Ti interlayer reinforced magnesium / aluminum composite plate and preparation method thereof

Abstract

The application discloses a Ti interlayer reinforced magnesium / aluminum composite plate and a preparation method thereof, and relates to the technical field of magnesium / aluminum composite material preparation. The application successfully realizes continuous combination of the Ti layer interface by introducing a Ti interlayer with a specific thickness at the magnesium / aluminum interface and optimizing rolling speed, rolling temperature and reduction rate in cooperation, and effectively solves the technical problems of easy tearing of the Ti foil under large deformation conditions and interface discontinuity in the rolling process. Moreover, the process parameter window of the application has strong process compatibility, can be directly connected with an existing rolling and heat treatment production line, has good engineering implementability and popularization value, and provides an efficient and feasible solution for industrial application of the magnesium / aluminum composite plate.

Description

Technical Field

[0001] This invention relates to the field of magnesium / aluminum composite material preparation technology, and in particular to a Ti interlayer reinforced magnesium / aluminum composite plate and its preparation method. Background Technology

[0002] Magnesium and magnesium alloys, with their low density, high specific strength, and excellent electromagnetic shielding properties, have shown broad application prospects in aerospace, rail transportation, and electronic products, becoming an important choice in the field of lightweight materials. However, magnesium and magnesium alloys themselves have significant drawbacks such as poor corrosion resistance and low formability, which severely limit their widespread promotion and large-scale application in more critical scenarios.

[0003] Aluminum alloys possess excellent corrosion resistance and good machinability. If magnesium alloys and aluminum alloys can be combined through a composite process to produce magnesium / aluminum composite plates, the performance advantages of both can be fully combined. This retains the lightweight characteristics of magnesium alloys while using aluminum alloys to improve the corrosion resistance and plastic processing capabilities of magnesium alloys, thus meeting the demand for high-performance lightweight materials in multiple fields.

[0004] There are various existing technologies for preparing magnesium / aluminum composite plates, including hot-pressing composite, explosive composite, welded joints, ultrasonic bonding, and rolling composite. Among them, the rolling composite process is the most promising composite method for large-scale continuous industrial production due to its simple and efficient operation, low requirements for production equipment, and environmentally friendly production process that does not require complex post-processing. It has outstanding advantages in industrial applications.

[0005] Despite the promising prospects of rolling composite technology, the preparation and promotion of magnesium / aluminum composite plates still face many key technological bottlenecks. Annealing is an indispensable step in the processing and application of magnesium / aluminum composite plates: on the one hand, annealing can improve the fibrous morphology of the aluminum alloy layer, control the distribution of precipitated phases, and thus increase the surface hardness of the material; on the other hand, it can also optimize the microstructure and properties of the magnesium alloy layer, providing the necessary microstructure plasticity for structural forming processes such as hot bending and stamping, ensuring the smooth progress of subsequent processing. However, during annealing and rolling heat treatment, intermetallic compounds are easily formed at the magnesium / aluminum interface. Due to the significant differences in physicochemical properties between magnesium and aluminum, magnesium / aluminum composite plates generally suffer from lower interfacial bonding strength compared to other dissimilar metal composite plates. The interfacial bonding performance directly determines the structural reliability and formability of the composite plate. The resulting intermetallic compounds can lead to interface embrittlement and performance degradation, significantly weakening the interfacial bonding stability. This makes the composite plate prone to cracking, delamination, or even failure during subsequent stamping, hot forming, or service, seriously affecting its processing performance and service reliability. This has become a core obstacle restricting the engineering promotion and application of magnesium / aluminum composite plates.

[0006] Furthermore, the eutectic temperature of magnesium and aluminum is approximately 437℃. When traditional magnesium / aluminum composite panels undergo high-temperature heat treatment above 430℃ (to further improve mechanical properties), they are prone to generating a eutectic liquid phase due to the temperature approaching the eutectic temperature, leading to localized melting of the panels. This not only damages the structural integrity of the composite panels but also poses a safety hazard, further limiting the processing technology range and application scenarios of magnesium / aluminum composite panels.

[0007] To suppress the formation of intermetallic compounds at the magnesium / aluminum interface, existing technologies typically employ adding a metal foil with good solid solubility in both magnesium and aluminum as an interlayer. This aims to improve the interfacial composition and microstructure of the magnesium / aluminum composite plate, thereby reducing the types and amounts of intermetallic compounds and ultimately enhancing interfacial bonding performance. However, practical experience shows that such methods only alter the types of intermetallic compounds formed or slightly increase their formation temperature, failing to fundamentally address the core issue of intermetallic compounds causing a decrease in interfacial bonding strength, resulting in limited improvement in interfacial performance.

[0008] Based on this, researchers have tried using titanium (Ti) as an interlayer material because it has potential advantages in interfacial stability: titanium and magnesium are almost mutually insoluble and no intermetallic compounds are formed at their interface; although titanium and aluminum will form a small amount of intermetallic compounds at high temperatures above 500°C, the amount formed is extremely small and its impact on interfacial performance is negligible.

[0009] However, in actual composite processes, the application of titanium interlayers still faces key technical challenges: due to the strong compatibility between titanium and magnesium, a large rolling reduction is required to achieve effective bonding at the interface; however, excessive reduction can cause the titanium foil to tear, preventing it from effectively blocking direct contact between magnesium and aluminum, thus losing its function of inhibiting the formation of intermetallic compounds at the magnesium / aluminum interface. If the thickness of the titanium layer is increased to avoid tearing of the titanium foil, it will lead to a significant increase in the differences in the plasticity of magnesium, titanium, and aluminum, resulting in a substantial decrease in deformation compatibility and ultimately reducing the interfacial bonding strength, thus creating a dilemma where tearing risk and bonding strength are difficult to balance.

[0010] Given the shortcomings of the existing technologies, there is an urgent need to develop a method for stable magnesium / aluminum composite rolling that can ensure the titanium foil does not tear, in order to solve the problem of unstable interface structure of magnesium / aluminum composite plates under high-temperature heat treatment, break through the existing process bottlenecks, and promote the industrialization and application of magnesium / aluminum composite plates. Summary of the Invention

[0011] The purpose of this invention is to provide a Ti interlayer reinforced magnesium / aluminum composite plate and its preparation method, thereby solving the problems existing in the prior art. This invention achieves stable control of the interface structure of the magnesium / aluminum composite plate by synergistically regulating the thickness of the Ti interlayer and rolling parameters, combined with a high-temperature heat treatment process. Under high-temperature conditions, it effectively suppresses the formation and diffusion of intermetallic compounds at the Mg / Al interface, while significantly improving the stability of the interfacial bonding strength and the overall mechanical properties of the composite plate.

[0012] To achieve the above objectives, the present invention provides the following solution: This invention provides a method for preparing a Ti interlayer reinforced magnesium / aluminum composite plate, comprising the following steps: (1) Using titanium foil as the intermediate layer, magnesium plate, titanium foil and aluminum plate are stacked sequentially; (2) The plates obtained by sequential stacking are rolled at 400-440℃ at a rolling speed of 60-120mm / s, and the total rolling deformation is 45-55% to obtain hot-rolled composite plates. (3) The hot-rolled composite plate is subjected to solution treatment and aging treatment in sequence to obtain the Ti intermediate layer reinforced magnesium / aluminum composite plate; The solution treatment is performed at a temperature of 480-530℃ for 20-60 minutes; the aging treatment is performed at a temperature of 160-200℃ for 6-9 hours. The magnesium plate has a thickness of 2-8 mm, the titanium foil has a thickness of 0.25-0.4 mm, and the aluminum plate has a thickness of 2-8 mm.

[0013] As a further preferred embodiment of the present invention, the length × width of the magnesium plate, titanium foil and aluminum plate can be (100-1500) mm × (50-400) mm.

[0014] As a further preferred embodiment of the present invention, the magnesium plate is of the Mg-Al-Zn series or the Mg-Zn-Zr series; the titanium foil is pure titanium foil; and the aluminum plate is a 5000 series or 6000 series aluminum alloy.

[0015] As a further preferred embodiment of the present invention, step (2) further includes a step of heat preservation treatment at 400-440°C before rolling of the sequentially stacked plates; the heat preservation treatment time is 20-50 min.

[0016] As a further preferred embodiment of the present invention, before sequential stacking in step (1), the method further includes a step of pre-treating the surfaces of the magnesium plate, titanium foil and aluminum plate to be bonded to remove the oxide layer.

[0017] Specifically, the surfaces to be bonded include one side of magnesium plate, two sides of titanium foil, and one side of aluminum plate; the surfaces to be bonded can be treated by polishing with a wire brush.

[0018] In step (2) of this invention, heat preservation is carried out in an air or argon atmosphere.

[0019] In step (3) of the present invention, the solution treatment and aging treatment are carried out in an air or argon atmosphere.

[0020] In this invention, a two-roll reversible rolling mill can be used for hot rolling composite.

[0021] This invention achieves continuous and stable bonding of the Mg / Ti / Al multilayer interface by precisely controlling the rolling speed, reduction rate, and Ti interlayer thickness, effectively avoiding the problem of Ti foil tearing during the rolling process and effectively isolating Mg / Al from direct contact.

[0022] The present invention also provides a Ti interlayer reinforced magnesium / aluminum composite plate prepared by the above preparation method.

[0023] This invention ensures high interfacial bonding strength while adding a continuous and stable Ti foil layer, enabling the composite plate to maintain high interfacial bonding strength and overall structural stability even at high temperatures. This significantly improves the forming or service temperature of the magnesium / aluminum composite plate, facilitating high-temperature heat treatment and forming processes.

[0024] The Ti interlayer reinforced magnesium / aluminum composite plate prepared by this invention has a Ti foil interlayer interface continuity of ≥95%, an interface bonding strength of ≥50MPa and up to 85MPa, wherein the aluminum layer hardness reaches 60-130Hv and the magnesium layer hardness reaches 40-50Hv.

[0025] The present invention discloses the following technical effects: This invention introduces a Ti interlayer of a specific thickness at the magnesium / aluminum interface and synergistically optimizes rolling speed, rolling temperature, and reduction rate to successfully achieve continuous bonding of the Ti layer interface, effectively solving the technical problems of easy tearing and interface discontinuity of Ti foil under large deformation conditions in the rolling process.

[0026] By leveraging the shielding effect of the Ti layer, this invention inhibits the direct diffusion between Mg and Al and the formation of intermetallic compounds at the interface reaction mechanism level, significantly improving the chemical and thermal stability of the composite interface and overcoming the bottleneck of the sharp decline in bonding performance caused by hot working in traditional magnesium / aluminum composite plates. In the heat treatment stage, this invention employs a two-stage process of high-temperature solution treatment and low-temperature aging under an air or argon atmosphere, achieving the dual effects of softening the magnesium layer structure and strengthening the aluminum layer through precipitation, further optimizing the comprehensive mechanical properties of the composite plate.

[0027] The process parameter window of this invention has strong process compatibility and can be directly connected with existing rolling and heat treatment production lines. It has good engineering feasibility and promotion value, and provides an efficient and feasible solution for the industrial application of magnesium / aluminum composite plates. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 is a process flow diagram of the preparation process of the Ti intermediate layer reinforced magnesium / aluminum composite plate of the present invention.

[0030] Figure 2 shows the macroscopic morphology of the hot-rolled Ti intermediate layer reinforced magnesium / aluminum composite plate in Example 1.

[0031] Figure 3 is a macroscopic morphology diagram of the continuity of the titanium foil interlayer interface in the heat-treated Ti interlayer reinforced magnesium / aluminum composite plate prepared in Example 1.

[0032] Figure 4 shows the interface SEM image and elemental distribution map of the heat-treated Ti intermediate layer reinforced magnesium / aluminum composite plate prepared in Example 1; where (a) is the interface SEM image and (b) is the elemental distribution map.

[0033] Figure 5 The image shows the elemental distribution map and SEM image of the hot-rolled Ti intermediate layer reinforced magnesium / aluminum composite plate in Comparative Example 2; where (a) is the elemental distribution map and (b) is the interface SEM image. Detailed Implementation

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0036] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0037] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0038] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0039] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0040] This invention provides a method for preparing a Ti interlayer reinforced magnesium / aluminum composite plate, comprising the following steps: (1) Grinding the blank: The magnesium plate, titanium foil, and aluminum plate with surface treatment to be bonded are stacked and bonded in the manner of magnesium plate / titanium foil / aluminum plate to obtain a stacked plate of the three metal plates; (2) Hot-rolled composite: The stacked plates in step (1) are heat-insulated and then hot-rolled to obtain a hot-rolled composite plate. The rolling temperature of hot-rolled composite is 400-440℃, the holding time is 20-50min, the rolling deformation is 45-55%, and the rolling speed is 60-120mm / s; (3) Heat treatment: The hot-rolled composite plate obtained in step (2) is subjected to solution treatment and aging treatment in sequence to obtain a Ti intermediate layer reinforced magnesium / aluminum composite plate; The solution treatment temperature is 480-530℃, and the aging treatment temperature is 160-200℃.

[0041] In step (1), the surfaces of the magnesium plate to be bonded (single-sided), the titanium foil to be bonded (double-sided), and the aluminum plate to be bonded (single-sided) are polished. The polishing direction is the same as the rolling direction of the plates. Polishing continues until the bright oxide layer on the plate surface disappears and the surface has a frosted appearance. The above polishing method can remove the oxide layer on the surface of the plates and foils to a certain extent, allowing fresh metal to be exposed. At the same time, the high-speed polishing with a wire brush gives the surface of the plates and foils a certain roughness, preventing them from shifting. During the rolling process, the removal of the oxide layer is beneficial to achieving metallurgical bonding between the plates and foils, and the introduction of roughness is beneficial to achieving mechanical interlocking between the plates and foils, providing bonding strength.

[0042] In step (1), the binding method is specifically aluminum wire winding or riveting to avoid loosening and misalignment of the stacked plates during the operation process before rolling bite.

[0043] The thicknesses of the aforementioned magnesium plate, titanium foil, and aluminum plate are 2-8 mm, 0.25-0.4 mm, and 2-8 mm, respectively, and their length × width is 100-1500 mm × 50-400 mm. The magnesium plate is of the Mg-Al-Zn series or Mg-Zn-Zr series, the aluminum plate is of the 5000 series or 6000 series, and the titanium foil is pure titanium foil.

[0044] Step (1) is the preliminary preparation for hot rolling of magnesium / aluminum composite plate. A Ti intermediate layer is added between magnesium plate and aluminum plate, and the surfaces of the plates and foils to be bonded are polished and washed. Then, they are bonded to fix the stacked plates. The example operation is strictly carried out in accordance with the above specific steps.

[0045] In step (2), the heat preservation process specifically involves placing the stacked plates in a heating device with an air or argon atmosphere for heat preservation. The heating device is pre-set to the heat preservation temperature, with a selectable temperature range of 400-440℃ and a selectable heat preservation time range of 20-50min.

[0046] The above-mentioned thermal insulation treatment can effectively improve the plastic deformation capacity of the stacked plate, especially effectively reduce the edge cracking of the magnesium layer; the heating and composite of the plate facilitates the diffusion of elements at the interface and makes it easier to achieve interface bonding.

[0047] In step (2), the specific method of rolling composite is to set the rolling deformation range to 45-55%, and to achieve the composite of magnesium / aluminum sheet reinforced with Ti interlayer by the biting of the rolling mill. The above rolling composite can realize the preparation of magnesium / aluminum composite sheet reinforced with Ti interlayer. The rolling introduces triaxial complex stress, which promotes interfacial bonding through plastic deformation and pressure of the sheet.

[0048] In step (3), the heat treatment specifically involves placing the hot-rolled composite plate in a heating device with an air or argon atmosphere, setting the heating device to the heat treatment temperature, wherein the solution treatment time is 20-60 minutes, the cooling method is water cooling, the aging time is 6-9 hours, and the plate is cooled in the furnace or air-cooled.

[0049] Solid solution dissolves the second phase to form a supersaturated solid solution; aging precipitates a dispersed strengthening phase, increasing the hardness of the Al alloy.

[0050] The magnesium / aluminum composite plate prepared by the above steps of the present invention has a Ti foil interlayer interface continuity of ≥95%; an interface bonding strength of ≥50 MPa, and up to 85 MPa; an aluminum layer hardness of 60-130 Hv and a magnesium layer hardness of 40-50 Hv.

[0051] Example 1 This embodiment provides a Ti interlayer reinforced magnesium / aluminum composite plate, and the preparation steps are as follows: (1) Raw material pretreatment: AZ31 magnesium plate, TA1 titanium foil, and 6013 aluminum plate were selected as substrates, with pre-rolling thicknesses of 6mm, 0.3mm, and 6mm, respectively. The surfaces of the three plates to be bonded were polished with a wire brush to completely remove the oxide layer, exposing the fresh metal surface. After polishing, the plates were stacked in the order of magnesium plate / titanium foil / aluminum plate, with a stack size of 500mm × 100mm. A binding device was used to secure the plates and prevent interlayer slippage (preparation process as follows). Figure 1 (As shown).

[0052] (2) Hot-rolled composite: The stacked plates, after being fixed as described above, were placed in a heating device and preheated at 420℃ for 35 minutes. Subsequently, they were rolled and laminated using a single-pass rolling mill at a speed of 120 mm / s, with a deformation of 50%, resulting in a hot-rolled Ti-reinforced magnesium / aluminum composite plate. This composite plate exhibited good macroscopic morphology (as shown in Figure 2) and dimensions of 1 m × 106 mm. The interfacial bonding rate was determined using ultrasonic non-destructive testing according to GB / T 5777-2019 "Metallic Materials - Ultrasonic Testing Methods," and the results showed an interfacial bonding rate > 95%. The interfacial bonding strength was tested according to GB / T 6396-2008 "Metallic Materials - Explosive Welded Joints - Shear Test Method," and the resulting rolled composite plate had an interfacial bonding strength of 85 MPa.

[0053] (3) Heat treatment: First, the hot-rolled Ti interlayer reinforced magnesium / aluminum composite plate was solution treated at 530℃ for 30 min and then cooled to room temperature by water cooling; then it was aged at 180℃ for 7 h and then cooled to room temperature by furnace cooling to obtain the Ti interlayer reinforced magnesium / aluminum composite plate (heat-treated Ti interlayer reinforced magnesium / aluminum composite plate).

[0054] Figure 3 shows the macroscopic morphology of the titanium foil interlayer interface continuity in the heat-treated Ti interlayer reinforced magnesium / aluminum composite plate. Figure 3 It can be seen that, through the coordinated control of various process parameters, the interface continuity of the Ti foil intermediate layer in the composite plate is ≥99%, and the continuous and stable bonding between the Ti layer and the magnesium and aluminum layers has been successfully achieved.

[0055] Figure 4, (a) is the interface SEM image of the heat-treated Ti intermediate layer reinforced magnesium / aluminum composite plate prepared in Example 1, and (b) is the elemental distribution spectrum of the heat-treated Ti intermediate layer reinforced magnesium / aluminum composite plate prepared in Example 1.

[0056] As shown in Figure 4, after heat treatment, no intermetallic compounds were formed at the interface of the composite plate, and the interfacial bonding strength remained at 83 MPa, achieving stable bonding after high-temperature treatment. The hardness test was conducted according to GB / T 4340.1-2009 "Metallic Materials - Vickers Hardness Test - Part 1: Test Method", with the aluminum alloy layer reaching a hardness of 127 Hv and the magnesium alloy layer reaching a hardness of 48 Hv.

[0057] Example 2 This embodiment provides a Ti interlayer reinforced magnesium / aluminum composite plate, and the preparation steps are as follows: (1) Raw material pretreatment: ZK60 magnesium plate (2 mm thick), TA1 titanium foil (0.25 mm thick), and 6013 aluminum plate (2 mm thick) were selected. The surfaces of the three plates to be bonded were polished with a wire brush to remove the oxide layer. After that, the plates were stacked in the order of magnesium plate / titanium foil / aluminum plate. The stack size was 1500 mm × 400 mm. A binding device was used to bind and fix the plates to prevent slippage between the layers.

[0058] (2) Hot-rolled composite: The stacked plates were held at 400℃ for 20 min and then hot-rolled for lamination. The roll speed was 60 mm / s, and the rolling was performed in a single pass with a total deformation of 45%. The resulting composite plate had a smooth macroscopic surface without delamination or peeling. The surface bonding rate was 96%, and the interfacial bonding strength was 55 MPa. (The surface bonding rate and interfacial bonding strength were tested using the same methods as in Example 1.) (3) Heat treatment: The hot-rolled composite plate was subjected to solution treatment and aging treatment sequentially. The solution treatment temperature was set at 480℃ and the holding time was 20 min, while the aging treatment temperature was set at 160℃ and the holding time was 6 h. The plate was then cooled to room temperature in the furnace. After heat treatment, the properties of the composite plate were tested (using the same method as in Example 1). The results showed that its interfacial bonding strength reached 54 MPa, and the Vickers hardness of the magnesium layer and the aluminum layer were 42 Hv and 65 Hv, respectively.

[0059] Example 3 This embodiment provides a Ti interlayer reinforced magnesium / aluminum composite plate, and the preparation steps are as follows: (1) Raw material pretreatment: AZ31 magnesium plate (6 mm thick), TA1 titanium foil (0.3 mm thick), and 6061 aluminum plate (6 mm thick) were selected. The surfaces of the three plates to be bonded were polished with a wire brush to completely remove the surface oxide layer and expose the fresh metal surface. After polishing, the plates were stacked in the order of magnesium plate / titanium foil / aluminum plate, with the stack size being 1500 mm × 200 mm. A binding device was used to bind and fix the plates together to prevent slippage between the layers.

[0060] (2) Hot-rolled composite: The stacked plates, after being fixed as described above, were placed in a heating device and held at 430°C for 40 min. Subsequently, they were rolled and composited at a roll speed of 90 mm / s in a single pass with a deformation of 50%. A hot-rolled Ti-intermediate-layer reinforced magnesium / aluminum composite plate was obtained, which exhibited good macroscopic morphology and a continuous and stable interface.

[0061] The same method as in Example 1 was used for the determination, and the results showed that the surface bonding rate was ≥98% and the interfacial bonding strength was 70 MPa.

[0062] (3) Heat treatment: The hot-rolled composite plate was subjected to solution treatment and aging treatment sequentially. The solution treatment temperature was set at 500℃ and the holding time at 40 min, while the aging treatment temperature was set at 180℃ and the holding time at 7 h. The plate was then cooled to room temperature in the furnace. After heat treatment, the properties of the composite plate were tested (using the same method as in Example 1). The results showed that its interfacial bonding strength reached 72 MPa, and the Vickers hardness of the magnesium layer and the aluminum layer were 46 Hv and 105 Hv, respectively.

[0063] Example 4 This embodiment provides a Ti interlayer reinforced magnesium / aluminum composite plate, and the preparation steps are as follows: (1) Raw material pretreatment: ZK60 magnesium plate (8 mm thick), TA1 titanium foil (0.4 mm thick), and 6016 aluminum plate (8 mm thick) were selected. The surfaces of the three plates to be bonded were polished with a wire brush to completely remove the surface oxide layer and expose the fresh metal surface. After polishing, the plates were stacked in the order of magnesium plate / titanium foil / aluminum plate. The size of the stacked plates was 1000 mm × 300 mm. A binding device was used to bind and fix them to prevent slippage between the layers.

[0064] (2) Hot-rolled composite: The stacked plates, after being fixed as described above, were placed in a heating device and held at 440°C for 50 minutes before hot rolling composite processing. The rolling speed was 120 mm / s, and the rolling was performed in a single pass with a deformation of 55%, resulting in a hot-rolled Ti intermediate layer reinforced magnesium / aluminum composite plate. The composite plate had a good macroscopic morphology and was free from wrinkles or peeling.

[0065] The same method as in Example 1 was used for the determination, and the results showed that the surface bonding rate was 99% and the interfacial bonding strength reached 74 MPa.

[0066] (3) Heat treatment: The hot-rolled composite plate was subjected to solution treatment and aging treatment sequentially. The solution treatment temperature was set at 530℃ and the holding time was 60 min, while the aging treatment temperature was set at 200℃ and the holding time was 9 h. The plate was then cooled to room temperature in the furnace. After heat treatment, the properties of the composite plate were tested (using the same method as in Example 1). The results showed that its interfacial bonding strength reached 72 MPa, and the Vickers hardness of the magnesium layer and the aluminum layer were 50 Hv and 130 Hv, respectively.

[0067] Comparative Example 1 This comparative example provides a magnesium / aluminum composite plate, which differs from Example 1 in that it does not include a Ti interlayer. The specific preparation steps are as follows: (1) Raw material pretreatment: AZ31 magnesium plate and 6013 aluminum plate were selected as the base material, and their thickness before rolling was 6mm. The surfaces of the two plates to be joined were polished with a wire brush to completely remove the surface oxide layer and expose the fresh metal surface. After polishing, the plates were stacked in the order of magnesium plate / aluminum plate. The size of the stacked plates was 500mm×100mm, and a binding device was used to fix them to prevent slippage between layers.

[0068] (2) Hot rolling composite: The stacked plates after the above stacking and fixing are placed in a heating device and kept at 420℃ for 35 minutes; then rolling composite is carried out, the roll speed is 120mm / s, the total rolling deformation is 50%, and a hot-rolled magnesium / aluminum composite plate with a size of 1m×106mm is obtained. The surface bonding rate is >95%, and the interfacial bonding strength under rolling is 98MPa. The bonding strength is higher than that of the magnesium / aluminum composite plate with Ti intermediate layer in Example 1. This is because the element compatibility between magnesium and aluminum is better, resulting in more metallurgical bonding. (3) Heat treatment: The hot-rolled magnesium / aluminum composite plate was first solution treated at 530℃ for 30 min and then cooled to room temperature by water cooling; then it was aged at 180℃ for 7 h and then cooled to room temperature by furnace cooling. Due to the absence of a Ti interlayer, a eutectic reaction occurred at the magnesium-aluminum interface, and the sample was ablated during the high-temperature heat treatment process, making it impossible to obtain a qualified heat-treated magnesium / aluminum composite plate. In other words, magnesium-aluminum composite plates without a Ti interlayer cannot be subjected to high-temperature treatment at 500℃.

[0069] Comparative Example 2 The only difference from Example 1 is that the thickness of the Ti intermediate layer used is 0.2 mm, while the other steps and parameters are the same as in Example 1.

[0070] The interfacial bonding strength of the hot-rolled Ti interlayer reinforced magnesium / aluminum composite plate prepared in Comparative Example 2 was 90 MPa, which was higher than that in Example 1. This is because the reduction in the thickness of the Ti interlayer facilitates the coordinated deformation of dissimilar metals, thereby improving the bonding strength.

[0071] Figure 5 In the figure, (a) is the elemental distribution map of the hot-rolled Ti intermediate layer reinforced magnesium / aluminum composite plate in Comparative Example 2, and (b) is the interface SEM image of the hot-rolled Ti intermediate layer reinforced magnesium / aluminum composite plate in Comparative Example 2.

[0072] Figure 5 The results show that the reduction in the thickness of the Ti interlayer leads to localized tearing of the Ti layer during rolling. The heat treatment results are similar to those of Comparative Example 1; the sample exhibits localized ablation during high-temperature heat treatment, verifying that the magnesium-aluminum composite plate with torn Ti interlayer cannot undergo high-temperature treatment at 500℃.

[0073] Comparative Example 3 The only difference from Example 1 is that the thickness of the Ti intermediate layer used is 1 mm, while the other steps and parameters are the same as in Example 1.

[0074] The interfacial bonding strength of the hot-rolled Ti interlayer reinforced magnesium / aluminum composite plate prepared in Comparative Example 3 was 26 MPa, significantly lower than that in Example 1. This is because as the thickness of the Ti interlayer increases, it becomes difficult for magnesium and aluminum to achieve coordinated plastic flow during rolling deformation, hindering interfacial strain transfer and resulting in uneven interfacial bonding, thus significantly reducing the bonding strength. Especially under this thickness condition, there is almost no effective coordinated deformation among the three metal layers, and the Ti layer mainly serves as a rigid barrier, leading to a drastic decrease in the composite interfacial strength. After heat treatment, the interfacial bonding strength of the magnesium / aluminum composite plate was 27 MPa, almost unchanged.

[0075] Comparative Example 4 The only difference from Example 1 is that the rolling temperature is 480°C.

[0076] The interfacial bonding strength of the hot-rolled Ti interlayer reinforced magnesium / aluminum composite plate prepared in Comparative Example 4 was 42 MPa, lower than that in Example 1. This is because the Ti interlayer underwent severe oxidation at high temperatures, forming a dense oxide film that hindered diffusion and bonding between dissimilar metals, thus reducing the interfacial bonding strength. Simultaneously, the large amount of brittle ceramic phase generated when the Ti layer surface is severely oxidized easily leads to localized tearing under rolling stress, further weakening the interfacial continuity and bonding performance. The heat treatment results were similar to Comparative Example 1; the sample experienced localized ablation during high-temperature heat treatment, verifying that the magnesium / aluminum composite plate with torn Ti interlayer could not withstand high-temperature treatment at 500°C.

[0077] Comparative Example 5 The only difference from Example 1 is that the rolling speed of the rolling compound is 30 mm / s.

[0078] Due to the excessively low rolling speed, the interface temperature rise during rolling is insufficient, significantly weakening the diffusion driving force between dissimilar metals and restricting interfacial plastic flow, making it difficult to form metallurgical or mechanical bonds. Ultimately, the composite plate interface exhibits obvious delamination and separation, failing to achieve effective bonding.

[0079] Comparative Example 6 The only difference from Example 1 is that the rolling speed of the rolling compound is 200 mm / s.

[0080] The interfacial bonding strength of the hot-rolled Ti interlayer reinforced magnesium / aluminum composite plate prepared in this comparative example was 58 MPa. Under high strain rates, the Ti foil could not fully participate in plastic flow, and the strain compatibility between the Ti interlayer and the magnesium and aluminum matrix decreased significantly, leading to local stress concentration, resulting in obvious tearing and fracture phenomena, ultimately causing interfacial discontinuity and a significant reduction in bonding strength. The heat treatment results were similar to those of Comparative Example 1; the sample underwent local ablation during high-temperature heat treatment, verifying that the magnesium / aluminum composite plate with torn Ti interlayer could not be subjected to high-temperature treatment at 500℃.

[0081] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a Ti interlayer reinforced magnesium / aluminum composite plate, characterized in that, Includes the following steps: (1) Using titanium foil as the intermediate layer, magnesium plate, titanium foil and aluminum plate are stacked sequentially; (2) The plates obtained by sequential stacking are rolled at 400-440℃ at a rolling speed of 60-120mm / s, and the total rolling deformation is 45-55% to obtain hot-rolled composite plates. (3) The hot-rolled composite plate is subjected to solution treatment and aging treatment in sequence to obtain the Ti intermediate layer reinforced magnesium / aluminum composite plate; The solution treatment temperature is 480-530℃; the aging treatment temperature is 160-200℃. The magnesium plate has a thickness of 2-8 mm, the titanium foil has a thickness of 0.25-0.4 mm, and the aluminum plate has a thickness of 2-8 mm.

2. The method for preparing the Ti interlayer reinforced magnesium / aluminum composite plate according to claim 1, characterized in that, The magnesium plate is of the Mg-Al-Zn or Mg-Zn-Zr series; the titanium foil is pure titanium foil; and the aluminum plate is a 5000 or 6000 series aluminum alloy.

3. The method for preparing the Ti interlayer reinforced magnesium / aluminum composite plate according to claim 1, characterized in that, In step (2), before rolling, the plate obtained by sequential stacking is also heat-insulated at 400-440°C.

4. The method for preparing the Ti interlayer reinforced magnesium / aluminum composite plate according to claim 3, characterized in that, The heat preservation treatment time is 20-50 minutes.

5. The method for preparing the Ti interlayer reinforced magnesium / aluminum composite plate according to claim 1, characterized in that, The solution treatment time is 20-60 minutes; the aging treatment time is 6-9 hours.

6. The method for preparing the Ti interlayer reinforced magnesium / aluminum composite plate according to claim 1, characterized in that, Before sequential stacking in step (1), the steps also include pre-treating the surfaces of the magnesium plate, titanium foil and aluminum plate to be bonded to remove the oxide layer.

7. The Ti interlayer reinforced magnesium / aluminum composite plate prepared by the method of preparing Ti interlayer reinforced magnesium / aluminum composite plate according to any one of claims 1-6.

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