matrix existed immediately adjacent to the gradient transition region within the 1060 layer; the center of this softening region was approximately 45 μm from the boundary of the gradient transition region. The gradient transition region was approximately 70 μm wide, and the size of the intermetallic compound reinforcing phase within it was less than 20 nm. Tensile testing showed a yield strength of 95 MPa, a tensile strength of 190 MPa, an elongation after fracture of 23.0%, and a strength-ductility product of 4.37 GPa·s.

[0031] Example 4 This embodiment provides a method for preparing a gradient interface aluminum alloy layered composite material. The difference between this method and Example 1 is that in step (3) solid diffusion bonding treatment, the heating rate is 8℃ / min, the temperature is adjusted to 490℃, the pressure is adjusted to 13MPa, and the holding time is extended to 2.5h; in step (4) gradient interface heat treatment, the temperature is adjusted to 490℃, the holding time is extended to 70min, and other conditions are the same as in Example 1.

[0032] Testing revealed that the composite material prepared in this embodiment exhibited good interfacial bonding. The concentrations of Zn and Mg elements decreased progressively towards the 1060 layer from the bonding interface inwards. The microhardness value within the gradient transition region increased progressively from the 1060 layer towards the 7075 layer. A softening region with a microhardness lower than that of the 1060 layer matrix existed immediately adjacent to the gradient transition region within the 1060 layer; the center of this softening region was approximately 35 μm from the boundary of the gradient transition region. The gradient transition region was approximately 55 μm wide, and the size of the intermetallic compound reinforcing phase within it was less than 20 nm. Tensile testing showed a yield strength of 105 MPa, a tensile strength of 215 MPa, an elongation after fracture of 19.2%, and a strength-ductility product of 4.13 GPa·s.

[0033] Example 5 This embodiment provides a method for preparing a gradient interface aluminum alloy layered composite material. The difference between this method and Example 1 is that in step (3) solid diffusion bonding treatment, the heating rate is 12℃ / min, the temperature is adjusted to 510℃, the pressure is adjusted to 17MPa, and the holding time is shortened to 1.5h; in step (4) gradient interface heat treatment, the temperature is adjusted to 510℃, the holding time is shortened to 50min, and other conditions are the same as in Example 1.

[0034] Testing revealed that the composite material prepared in this embodiment exhibited good interfacial bonding. The concentrations of Zn and Mg elements decreased progressively towards the 1060 layer from the bonding interface inwards. The microhardness value within the gradient transition region increased progressively from the 1060 layer towards the 7075 layer. A softening region with a microhardness lower than that of the 1060 layer matrix existed immediately adjacent to the gradient transition region within the 1060 layer; the center of this softening region was approximately 40 μm from the boundary of the gradient transition region. The gradient transition region was approximately 65 μm wide, and the size of the intermetallic compound reinforcing phase within it was less than 20 nm. Tensile testing showed a yield strength of 100 MPa, a tensile strength of 218 MPa, an elongation after fracture of 21%, and a strength-ductility product of 4.58 GPa·s.

[0035] Comparative Example 1 This comparative example provides a method for preparing a gradient interface aluminum alloy layered composite material. The difference between this method and Example 1 is that step (4) gradient interface heat treatment is omitted, that is, solid diffusion bonding is performed and then the material is directly cooled. Other conditions are the same as in Example 1.

[0036] Testing revealed that the composite material prepared in this comparative example exhibited only moderate interfacial bonding. From the bonding interface towards the interior of the soft aluminum alloy layer, there was no significant gradient change in the concentrations of Zn and Mg elements, but abrupt changes in composition occurred on both sides of the interface. Nanoindentation testing showed no significant increasing trend in microhardness values ​​within the gradient transition region, abrupt changes in hardness on both sides of the interface, and no softening zone with a microhardness lower than that of the 1060 layer matrix was observed in the region immediately adjacent to the interface within the 1060 layer. Figure 3 There is no gradient transition region. Transmission electron microscopy shows that the interface is clear, the tissue on both sides is similar to the original plate, and the reinforcing phase at the interface is scarce and larger than 20 nm in size. Figure 6 Tensile tests showed that its yield strength was 87 MPa, tensile strength was 164 MPa, elongation after fracture was 14.9%, and the strength-ductility product was only 2.44 GPa·s.

[0037] Comparative Example 2 This comparative example provides a method for preparing a gradient interface aluminum alloy layered composite material. The difference between this method and Example 1 is that in step (4) gradient interface heat treatment, the temperature is adjusted to 300℃, the holding time is still 60min, and other conditions are the same as in Example 1.

[0038] Testing revealed that the composite material prepared in this comparative example exhibited significantly deteriorated performance. From the bonding interface towards the interior of the soft aluminum alloy layer, there was no significant gradient change in the concentrations of Zn and Mg. Nanoindentation testing showed no significant increasing trend in microhardness values ​​within the gradient transition region, the hardness distribution gradient was indistinct, and the overall hardness was low. Furthermore, no softening zones with microhardness lower than that of the 1060 layer matrix were observed in the immediate interfacial region of the 1060 layer. Figure 4 Transmission electron microscopy revealed severe coarsening of the precipitates near the interface on the 7075 side (Ostwald ripening), while almost no Zn or Mg diffusion was observed on the 1060 side. The intermetallic compound reinforcing phases in the gradient transition region were scarce and larger than 20 nm in size. Figure 7 Tensile tests showed that its yield strength was 74 MPa, tensile strength was 163 MPa, elongation after fracture was 17.3%, and the strength-ductility product was only 2.82 GPa·s.

[0039] Comparative Example 3 This comparative example provides a method for preparing a gradient interface aluminum alloy layered composite material. The difference between this method and Example 1 is that in step (4) of the gradient interface heat treatment, the temperature is adjusted to 550°C and the holding time is shortened to 30 min. Other conditions are the same as in Example 1.

[0040] Testing revealed localized overheating in the interface region of the composite material prepared in this comparative example. From the bonding interface towards the interior of the soft aluminum alloy layer, the concentration distribution of Zn and Mg elements was disordered, lacking a clear gradient. The hardness distribution showed no obvious gradient, with significant grain coarsening. Furthermore, no softening zone with a microhardness lower than the 1060 layer matrix was observed immediately adjacent to the interface in the 1060 layer. The microstructure in the interface region was coarsened, and the intermetallic compound reinforcing phases in the gradient transition region were scarce and larger than 20 nm in size. Tensile testing showed a yield strength of 80 MPa, a tensile strength of 158 MPa, an elongation after fracture of 15%, and a strength-ductility product of 2.37 GPa·s.

[0041] Comparative Example 4 This comparative example provides a method for preparing a gradient interface aluminum alloy layered composite material. The difference between this method and Example 1 is that in step (3) solid diffusion bonding treatment, the temperature is adjusted to 450℃, the pressure is still 15MPa, the heat preservation time is extended to 3h, and other conditions are the same as in Example 1.

[0042] Testing revealed that the composite material prepared in this comparative example exhibited weak interfacial bonding. From the bonding interface towards the interior of the soft aluminum alloy layer, the concentration gradient of Zn and Mg elements did not change significantly, indicating insufficient solid-state diffusion bonding. The microhardness increase trend within the gradient transition zone was incomplete, with abrupt changes in hardness distribution. Furthermore, no softening zone with a microhardness lower than that of the 1060 layer matrix was observed immediately adjacent to the interface in the 1060 layer. The microstructure in the interfacial region was uneven, and the intermetallic compound reinforcing phase was sparsely distributed within the gradient transition zone. Tensile testing showed a yield strength of 90 MPa, a tensile strength of 150 MPa, an elongation after fracture of 13%, and a strength-ductility product of 1.95 GPa·s.

[0043] Comparative Example 5 This comparative example provides a method for preparing a layered micro-gradient composite material, the specific steps of which are as follows: (1) Material preparation: 1060 industrial pure aluminum plate with a thickness of 1.0mm and 7075-T6 aluminum alloy plate with a thickness of 1.5mm are selected. The two plates are annealed at 350℃ for 2 hours and then air-cooled to room temperature. (2) Surface treatment: The surfaces of the two plates to be joined are polished with a stainless steel wire brush with a diameter of 0.2 mm. The direction of the polishing stripes is perpendicular to the subsequent rolling direction. Then, the plates are ultrasonically cleaned with anhydrous ethanol for 15 min and dried. (3) Stacking and assembly: Stack the three layers in the order of “1060 / 7075 / 1060”, and use aluminum nails to rivet and fix the four corners to obtain the composite blank; (4) Hot rolling composite: The composite billet is placed in a heating furnace and heated to 450°C. After holding for 20 minutes, it is taken out and hot rolled in a single pass. The rolling reduction is 40%, and the thickness of the composite plate after rolling is about 2.0 mm. (5) Cumulative stacking: The hot-rolled metal composite plate is cut into two pieces, stacked together and hot-rolled again. This process is repeated twice to obtain a 6-layer metal composite plate with a final thickness of about 2.0 mm. (6) Heat treatment: The composite plate after cumulative rolling is subjected to solution aging treatment at a temperature of 470℃. After holding for 1 hour, it is water quenched and then aged at 120℃ for 2 hours. After air cooling to room temperature, aluminum alloy layered micro-gradient composite material is obtained.

[0044] Testing revealed a compositional variation zone near the interface of the composite material prepared in this comparative example. The concentration distribution of alloying elements fluctuated from the interface towards both sides, without a clear decreasing trend. The microhardness within the gradient transition zone increased from the 1060 layer to the 7075 layer, but no softening zone with a microhardness lower than the matrix of the 1060 layer was observed immediately adjacent to the interface. Second-phase particles were distributed on both sides of the interface, mainly originating from the fragmentation and evolution of the original 7075 phase, with sizes ranging from submicron to micrometer. The intermetallic compound reinforcing phase on the 1060 layer side had a size greater than 20 nm. Tensile testing showed a tensile strength of 178 MPa, an elongation after fracture of 15.2%, and a strength-ductility product of 2.71 GPa·s.

[0045] Table 1

[0046] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A gradient interface aluminum alloy layered composite material, characterized in that, It includes at least one soft aluminum alloy layer and at least one hard aluminum alloy layer. The interface region between the soft aluminum alloy layer and the hard aluminum alloy layer has a gradient transition region exhibiting changes in alloying elements, microhardness, and microstructure. The soft aluminum alloy layer has a softening region with a microhardness lower than that of the soft aluminum alloy layer matrix in the region immediately adjacent to the gradient transition region. The gradient transition region has the following characteristics: The concentration of alloying elements in the hard aluminum alloy layer decreases from the concentration in the soft aluminum alloy layer. The microhardness value in the gradient transition zone increases from the soft aluminum alloy layer to the hard aluminum alloy layer. The size of the intermetallic compound strengthening phase in the gradient transition region is less than 20 nm.

2. The gradient interface aluminum alloy layered composite material according to claim 1, characterized in that, The width of the gradient transition region is 50~100μm, optionally 55~80μm; And / or, the center of the softened region is located within the range of 0 to 100 μm from the boundary of the gradient transition region, optionally 25 to 75 μm from the boundary of the gradient transition region.

3. The gradient interface aluminum alloy layered composite material according to claim 1, characterized in that, In the gradient interface aluminum alloy layered composite material, the soft aluminum alloy layer and the hard aluminum alloy layer are arranged in an alternating stacked manner, and the overall layered structure includes any one of a double-layer structure, a three-layer symmetrical sandwich structure, or a multi-layer alternating stacked structure.

4. The gradient interface aluminum alloy layered composite material according to claim 3, characterized in that, The three-layer symmetrical sandwich structure includes a stacked arrangement of "soft aluminum alloy layer / hard aluminum alloy layer / soft aluminum alloy layer".

5. A method for preparing a gradient interface aluminum alloy layered composite material as described in any one of claims 1 to 4, characterized in that, Includes the following steps: Pretreatment is performed on the bonding surface between soft aluminum alloy sheet and hard aluminum alloy sheet. The pre-treated boards are stacked and assembled according to a preset layered structure to obtain a laminated assembly. Solid-state diffusion bonding treatment is applied to the laminated assembly; Gradient interface heat treatment is performed on the laminated billet after solid diffusion bonding treatment.

6. The preparation method according to claim 5, characterized in that, The solid-state diffusion bonding process is performed at a temperature T1 lower than the solidus temperature of the hard aluminum alloy; optionally, T1 is 490~510℃. And / or, the pressure P1 of the solid-state diffusion bonding process is 13~17MPa; And / or, the solid-state diffusion bonding process t1 is 1.5~2.5h; And / or, the heating rate of the solid-state diffusion bonding process is 5~15℃ / min, preferably 8~12℃ / min.

7. The preparation method according to claim 5, characterized in that, The temperature of the gradient interface heat treatment is T2≤T1; optionally, T2 is 470℃~530℃, more preferably 490~510℃. And / or, the time t2 of the gradient interface heat treatment is 0.5h to 2h, preferably 50 to 70min.

8. The preparation method according to claim 5, characterized in that, The solid-state diffusion bonding process is performed under vacuum or inert gas protection. And / or, the gradient interface heat treatment is performed in an inert atmosphere and / or air; And / or, the pretreatment includes precision machining of the mating surfaces to a mirror finish and cleaning to remove contaminants.

9. An aluminum alloy component, characterized in that, The aluminum alloy component comprises the gradient interface aluminum alloy layered composite material according to any one of claims 1 to 4, or the gradient interface aluminum alloy layered composite material prepared by the preparation method of the gradient interface aluminum alloy layered composite material according to any one of claims 5 to 8.

10. A terminal product, characterized in that, The terminal product includes the aluminum alloy component as described in claim 9.

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