High-performance magnesium-aluminum composite board based on high-toughness and corrosion-resistant crossed aluminum alloy and preparation method of high-performance magnesium-aluminum composite board

Abstract

The invention belongs to the technical field of metal layered composite materials, and particularly relates to a magnesium-aluminum composite plate based on a high-toughness and corrosion-resistant crossed aluminum alloy and a preparation method of the magnesium-aluminum composite plate. According to the composite board, aluminum cross alloy serves as a composite layer material, the aluminum cross alloy is Al-Mg-Zn-(Cu) series or Al-Mg-Cu series alloy, the magnesium content of the aluminum cross alloy ranges from 3.0 wt% to 8.6 wt%, and Zn / Mg < lt >; 1 or Cu / Milt; 1. The preparation method comprises the following steps: performing heat treatment on a magnesium alloy plate; carrying out 45-degree cross polishing cleaning on the composite interface; after assembly, asymmetrical rolling with a small reduction rate (25%-40%) is firstly carried out to realize primary compounding and interface structure control; performing intermediate heat treatment to optimize interface bonding; and finally, synchronous rolling with the large reduction rate (60%-80%) is carried out so as to strengthen combination and optimize the plate shape. By utilizing the unique performance of the aluminum cross alloy, the prepared composite plate has the advantages of high interface bonding strength, good overall obdurability, flat plate shape, good corrosion resistance and the like, and is particularly suitable for traffic and transportation equipment structural parts with strict requirements on light weight, safety and formability.

Description

Technical Field

[0001] This invention belongs to the field of metal layered composite material technology, specifically relating to a magnesium-aluminum composite plate based on a high-strength, high-toughness, and corrosion-resistant cross-laminated aluminum alloy and its preparation method. This invention uses a novel "cross-laminated aluminum alloy" as the cladding material and achieves a synergistic improvement in interfacial bonding strength, overall mechanical properties, and plate shape quality through an optimized asynchronous-synchronous composite rolling process. Background Technology

[0002] Lightweighting is one of the core trends in the development of high-end equipment manufacturing industries such as aerospace and new energy vehicles. Magnesium alloys, as the lightest metallic structural materials, possess extremely high specific strength and specific stiffness, but their low absolute strength, poor corrosion resistance, and poor room temperature formability limit their widespread application. Aluminum alloys, especially the 5xxx series (Al-Mg), have good formability and corrosion resistance, but their strength is limited and cannot be strengthened by heat treatment; while the 2xxx (Al-Cu-Mg) and 7xxx (Al-Zn-Mg-Cu) series aluminum alloys have very high strength, their formability is poor. The properties of traditional single materials are no longer sufficient to meet the integrated requirements of "high formability + high strength" for modern structural components.

[0003] To balance the lightweight advantages of magnesium and the surface properties of aluminum, magnesium-aluminum composite plates have emerged. Rolling lamination is the mainstream process for preparing this type of layered composite material. However, traditional rolling lamination methods for preparing magnesium-aluminum composite plates face two major challenges: First, the significant differences in the physical and mechanical properties of magnesium and aluminum make coordination difficult during deformation, easily leading to low interfacial bonding strength and the formation of continuous and brittle intermetallic compounds (such as Al3Mg2, Mg17Al12) at the interface, severely deteriorating the mechanical properties and subsequent processing capabilities of the composite plate. Second, while asynchronous rolling can reduce rolling force and promote interfacial lamination, multi-pass rolling easily leads to severe plate warping and exacerbates the growth of interfacial compounds, negatively impacting bonding strength.

[0004] The recently proposed "cross-alloy" design concept (such as Al-Mg-Zn-(Cu)) optimizes the composition of alloys to simultaneously possess the excellent formability of 5xxx series alloys and the high strength of 7xxx series alloys, providing a new approach for developing high-performance layered composite materials. However, there is currently no research on combining such cutting-edge cross-alloy aluminum alloys with magnesium alloys, nor is there a matching composite preparation process. Therefore, developing a high-performance magnesium-aluminum composite plate based on cross-alloy aluminum alloys and equipped with precise interface and plate shape control technology, along with its preparation method, has significant theoretical value and broad application prospects. Summary of the Invention

[0005] The main objective of this invention is to overcome the shortcomings of existing magnesium-aluminum composite plates, such as low interfacial bonding strength, poor plate shape quality, and difficulty in simultaneously achieving strength and formability of the composite materials. This invention provides a high-performance magnesium-aluminum composite plate based on a high-strength, high-toughness, and corrosion-resistant cross-linked aluminum alloy, along with its preparation method. Through innovative material design and manufacturing processes, this invention achieves a synergistic improvement in the interfacial bonding strength, overall mechanical properties, and plate shape quality of the composite plate.

[0006] To achieve this objective, the present invention adopts the following technical solution: On the one hand, the present invention provides a high-performance magnesium-aluminum composite plate based on a high-strength, high-toughness, and corrosion-resistant cross-linked aluminum alloy.

[0007] The composite plate includes a cross-layered aluminum alloy layer and a magnesium alloy layer, which are rolled together to form a metallurgical interface. The cross-alloy is an age-hardening Al-Mg-based alloy selected from one or a combination of the following two systems: Al-Mg-Zn-(Cu) alloy: composed of the following components by mass percentage: Mg: 3.0-8.6 wt.%, Zn: 2.0-2.9 wt.%, Cu: 0-1.0 wt.%, Sc: 0.12-0.27 wt.%, Zr: 0.12-0.36 wt.%, with the remainder being Al, and the Zn / Mg weight ratio being less than 1; Al-Mg-Cu alloy: composed of the following components by mass percentage: Mg: 3.0-8.6 wt.%, Cu: 0.2-1.0 wt.%, Sc: 0.12-0.27 wt.%, Zr: 0.12-0.36 wt.%, with the remainder being Al, and the Cu / Mg weight ratio being less than 1.

[0008] Furthermore, the Al-Mg-Zn-(Cu) cross-linked aluminum alloy layer contains the T-Mg32(Al, Zn, Cu)49 phase as the main strengthening phase. Preferably, it also contains a dispersed Al3(Sc, Zr) phase.

[0009] Preferably, the thickness ratio of the cross-layer aluminum alloy to the magnesium alloy layer is 1:2.8 to 1:3.8. More preferably, the thickness ratio is 1:3.0 to 1:3.5. Most preferably, the thickness ratio is 1:3.3.

[0010] Furthermore, the composite plate possesses excellent interfacial bonding strength and comprehensive mechanical properties. Preferably, its interfacial bonding strength is not less than 85 MPa.

[0011] Preferably, the metallurgical interface between the cross-layer aluminum alloy and the magnesium alloy is a discontinuous, stepped intermetallic compound layer with a thickness of 0.5-5.0 micrometers. This compound layer mainly consists of Al3Mg2 and Mg. 17 Al12 The phase composition and its stepped morphology can effectively passivate the crack propagation path and alleviate the stress concentration at the interface, thereby significantly improving the toughness and crack propagation resistance of the interface while achieving high-strength metallurgical bonding.

[0012] Furthermore, the cross-linked aluminum alloy material itself, under peak aging conditions, has a tensile strength of not less than 400 MPa, a yield strength of not less than 310 MPa, and an elongation of not less than 11%.

[0013] Secondly, the present invention provides a method for preparing the above-mentioned high-performance magnesium-aluminum composite plate.

[0014] The method includes the following steps: S1. Raw material preparation: Prepare cross-shaped aluminum alloy plates and magnesium alloy plates of equal length and width, with a thickness ratio of 2.8 to 3.8.

[0015] S2. Magnesium plate pretreatment: The magnesium alloy plate is subjected to solution heat treatment at a temperature of 300-450℃ and a holding time of 120-360 minutes, followed by air cooling to room temperature.

[0016] S3. Surface treatment and assembly: The surfaces of the aluminum alloy plate and magnesium alloy plate to be laminated are ground and cleaned to remove oxide layer and oil stains. Then, the cleaned surfaces to be laminated are placed face to face and fixed by riveting and binding to obtain the composite blank.

[0017] S4. Preheating of composite slab: The composite slab is heated to a temperature of 300-450℃ and held for 20-50 minutes.

[0018] S5. Asynchronous rolling: The preheated composite slab is asynchronously rolled, with the rolling speed ratio between the magnesium side and the aluminum side being 1.15-1.35, the rolling reduction rate being 25%-40%, and the rolling speed being 0.5-1.5 m / s.

[0019] S6. Intermediate heat treatment: The composite plate after asynchronous rolling is subjected to heat treatment to control the interface properties. The heat treatment temperature is 300-450℃ and the holding time is 10-30 minutes.

[0020] S7. Synchronous rolling: The heat-treated composite plate is synchronously rolled with a reduction rate of 60%-80% to obtain the final magnesium-aluminum composite plate.

[0021] Preferably, the heat treatment process in step S2 is a heat treatment temperature of 350-400℃ and a holding time of 150-180 minutes. Further, for AZ31 series magnesium alloys, the heat treatment temperature is set to 380-400℃; for Mg-Sn series magnesium alloys, the heat treatment temperature is set to 350-370℃.

[0022] Preferably, the grinding and cleaning in step S3 is performed by cross grinding with an angle grinder, wherein the grinding trajectory is at an angle of 30° to 60° with the rolling direction, preferably 45°, to form a rough morphology with specific grooves, increase the bonding area and mechanically remove the oxide layer; subsequently, acetone and anhydrous ethanol are used for cleaning in sequence and then air-dried. Preferably, in step S3, the slab assembly involves drilling holes at the beginning of the slab and riveting it with cross-shaped aluminum alloy rivets to provide stable axial positioning, and drilling holes at the end and binding it with metal wires with a diameter of 1.5-3mm. This composite fixing method of "rigid riveting at the beginning and flexible binding at the end" can effectively prevent interlayer misalignment during the rolling process and reserve a certain space for the longitudinal flow of metal during rolling deformation, thereby synergistically ensuring the uniformity of the composite interface and the bonding quality.

[0023] Preferably, the asynchronous rolling described in step S5 is implemented by rolling at different speeds with the same diameter or rolling at different diameters with the same speed. Furthermore, when using the same diameter but different speed method, the ratio of the linear speed of the magnesium-side roll to the linear speed of the aluminum-side roll is controlled at 1.20-1.30; when using the same speed but different diameter method, the ratio of the diameter of the magnesium-side roll to the diameter of the aluminum-side roll is controlled at 1.20-1.30.

[0024] Preferably, the intermediate heat treatment process in step S6 is as follows: holding temperature 300-450℃, holding time 15-25 minutes.

[0025] Preferably, after the synchronous rolling in step S7, the obtained magnesium-aluminum composite plate is further subjected to a pre-aging treatment, wherein the pre-aging process is to hold at 80-120°C for 3-12 hours.

[0026] Furthermore, in step S7, the total reduction rate of the synchronous rolling is preferably 65%-75%. Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention is the first to apply the "cross-alloy" system to magnesium-aluminum composite plates. By introducing Zn and / or Cu into the Al-Mg matrix and strictly controlling the element ratio, this alloy cleverly integrates the excellent formability of 5xxx series alloys with the high strength characteristics of 7xxx / 2xxx series alloys, fundamentally solving the bottleneck of single performance in multilayer materials.

[0027] 2. This invention innovatively employs a composite process of "asynchronous rolling with low reduction rate + intermediate heat treatment + synchronous rolling with high reduction rate". This combined process utilizes asynchronous rolling to promote initial interface bonding, precisely controls the formation and thickness of interface compounds through intermediate heat treatment, and finally uses synchronous rolling with high reduction rate to strongly consolidate the interface and correct the plate shape, thus solving the technical problem of achieving both high bonding strength and excellent plate shape in one fell swoop.

[0028] 3. The magnesium-aluminum composite plate prepared by this invention has high interfacial bonding strength (not less than 85 MPa), flat plate shape, and high strength, high toughness, high formability and excellent corrosion resistance, which comprehensively surpasses the magnesium-aluminum composite plates prepared by traditional processes.

[0029] 4. The method described in this invention has a compact process, low equipment requirements, and is easy to scale up for industrial production. By adjusting the specific composition and heat treatment regime of the cross-alloy, the final performance of the composite plate can be flexibly customized to meet the application needs of different fields, from automotive bodies to aerospace structural components. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This results in the formation of discontinuous, stepped intermetallic compound layers at the interface; Figure 2 This is a process flow diagram for preparing a high-performance magnesium-aluminum composite plate according to Example 1 of the present invention. Figure 3 The image shows the microstructure of the cross-linked aluminum alloy selected in Example 1 (SEM image). Figure 4 The image shows the SEM image of the interface microstructure of the magnesium-aluminum composite plate prepared in Example 2. Detailed Implementation

[0032] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0033] Example 1 This implementation uses an Al-Mg-Zn-Cu intercalated aluminum alloy with the following mass percentages: Mg 7.2%, Zn 2.8%, Cu 0.5%, Sc 0.2%, Zr 0.25%, with the balance being Al. The Zn / Mg ratio is approximately 0.67. The sheet dimensions are 200 mm × 100 mm × 1.5 mm. Alternatively, AZ31B alloy is used, with sheet dimensions of 200 mm × 100 mm × 5.0 mm. The magnesium to aluminum sheet thickness ratio is 3.3. Asynchronous rolling is achieved using a mill with the same speed but different diameters, meaning the upper and lower rolls have the same angular velocity (w1 = w2) but different roll diameters (R1 ≠ R2). The process flow diagram is shown below. Figure 2 As shown.

[0034] The specific preparation steps in this embodiment are as follows: S1. Place the AZ31B magnesium alloy plate in a vacuum heating furnace for solution heat treatment at a temperature of 400℃. After holding at this temperature for 3 hours, air cool to room temperature to obtain a uniform and refined matrix structure.

[0035] S2. For the surfaces of the cross-laminated aluminum alloy and magnesium alloy plates to be laminated, use an angle grinder to perform cross-grinding at a 45° angle to the rolling direction to create a uniform rough morphology and increase the bonding area. After grinding, use acetone and anhydrous ethanol sequentially for ultrasonic cleaning to remove oil and impurities, and then dry with clean compressed air. Align the treated plates with the surfaces to be laminated facing each other, and drill holes at both ends of the plate blank. The first part is riveted using cross-laminated aluminum alloy rivets of the same material as the cladding, and the second part is bound with annealed pure aluminum wire with a diameter of 2mm, achieving a composite fixation of "rigid riveting at the first end and flexible binding at the second end".

[0036] S3. Place the fixed composite slab into the heating furnace and keep it at 400℃ for 15 minutes.

[0037] S4. Quickly feed the preheated slab into the rolling mill. Set the diameter of the magnesium-side rolls to φ320 mm, the diameter of the aluminum-side rolls to φ272 mm, and the speed ratio to 1.18. Perform single-pass rolling at a rolling speed of 0.5 m / s, with a reduction rate of 30%.

[0038] S5. After asynchronous rolling, the composite plate is air-cooled to room temperature, and then immediately subjected to intermediate heat treatment at 400°C for 15 minutes to regulate the growth of interfacial compounds.

[0039] S6. The slab after intermediate heat treatment is fed into a synchronous rolling mill and rolled at a rolling speed of 0.5 m / s to a total thickness of 1.95 mm, with a total reduction rate of 70%.

[0040] S7. The composite plate after synchronous rolling is subjected to pre-aging treatment, which is to keep it at 100℃ for 6 hours to stabilize the performance of the cross aluminum alloy layer.

[0041] Figure 3 The image shown is a SEM image of the cross-aluminum alloy layer used in the composite plate of Example 1. Its tensile strength reaches 457 MPa, yield strength reaches 322 MPa, and elongation is 13.1%, which meets the performance requirements described in the invention.

[0042] The prepared magnesium-aluminum composite plate has no oxide inclusions, cracks or other defects at the interface, and the metallurgical bond is tight. Tensile and shear tests were conducted, and the interfacial bond strength was measured to be 92 MPa, which is higher than the requirement of not less than 85 MPa.

[0043] An intermetallic compound layer, approximately 3.5 micrometers thick and discontinuously stepped, was formed at the interface of the composite plate. Figure 1As shown, the compound layer is mainly composed of Al3Mg2 and Mg. 17 Al 12 The phase composition and its stepped morphology can effectively passivate the crack propagation path and alleviate the stress concentration at the interface, thereby significantly improving the toughness and crack propagation resistance of the interface while achieving high-strength metallurgical bonding.

[0044] Example 2 In this embodiment, the cross-layer aluminum alloy is an Al-Mg-Cu cross-layer aluminum alloy with the following mass percentages: Mg 5.0%, Cu 0.8%, Sc 0.15%, Zr 0.30%, and the balance being Al. The calculated Cu / Mg ratio is 0.16. The sheet size is 300 mm × 300 mm × 1.5 mm. The magnesium alloy sheet is a Mg-Sn series alloy with a sheet size of 300 mm × 300 mm × 4.5 mm. The initial thickness ratio of the magnesium to aluminum sheets is 3.0. Asynchronous rolling is achieved using a mill with the same diameter but different speeds, meaning the upper and lower rolls have the same diameter (R1=R2) but different angular velocities (w1≠w2).

[0045] The specific preparation steps in this embodiment are as follows: S1. Prepare Al-Mg-Cu series cross-laminated aluminum alloy plates and Mg-Sn alloy plates of the above specifications.

[0046] S2. Place the Mg-Sn alloy plate in a vacuum heating furnace for solution heat treatment at 350℃ for 360 min, and then air cool to room temperature.

[0047] S3. Grind the two surfaces to be laminated at a 45° angle to the rolling direction. Then, use acetone and anhydrous ethanol for ultrasonic cleaning and drying. Finally, fix the billet by "riveting with cross-shaped aluminum alloy rivets at the head end and binding with φ2.5mm annealed pure aluminum wire at the tail end".

[0048] S4. Hold the assembled slab at 350℃ for 20 minutes.

[0049] S5. Feed the preheated slab into the rolling mill. Set the ratio of the linear speed of the magnesium side to the aluminum side rolls to 1.30, and perform single-pass rolling at a rolling speed of 1.0 m / s with a reduction rate of 40%.

[0050] S6. After asynchronous rolling, the composite plate is kept at 350℃ for 20 minutes.

[0051] S7. The heat-treated slab is synchronously rolled at a speed of 1.0 m / s until the total thickness is 1.5 mm and the total reduction rate is 75%.

[0052] S8. Perform a pre-aging treatment of the final composite board at 90℃ for 10 hours.

[0053] The Al-Mg-Cu cross-laminated aluminum alloy layer has a tensile strength of 465 MPa, a yield strength of 325 MPa, and an elongation of 12.7%.

[0054] Figure 4 The image shows the interface of the composite plate prepared in Example 2. A layer of intermetallic compound, approximately 4.2 micrometers thick and distributed in a discontinuous, stepped pattern, is formed at the interface. The interface shows good bonding, without cracks, pores, or other defects. The measured interfacial bonding strength is 87 MPa.

[0055] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A high-performance magnesium-aluminum composite plate based on a high-strength, high-toughness, corrosion-resistant cross-linked aluminum alloy, characterized in that, include: A cross-layer aluminum alloy and a layer magnesium alloy are provided, wherein the cross-layer aluminum alloy and the layer magnesium alloy are combined by rolling to form a metallurgical interface; the thickness ratio of the cross-layer aluminum alloy to the layer magnesium alloy is 1:2.8 to 1:3.

8.

2. The high-performance magnesium-aluminum composite plate according to claim 1, characterized in that, The cross-layer aluminum alloy is an age-hardenable Al-Mg-Zn-(Cu) alloy or an Al-Mg-Cu alloy.

3. The high-performance magnesium-aluminum composite plate according to claim 2, characterized in that, The Al-Mg-Zn-(Cu) alloy, by mass percentage, comprises the following components: Mg: 3.0-8.6 wt.%, Zn: 2.0-2.9 wt.%, Cu: 0-1.0 wt.%, Sc: 0.12-0.27 wt.%, Zr: 0.12-0.36 wt.%, with the remainder being Al, and the Zn / Mg weight ratio being less than 1; the Al-Mg-Cu alloy comprises the following components: Mg: 3.0-8.6 wt.%, Cu: 0.2-1.0 wt.%, Sc: 0.12-0.27 wt.%, Zr: 0.12-0.36 wt.%, with the remainder being Al, and the Cu / Mg weight ratio being less than 1.

4. The high-performance magnesium-aluminum composite plate according to claim 3, characterized in that, The Al-Mg-Zn-(Cu) alloy layer contains the main strengthening phase T-Mg32(Al, Zn, Cu)49, which also contains the dispersed Al3(Sc, Zr) phase.

5. The high-performance magnesium-aluminum composite plate according to claim 1, characterized in that, The metallurgical bonding interface between the cross-aluminum alloy layer and the magnesium alloy layer is a discontinuous, stepped intermetallic compound layer with a thickness of 0.5-5.0 micrometers.

6. A method for preparing a high-performance magnesium-aluminum composite plate according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Raw material preparation: Prepare cross-shaped aluminum alloy plates and magnesium alloy plates of equal length and width, with a thickness ratio of 1:2.8 to 1:3.8; S2. Magnesium plate pretreatment: The magnesium alloy plate is heat-treated at a temperature of 300-450℃ for 120-360 minutes, and then air-cooled to room temperature. S3. Surface treatment and assembly: The surfaces of the aluminum alloy plate and magnesium alloy plate to be laminated are ground and cleaned to remove oxide layer and oil stains. Then the cleaned surfaces to be laminated are placed face to face and fixed by riveting and binding to obtain the composite plate blank. S4. Preheating of composite slab: The composite slab is heated to a temperature of 300-450℃ and held for 20-50 minutes. S5. Asynchronous rolling: The preheated composite slab is asynchronously rolled, wherein the rolling speed ratio between the magnesium side and the aluminum side is 1.15-1.35, the rolling reduction rate is 25%-40%, and the rolling speed is 0.5-1.5 m / s. S6. Intermediate heat treatment: The composite plate after asynchronous rolling is subjected to heat treatment to control the interface properties. The heat treatment temperature is 300-450℃ and the holding time is 10-30 minutes. S7. Synchronous rolling: The heat-treated composite plate is synchronously rolled with a reduction rate of 60%-80% to obtain the final magnesium-aluminum composite plate.

7. The method according to claim 6, characterized in that, The heat treatment process in step S2 is as follows: heat treatment temperature 350-400℃, holding time 150-180 minutes; the intermediate heat treatment process in step S6 is as follows: holding temperature 300-450℃, holding time 15-25 minutes.

8. The method according to claim 6, characterized in that, The grinding and cleaning described in step S3 involves using an angle grinder to perform cross grinding at 30° to 60°, followed by cleaning with acetone and anhydrous ethanol and air drying; the assembly of the blank involves drilling holes at the head of the blank and riveting it with cross aluminum alloy rivets, and drilling holes at the tail and binding it with metal wire with a diameter of 1.5-3mm.

9. The method according to claim 6, characterized in that, The asynchronous rolling described in step S5 is implemented by rolling at different speeds with the same diameter or rolling at different diameters with the same speed.

10. The method according to claim 6, characterized in that, After the synchronous rolling described in step S7, the process further includes a pre-aging treatment of the obtained magnesium-aluminum composite plate, wherein the pre-aging process is to hold at 80-120℃ for 3-12 hours.

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