Cluster-reinforced high-strength and high-plasticity Al-Cu-Mg aluminum alloy and preparation method thereof

Abstract

The invention discloses a cluster-reinforced high-strength and high-plasticity Al-Cu-Mg aluminum alloy and a preparation method, and belongs to the technical field of high-performance alloy materials, and the aluminum alloy comprises the following components in percentage by mass: about 2.5% of Cu, 0.5% of Mg, and the balance of Al and inevitable impurity elements. According to the preparation method, after homogenization and solution treatment are conducted, severe plastic deformation rolling is utilized, artificial aging is conducted, the aluminum alloy is of an ultra-fine grain structure, no precipitated phase is formed in the aging process, a large number of Cu-Mg clusters are formed, dislocation movement is hindered, the alloy is strengthened, in addition, a large number of Cu and Mg atoms are segregated at the dislocation position, and the mechanical property of the alloy is improved. The copper alloy has strong interaction with dislocation, the dislocation plugging capacity is improved, the work hardening capacity is enhanced, and therefore the ductility of the alloy is improved.

Description

Technical Field

[0001] This invention relates to the field of high-performance alloy materials technology, specifically to a cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy and its preparation method. Background Technology

[0002] Aluminum alloys are widely used in the automotive, marine, and aerospace industries due to their high specific strength, good toughness, strong resistance to oxidation and corrosion, and ease of processing. Al-Cu-Mg aluminum alloys are heat-treatable alloys; by designing their composition and manufacturing processes, they can achieve the properties required for various working scenarios, making them widely used in aerospace, automotive, and other fields. With the continuous development of automotive and aerospace technologies, higher requirements are being placed on the strength and ductility of aluminum alloys.

[0003] Large plastic deformation technology is an important strengthening and toughening method for aluminum alloys, affecting the precipitation behavior and microstructure of Al-Cu-Mg alloys. Existing large plastic deformation technologies include equal channel angle extrusion, high-pressure torsion, and cumulative rolling, etc.; however, due to limitations such as extremely high pressure, special mold design, and operational difficulty, these technologies are currently only suitable for small-sized samples. Large plastic deformation technology can enable aluminum alloys to achieve an ultrafine grain structure, enhancing the fine grain strengthening of the alloy. At the same time, large plastic deformation technology can introduce a large number of defects (such as vacancies and dislocations) into the aluminum alloy. Defects are favorable nucleation sites and diffusion channels for atoms. Therefore, the nucleation rate of precipitates in aluminum alloys after large plastic deformation is faster, and it can even change the precipitation sequence of traditional Al-Cu-Mg alloys (i.e., supersaturated solid solution → Cu-Mg atomic clusters / GPB region → S" phase / GPB2 region → S′ phase → S phase), skipping the GPB region and directly forming stable precipitates S′ / S. This process can significantly enhance the precipitation strengthening of Al-Cu-Mg alloys, thereby significantly improving their strength. However, when dislocations bypass the precipitated phase via the Orowan mechanism, they leave dislocation loops around the precipitated phase, leading to strain localization. Furthermore, the interface between the precipitated phase and the matrix is ​​a potential site for microcrack initiation. Therefore, while precipitation strengthening enhances the alloy's strength, it also significantly impairs its ductility and toughness. Thus, researching how to obtain Al-Cu-Mg alloys with an ultrafine grain structure exhibiting a superior balance of high strength and high ductility has become a pressing scientific challenge for the materials science community. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy and its preparation method, achieving a good match between high tensile strength and large tensile ductility in aluminum alloys.

[0005] This invention is achieved through the following technical solution: A cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy, comprising, by mass percentage, 2.2-2.8% Cu, 0.4-0.6% Mg, with the balance being Al and unavoidable impurity elements; The microstructure of the aluminum alloy includes ultrafine grains and Cu-Mg clusters distributed in the ultrafine grains and dislocations, and the microstructure does not contain S′ phase or S phase precipitates.

[0006] Preferably, the average grain size of the ultrafine grains is 50-60 nm.

[0007] Preferably, the aluminum alloy has a tensile strength of 447-489 MPa, a yield strength of 385-429 MPa, and a uniform elongation of not less than 16.5%.

[0008] A method for preparing a cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy includes the following steps: Step 1: The aluminum alloy ingot having the composition described in claim 1 is subjected to homogenization treatment and solution treatment in sequence, followed by quenching; Step 2: The aluminum alloy ingot treated in Step 1 is subjected to plastic deformation rolling at room temperature, with a total deformation of not less than 90%; Step 3: The rolled aluminum alloy is subjected to artificial aging treatment, followed by quenching, to obtain the cluster-strength and ductile Al-Cu-Mg aluminum alloy.

[0009] 5. The method for cluster-strengthened high-strength and high-ductility Al-Cu-Mg aluminum alloy according to claim 5, characterized in that, in step 1, the homogenization treatment temperature is 460-480 ℃ and the time is 6 h.

[0010] Preferably, in step 1, the solution treatment temperature is 585-595 ℃ and the time is 3 h.

[0011] Preferably, in step 2, the multi-pass compression ratio of the rolling process is 3%-6%.

[0012] Preferably, in step S3, the temperature of the artificial aging treatment is 120-125 ℃, and the time is 24 h.

[0013] Preferably, all quenching is water-based quenching.

[0014] Preferably, in step 1, when smelting the alloy, high-purity aluminum, Al-50 wt.% Cu master alloy and Al-20 wt.% Mg master alloy are used as raw materials, the smelting temperature is 760±5℃, the holding time is 45±5 min, and argon gas is introduced during the smelting process for degassing treatment, the number of degassing times is not less than 3 times, and the duration of each time is not less than 3 min.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: This invention provides a cluster-strengthened, high-strength, high-ductility Al-Cu-Mg aluminum alloy. Addressing the issue of low strength-ductility product in precipitate-strengthened alloys, this invention achieves a synergistic strengthening effect between ultrafine grain structure and cluster structure by optimizing alloy composition design, heat treatment process, and rolling method. This ensures high strength while maintaining superior ductility compared to alloys with ultrafine grains and precipitates. Specifically, by controlling the composition of the Al-Cu-Mg alloy within a suitable range and employing homogenization and solution treatment to reduce the eutectic phase content in the ingot, the risk of cracking during rolling is avoided. Subsequently, high-ductility deformation rolling is performed at room temperature to obtain an ultrafine grain structure. Aging treatment then promotes the formation of numerous solute-defect clusters rather than precipitates, thereby achieving strength and toughness. This aluminum alloy exhibits excellent room-temperature mechanical properties and a significant synergistic advantage in strength and ductility. More importantly, this preparation method fully utilizes the regulatory role of cluster strengthening in the ultrafine grain structure, highlighting the broad research prospects for improving alloy mechanical properties through cluster strengthening, and successfully achieving a good match between high tensile strength and high tensile ductility. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is the cluster structure of the Al-Cu-Mg aluminum alloy of the present invention; Figure 2 Tensile property curves for Al-Cu-Mg basic alloy and Al-Cu-Mg aluminum alloy sheet of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] A cluster-reinforced high-strength, high-ductility Al-Cu-Mg aluminum alloy, comprising, by mass percentage, 2.2-2.8% Cu, 0.4-0.6% Mg, with the balance being Al and unavoidable impurity elements.

[0021] The raw materials used in the alloy smelting include: high-purity aluminum, Al-50 wt.% Cu master alloy, and Al-20 wt.% Mg master alloy.

[0022] The microstructure of the aluminum alloy includes ultrafine grains and Cu-Mg clusters distributed within the grains and at dislocations, and the microstructure does not contain S′ phase or S phase precipitates, with an average grain size of 50-60 nm for the ultrafine grains.

[0023] The tensile strength Rm of this aluminum alloy is 463.31-472.09 MPa, the yield strength Rp0.2 is 392.62-408.04 MPa, and the uniform elongation δ / % is (16.66-17.56) ±0.5.

[0024] This aluminum alloy, through precise control of Cu and Mg contents at 2.2–2.8% and 0.4–0.6% respectively, and combined with advanced fabrication processes, forms a unique microstructure within the aluminum matrix, dominated by "ultrafine grains + Cu-Mg clusters," and free of S′ phase or S-phase precipitates. This structure achieves synergistic strengthening and toughening across multiple scales and mechanisms: ultrafine grains provide basic strength through the Hall-Page effect; nanoscale Cu-Mg clusters distributed within the grains and at dislocations act as cuttable coherent barriers, effectively delaying necking while enhancing strength; and, crucially, the selective segregation of clusters at dislocations significantly enhances dislocation interaction and entanglement capabilities, thereby substantially increasing the work hardening rate and enabling the material to maintain continuous and uniform elongation during deformation.

[0025] Correspondingly, this application also provides a method for preparing a cluster-strengthened high-strength and high-ductility Al-Cu-Mg aluminum alloy, comprising the following steps: Step 1: Prepare Al-Cu-Mg aluminum alloy ingots; According to the composition design, appropriate raw materials were selected for alloy preparation, with the weight of the raw materials accurate to 0.01 g. The alloy was then melted using a crucible melting method. During the melting process, the resistance furnace was heated to 720 °C, and a graphite crucible containing high-purity aluminum was placed in the furnace and held at that temperature for 1 hour until it was completely melted. Then, intermediate alloys such as Al-50 wt.% Cu and Al-20 wt.% Mg were placed in the furnace, and the resistance furnace was heated to 760 °C and held for 45 minutes until the intermediate alloys were completely melted. After stirring and observing that the alloy was completely melted, oxides and inclusions on the surface of the molten metal were removed with a slag skimmer. Then, argon gas was repeatedly purged into the molten metal to degas it three times, each time for 3 minutes. After degassing, the slag skimming process was repeated. After standing for 15 minutes, the mixture was stirred again to make the alloy composition more uniform. After standing for another 15 minutes, the mixture was cooled in a casting mold to obtain an ingot; thus, an Al-Cu-Mg aluminum alloy ingot was obtained. Step 2: Homogenize and solution treat the aluminum alloy ingot; The aluminum alloy ingot was homogenized at 460-480 ℃ for 6 h, and then quenched to room temperature. The aluminum alloy structure showed uniform equiaxed grains. Then, the homogenized aluminum alloy was solution treated at 585-595 ℃ for 3 h, and then quenched to room temperature. The undissolved eutectic phase in the aluminum alloy structure was further dissolved, and the solid solubility of Cu element was increased.

[0026] The aluminum alloy ingot is quenched using water-based quenching.

[0027] Step 3: Perform large plastic deformation rolling on the heat-treated aluminum alloy; Aluminum alloy with a thickness of 20-22mm is rolled to 1-1.2mm, with a total deformation of about 95% and a rolling compression ratio of about 5% per pass. The rolling is carried out at room temperature.

[0028] Step 4, Time-sensitive processing; The rolled aluminum alloy was subjected to aging treatment at 120-125 ℃ for 24 h, followed by water quenching to room temperature to obtain a cluster-strength and high-ductility Al-Cu-Mg aluminum alloy sheet. The microstructure consisted of Cu-Mg clusters, and the cluster distribution characteristics were as follows: Figure 1 As shown.

[0029] In this preparation process, large plastic deformation rolling is used to obtain an ultrafine grain structure in the aluminum alloy, with a grain size between 50-60 nm. Then, aging treatment is used to prevent the formation of precipitates in the aluminum alloy and instead form a large number of Cu-Mg clusters, which hinder dislocation movement and strengthen the alloy. In addition, a large number of Cu and Mg atoms are segregated at the dislocation sites and have strong interactions with the dislocations, which improves the dislocation pile-up ability, enhances the work hardening ability, and thus improves the elongation of the alloy.

[0030] The strengthening mechanism of this aluminum alloy stems from the precise synergy between its composition design, process path, and microstructure. First, by accurately controlling the Cu and Mg contents (Cu: 2.2-2.8 wt.%, Mg: 0.4-0.6 wt.%) and employing a process combination of "large plastic deformation rolling + low-temperature long-term aging", the material forms a characteristic microstructure with "ultrafine-grained matrix (50-60 nm) + coherent Cu-Mg clusters" as its core. In this system: ultrafine grain boundaries form the strength foundation through the Hall-Page effect; nanoscale Cu-Mg clusters, acting as cutable flexible barriers, provide significant strength increments while maximizing plasticity potential due to their fully coherent characteristics; and the deepest strengthening mechanism lies in the selective segregation of solute atoms along dislocation lines. This cluster-dislocation composite structure not only effectively pins dislocations but also significantly enhances work hardening capacity by promoting dislocation entanglement and pile-up, ultimately achieving an excellent match between strength (tensile strength 447-489 MPa, yield strength 385-429 MPa) and plasticity (uniform elongation approximately 17.5%). This multi-scale synergistic mechanism essentially achieves a paradigm shift from "resisting deformation" to "managing deformation" by suppressing traditional precipitates and instead utilizing the interaction between clusters and defects.

[0031] Example 1 A cluster-reinforced high-strength, high-ductility Al-Cu-Mg aluminum alloy sheet, comprising, by mass percentage, 2.4% Cu, 0.4% Mg, with the balance being Al and unavoidable impurity elements.

[0032] The preparation method of this Al-Cu-Mg aluminum alloy is as follows: Step 1: Prepare Al-Cu-Mg aluminum alloy ingots; According to the composition design, appropriate raw materials were selected for alloy preparation, with the weight of the raw materials accurate to 0.01 g. The alloy was then melted using a crucible melting method. During the melting process, the resistance furnace was heated to 720 °C, and a graphite crucible containing high-purity aluminum was placed in the furnace and held at that temperature for 1 hour until it was completely melted. Then, intermediate alloys such as Al-50 wt.% Cu and Al-20 wt.% Mg were placed in the furnace, and the resistance furnace was heated to 760 °C and held for 45 minutes until the intermediate alloys were completely melted. After stirring and observing that the alloy was completely melted, oxides and inclusions on the surface of the molten metal were removed with a slag skimmer. Then, argon gas was repeatedly purged into the molten metal to degas it three times, each time for 3 minutes. After degassing, the slag skimming process was repeated. After standing for 15 minutes, the mixture was stirred again to make the alloy composition more uniform. After standing for another 15 minutes, the mixture was cooled in a casting mold to obtain an ingot; thus, an Al-Cu-Mg aluminum alloy ingot was obtained. Step 2: Homogenization and solution treatment; The aluminum alloy ingot was homogenized at 460 °C for 6 h and then quenched to room temperature. The aluminum alloy structure showed uniform equiaxed grains. The homogenized aluminum alloy was then solution treated at 585 °C for 3 h and then quenched to room temperature. The undissolved eutectic phase in the aluminum alloy structure was further dissolved, and the solid solubility of Cu element was increased.

[0033] The aluminum alloy ingot is quenched using water-based quenching.

[0034] Step 3: Perform large plastic deformation rolling on the heat-treated aluminum alloy; A 20 mm thick aluminum alloy is rolled to 1 mm, with a total deformation of approximately 95% and a rolling compression ratio of approximately 5% per pass. The rolling is carried out at room temperature.

[0035] Step 4, Time-sensitive processing; The rolled aluminum alloy was subjected to aging treatment at a temperature of 120 ℃ for 24 h. After aging, it was quenched in water medium to room temperature to obtain a cluster-strength and ductile Al-Cu-Mg aluminum alloy sheet with Cu-Mg clusters as its microstructure.

[0036] The aluminum alloy obtained through the above process exhibits a large number of Cu-Mg clusters in its microstructure, which hinder dislocation movement and strengthen the alloy. Furthermore, the abundant Cu and Mg atoms segregating at dislocation sites and interacting strongly with them enhance dislocation pile-up capacity and work hardening ability, thereby increasing the alloy's elongation. Therefore, the cluster structure allows the aluminum alloy to simultaneously achieve high strength and high ductility. According to the requirements of GB / T228.1-2010 standard, the mechanical properties of the alloy were measured as follows: Tensile strength R... m The yield strength is 463.31 MPa, and the yield strength R is... p0.2 The strength is 392.62 MPa, and the uniform elongation δ / % is 17.56±0.5. This alloy exhibits extremely excellent strength and ductility.

[0037] Example 2 A cluster-strengthened high-strength, high-ductility Al-Cu-Mg aluminum alloy, comprising, by mass percentage, 2.8% Cu, 0.5% Mg, with the balance being Al and unavoidable impurity elements.

[0038] The preparation method of this Al-Cu-Mg aluminum alloy is as follows: Step 1: Prepare Al-Cu-Mg aluminum alloy ingots; According to the composition design, appropriate raw materials were selected for alloy preparation, with the weight of the raw materials accurate to 0.01 g. The alloy was then melted using a crucible melting method. During the melting process, the resistance furnace was heated to 720 °C, and a graphite crucible containing high-purity aluminum was placed in the furnace and held at that temperature for 1 hour until it was completely melted. Then, intermediate alloys such as Al-50 wt.% Cu and Al-20 wt.% Mg were placed in the furnace, and the resistance furnace was heated to 760 °C and held for 45 minutes until the intermediate alloys were completely melted. After stirring and observing that the alloy was completely melted, oxides and inclusions on the surface of the molten metal were removed with a slag skimmer. Then, argon gas was repeatedly purged into the molten metal to degas it three times, each time for 3 minutes. After degassing, the slag skimming process was repeated. After standing for 15 minutes, the mixture was stirred again to make the alloy composition more uniform. After standing for another 15 minutes, the mixture was cooled in a casting mold to obtain an ingot; thus, an Al-Cu-Mg aluminum alloy ingot was obtained. Step 2: Homogenization and solution treatment; The aluminum alloy ingot was homogenized at 470 °C for 6 h and then quenched to room temperature. The aluminum alloy structure showed uniform equiaxed grains. The homogenized aluminum alloy was then solution treated at 590 °C for 3 h and then quenched to room temperature. The undissolved eutectic phase in the aluminum alloy structure was further dissolved, and the solid solubility of Cu element was increased.

[0039] The aluminum alloy ingot is quenched using water-based quenching.

[0040] Step 3: Perform large plastic deformation rolling on the heat-treated aluminum alloy; A 22mm thick aluminum alloy is rolled to 1.2mm, with a total deformation of approximately 94% and a rolling compression ratio of approximately 5% per pass. The rolling is carried out at room temperature.

[0041] Step 4, Time-sensitive processing; The rolled aluminum alloy was subjected to aging treatment at a temperature of 125 ℃ for 24 h. After aging, it was quenched in water medium to room temperature to obtain a cluster-strength and ductile Al-Cu-Mg aluminum alloy sheet with Cu-Mg clusters as its microstructure.

[0042] The microstructure of the cluster-strengthened high-strength and high-ductility Al-Cu-Mg aluminum alloy obtained in this embodiment is similar to that of Example 1. The mechanical properties of the alloy were measured according to the requirements of GB / T228.1-2010 standard as follows: tensile strength R... m The yield strength is 472.09 MPa, and the yield strength R is... p0.2 The strength is 408.04 MPa, and the uniform elongation δ / % is 16.82 ± 0.5. This alloy exhibits extremely excellent strength and ductility.

[0043] Example 3 A cluster-strengthened high-strength and high-ductility Al-Cu-Mg aluminum alloy, comprising, by mass percentage, 2.2% Cu, 0.6% Mg, with the balance being Al and unavoidable impurity elements.

[0044] The preparation method of this Al-Cu-Mg aluminum alloy is as follows: Step 1: Prepare Al-Cu-Mg aluminum alloy ingots; According to the composition design, appropriate raw materials were selected for alloy preparation, with the weight of the raw materials accurate to 0.01 g. The alloy was then melted using a crucible melting method. During the melting process, the resistance furnace was heated to 720 °C, and a graphite crucible containing high-purity aluminum was placed in the furnace and held at that temperature for 1 hour until it was completely melted. Then, intermediate alloys such as Al-50 wt.% Cu and Al-20 wt.% Mg were placed in the furnace, and the resistance furnace was heated to 760 °C and held for 45 minutes until the intermediate alloys were completely melted. After stirring and observing that the alloy was completely melted, oxides and inclusions on the surface of the molten metal were removed with a slag skimmer. Then, argon gas was repeatedly purged into the molten metal to degas it three times, each time for 3 minutes. After degassing, the slag skimming process was repeated. After standing for 15 minutes, the mixture was stirred again to make the alloy composition more uniform. After standing for another 15 minutes, the mixture was cooled in a casting mold to obtain an ingot; thus, an Al-Cu-Mg aluminum alloy ingot was obtained. Step 2: Homogenization and solution treatment; The aluminum alloy ingot was homogenized at 480 °C for 6 h and then quenched to room temperature. The aluminum alloy structure showed uniform equiaxed grains. The homogenized aluminum alloy was then solution treated at 595 °C for 3 h and then quenched to room temperature. The undissolved eutectic phase in the aluminum alloy structure was further dissolved, and the solid solubility of Cu element was increased.

[0045] The aluminum alloy ingot is quenched using water-based quenching.

[0046] Step 3: Perform large plastic deformation rolling on the heat-treated aluminum alloy; Aluminum alloy with a thickness of 22mm is rolled to 1.2mm, with a total deformation of approximately 92% and a rolling compression ratio of approximately 4% per pass. The rolling is carried out at room temperature.

[0047] Step 4, Time-sensitive processing; The rolled aluminum alloy was subjected to aging treatment at a temperature of 123 ℃ for 24 h. After aging, it was quenched in water medium to room temperature to obtain a cluster-strength and ductile Al-Cu-Mg aluminum alloy sheet with Cu-Mg clusters as its microstructure.

[0048] The microstructure of the cluster-strengthened high-strength and high-ductility Al-Cu-Mg aluminum alloy obtained in this embodiment is similar to that of Example 1. The mechanical properties of the alloy were measured according to the requirements of GB / T228.1-2010 standard as follows: tensile strength R... m The yield strength is 467.53 MPa, and the yield strength R is... p0.2 The strength is 394.83 MPa, and the uniform elongation δ / % is 16.66 ± 0.5. This alloy exhibits extremely excellent strength and ductility.

[0049] Comparative Example 1 An Al-Cu-Mg aluminum alloy, by mass percentage comprising 2.4% Cu, 0.6% Mg, with the balance being Al and unavoidable impurities.

[0050] The preparation method of this Al-Cu-Mg aluminum alloy is as follows: Step 1: Prepare Al-Cu-Mg aluminum alloy ingots; According to the composition design, appropriate raw materials were selected for alloy preparation, with the weight of the raw materials accurate to 0.01 g. The alloy was then melted using a crucible melting method. During the melting process, the resistance furnace was heated to 720 °C, and a graphite crucible containing high-purity aluminum was placed in the furnace and held at that temperature for 1 hour until it was completely melted. Then, intermediate alloys such as Al-50 wt.% Cu and Al-20 wt.% Mg were placed in the furnace, and the resistance furnace was heated to 760 °C and held for 45 minutes until the intermediate alloys were completely melted. After stirring and observing that the alloy was completely melted, oxides and inclusions on the surface of the molten metal were removed with a slag skimmer. Then, argon gas was repeatedly purged into the molten metal to degas it three times, each time for 3 minutes. After degassing, the slag skimming process was repeated. After standing for 15 minutes, the mixture was stirred again to make the alloy composition more uniform. After standing for another 15 minutes, the mixture was cooled in a casting mold to obtain an ingot; thus, an Al-Cu-Mg aluminum alloy ingot was obtained. Step 2: Homogenization and solution treatment; The aluminum alloy ingot was homogenized at 465 °C for 6 h and then quenched to room temperature. The aluminum alloy structure showed uniform equiaxed grains. The homogenized aluminum alloy was then solution treated at 590 °C for 3 h and then quenched to room temperature. The undissolved eutectic phase in the aluminum alloy structure was further dissolved, and the solid solubility of Cu element was increased.

[0051] The aluminum alloy ingot is quenched using water-based quenching.

[0052] Step 3: Perform large plastic deformation rolling on the heat-treated aluminum alloy; A 22mm thick aluminum alloy sheet was rolled to 1.2mm, with a total deformation of approximately 95% and a rolling compression ratio of approximately 5% per pass. Rolling was performed at room temperature to obtain an Al-Cu-Mg aluminum alloy sheet with a microstructure consisting of a small amount of Cu-Mg clusters. Due to the lack of aging treatment, the cluster content in the alloy was very low, resulting in lower strength and ductility. According to the requirements of GB / T228.1-2010 standard, the mechanical properties of the alloy were measured as follows: tensile strength Rm = 331.79 MPa, yield strength Rp0.2 = 323.61 MPa, and uniform elongation δ / % = 3.95 ± 0.5.

[0053] Figure 1 This is the cluster microstructure of the Al-Cu-Mg aluminum alloy of the present invention. (a) shows the concentration distribution of Cu and Mg atoms at the interface between the cluster and the matrix; (b) shows the distribution of Cu-Mg atom pairs and a comparison diagram of the nearest neighbor distribution of Cu-Mg atom pairs. It can be seen that Cu and Mg atoms form composite clusters in the alloy, and a large number of Cu and Mg atoms are segregated at dislocations.

[0054] Figure 2 The tensile property curves of the two embodiments, Al-Cu-Mg basic alloy and Al-Cu-Mg aluminum alloy sheet of the present invention, demonstrate an excellent match between strength and plasticity.

[0055] The method for preparing Al-Cu-Mg aluminum alloy provided by this invention involves subjecting a homogenized and solution-treated aluminum alloy ingot to large plastic deformation rolling and aging treatment to obtain a high-strength and high-ductility Al-Cu-Mg aluminum alloy. This Al-Cu-Mg aluminum alloy comprises approximately 2.5% Cu, 0.5% Mg, with the balance being Al and unavoidable impurity elements. By adjusting the elemental composition, heat treatment methods (including homogenization, solution treatment, and aging treatment), and rolling techniques, the synergistic effect of ultrafine grains and clusters in the Al-Cu-Mg aluminum alloy is achieved, resulting in high strength while retaining better ductility than the "ultrafine grains + precipitated phases" method. The Al-Cu-Mg aluminum alloy of this invention exhibits high tensile strength (~489 MPa) and large uniform elongation (~17.5%), demonstrating excellent mechanical properties. This excellent combination of strength and ductility originates from the formation of Cu-Mg clusters in the aluminum alloy. Cu-Mg clusters hinder dislocation movement, thereby increasing the alloy's strength. Meanwhile, the aggregation of Cu and Mg atoms around dislocations enhances the alloy's work hardening ability, thus increasing its elongation. Compared to currently reported aluminum alloys, its mechanical properties exhibit a significant advantage in strength and ductility. More importantly, this research fully utilizes the regulation of cluster strengthening in ultrafine grain structures, demonstrating a promising future for exploring and utilizing cluster strengthening to improve the mechanical properties of alloys. It achieves a good match between high tensile strength and high tensile ductility, providing important theoretical and technological references for the formulation of methods for preparing large-size, high-strength, and high-toughness aluminum alloy thin plates.

[0056] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A cluster-reinforced high-strength, high-ductility Al-Cu-Mg aluminum alloy, characterized in that, It contains 2.2-2.8% Cu and 0.4-0.6% Mg by mass, with the balance being Al and unavoidable impurity elements; The microstructure of the aluminum alloy includes ultrafine grains and Cu-Mg clusters distributed in the ultrafine grains and dislocations, and the microstructure does not contain S′ phase or S phase precipitates.

2. The cluster-reinforced high-strength, high-ductility Al-Cu-Mg aluminum alloy according to claim 1, characterized in that, The average grain size of the ultrafine grains is 50-60 nm.

3. A cluster-reinforced high-strength, high-ductility Al-Cu-Mg aluminum alloy according to claim 1, characterized in that, The aluminum alloy has a tensile strength of 447-489 MPa, a yield strength of 385-429 MPa, and a uniform elongation of not less than 16.5%.

4. A method for preparing the cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy according to any one of claims 1-3, characterized in that, Includes the following steps: Step 1: The aluminum alloy ingot having the composition described in claim 1 is subjected to homogenization treatment and solution treatment in sequence, followed by quenching; Step 2: The aluminum alloy ingot treated in Step 1 is subjected to plastic deformation rolling at room temperature, with a total deformation of not less than 90%; Step 3: The rolled aluminum alloy is subjected to artificial aging treatment, followed by quenching, to obtain the cluster-strength and ductile Al-Cu-Mg aluminum alloy.

5. The method for preparing cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy according to claim 5, characterized in that, In step 1, the homogenization treatment is carried out at a temperature of 460-480 ℃ for 6 h.

6. The method for preparing cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy according to claim 4, characterized in that, In step 1, the solution treatment temperature is 585-595 ℃ and the time is 3 h.

7. The method for preparing cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy according to claim 4, characterized in that, In step 2, the multi-pass compression ratio of the rolling process is 3%-6%.

8. The method for preparing cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy according to claim 4, characterized in that, In step S3, the temperature of the artificial aging treatment is 120-125 ℃, and the time is 24 h.

9. The method for cluster-strengthened high-strength and high-ductility Al-Cu-Mg aluminum alloy according to claim 4, characterized in that, All quenching processes were carried out using water-based quenching.

10. The method for preparing cluster-reinforced high-strength and high-ductility Al-Cu-Mg aluminum alloy according to claim 4, characterized in that, In step 1, when smelting the alloy, high-purity aluminum, Al-50 wt.% Cu master alloy and Al-20 wt.% Mg master alloy are used as raw materials. The smelting temperature is 760±5℃ and the holding time is 45±5 min. Argon gas is introduced during the smelting process for degassing. The degassing is carried out no less than 3 times and each time lasts no less than 3 min.

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