Preparation process of a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy material

Abstract

The present invention discloses a preparation process for a high-strength, corrosion-resistant, cluster-structured aluminum-lithium alloy material, which belongs to the technical field of aluminum alloy production processes. The high-strength, corrosion-resistant, cluster-structured aluminum-lithium alloy described in the present invention contains, by mass percentage, 2.5% to 2.8% Mg, 0.5% to 0.8% Li, 0.3% to 0.4% Cu, 0.1% to 0.2% Zr, 0.1% to 0.2% Sc, and the remainder is Al and other trace elements. The preparation method for the high-strength, corrosion-resistant, cluster-structured aluminum-lithium alloy described in the present invention comprises the following steps: subjecting the aluminum-lithium alloy ingot to step-by-step solid solution and quenching, rapid heating and quenching cycles, artificial pre-failure treatment, asynchronous rolling, and artificial aging treatment to finally obtain a high-strength, corrosion-resistant, cluster-structured aluminum-lithium alloy material. The aluminum-lithium alloy obtained by the present invention has the characteristics of high strength, excellent corrosion resistance, and the like.

Description

Technical Field

[0001] The invention relates to a preparation process of a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy material, belonging to the technical field of aluminum alloy production processes. Background Art

[0002] Aluminum-lithium alloy is a lightweight, high-strength alloy with low density, excellent mechanical properties and corrosion resistance. Because it is lighter than traditional aluminum alloys but has higher strength, it makes aluminum-lithium alloy an ideal material for aerospace, automobile manufacturing, marine engineering and other fields. It can greatly reduce the weight of the structure, reduce fuel use, and reduce carbon emissions, which is in line with current development trends. Cluster strengthening, as an emerging material processing technology, involves the interaction of multiple disciplines. Its core is composed of dozens to hundreds of tiny atoms. By utilizing the characteristics of these materials, the matrix material is strengthened, which can significantly improve the material's strength, corrosion resistance and other performance. However, aluminum-lithium alloys currently have a certain low-temperature brittleness, and their strength and toughness will decrease as the temperature decreases, which limits their application range in marine engineering.

[0003] Chinese invention patent CN 112226707A discloses a method for processing aluminum alloys at room temperature. This method uses repetitive plastic deformation to cyclically strengthen the aluminum alloy sample after solution treatment. The plastic deformation stimulates the generation of vacancies in the matrix, significantly promoting the formation of atomic clusters. These clusters are composed of a large number of small, uniformly distributed atomic clusters within the aluminum matrix, thereby achieving cluster strengthening. Because this method does not require elevated temperature heat treatment, it consumes less energy and takes less time. It also avoids the "precipitation-free zone" that can impair mechanical and corrosion properties, making it a promising alternative to aging heat treatment for strengthening.

[0004] Chinese invention patent CN 116479294A discloses a strong and tough aluminum alloy plate with a heterogeneous structure. The heat-treatable aluminum alloy contains Zr and Sc elements. The heterogeneous structure includes recrystallized structure and fibrous structure present in the microstructure of the aluminum alloy plate. The smallest distribution unit of the recrystallized structure is a recrystallized structure cluster, which is formed by the aggregation of single recrystallized grains. The recrystallized structure clusters are distributed in the fibrous structure to ultimately obtain a high-strength, high-toughness aluminum alloy plate with a specific heterogeneous structure.

[0005] In summary, although the aluminum alloy material obtained by the above process forms clusters and improves the mechanical properties and corrosion resistance of the aluminum-lithium alloy, simple cluster strengthening cannot guarantee the reduction of low-temperature brittleness and may still cause cracks due to changes in the crystal structure at the grain boundaries in low-temperature environments, which limits its application in marine engineering. Therefore, an aluminum-lithium alloy material with low low-temperature brittleness while maintaining mechanical properties and corrosion resistance is proposed to expand the application range of aluminum-lithium alloys in low-temperature environments such as the ocean. Summary of the Invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a preparation process of a high-strength, corrosion-resistant cluster structure aluminum-lithium alloy material. The specific steps are as follows:

[0007] (1) Mg, Li, Cu, Zr, Sc, Al and other trace elements are smelted and cast (the smelting and casting in this step are conventional methods without special requirements) to form an aluminum-lithium alloy ingot.

[0008] (2) The aluminum-lithium alloy ingot obtained in step (1) is subjected to a step-by-step solution treatment process. After the solution treatment is completed, the ingot is placed in cold water for quenching. After the quenching is completed, the moisture is wiped off.

[0009] (3) The aluminum-lithium alloy ingot processed in step (2) is rapidly heated and quenched, and the aluminum-lithium alloy is heated and quickly transferred to water for quenching, and this process is repeated at least three times.

[0010] (4) subjecting the aluminum-lithium alloy ingot processed in step (3) to artificial pre-aging treatment.

[0011] (5) Asynchronously cold rolling the aluminum-lithium alloy ingot processed in step (4).

[0012] (6) artificially aging the aluminum-lithium alloy ingot processed in step (5).

[0013] Preferably, the total mass percentage of Mg, Li, Cu, Zr, Sc, Al and other trace elements in step (1) is 100%, of which Mg is 2.5% to 2.8%, Li is 0.5% to 0.8%, Cu is 0.3% to 0.4%, Zr is 0.1% to 0.2%, Sc is 0.1% to 0.2%, and the balance is Al and other trace elements. Zr can be used as a modifier. A small amount of Zr added to the aluminum-lithium alloy can not only refine the grain structure but also promote the formation of Mg-Cu clusters. A small amount of Sc can form a nanophase, which cooperates with Zr to strengthen the aluminum-lithium alloy.

[0014] Preferably, in step (2), the first-stage solution temperature is 420°C to 440°C, and the solution time is 1 hour; the second-stage solution temperature is 480°C to 500°C, and the solution time is 1 hour; the third-stage solution temperature is 520°C to 540°C, and the solution time is 1 hour.

[0015] Preferably, in step (3), the heating rate is not less than 120°C / s, the temperature is raised to 540°C to 580°C, and the time for transferring to water is less than 15s.

[0016] Preferably, in step (4), the temperature of artificial aging is 120-150° C., and the aging time is 8-10 hours.

[0017] Preferably, the total cold rolling pressure in step (5) is 70%-80%, the number of cold rolling passes is 7-10, and the pressure of each pass is 7%-10%.

[0018] Preferably, the cold rolling in step (5) adopts asynchronous cold rolling, the rotation rate ratio of the upper and lower rollers is 1.3 to 1.4, and the single pressing amount is as large as possible, through a large deformation amount, to obtain higher crystal defects and promote the formation of clusters.

[0019] Preferably, the aging temperature in step (6) is selected to be 100° C. to 120° C., and the holding time is 20 h to 24 h.

[0020] Principle of the invention: In the present invention, the addition of a trace amount of Cu element can promote the formation of Mg-Cu clusters. Because the binding ability of Cu with vacancies is stronger than that of Mg with vacancies, and the binding ability of Cu element with Mg element is relatively strong, Cu will preferentially bind to vacancies to form clusters. However, the low Cu content will greatly attract Mg element to participate in the formation of clusters. Mg element will serve as the main body of cluster formation, with a higher density and a significant strengthening effect.

[0021] The present invention also retains vacancies in the matrix through rapid heating and cooling, and increases the number of defects and vacancies through large cold deformation, providing a good environment for the formation of Mg-Cu clusters. However, since the extremely cold and hot process methods will bring great residual stress to the matrix, in order to prevent the ingot from cracking, a step-by-step solid solution process is established by establishing a temperature gradient, which reduces the stress of the material itself, forms a uniform structure, and improves the mechanical properties and corrosion resistance of the material.

[0022] In the present invention, artificial pre-aging treatment and asynchronous rolling are used to increase the number of vacancies. Artificial pre-aging treatment can promote the precipitation of nanophase Al3Zr. Compared with conventional cold rolling, asynchronous rolling causes uneven stress distribution of the material under the action of the upper and lower rollers by setting upper and lower rollers with different rotation speeds. In areas with greater stress, large plastic deformation is prone to occur, thus forming vacancies. The role of pre-aging is to reduce the residual stress introduced into the matrix due to the extreme cold and hot processes, promote the adjustment and optimization of the grain boundaries and dislocation structure of the alloy material, thereby improving the plasticity and processing performance of the material and reducing the formation of cracks in stress concentration areas during asynchronous rolling.

[0023] Beneficial effects of the present invention

[0024] (1) The present invention forms conditions conducive to the formation of Mg-Cu clusters through processes such as step-by-step solution treatment, cyclic extreme cooling and heating, pre-aging, and asynchronous cold rolling;

[0025] (2) Through the synergistic effect of Zr and Sc elements, the grains are refined to form a fine and dispersed strengthening phase; ultimately, through the synergistic strengthening effect of cluster structure and fine grain structure, an aluminum-lithium alloy with high strength and corrosion resistance is obtained.

[0026] (3) Compared with conventional aluminum alloys, it not only improves mechanical properties but also reduces low-temperature brittleness. This is because at low temperatures, grain boundaries and internal defects easily serve as crack initiation points, leading to increased brittleness of the material. The cluster structure and fine grain structure used in the present invention can work together to slow the growth rate of grain boundaries and defects, inhibit crack expansion, and thus reduce the low-temperature brittleness of the material.

[0027] (4) The invention can maintain good mechanical properties in a low-temperature corrosion environment and has great application prospects in a low-temperature corrosion environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of the present invention;

[0029] Figure 2 This is a schematic diagram of the production process of the high-strength, corrosion-resistant cluster structure aluminum-lithium alloy of the present invention. DETAILED DESCRIPTION

[0030] The present invention will be further described in detail below with reference to specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0031] Example 1

[0032] A method for preparing a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy. The chemical composition of a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy implemented in the present invention is shown in Table 1.

[0033] Table 1 Chemical composition of aluminum-lithium alloy of Example 1

[0034] Mg Cu Li Zr Sc margin 2.543％ 0.354％ 0.642％ 0.164％ 0.142％ Aluminum and other elements

[0035] The specific preparation steps are as follows:

[0036] (1) According to the composition in Table 1, pure aluminum and intermediate alloys of various elements are first smelted and cast to form an aluminum alloy ingot with a size of 20 mm × 10 mm × 10 mm.

[0037] (2) The aluminum-lithium alloy ingot prepared in step (1) is subjected to step-by-step solution treatment, wherein the first-stage solution temperature is 420°C and the solution time is 1 hour; the second-stage solution temperature is 480°C and the solution time is 1 hour; the third-stage solution temperature is 520°C and the solution time is 1 hour; after the solution treatment, the sample is placed in cold water for quenching, and after the quenching is completed, the sample is taken out and the water is wiped off.

[0038] (3) The aluminum-lithium alloy ingot processed in step (2) is placed in a high-frequency induction heating device for rapid heating at a heating rate of 120°C / s. After heating to 540°C, it is immediately placed in cold water for rapid cooling and quenching. This process is repeated three times. After the last quenching, the sample is wiped dry.

[0039] (4) The aluminum-lithium alloy ingot processed in step (3) is placed in an open heating furnace for artificial pre-aging treatment. The furnace temperature is 120° C. and the aging time is 8 h.

[0040] (5) The aluminum-lithium alloy ingot processed in step (4) is subjected to cold deformation treatment by asynchronous cold rolling, with the upper and lower roller speed ratio being 1.3, the total pressure being 70%, the number of cold rolling passes being 10, and the single pressure being 7%. A larger pressure is more conducive to the generation of vacancies.

[0041] (6) The aluminum-lithium alloy ingot treated in step (5) is artificially aged by placing the sample in a heating furnace at a temperature of 100° C. and keeping the temperature for 24 hours. Thus, a high-strength, corrosion-resistant aluminum-lithium alloy with synergistic strengthening of cluster structure and fine grain structure is obtained.

[0042] Example 2

[0043] A method for preparing a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy. The chemical composition of a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy implemented in the present invention is shown in Table 2.

[0044] Table 2 Chemical composition of aluminum-lithium alloy of Example 2

[0045] Mg Cu Li Zr Sc margin 2.792％ 0.301％ 0.502％ 0.101％ 0.197％ Aluminum and other elements

[0046] The specific preparation steps are as follows:

[0047] (1) According to the composition in Table 2, pure aluminum and intermediate alloys of various elements are first smelted and cast to form an aluminum alloy ingot with a size of 20 mm × 10 mm × 10 mm.

[0048] (2) The aluminum-lithium alloy ingot prepared in step (1) is subjected to step-by-step solution treatment, wherein the first-stage solution temperature is 440°C and the solution time is 1 hour; the second-stage solution temperature is 500°C and the solution time is 1 hour; the third-stage solution temperature is 520°C and the solution time is 1 hour; after the solution treatment, the sample is placed in cold water for quenching, and after the quenching is completed, the sample is taken out and the water is wiped off.

[0049] (3) The aluminum-lithium alloy ingot treated in step (2) was placed in a high-frequency induction heating device for rapid heating at a rate of 130°C / s. After reaching 540°C, the ingot was immediately placed in cold water for rapid cooling. This process was repeated four times. After the final quenching, the sample was wiped dry.

[0050] (4) The aluminum-lithium alloy ingot processed in step (3) is placed in an open heating furnace for artificial pre-aging treatment, with the furnace temperature at 150° C. and the aging time being 8 h.

[0051] (5) The aluminum-lithium alloy ingot processed in step (4) is subjected to cold deformation treatment by asynchronous cold rolling, with the upper and lower roller speed ratio being 1.4, the total pressure being 70%, the number of cold rolling passes being 7, and the single pressure being 10%. A larger pressure is more conducive to the generation of vacancies.

[0052] (6) The aluminum-lithium alloy ingot treated in step (5) is artificially aged by placing the sample in a heating furnace at a temperature of 100° C. and keeping the temperature for 24 hours. Thus, a high-strength, corrosion-resistant aluminum-lithium alloy with synergistic strengthening of cluster structure and fine grain structure is obtained.

[0053] Example 3

[0054] A method for preparing a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy. The chemical composition of a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy implemented in the present invention is shown in Table 3.

[0055] Table 3 Chemical composition of aluminum-lithium alloy of Example 3

[0056] Mg Cu Li Zr Sc margin 2.502％ 0.396％ 0.799％ 0.195％ 0.101％ Aluminum and other elements

[0057] The specific preparation steps are as follows:

[0058] (1) According to the composition in Table 3, pure aluminum and intermediate alloys of various elements are first smelted and cast to form an aluminum alloy ingot with a size of 20 mm × 10 mm × 10 mm.

[0059] (2) The aluminum-lithium alloy ingot prepared in step (1) is subjected to step-by-step solution treatment, wherein the first-stage solution temperature is 420°C and the solution time is 1 hour; the second-stage solution temperature is 480°C and the solution time is 1 hour; the third-stage solution temperature is 540°C and the solution time is 1 hour; after the solution treatment, the sample is placed in cold water for quenching, and after the quenching is completed, the sample is taken out and the water is wiped off.

[0060] (3) The aluminum-lithium alloy ingot processed in step (2) is placed in a high-frequency induction heating device for rapid heating at a heating rate of 140°C / s. When the temperature reaches 580°C, it is immediately placed in cold water for rapid cooling. This process is repeated five times. After quenching, the sample is wiped dry.

[0061] (4) The aluminum-lithium alloy ingot processed in step (3) is placed in an open heating furnace for artificial pre-aging treatment. The furnace temperature is 120° C. and the aging time is 10 h.

[0062] (5) The aluminum-lithium alloy ingot processed in step (4) is subjected to cold deformation treatment by adopting asynchronous cold rolling, with the speed ratio of the upper and lower rollers being 1.3, the total pressing amount being 80%, the number of cold rolling passes being 10, and the single pressing amount being 8%. A larger pressing amount is more conducive to the generation of vacancies.

[0063] (6) The aluminum-lithium alloy ingot treated in step (5) is artificially aged by placing the sample in a heating furnace at a temperature of 120° C. and keeping the temperature for 20 hours. Thus, a high-strength, corrosion-resistant aluminum-lithium alloy with synergistic strengthening of cluster structure and fine grain structure is obtained.

[0064] Comparative Example 1

[0065] For comparison, the chemical composition of the aluminum-lithium alloy in this embodiment is the same as that in Example 1, as shown in Table 1. The preparation steps are different from those in Example 1. The specific preparation steps are as follows:

[0066] (1) According to the composition in Table 1, pure aluminum and intermediate alloys of various elements are first smelted and cast to form an aluminum alloy ingot with a size of 20 mm × 10 mm × 10 mm.

[0067] (2) The aluminum-lithium alloy ingot prepared in step (1) is subjected to step-by-step solution treatment, wherein the first-stage solution temperature is 420°C and the solution time is 1 hour; the second-stage solution temperature is 480°C and the solution time is 1 hour; the third-stage solution temperature is 520°C and the solution time is 1 hour; after the solution treatment, the sample is placed in cold water for quenching, and after the quenching is completed, the sample is taken out and the water is wiped off.

[0068] (3) The aluminum-lithium alloy ingot processed in step (2) is placed in a high-frequency induction heating device for rapid heating at a heating rate of 120°C / s. When the temperature reaches 540°C, it is immediately placed in cold water for rapid cooling. After quenching, the sample is wiped dry.

[0069] (4) The aluminum-lithium alloy ingot processed in step (3) is placed in an open heating furnace for artificial pre-aging treatment. The furnace temperature is 120° C. and the aging time is 8 h.

[0070] (5) The aluminum-lithium alloy ingot processed in step (4) is subjected to cold deformation treatment by asynchronous cold rolling, with the upper and lower roller speed ratio being 1.3, the total pressure being 70%, the number of cold rolling passes being 10, and the single pressure being 7%. A larger pressure is more conducive to the generation of vacancies.

[0071] (6) The aluminum-lithium alloy ingot treated in step (5) is artificially aged by placing the sample in a heating furnace at a temperature of 100° C. and keeping the temperature for 24 hours. Thus, a high-strength, corrosion-resistant aluminum-lithium alloy with synergistic strengthening of cluster structure and fine grain structure is obtained.

[0072] Comparative Example 2

[0073] For comparison, the chemical composition of the aluminum-lithium alloy in this embodiment is the same as that in Example 1, as shown in Table 1. The preparation steps are different from those in Example 1. The specific preparation steps are as follows:

[0074] (1) According to the composition in Table 1, pure aluminum and intermediate alloys of various elements are first smelted and cast to form an aluminum alloy ingot with a size of 20 mm × 10 mm × 10 mm.

[0075] (2) The aluminum-lithium alloy ingot prepared in step (1) is subjected to step-by-step solution treatment, wherein the first-stage solution temperature is 420°C and the solution time is 1 hour; the second-stage solution temperature is 480°C and the solution time is 1 hour; the third-stage solution temperature is 520°C and the solution time is 1 hour; after the solution treatment, the sample is placed in cold water for quenching, and after the quenching is completed, the sample is taken out and the water is wiped off.

[0076] (3) The aluminum-lithium alloy ingot processed in step (2) is placed in a high-frequency induction heating device for rapid heating at a heating rate of 120°C / s. When the temperature reaches 540°C, it is immediately placed in cold water for rapid cooling. This process is repeated twice. After quenching, the sample is wiped dry.

[0077] (4) The aluminum-lithium alloy ingot processed in step (3) is placed in an open heating furnace for artificial pre-aging treatment. The furnace temperature is 120° C. and the aging time is 8 h.

[0078] (5) The aluminum-lithium alloy ingot processed in step (4) is subjected to cold deformation treatment by asynchronous cold rolling, with the upper and lower roller speed ratio being 1.3, the total pressure being 70%, the number of cold rolling passes being 10, and the single pressure being 7%. A larger pressure is more conducive to the generation of vacancies.

[0079] (6) The aluminum-lithium alloy ingot treated in step (5) is artificially aged by placing the sample in a heating furnace at a temperature of 100° C. and keeping the temperature for 24 hours. Thus, a high-strength, corrosion-resistant aluminum-lithium alloy with synergistic strengthening of cluster structure and fine grain structure is obtained.

[0080] Comparative Example 3

[0081] For comparison, the chemical composition of the aluminum-lithium alloy in this embodiment is the same as that in Example 1, as shown in Table 1. The preparation steps are different from those in Example 1. The specific preparation steps are as follows:

[0082] (1) According to the composition in Table 1, pure aluminum and intermediate alloys of various elements are first smelted and cast to form an aluminum alloy ingot with a size of 20 mm × 10 mm × 10 mm.

[0083] (2) The aluminum-lithium alloy ingot prepared in step (1) is slowly heated to 520° C. for high-temperature solution treatment to rearrange the solute atoms in the solid solution and refine the grains. After the solution treatment is completed, the sample is placed in cold water for rapid quenching to avoid the formation of larger grains and to fix the fine grain structure in the lattice.

[0084] (3) The aluminum-lithium alloy ingot treated in step (2) is placed in an open heating furnace for aging treatment at a temperature of 120° C. for 8 hours, so that the solute atoms in the alloy are precipitated to form a fine, evenly distributed precipitate phase.

[0085] (4) The aluminum-lithium alloy ingot treated in step (3) is subjected to cold deformation treatment. The sample is cold-deformed by cold rolling with a total reduction of 70%, 10 cold rolling passes, and a single reduction of 7%, so that the solute atoms in the alloy precipitate to form a fine, uniformly distributed precipitate phase. This method can obtain a traditional fine-grained strengthened aluminum alloy material.

[0086] Comparative Example 4

[0087] For comparison, this embodiment differs from embodiment 1 in that Zr and Sc are not added, and the operation steps are the same as those of embodiment 1. The chemical composition of the aluminum-lithium alloy in this embodiment is shown in Table 4.

[0088] Table 4 Chemical composition of aluminum-lithium alloy of comparative example 2

[0089] Mg Cu Li margin 2.543％ 0.354％ 0.642％ Aluminum and other elements

[0090] The specific preparation method is as follows:

[0091] (1) According to the composition in Table 4, pure aluminum and intermediate alloys of various elements are first smelted and cast to form an aluminum alloy ingot with a size of 20 mm × 10 mm × 10 mm.

[0092] (2) The aluminum-lithium alloy ingot prepared in step (1) is subjected to step-by-step solution treatment, wherein the first-stage solution temperature is 420°C and the solution time is 1 hour; the second-stage solution temperature is 480°C and the solution time is 1 hour; the third-stage solution temperature is 520°C and the solution time is 1 hour; after the solution treatment, the sample is placed in cold water for quenching, and after the quenching is completed, the sample is taken out and the water is wiped off.

[0093] (3) The aluminum-lithium alloy ingot processed in step (2) is placed in a high-frequency induction heating device for rapid heating at a heating rate of 120°C / s. After the temperature reaches 540°C, it is immediately placed in cold water for rapid cooling. This process is repeated three times. After the last quenching, the sample is wiped dry.

[0094] (4) The aluminum-lithium alloy ingot processed in step (3) is placed in an open heating furnace for artificial pre-aging treatment. The furnace temperature is 120° C. and the aging time is 8 h.

[0095] (5) The aluminum-lithium alloy ingot processed in step (4) is subjected to cold deformation treatment by adopting asynchronous cold rolling, with the speed ratio of the upper and lower rollers being 1.3, the total pressing amount being 70%, the number of cold rolling passes being 10, and the single pressing amount being not less than 7%. A larger pressing amount is more conducive to the generation of vacancies.

[0096] (6) The aluminum-lithium alloy ingot treated in step (5) is artificially aged by placing the sample in a heating furnace at a temperature of 100° C. and keeping the temperature for 24 hours. Thus, a high-strength, corrosion-resistant aluminum-lithium alloy with synergistic strengthening of cluster structure and fine grain structure is obtained.

[0097] According to the examples, a high-strength, corrosion-resistant cluster structure aluminum-lithium alloy was prepared, and its performance test was described:

[0098] According to the mechanical property data of high-strength multi-level heterogeneous structure aluminum-lithium alloys prepared by different processes in Table 5, it can be seen that the yield strength, tensile strength, and hardness of Examples 1 to 3 are better than those of Comparative Example 1 and Comparative Example 2. The reason is that: among the embodiments, Example 1 has the most cycles of extreme cold and extreme heat. In each cycle of extreme heat and extreme cold, the generation and filling of vacancies will alternate, and rapid temperature changes will accelerate the formation and aggregation of vacancies, thereby increasing the number of retained vacancies. Therefore, increasing the number of cycles of extreme heat and extreme cold can further increase vacancies and promote the formation of clusters. The number of cycles of Example 1 is higher than that of Comparative Example 1, and the number of cycles of Comparative Example 1 is higher than that of Comparative Example 2. Therefore, the number of clusters formed is also the largest in Example 1 and the least in Comparative Example 2. Therefore, the mechanical properties of Example 1 are the best, and the longer aging time also promotes the uniform distribution of fine grains around the cluster structure, forming an interactive synergistic effect between fine-grained structure and cluster structure, and its corrosion resistance is also improved.

[0099] Comparative Example 3 is a traditional processing technology for forming a fine-grained strengthened aluminum-lithium alloy. The difference from Example 1 is that no temperature gradient is set for step-by-step solution, which leads to excessive residual stress in the material and the phenomenon of easy cracking at the grain boundaries. The extremely cold and hot process is also only performed once, which is a relatively small number of times. Although it has the effect of promoting the formation of clusters, the vacancy concentration formed is low and the promotion effect is not obvious, which leads to less cluster formation and limited strengthening effect. In addition, no cold rolling treatment is performed, and the grain size of the formed material is coarser than that of the embodiment, and the degree of fine graining is limited. By comparing Example 1 with Comparative Example 3, it can be found that the yield strength, tensile strength and exfoliation corrosion grade of the aluminum-lithium alloy material obtained in Comparative Example 3 are not as good as those in Example 1.

[0100] Comparison of Example 1 with Comparative Example 4 reveals that the yield strength, tensile strength, and exfoliation corrosion rating of the aluminum-lithium alloy material obtained in Comparative Example 4 are not as good as those in Example 1. This is because the synergistic effect of the Zr and Sc elements refines the grains, forming a fine and dispersed strengthening phase. Ultimately, the synergistic strengthening effect of the cluster structure and the fine grain structure results in a high-strength, corrosion-resistant aluminum-lithium alloy.

[0101] Table 5 Mechanical properties of high-strength corrosion-resistant cluster structure aluminum-lithium alloys of Examples and Comparative Examples

[0102] Sample number Yield strength / MPa Tensile strength / MPa Exfoliation corrosion grade Example 1 414.6 502.8 EA Example 2 413.7 497.2 EA Example 3 414.2 505.8 EA Comparative Example 1 394.1 491.9 EA Comparative Example 2 380.5 478.3 EA Comparative Example 3 308.6 430.1 EB Comparative Example 4 331.7 445.2 EB

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A process for preparing a high-strength, corrosion-resistant cluster-structured aluminum-lithium alloy material, characterized by: The number of vacancies in aluminum-lithium alloys is increased by combining extremely cold and hot conditions with mechanical-thermal coupling. The specific steps are as follows: (1) Smelting and casting Mg, Li, Cu, Zr, Sc, Al and other trace elements to form an aluminum-lithium alloy ingot; (2) subjecting the aluminum-lithium alloy ingot obtained in step (1) to a three-stage solid solution treatment process, placing the ingot in cold water for quenching after the three-stage solid solution treatment, and wiping off the moisture after the quenching; (3) rapidly heating and quenching the aluminum-lithium alloy ingot processed in step (2), heating the aluminum-lithium alloy and rapidly transferring it to water for quenching, and repeating this process at least three times; (4) subjecting the aluminum-lithium alloy ingot processed in step (3) to artificial pre-aging treatment; (5) performing asynchronous cold rolling on the aluminum-lithium alloy ingot processed in step (4); (6) artificially aging the aluminum-lithium alloy ingot processed in step (5); The total mass percentage of Mg, Li, Cu, Zr, Sc, Al and other trace elements in step (1) is 100%, of which Mg is 2.5% to 2.8%, Li is 0.5% to 0.8%, Cu is 0.3% to 0.4%, Zr is 0.1% to 0.2%, Sc is 0.1% to 0.2%, and the balance is Al and other trace elements; In step (3), the heating rate is not less than 120°C / s, the temperature is raised to 540°C~580°C, and the time for transferring to water is less than 15s; The total cold rolling pressure in step (5) is 70%-80%, the cold rolling passes are 7-10, and the pressure reduction each time is 7%-10%; the cold rolling in step (5) adopts asynchronous cold rolling, and the rotation rate ratio of the upper and lower rollers is 1.3~1.

4.

2. The process for preparing the high-strength, corrosion-resistant cluster structure aluminum-lithium alloy material according to claim 1, characterized in that: In step (2), the first-stage solution temperature is 420°C to 440°C, and the solution time is 1 hour; the second-stage solution temperature is 480°C to 500°C, and the solution time is 1 hour; the third-stage solution temperature is 520°C to 540°C, and the solution time is 1 hour.

3. The process for preparing the high-strength, corrosion-resistant cluster structure aluminum-lithium alloy material according to claim 1, characterized in that: In the step (4), the temperature of artificial aging is 120°C to 150°C, and the aging time is 8h to 10h.

4. The process for preparing the high-strength, corrosion-resistant cluster structure aluminum-lithium alloy material according to claim 1, characterized in that: In step (6), the aging temperature is selected to be 100°C~120°C, and the holding time is 20h~24h.

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