High-magnesium aluminum alloy based on bimodal particle strengthening and preparation method thereof

Abstract

The invention provides a high-magnesium aluminum alloy based on bimodal particle strengthening and a preparation method of the high-magnesium aluminum alloy, and belongs to the technical field of non-ferrous metal material preparation. The high-magnesium aluminum alloy based on bimodal particle strengthening comprises, by weight, 7.0%-10.0% of Mg, 0.2%-0.4% of Mn, 0.1%-0.3% of Zr, 0.2%-0.3% of Ti and the balance Al and inevitable impurities, material preparation, smelting and casting are conducted according to the chemical components, and a cast ingot is obtained; and then critical high-temperature rolling and medium-temperature rolling are sequentially carried out, rapid cooling is carried out to the room temperature, annealing treatment is carried out, and the high-magnesium aluminum alloy based on bimodal particle strengthening is obtained. According to the method, microalloying and rolling processes are not simply superposed, precipitated phases with specific sizes and distribution are designed in advance for subsequent two-step rolling processes through Mn + Zr + Ti multi-element microalloying design, and the final product has ultrahigh strength and good plasticity.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal material preparation technology, and particularly relates to a high magnesium aluminum alloy based on dual-modal particle reinforcement and its preparation method. Background Technology

[0002] Aluminum alloys, due to their low density, high specific strength, and excellent corrosion resistance, play a crucial role in lightweight structural design for aerospace, rail transportation, and new energy vehicles, becoming key materials supporting the development of these fields. Currently, high-strength aluminum alloys (tensile strength greater than 480 MPa) are mainly concentrated in the 2xxx and 7xxx series. However, these traditional systems have significant shortcomings: 1) 2xxx series Al-Cu alloys have poor weldability and corrosion resistance; 2) 7xxx series Al-Zn-Mg-Cu alloys are currently the strongest commercially available aluminum alloys, with their strength increasing with increasing Zn and Mg content. However, to suppress stress corrosion cracking, the Zn / Mg ratio in the alloy must be controlled above 2, which limits further increases in Mg content. Furthermore, the high Zn content also makes its corrosion resistance inferior to that of the 5xxx series.

[0003] 5xxx series Al-Mg alloys possess excellent corrosion resistance and weldability, with their strength primarily derived from solid solution strengthening by Mg atoms. Traditional 5xxx series alloys typically have a Mg content not exceeding 7 wt.%, resulting in tensile strengths below 400 MPa, limiting their application in load-bearing structural components. Increasing the Mg content to 7-10 wt.% is considered an effective way to further improve the strength and reduce the density of 5xxx series alloys. However, high Mg content also presents significant challenges: 1) High Mg content leads to a widening of the solid-liquid two-phase region, making the as-cast material prone to shrinkage porosity, hot cracking, and coarse, continuous network β-Al3Mg2 phases, resulting in extremely brittle materials that are susceptible to cracking during hot working; 2) Traditional rolling processes typically control deformation per pass below 15%, requiring multiple annealing processes, resulting in extremely low processing efficiency and a lack of processing methods that balance high forming efficiency with excellent overall performance. Existing technologies attempt to address these issues, but limitations remain.

[0004] Professor Li Jianguo's team at Tsinghua University (Study on Microstructure and Mechanical Properties of Al-10Mg Alloys, Tsinghua University Master's Thesis, 2019) successfully prepared Al-10Mg as-cast fine-grained microstructure using centrifugal casting. However, subsequent medium-temperature rolling and cold rolling processes required multiple intermediate annealing treatments to eliminate work hardening, resulting in a cumbersome production process, long cycle time, and high energy consumption, which is not conducive to continuous industrial production. Patent CN109332384A proposes a rolling preparation method for high-magnesium aluminum alloys. By strictly controlling key rolling parameters (temperature, reduction per pass), the risk of cracking is reduced, realizing the transformation of high-magnesium aluminum alloy sheets from laboratory to mass production. However, multiple annealings are still required between rolling passes, resulting in a long process flow and low product yield.

[0005] A team led by Wang Huiyuan at Jilin University (Scientific Reports | 5:17100 | DOI: 10.1038 / srep17100) has successfully prepared an Al-9Mg alloy with both high strength and ductility (tensile strength of approximately 597 MPa and elongation after fracture of 7.7%) and high thermal stability using a low-temperature, high-strain liner controlled rolling technique. This technique achieves the conversion of shear stress in the rolling direction to compressive stress in the normal direction through a hard plate clamping principle, enabling low cracking and large plastic deformation with a single large reduction. However, the complex design and manufacturing of the liner structure and the control of rolling process parameters limit its large-scale application.

[0006] Jihua Chen et al. from Hunan University (Trans. Nonferrous Met. Soc. China 31(2021) 2885−2898) used a high strain rate (8.6 s⁻¹) -1 A study was conducted on small samples of Al-9.2Mg-0.8Mn-0.2Zr-0.15Ti aluminum alloy underwent high-temperature rolling at 400℃. It was found that 72% single-pass rolling resulted in dynamic recrystallization of the alloy microstructure, leading to a low dislocation density and a tensile strength of 462 MPa and an elongation of 27.2%. Two-pass (40%+53%) high-temperature rolling (with a 5-minute intermediate hold) revealed a bimodal grain structure. The recrystallized fine grains provided ductility, while the non-recrystallized coarse grains provided strength, resulting in a good balance of strength and toughness (tensile strength 507 MPa, elongation 24.9%). Four-pass (20%+25%+33%+30%) high-temperature rolling produced a coarse-grained, elongated microstructure with a strong β-fiber texture and high dislocation density, achieving a strength of 550 MPa. However, localized stress concentration reduced the elongation to only 13.5%. The research results show that aluminum-magnesium alloy plates with good strength and toughness can be obtained in the laboratory through high-temperature rolling with large deformation in a limited number of passes. However, in actual industrial production, for large-size samples, the high-temperature heating of 400℃ and the heat preservation between passes are much higher than the critical temperature of hot brittleness of aluminum-magnesium alloy (350℃). In addition, the preheating time needs to be increased to ensure temperature uniformity, which can easily lead to a large number of β phase nucleation and aggregation, resulting in deformation and cracking of the plate, which brings uncertainty to industrial control.

[0007] In addition, researchers have improved the strength of high magnesium-aluminum alloys through processes such as equal diameter angular extrusion, cumulative rolling, high-pressure torsion, and friction stir welding. However, these processes are often accompanied by the problem of "strength-plasticity inversion", resulting in low material forming efficiency, limited processing size, and high energy consumption, making it difficult to meet the needs of large-scale, low-cost industrial production.

[0008] Therefore, there is an urgent need in this field for an integrated "alloy-process" design solution to fundamentally solve the problems of difficult machining, low efficiency, and uneven performance of high magnesium-aluminum alloys. Summary of the Invention

[0009] To address the problems of cumbersome process flow, high energy consumption, poor microstructure uniformity, and easy cracking in existing high-magnesium aluminum alloy processing technology of "multi-pass low-temperature rolling + intermediate multiple annealing", this invention proposes a high-magnesium aluminum alloy based on dual-modal particle reinforcement and its preparation method. Based on Al-Mg alloy (Mg content of 7~10 wt.%), through multi-element microalloying and two-step synergistic rolling, a dual-modal microstructure with synergistic reinforcement of micron- and nano-scale precipitates is constructed in the matrix, achieving a match between high strength and good plasticity of the material, and significantly improving processing efficiency.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] This invention proposes a high magnesium-aluminum alloy based on dual-modal particle reinforcement, whose chemical composition by weight percentage includes: Mg: 7.0~10.0%, Mn: 0.2~0.4%, Zr: 0.1~0.3%, Ti: 0.2~0.3%, with the balance being Al and unavoidable impurities.

[0012] Furthermore, the high magnesium-aluminum alloy based on dual-modal particle strengthening has the following chemical composition by weight percentage: Mg: 8.0~9.0%, Mn: 0.3~0.36%, Zr: 0.2~0.25%, Ti: 0.22~0.25%, with the balance being Al and unavoidable impurities.

[0013] Furthermore, the high magnesium-aluminum alloy based on dual-modal particle strengthening has the following chemical composition by weight percentage: Mg: 9.0%, Mn: 0.3%, Zr: 0.2%, Ti: 0.25%, with the balance being Al and unavoidable impurities.

[0014] This invention also proposes a method for preparing the above-mentioned high-magnesium aluminum alloy based on dual-modal particle reinforcement, comprising the following steps:

[0015] (1) Prepare materials according to the chemical composition, carry out alloy smelting and semi-continuous casting to obtain ingots;

[0016] (2) The ingot is subjected to a two-step co-rolling process, which includes critical high-temperature rolling and medium-temperature rolling;

[0017] (3) After rolling, the material is rapidly cooled to room temperature and then annealed to obtain the high magnesium-aluminum alloy based on dual-mode particle strengthening.

[0018] Further, in step (2), the critical high temperature rolling is to perform homogenization heat treatment on the ingot in the critical solution temperature range (Ts±10℃), and then perform single-pass hot rolling.

[0019] Furthermore, the homogenization heat treatment holding time is 4~12 h, the single-pass deformation of the single-pass hot rolling is 70%~90%, and the single-pass hot rolling speed is 5~10 m / s.

[0020] Furthermore, in step (2), the medium-temperature rolling involves cooling the plate after critical high-temperature rolling and then performing single-pass rolling.

[0021] Furthermore, the cooling adopts forced air cooling, with a cooling rate of 15~20 ℃ / s, cooling to 300~350℃, the single-pass deformation of the single-pass rolling is 30%~50%, and the single-pass hot rolling speed is 5~10 m / s.

[0022] Furthermore, in step (3), the annealing temperature is 150~180℃ and the holding time is 2h.

[0023] Furthermore, the high magnesium-aluminum alloy based on dual-modal particle reinforcement prepared by the above method has a tensile strength of 548-613 MPa and an elongation after fracture of 13.5-18.6%.

[0024] Furthermore, the above-mentioned method for preparing high-magnesium aluminum alloys based on dual-modal particle reinforcement specifically includes the following steps:

[0025] (1) Alloy melting and casting: Prepare materials according to the above proportions, and use vacuum melting or protective atmosphere melting to ensure uniform composition and reduce oxide inclusions. After melting, obtain ingots through semi-continuous casting process. The key to this process is to control the cooling rate (20-30 ℃ / s) to obtain a fine-grained, coarse-grained β-Al3Mg2 phase precipitation that is effectively suppressed, and contains high-density micron-sized Al6Mn and other precipitated phases in the as-cast structure.

[0026] (2) Two-step synergistic rolling process: abandoning the traditional multi-pass annealing, adopting a continuous, asymmetric temperature path of "solution critical high temperature large deformation + medium temperature rolling":

[0027] a) Critical High-Temperature Rolling: The obtained fine-grained ingot is heated to the critical solution temperature range (Ts±10℃, Ts: critical solution temperature) for homogenization heat treatment, with a holding time of 4~12 h. Immediately after homogenization, single-pass large deformation hot rolling is performed, with the deformation amount controlled at 70%~90% and the rolling speed maintained at 5~10 m / s. During this stage, most of the coarse β phase dissolves, eliminating the damage to plasticity caused by brittleness. At the same time, the alloy exhibits high-temperature superplasticity, and its flow stress is significantly reduced, effectively avoiding the risk of cracking during a single large deformation. More importantly, the micron-sized Al6Mn phase precipitated in the as-cast state and during homogenization, as well as some undissolved β phase, act as "local deformation resistance points," inducing a strong strain gradient around them, forming a high orientation difference region and intensifying grain boundary serration, thereby greatly promoting the nucleation process of dynamic recrystallization.

[0028] b) Intermediate-temperature rolling: After completing the critical high-temperature rolling, reheating is unnecessary. Utilizing the residual heat from rolling, the plate is rapidly cooled to the intermediate-temperature range (300-350 ℃) using forced air cooling (cooling rate 15-20 ℃ / s). Then, single-pass rolling is performed at this temperature, with single-pass deformation controlled at 30%-50% and a rolling rate of 5-10 m / s. During this process, rapid cooling effectively suppresses the coarsening of the β phase in the high-temperature region. Intermediate-temperature rolling utilizes the strain energy accumulated during the continuous cooling process from high to intermediate temperature to synergistically trigger two microscopic mechanisms: firstly, to further promote the dynamic recrystallization process; and secondly, to achieve strain-induced precipitation of nanoscale precipitates (such as Al3(Zr,Ti), where the atomic ratio of Zr to Ti is 1:1-4:1). These nanoscale precipitates, through a strong Zener pinning effect, hinder grain boundary migration, thereby obtaining a uniform and fine recrystallized grain structure.

[0029] (3) Low-temperature annealing: After medium-temperature rolling, the plate is immediately cooled to room temperature by spraying or other rapid cooling methods, and then subjected to low-temperature annealing treatment at 150~180℃ for 2 hours. This treatment aims to eliminate residual stress and further induce the precipitation of high-density nanoscale reinforcing phases, so that the strengthening effect reaches its peak.

[0030] Compared with the prior art, the present invention has the following advantages and technical effects:

[0031] 1. Synergistic Innovation of Composition and Process: This invention does not simply superimpose microalloying with rolling processes, but rather pre-designs precipitates of specific sizes and distributions for the subsequent two-step rolling process through a "Mn+Zr+Ti" multi-element microalloying design. In critical high-temperature rolling, micron-sized particles serve as recrystallization nucleation sites; in medium-temperature rolling, strain energy induces the precipitation of nano-sized particles, forming a "dual-mode particle strengthening system" and significantly refining the grain structure.

[0032] 2. Significant advantages in high-efficiency processing: This invention utilizes a two-step continuous rolling process of "high temperature + medium temperature" and fully leverages the residual heat from rolling, completely eliminating the multiple intermediate annealing steps and the repeated heating process required for two-step deformation at the same temperature in traditional processes. This significantly shortens the entire processing flow, dramatically improves production efficiency, and significantly reduces energy consumption and production costs, making it highly suitable for continuous industrial production.

[0033] 3. Superior microstructure and properties: This invention successfully prepares a fine-grained and uniformly distributed microstructure through the synergistic effect of large-particle-induced recrystallization nucleation and small-particle-pinned grain boundaries. This structure effectively overcomes the defects of bimodal microstructure and large performance fluctuations commonly found in existing technologies. The final product possesses both ultra-high strength (tensile strength 548-613 MPa) and good plasticity (elongation after fracture 13.5-18.6%), with comprehensive performance surpassing that of high-magnesium aluminum alloys prepared by existing traditional processes. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0035] Figure 1 This is a process flow diagram of the high magnesium aluminum alloy based on dual-modal particle strengthening according to the present invention;

[0036] Figure 2 This embodiment shows the characteristics of the high-magnesium aluminum alloy based on dual-mode particle strengthening and its typical dual-mode precipitate distribution diagram;

[0037] Figure 3 The stress-strain curves of the alloy plates in Example 1 and Comparative Example 1 of this invention are shown. Detailed Implementation

[0038] 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.

[0039] 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. Every smaller range between any stated value or intermediate value within a stated range, and 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.

[0040] 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.

[0041] 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 apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0042] 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.

[0043] This invention proposes a high-magnesium aluminum alloy based on dual-modal particle reinforcement. The chemical composition, by weight percentage, includes: Mg: 7.0~10.0%, Mn: 0.2~0.4%, Zr: 0.1~0.3%, Ti: 0.2~0.3%, with the balance being Al and unavoidable impurities.

[0044] In a preferred embodiment of the present invention, the high magnesium-aluminum alloy based on dual-mode particle reinforcement has the following chemical composition by weight percentage: Mg: 8.0~9.0%, Mn: 0.3~0.36%, Zr: 0.2~0.25%, Ti: 0.22~0.25%, with the balance being Al and unavoidable impurities; more preferably, the high magnesium-aluminum alloy based on dual-mode particle reinforcement has the following chemical composition by weight percentage: Mg: 9.0%, Mn: 0.3%, Zr: 0.2%, Ti: 0.25%, with the balance being Al and unavoidable impurities.

[0045] In a preferred embodiment of the present invention, the raw material for the above-mentioned high-magnesium aluminum alloy based on dual-modal particle strengthening includes Al-5Ti-1B grain refiner (composed of 5% titanium and 1% boron in an aluminum matrix), and the addition of Ti element is synergistically introduced with the Al-5Ti-1B grain refiner. For example, the amount of Al-5Ti-1B grain refiner added is 0.2~0.6 wt.% of the weight of the high-magnesium aluminum alloy raw material.

[0046] This invention also proposes a method for preparing the above-mentioned high-magnesium aluminum alloy based on dual-modal particle reinforcement, comprising the following steps:

[0047] (1) Prepare materials according to chemical composition, carry out alloy smelting and semi-continuous casting to obtain ingots;

[0048] (2) The ingot is subjected to two-step synergistic rolling, which includes critical high-temperature rolling and medium-temperature rolling;

[0049] (3) After rolling, the material is rapidly cooled to room temperature and then annealed to obtain a high magnesium-aluminum alloy based on dual-mode particle strengthening.

[0050] More specifically, the preparation method of high magnesium-aluminum alloy based on dual-modal particle reinforcement in this embodiment of the invention includes the following steps:

[0051] (1) Alloy melting and casting: Prepare materials according to the above proportions (chemical composition by weight percentage: Mg: 7.0~10.0%, Mn: 0.2~0.4%, Zr: 0.1~0.3%, Ti: 0.2~0.3%, balance being Al and unavoidable impurities). Vacuum melting or protective atmosphere melting is used to ensure uniform composition and reduce oxide inclusions. After melting, ingots are obtained through a semi-continuous casting process. The key to this process is to control the cooling rate (20-30 ℃ / s) to obtain a fine-grained, coarse β-Al3Mg2 phase precipitation that is effectively suppressed, and contains high-density micron-sized Al3(Zr,Ti), Al6Mn and other precipitates in the as-cast structure.

[0052] (2) Two-step synergistic rolling process: abandoning the traditional multi-pass annealing, adopting a continuous, asymmetric temperature path of "solution critical high temperature large deformation + medium temperature rolling":

[0053] a) Critical High-Temperature Rolling: The obtained fine-grained ingot is heated to the critical solution temperature range (Ts±10℃, Ts: critical solution temperature) for homogenization heat treatment, with a holding time of 4~12h. Immediately after homogenization, single-pass large deformation hot rolling is performed, with the deformation amount controlled at 70%~90% and the rolling speed maintained at 5~10 m / s. During this stage, most of the coarse β phase dissolves, eliminating the damage to plasticity caused by brittleness. At the same time, the alloy exhibits high-temperature superplasticity, and its flow stress is significantly reduced, effectively avoiding the risk of cracking during a single large deformation. More importantly, the micron-sized Al6Mn phase precipitated in the as-cast state and during homogenization, as well as some undissolved β phase (usually >1μm in size), act as "local deformation resistance points," inducing a strong strain gradient around them, forming a high orientation difference region and intensifying grain boundary serration, thereby greatly promoting the nucleation process of dynamic recrystallization.

[0054] b) Medium-temperature rolling: After completing the critical high-temperature rolling, reheating is unnecessary. Utilizing the residual heat from rolling, the plate is rapidly cooled to the medium-temperature range (300-350℃) using forced air cooling (cooling rate 15-20℃ / s). Then, single-pass rolling is performed at this temperature, with single-pass deformation controlled at 30%-50% and a rolling rate of 5-10 m / s. During this process, rapid cooling effectively suppresses the coarsening of the β phase in the high-temperature region. Medium-temperature rolling utilizes the strain energy accumulated during the continuous cooling process from high to medium temperature to synergistically trigger two microscopic mechanisms: firstly, to further promote the dynamic recrystallization process; and secondly, to achieve strain-induced precipitation of nanoscale precipitates (such as Al3(Zr,Ti), where the atomic ratio of Zr to Ti is 1:1-4:1). These nanoscale precipitates, through a strong Zener pinning effect, hinder grain boundary migration, thereby obtaining a uniform and fine recrystallized grain structure.

[0055] (3) Low-temperature annealing: After medium-temperature rolling, the plate is immediately cooled to room temperature by spraying or other rapid cooling methods, and then subjected to low-temperature annealing treatment at 150~180℃ for 2 hours. This treatment aims to eliminate residual stress and further induce the precipitation of high-density nanoscale reinforcing phases, so that the strengthening effect reaches its peak.

[0056] The process flow diagram of the high-magnesium aluminum alloy based on dual-modal particle strengthening is shown below. Figure 1 .

[0057] In this embodiment of the invention, room temperature refers to "25±3℃".

[0058] The technical solution of the present invention will be further illustrated by the following embodiments.

[0059] Example 1

[0060] A method for preparing a high-magnesium aluminum alloy (Al-9Mg-0.3Mn-0.2Zr-0.25Ti) based on dual-modal particle reinforcement includes the following steps:

[0061] (1) Alloy melting and casting: Prepare materials (the chemical composition must meet the following requirements by weight percentage: Mg: 9.0%, Mn: 0.3%, Zr: 0.2%, Ti: 0.25%, with the balance being Al and unavoidable impurities), and add 0.4wt.% of Al-5Ti-1B grain refiner to the raw materials. Melt using high-purity argon gas protection to ensure uniform composition and reduce oxide inclusions. After melting, obtain an ingot with a thickness of 100mm through a semi-continuous casting process.

[0062] (2) Two-step co-rolling process:

[0063] a) Critical high temperature rolling: The obtained ingot is homogenized at 450℃ for 8 hours. After homogenization, it is immediately subjected to single-pass hot rolling with a single-pass deformation of 80% and a rolling speed of 8 m / s.

[0064] b) Medium-temperature rolling: After the critical high-temperature rolling is completed, there is no need to reheat. The residual heat of rolling is used to rapidly cool the plate to the medium-temperature zone (320℃) by forced air cooling (cooling rate 20℃ / s). Then, single-pass rolling is carried out at this temperature, with the deformation amount of a single pass controlled at 40% and the rolling rate at 8 m / s.

[0065] (3) Low temperature annealing: After the medium temperature rolling is completed, the plate is immediately cooled to room temperature by spray rapid cooling, and then subjected to low temperature annealing treatment at 180℃ for 2 hours to obtain a high magnesium aluminum alloy based on dual-mode particle strengthening.

[0066] Performance testing

[0067] The tensile strength and elongation after fracture were tested in accordance with GB / T 228.1-2010 "Metallic materials, tensile testing - Part 1: Test method at room temperature", and the same applies below.

[0068] The high magnesium-aluminum alloy based on dual-modal particle reinforcement obtained in this embodiment has a tensile strength of 613 MPa and an elongation after fracture of 14.8%.

[0069] The characteristics of the high-magnesium aluminum alloy based on dual-mode particle strengthening obtained in this embodiment and its typical dual-mode precipitate distribution diagram are shown below. Figure 2 As can be seen, this invention constructs a "dual-modal particle reinforcement system" and significantly refines the grain structure.

[0070] Example 2

[0071] A method for preparing a high-magnesium aluminum alloy (Al-8Mg-0.35Mn-0.25Zr-0.22Ti) based on dual-modal particle reinforcement includes the following steps:

[0072] (1) Alloy melting and casting: Prepare materials (the chemical composition must meet the following requirements by weight percentage: Mg: 8%, Mn: 0.35%, Zr: 0.25%, Ti: 0.22%, with the balance being Al and unavoidable impurities), and add 0.3wt.% of Al-5Ti-1B grain refiner to the raw materials. Melt using high-purity argon gas protection to ensure uniform composition and reduce oxide inclusions. After melting, obtain an ingot with a thickness of 100mm through a semi-continuous casting process.

[0073] (2) Two-step co-rolling process:

[0074] a) Critical high temperature rolling: The obtained fine-grained ingot is heated to 445℃ for homogenization heat treatment for 10h. After homogenization treatment, single-pass large deformation hot rolling is immediately carried out, with the deformation amount controlled at 75% and the rolling speed maintained at 8 m / s.

[0075] b) Medium-temperature rolling: After completing the critical high-temperature rolling, there is no need for reheating. Utilizing the residual heat from rolling, the plate is rapidly cooled to the medium-temperature zone (330℃) using forced air cooling (cooling rate 15℃ / s). Subsequently, single-pass rolling is performed at this temperature, with the deformation per pass controlled at 40% and the rolling rate at 8 m / s.

[0076] (3) Low temperature annealing: After the medium temperature rolling is completed, the plate is immediately cooled to room temperature by spray rapid cooling, and then subjected to low temperature annealing treatment at 180℃ for 2 hours to obtain a high magnesium aluminum alloy based on dual-mode particle strengthening.

[0077] Performance testing

[0078] The high magnesium-aluminum alloy based on dual-modal particle reinforcement obtained in this embodiment has a tensile strength of 548 MPa and an elongation after fracture of 16.2%.

[0079] Example 3

[0080] A method for preparing a high-magnesium aluminum alloy (Al-7Mg-0.4Mn-0.1Zr-0.2Ti) based on dual-modal particle reinforcement includes the following steps:

[0081] (1) Alloy melting and casting: Prepare materials (the chemical composition must meet the following requirements by weight percentage: Mg: 7%, Mn: 0.4%, Zr: 0.1%, Ti: 0.2%, with the balance being Al and unavoidable impurities), and add 0.3wt.% of Al-5Ti-1B grain refiner to the raw materials. Melt using high-purity argon gas protection to ensure uniform composition and reduce oxide inclusions. After melting, obtain an ingot with a thickness of 100mm through a semi-continuous casting process.

[0082] (2) Two-step co-rolling process:

[0083] a) Critical high temperature rolling: The obtained fine-grained ingot is heated to 445℃ for homogenization heat treatment for 4 hours. After homogenization treatment, single-pass large deformation hot rolling is immediately carried out. The deformation amount of a single pass is controlled at 70%, and the rolling speed is maintained at 9 m / s.

[0084] b) Medium-temperature rolling: After completing the critical high-temperature rolling, there is no need for reheating. Utilizing the residual heat from rolling, the plate is rapidly cooled to the medium-temperature zone (350℃) by forced air cooling (cooling rate 20℃ / s). Subsequently, single-pass rolling is carried out at this temperature, with the deformation per pass controlled at 50% and the rolling rate at 9 m / s.

[0085] (3) Low temperature annealing: After the medium temperature rolling is completed, the plate is immediately cooled to room temperature by spray rapid cooling, and then subjected to low temperature annealing treatment at 160℃ for 2 hours to obtain a high magnesium aluminum alloy based on dual-mode particle strengthening.

[0086] Performance testing

[0087] The high magnesium-aluminum alloy based on dual-modal particle reinforcement obtained in this embodiment has a tensile strength of 556 MPa and an elongation after fracture of 18.6%.

[0088] Example 4

[0089] A method for preparing a high-magnesium aluminum alloy (Al-10Mg-0.2Mn-0.3Zr-0.3Ti) based on dual-modal particle reinforcement includes the following steps:

[0090] (1) Alloy melting and casting: Prepare materials (the chemical composition must meet the following requirements by weight percentage: Mg: 10%, Mn: 0.2%, Zr: 0.3%, Ti: 0.3%, with the balance being Al and unavoidable impurities), and add 0.5wt.% of Al-5Ti-1B grain refiner to the raw materials. Melt using high-purity argon gas protection to ensure uniform composition and reduce oxide inclusions. After melting, obtain an ingot with a thickness of 100mm through a semi-continuous casting process.

[0091] (2) Two-step co-rolling process:

[0092] a) Critical high temperature rolling: The obtained fine-grained ingot is heated to 445℃ for homogenization heat treatment for 12 hours. After homogenization treatment, single-pass large deformation hot rolling is immediately carried out. The deformation amount of a single pass is controlled at 90%, and the rolling speed is maintained at 5 m / s.

[0093] b) Medium-temperature rolling: After completing the critical high-temperature rolling, there is no need for reheating. Utilizing the residual heat from rolling, the plate is rapidly cooled to the medium-temperature zone (300℃) by forced air cooling (cooling rate 15℃ / s). Subsequently, single-pass rolling is carried out at this temperature, with the deformation per pass controlled at 30% and the rolling rate at 5 m / s.

[0094] (3) Low temperature annealing: After the medium temperature rolling is completed, the plate is immediately cooled to room temperature by spray rapid cooling, and then subjected to low temperature annealing treatment at 150℃ for 2 hours to obtain a high magnesium aluminum alloy based on dual-mode particle strengthening.

[0095] Performance testing

[0096] The high magnesium-aluminum alloy based on dual-modal particle reinforcement obtained in this embodiment has a tensile strength of 612 MPa and an elongation after fracture of 13.5%.

[0097] Comparative Example 1

[0098] Traditional process: Using the same alloy composition as in Example 1, but the processing technology is changed to multi-pass cold rolling (total deformation per pass is 50%), followed by an intermediate annealing (320℃, 1h) after each pass, specifically:

[0099] (1) Alloy melting and casting: Prepare materials (the chemical composition must meet the following requirements by weight percentage: Mg: 9.0%, Mn: 0.3%, Zr: 0.2%, Ti: 0.25%, with the balance being Al and unavoidable impurities), add 0.3wt.% of Al-5Ti-1B grain refiner to the raw materials, and use high-purity argon gas for protection during melting to ensure uniform composition and reduce oxide inclusions. After melting, obtain an ingot with a thickness of 100 mm through a semi-continuous casting process;

[0100] (2) Multi-pass cold rolling: After homogenization treatment, the obtained ingot is subjected to multi-pass cold rolling with a single-pass deformation of 10%. After each pass, an intermediate annealing (320 °C, 1 h) is performed until the deformation of each pass is 50%. The ingot is then cooled to room temperature to obtain a magnesium-aluminum alloy.

[0101] Performance testing

[0102] The testing method is the same as in Example 1.

[0103] The magnesium-aluminum alloy obtained in this comparative example has a tensile strength of 505 MPa and an elongation after fracture of 13.6%, which is significantly lower than that of Example 1. Furthermore, the production process takes about 60% longer and energy consumption is significantly increased.

[0104] The stress-strain curves of the alloy plates in Example 1 and Comparative Example 1 of this invention are shown below. Figure 3 .

[0105] This invention employs a two-step continuous rolling process (high temperature + medium temperature) and fully utilizes the residual heat from rolling, completely eliminating the multiple intermediate annealing steps and the repeated heating process required for two-step deformation at the same temperature in traditional processes. This significantly shortens the entire processing flow, dramatically improves production efficiency, and significantly reduces energy consumption and production costs, making it highly suitable for continuous industrial production. This invention successfully prepares a fine-grained, uniformly distributed microstructure through the synergistic effect of large-particle-induced recrystallization nucleation and small-particle-pinned grain boundaries. This structure effectively overcomes the defects of bimodal non-uniform microstructure and large performance fluctuations commonly found in traditional processes. The final product possesses both ultra-high strength and good plasticity, with overall performance surpassing that of high-magnesium aluminum alloys prepared by existing traditional processes.

[0106] Comparative Example 2

[0107] Same as Example 1, except that the critical high-temperature rolling step is omitted. Specifically:

[0108] (1) Alloy melting and casting: Same as in Example 1.

[0109] (2) Medium temperature rolling: The ingot is heated to the medium temperature zone (320 ℃), and then rolled in a single pass at this temperature. The deformation in a single pass is controlled at 40%, and the rolling speed is 8 m / s.

[0110] (3) Low temperature annealing: Same as in Example 1.

[0111] Performance testing: The high-magnesium aluminum alloy obtained in this comparative example has a tensile strength of 485 MPa and an elongation after fracture of 15.4%. Compared with Example 1, Comparative Example 2 has a strength of only 485 MPa (a decrease of 20.9% compared to Example 1). This is because it lacks dynamic recrystallization nucleation induced by micron-sized particles, resulting in insufficient grain refinement; moreover, the coarse β phase is not fully dissolved, and the residual brittle phase weakens the strengthening effect. The dual-mode strengthening system directly lacks the support of micron-sized particle cores; there is no significant advantage in plasticity (elongation of 15.4%). Although medium-temperature rolling can still partially promote recrystallization, the superposition effect of the residual brittle phase and coarse grains results in plasticity that is not better than Example 1, and the strength is significantly reduced, which violates the goal of matching strength and plasticity.

[0112] Comparative Example 3

[0113] Same as Example 1, except that the intermediate temperature rolling step is omitted. Specifically:

[0114] (1) Alloy melting and casting: Same as in Example 1.

[0115] (2) Critical high temperature rolling: The obtained ingot is homogenized at 450℃ for 8 hours. After homogenization, it is immediately subjected to single-pass hot rolling with a single-pass deformation of 80% and a rolling speed of 8 m / s.

[0116] (3) Low temperature annealing: After the critical high temperature rolling is completed, the plate is immediately cooled to room temperature by spray rapid cooling, and then subjected to low temperature annealing treatment at 180℃ for 2 hours.

[0117] Performance testing: The high-magnesium aluminum alloy obtained in this comparative example has a tensile strength of 473 MPa and an elongation after fracture of 20.7%. Compared with Example 1, the strength of Comparative Example 3 is only 473 MPa (a decrease of 22.8% compared with Example 1), because the "strain-induced nanophase precipitation" step of medium-temperature rolling is missing. The dual-mode strengthening system lacks the key strengthening link of nanoscale particles; at the same time, the dynamic recrystallization is insufficient, the grain size is too large, and the strengthening effect is greatly weakened; although the plasticity is high (elongation of 20.7%), the strength is too low and cannot meet the requirements of the main load-bearing structural components.

[0118] Comparative Example 4

[0119] Same as Example 1, except that the low-temperature annealing step is omitted, specifically:

[0120] (1) Alloy melting and casting: Same as in Example 1.

[0121] (2) Two-step co-rolling process: Same as in Example 1, the plate obtained after medium-temperature rolling is the final product.

[0122] Performance testing: The high magnesium-aluminum alloy obtained in this comparative example has a tensile strength of 595 MPa and an elongation after fracture of 10.2%.

[0123] Compared to Example 1, Comparative Example 4 showed a sharp drop in plasticity (elongation of 10.2%, a decrease of 31.1% compared to Example 1). This is because residual stress was not eliminated, and stress concentration during stretching easily led to local cracks, resulting in a sharp deterioration in plasticity and the common strength-plasticity inversion problem in the prior art.

[0124] The above are merely preferred embodiments 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 scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-magnesium aluminum alloy based on dual-modal particle strengthening, characterized in that, The chemical composition, by weight percentage, includes: Mg: 7.0~10.0%, Mn: 0.2~0.4%, Zr: 0.1~0.3%, Ti: 0.2~0.3%, with the balance being Al and unavoidable impurities.

2. The high-magnesium aluminum alloy based on dual-modal particle strengthening according to claim 1, characterized in that, The chemical composition by weight percentage includes: Mg: 8.0~9.0%, Mn: 0.3~0.36%, Zr: 0.2~0.25%, Ti: 0.22~0.25%, with the balance being Al and unavoidable impurities.

3. The high-magnesium aluminum alloy based on dual-modal particle strengthening according to claim 2, characterized in that, The chemical composition, by weight percentage, includes: Mg: 9.0%, Mn: 0.3%, Zr: 0.2%, Ti: 0.25%, with the balance being Al and unavoidable impurities.

4. A method for preparing a high-magnesium aluminum alloy based on dual-modal particle strengthening as described in any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Prepare materials according to the chemical composition, carry out alloy smelting and semi-continuous casting to obtain ingots; (2) The ingot is subjected to a two-step co-rolling process, which includes critical high-temperature rolling and medium-temperature rolling; (3) After rolling, the material is rapidly cooled to room temperature and then annealed to obtain the high magnesium-aluminum alloy based on dual-mode particle strengthening.

5. The method for preparing high-magnesium aluminum alloy based on dual-modal particle reinforcement according to claim 4, characterized in that, In step (2), the critical high temperature rolling is to perform homogenization heat treatment on the ingot in the critical solution temperature range, and then perform single-pass hot rolling.

6. The method for preparing high-magnesium aluminum alloy based on dual-modal particle reinforcement according to claim 5, characterized in that, The homogenization heat treatment holding time is 4~12h, the single-pass deformation of the single-pass hot rolling is 70%~90%, and the single-pass hot rolling speed is 5~10 m / s.

7. The method for preparing high-magnesium aluminum alloy based on dual-modal particle reinforcement according to claim 4, characterized in that, In step (2), the medium-temperature rolling process involves cooling the plate after it has been rolled at the critical high temperature, followed by single-pass rolling.

8. The method for preparing high-magnesium aluminum alloy based on dual-modal particle reinforcement according to claim 7, characterized in that, The cooling is achieved by forced air cooling at a rate of 15-20℃ / s, cooling to 300-350℃. The deformation of a single pass is 30%-50%, and the rolling speed is 5-10 m / s.

9. The method for preparing high-magnesium aluminum alloy based on dual-modal particle reinforcement according to claim 4, characterized in that, In step (3), the annealing temperature is 150~180 ℃ and the holding time is 2 h.

10. The method for preparing high-magnesium aluminum alloy based on dual-modal particle reinforcement according to claim 4, characterized in that, The high magnesium-aluminum alloy based on dual-modal particle reinforcement prepared by the method has a tensile strength of 548-613 MPa and an elongation after fracture of 13.5-18.6%.

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