High-strength light aluminum alloy and preparation method and application thereof

Abstract

The invention relates to the technical field of aluminum alloys, in particular to a high-strength light aluminum alloy and a preparation method and application thereof. The aluminum alloy comprises the following chemical components in percentage by weight: 3.5 to 6.5 percent of Mg, 2.5 to 5.0 percent of Zn, 0.2 to 1.0 percent of Cu, 0.1 to 0.4 percent of Mn, 0.05 to 0.25 percent of Zr, 0.05 to 0.25 percent of Sc, 0 to 0.12 percent of Fe, 0 to 0.12 percent of Si and the balance of Al and inevitable impurity elements. Wherein the mass ratio of Mg to Zn is 1.0-2.0, the total content of Mn, Zr and Sc does not exceed 0.5%, the total content of Zr and Sc does not exceed 0.38%, and the mass ratio of Zr to Sc is 0.6-1.5. By accurately controlling the contents and proportions of elements such as Mg, Zn, Cu, Mn, Zr, Sc and the like, perfect combination of high strength and light weight of the alloy is realized. The density of the alloy is smaller than or equal to 2.72 g / cm < 3 >, the yield strength is larger than or equal to 350 MPa, the tensile strength is larger than or equal to 450 MPa, the ductility is larger than or equal to 10%, the welding coefficient is not smaller than 0.75, and the exfoliation corrosion performance is not lower than the EA level.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and particularly relates to a high-strength and lightweight aluminum alloy, a preparation method thereof, and an application thereof. Background Art

[0002] Under the background of the rapid development of the aerospace industry, the selection of materials is no longer limited to the improvement of strength alone, but increasingly emphasizes the optimization of its comprehensive performance. In particular, energy conservation and emission reduction have become key factors that cannot be ignored. In order to effectively reduce the consumption of power fuel and improve the efficiency of large carriers, reducing the structural weight has become an inevitable trend and the key direction of current R & D work.

[0003] In terms of the application of existing alloys, the high-strength 7xxx series alloys enhance the overall strength and toughness by continuously increasing the total amount of elements, and then achieve weight reduction through optimizing the structural design. However, such alloys have deficiencies in welding performance and corrosion resistance, and due to the addition of elements such as Zn, the alloy density is significantly increased, thus limiting its weight reduction potential to a certain extent. In contrast, the 5xxx series alloys have become one of the preferred materials for weight reduction requirements due to their low density and excellent welding performance. However, this alloy cannot adjust its properties through precipitation, and can only introduce work hardening through deformation on the basis of solid solution, so it is difficult to break through the strength bottleneck, which limits its application range. These limitations are all based on the theoretical research of conventional alloy series. Although each series of alloys has significant advantages, they also have insurmountable disadvantages, and it is urgent to break through the traditional design ideas and innovate by combining the characteristics of different alloy systems.

[0004] In recent years, domestic and foreign scholars and experts have introduced the concept of "crossover alloy" and carried out relevant research. By adjusting the content of different main elements, the alloy properties are improved. Among them, the method of adding Zn and Cu to the Al-Mg alloy for design is particularly popular. By controlling the precipitation of the T phase or η phase, precipitation strengthening is introduced into the solid-solution strengthened 5xxx alloy, thereby significantly improving the alloy strength. At the same time, the formation of the precipitation phase inhibits the precipitation of the β phase at the grain boundary during the low-temperature heat treatment process to a certain extent, so that the corrosion performance of such alloys has been improved to a certain extent compared with traditional 7xxx alloys. On this basis, the alloy strength can be further improved by means of microalloying.

[0005] However, most of the current Al-Mg alloys only focus on promoting precipitation and improving alloy strength by increasing the content of main elements and micro-alloying elements. Although a few consider properties such as corrosion resistance, the overall degree of alloying is relatively high, and the synergy among properties such as density, strength, and corrosion resistance is not comprehensively considered. Moreover, there is no optimized research on the welding performance of the alloy itself. At the same time, the current aging process is mainly for the application direction of automotive sheets, using a low-temperature pre-aging + aging process, and its applicability to aerospace aircraft components remains to be verified. Summary of the Invention

[0006] Aiming at the problems of poor synergy among properties such as density, strength, and corrosion resistance, and poor welding performance of Al-Mg alloys existing in the above-mentioned prior art, the present invention provides a high-strength and lightweight aluminum alloy, its preparation method, and application.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A high-strength and lightweight aluminum alloy, the chemical composition of which by weight percentage includes: Mg 3.5 - 6.5%, Zn 2.5 - 5.0%, Cu 0.2 - 1.0%, Mn 0.1 - 0.4%, Zr 0.05 - 0.25%, Sc 0.05 - 0.25%, Fe 0 - 0.12%, Si 0 - 0.12%, and the balance is Al and inevitable impurity elements; wherein, the Mg / Zn mass ratio = 1.0 - 2.0, the total content of Mn, Zr, and Sc does not exceed 0.5%, the total content of Zr and Sc does not exceed 0.38%, and the Zr / Sc mass ratio = 0.6 - 1.5.

[0009] Further, the chemical composition of which by weight percentage includes: Mg 3.8 - 6.0%, Zn 2.6 - 4.8%, Cu 0.3 - 0.9%, Mn 0.15 - 0.38%, Zr 0.08 - 0.20%, Sc 0.08 - 0.22%, Fe 0.02 - 0.10%, Si 0.02 - 0.10%, and the balance is Al and inevitable impurity elements; wherein, the Mg / Zn mass ratio = 1.1 - 1.9, the total content of Mn, Zr, and Sc does not exceed 0.45%, the total content of Zr and Sc does not exceed 0.35%, and the Zr / Sc mass ratio = 0.7 - 1.4.

[0010] Further, its chemical composition by weight percentage includes: Mg 4.0 - 5.8%, Zn 2.8 - 4.5%, Cu 0.35 - 0.8%, Mn 0.2 - 0.35%, Zr 0.1 - 0.18%, Sc 0.09 - 0.20%, Fe 0.03 - 0.09%, Si 0.03 - 0.08%, and the balance is Al and inevitable impurity elements; wherein, the mass ratio of Mg / Zn = 1.2 - 1.7, the total content of Mn, Zr, and Sc does not exceed 0.43%, the total content of Zr and Sc does not exceed 0.32%, and the mass ratio of Zr / Sc = 0.8 - 1.3.

[0011] Further, the alloy density ≤ 2.72 g / cm 3 ; after solution aging treatment, the yield strength of the alloy ≥ 350 MPa, the tensile strength ≥ 450 MPa, the elongation ≥ 10%, the welding coefficient is not less than 0.75, and the exfoliation corrosion performance of the alloy is not lower than EA level.

[0012] In the alloy, Mg mainly plays a role in solution strengthening. The addition of Zn promotes the precipitation of T phase or η phase, making full use of the age precipitation strengthening mechanism to achieve the improvement of the alloy strength. The addition of Cu is used to regulate the alloy structure and increase the corrosion resistance of the alloy at the same time. The addition of trace elements Mn, Zr, and Sc can, on the one hand, form fine and dispersed phases to improve the alloy properties, and on the other hand, control the grain size of the alloy, making the alloy have better grain structure. Especially the addition of Sc content has a very significant effect on refining grains and inhibiting recrystallization. However, it is necessary to strictly control the total amount of trace elements Mn, Zr, and Sc to reduce the formation of coarse primary phases during the ingot preparation process, which has an adverse effect. When Zr and Sc elements are added synergistically, a core-shell structure Al3(Sc,Zr) dispersed phase is formed. By reasonable addition of Zr and Sc content and ratio control, relatively more uniform dispersed phase particles can be effectively precipitated. The control of the content of impurity Fe element aims to reduce the raw material cost and subsequent use cost of the whole alloy, and reduce the formation of coarse crystal phases at the same time.

[0013] The present invention also includes the following technical solutions:

[0014] A preparation method of a high-strength and lightweight aluminum alloy, comprising the following steps:

[0015] (1) Melting and casting the alloy according to a certain component ratio to obtain an aluminum alloy ingot;

[0016] (2) Keeping the aluminum alloy ingot at 280 - 340 °C for 0.5 - 10 h for the first-stage homogenization treatment; then, keeping it at 460 - 490 °C for 4 - 16 h for the second-stage homogenization treatment to obtain a homogenized aluminum alloy ingot;

[0017] (3) Perform deformation treatment on the homogenized aluminum alloy ingot;

[0018] (4) Keep the deformed aluminum alloy at 465 - 495 °C for 30 - 90 min for solution treatment;

[0019] (5) Perform single - stage or two - stage aging treatment on the solution - treated aluminum alloy to obtain the high - strength lightweight aluminum alloy; the single - stage aging treatment includes keeping at 110 - 135 °C for 8 - 30 h; the two - stage aging treatment includes first keeping at 110 - 135 °C for 2 - 8 h for the first - stage aging treatment, and then keeping at 155 - 175 °C for 6 - 20 h for the second - stage aging treatment.

[0020] Furthermore, in step (2), the heating rate between the first - stage homogenization treatment and the second - stage homogenization treatment is 10 - 50 °C / h.

[0021] Furthermore, in step (3), the deformation treatment includes one or more deformation methods such as rolling, forging, and extrusion.

[0022] The present invention also includes the following technical solutions:

[0023] An aerospace flight structural member made of the high - strength lightweight aluminum alloy.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The present invention provides a high - strength lightweight aluminum alloy. By precisely controlling the content and ratio of elements such as Mg, Zn, Cu, Mn, Zr, and Sc, the perfect combination of the high strength and lightweight characteristics of the alloy is achieved. The density of the alloy ≤ 2.72 g / cm 3 , which has a lower density compared with traditional aluminum alloys, can significantly reduce the structural weight and improve energy efficiency in the fields of aerospace, transportation, etc. After solution aging treatment, the yield strength of the alloy ≥ 350 MPa, the tensile strength ≥ 450 MPa, and the elongation ≥ 10%, showing excellent mechanical properties. At the same time, the welding coefficient is not less than 0.75, ensuring the reliability and stability of the alloy during the welding process. The exfoliation corrosion performance of the alloy is not lower than EA level, indicating its excellent corrosion resistance and the ability to maintain the integrity and safety of the structure in harsh environments. The preparation method of the present invention includes two - stage homogenization treatment, which helps to eliminate compositional segregation and intra - granular segregation in the ingot, and improve the uniformity and performance stability of the alloy. The deformation treatment can further improve the microstructure of the alloy, and enhance the mechanical properties and processing performance. The solution treatment and aging treatment achieve the optimal balance between maximizing the strength and optimizing the toughness of the alloy by precisely controlling the temperature and time. Description of the Drawings

[0026] The embodiments of the present invention will be further described below with reference to the accompanying drawings, where:

[0027] Figure 1 Figure 4 shows the grain structure of the alloy in the aged state of Example 5;

[0028] Figure 2 Figure 8 shows the grain structure of the alloy in the aged state of Comparative Example 2. Detailed implementation manners

[0029] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below through specific embodiments with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0030] Example 1

[0031] The alloy was melted and cast according to a certain component ratio to obtain an aluminum alloy ingot; the aluminum alloy ingot was held at 300 °C for 4 h for the first-stage homogenization treatment, and then held at 470 °C for 12 h for the second-stage homogenization treatment to obtain a homogenized aluminum alloy ingot; the homogenized aluminum alloy ingot was held at 430 °C for 2 h and then subjected to hot rough rolling and hot finish rolling to obtain the deformed aluminum alloy; the deformed aluminum alloy was held at 475 °C for 40 min for solution treatment; the solution-treated aluminum alloy was held at 121 °C for 16 h for aging treatment to obtain a high-strength and lightweight aluminum alloy. The components and weight percentages of the high-strength and lightweight aluminum alloy prepared in this example are Mg 3.95%, Zn 3.01%, Cu 0.6%, Mn 0.23%, Zr 0.12%, Sc 0.15%, Fe 0.07%, Si 0.08%, and the balance is Al.

[0032] Example 2

[0033] The alloy was melted and cast according to a certain component ratio to obtain an aluminum alloy ingot; the aluminum alloy ingot was held at 310 °C for 3 h for the first-stage homogenization treatment, and then held at 472 °C for 10 h for the second-stage homogenization treatment to obtain a homogenized aluminum alloy ingot; the homogenized aluminum alloy ingot was held at 440 °C for 2 h and then subjected to hot rough rolling and hot finish rolling to obtain the deformed aluminum alloy; the deformed aluminum alloy was held at 490 °C for 35 min for solution treatment; the solution-treated aluminum alloy was held at 130 °C for 14 h for aging treatment to obtain a high-strength and lightweight aluminum alloy. The components and weight percentages of the high-strength and lightweight aluminum alloy prepared in this example are Mg 4.52%, Zn 3.5%, Cu 0.57%, Mn 0.22%, Zr 0.11%, Sc 0.14%, Fe 0.07%, Si 0.06%, and the balance is Al.

[0034] Example 3

[0035] The alloy is melted and cast according to a certain component ratio to obtain an aluminum alloy ingot; the aluminum alloy ingot is held at 280 °C for 10 h for the first-stage homogenization treatment, and then held at 460 °C for 16 h for the second-stage homogenization treatment to obtain a homogenized aluminum alloy ingot; the homogenized aluminum alloy ingot is held at 440 °C for 2 h and then subjected to hot rough rolling and hot finish rolling to obtain a deformed aluminum alloy; the deformed aluminum alloy is held at 465 °C for 90 min for solution treatment; the solution-treated aluminum alloy is held at 110 °C for 30 h for aging treatment to obtain a high-strength and lightweight aluminum alloy. The components and weight percentages of the high-strength and lightweight aluminum alloy prepared in this example are Mg 5.01%, Zn 3.57%, Cu 0.69%, Mn 0.21%, Zr 0.13%, Sc 0.16%, Fe 0.06%, Si 0.06%, and the balance is Al.

[0036] Example 4

[0037] The alloy is melted and cast according to a certain component ratio to obtain an aluminum alloy ingot; the aluminum alloy ingot is held at 340 °C for 0.5 h for the first-stage homogenization treatment, and then held at 490 °C for 4 h for the second-stage homogenization treatment to obtain a homogenized aluminum alloy ingot; the homogenized aluminum alloy ingot is held at 430 °C for 2 h and then subjected to hot rough rolling and hot finish rolling to obtain a deformed aluminum alloy; the deformed aluminum alloy is held at 495 °C for 30 min for solution treatment; the solution-treated aluminum alloy is held at 135 °C for 8 h for aging treatment to obtain a high-strength and lightweight aluminum alloy. The components and weight percentages of the high-strength and lightweight aluminum alloy prepared in this example are Mg 5.21%, Zn 4.45%, Cu 0.59%, Mn 0.2%, Zr 0.11%, Sc 0.14%, Fe 0.05%, Si 0.06%, and the balance is Al.

[0038] Example 5

[0039] The alloy is melted and cast according to a certain component ratio to obtain an aluminum alloy ingot; the aluminum alloy ingot is held at 320 °C for 2 h for the first-stage homogenization treatment, and then held at 475 °C for 15 h for the second-stage homogenization treatment to obtain a homogenized aluminum alloy ingot; the homogenized aluminum alloy ingot is held at 440 °C for 2 h and then subjected to hot rough rolling and hot finish rolling to obtain the deformed aluminum alloy; the deformed aluminum alloy is held at 470 °C for 50 min for solution treatment; the solution-treated aluminum alloy is held at 135 °C for 2 h for the first-stage aging treatment, and then held at 175 °C for 6 h for the second-stage aging treatment to obtain a high-strength and lightweight aluminum alloy. In this embodiment, the components and weight percentages of the obtained high-strength and lightweight aluminum alloy are Mg 5.02%, Zn 4.01%, Cu 0.6%, Mn 0.23%, Zr 0.12%, Sc 0.15%, Fe 0.08%, Si 0.08%, and the balance is Al.

[0040] Example 6

[0041] The alloy is melted and cast according to a certain component ratio to obtain an aluminum alloy ingot; the aluminum alloy ingot is held at 290 °C for 13 h for the first-stage homogenization treatment, and then held at 480 °C for 7 h for the second-stage homogenization treatment to obtain a homogenized aluminum alloy ingot; the homogenized aluminum alloy ingot is held at 440 °C for 2 h and then subjected to hot rough rolling and hot finish rolling to obtain the deformed aluminum alloy; the deformed aluminum alloy is held at 485 °C for 45 min for solution treatment; the solution-treated aluminum alloy is held at 110 °C for 8 h for the first-stage aging treatment, and then held at 155 °C for 20 h for the second-stage aging treatment to obtain a high-strength and lightweight aluminum alloy. In this embodiment, the components and weight percentages of the obtained high-strength and lightweight aluminum alloy are Mg 5.56%, Zn 4.57%, Cu 0.63%, Mn 0.22%, Zr 0.12%, Sc 0.16%, Fe 0.07%, Si 0.08%, and the balance is Al.

[0042] Comparative Example 1

[0043] The difference between this comparative example and Example 3 is that the aluminum alloy compositions are different. In this comparative example, the components and weight percentages of the aluminum alloy are Mg 4.98%, Zn 1.8%, Cu 0.3%, Mn 0.2%, Zr 0.12%, Sc 0.12%, Fe 0.08%, Si 0.08%, and the balance is Al.

[0044] Comparative Example 2

[0045] The difference between this comparative example and Example 5 lies in the different aluminum alloy compositions. In this comparative example, the components and weight percentages of the aluminum alloy are Mg 5.06%, Zn 3.97%, Cu 0.58%, Mn 0.22%, Zr 0.12%, Sc 0.2%, Fe 0.09%, Si 0%, and the balance is Al.

[0046] Comparative Example 3

[0047] The difference between this comparative example and Example 5 lies in the different aluminum alloy compositions. In this comparative example, the components and weight percentages of the aluminum alloy are Mg 5.0%, Zn 3.95%, Cu 1.52%, Mn 0.23%, Zr 0.12%, Sc 0.14%, Fe 0.07%, Si 0.08%, and the balance is Al.

[0048] Comparative Example 4

[0049] The difference between this comparative example and Example 5 is that the deformed aluminum alloy is held at 470 °C for 15 min for solution treatment.

[0050] Performance evaluations were respectively carried out on the alloy sheets completed in the examples and comparative examples of the present invention. The specific results are shown in Table 1:

[0051] Table 1

[0052]

[0053] The addition of the main alloying element Zn can effectively improve the mechanical properties of the alloy. Compared with Example 3, the Zn content in Comparative Example 1 is lower. Although the aluminum alloy in Comparative Example 1 has good corrosion resistance and welding properties, its mechanical properties are insufficient.

[0054] Based on the microalloying regulation of the alloy, the aluminum alloy in the examples still retains a very good fibrous crystal structure after solution treatment, and the effect of inhibiting recrystallization is remarkable. Attached Figure 1 Shown is the grain structure of the alloy in the aged state of Example 5. In contrast, without the regulation of the Sc element, the effect of inhibiting recrystallization of the alloy is significantly attenuated, showing a large amount of recrystallized structure, and the grain size is coarser. Attached Figure 2 Shown is the photo of the grain structure in the aged state of Comparative Example 2.

[0055] Adding the Cu element can improve the corrosion resistance and mechanical properties to a certain extent. However, an excessive amount of Cu is added in Comparative Example 3. Compared with Example 5, the welding properties of the aluminum alloy in Comparative Example 3 are significantly reduced.

[0056] The solution time of Comparative Example 4 is too short relative to Example 5, and the coarse phases in the alloy do not fully dissolve back, resulting in poor exfoliation corrosion properties of the aluminum alloy in Comparative Example 4.

[0057] In summary, the aluminum alloys in the embodiments of the present invention all have good mechanical, corrosion, and welding properties. Compared with the comparative examples, the comprehensive properties of the aluminum alloys in the embodiments are significantly better.

[0058] The present invention provides a high-strength and lightweight aluminum alloy. By precisely controlling the contents and ratios of elements such as Mg, Zn, Cu, Mn, Zr, and Sc, the perfect combination of the high strength and lightweight characteristics of the alloy is achieved. The density of the alloy is ≤2.72 g / cm 3 , which has a lower density compared with traditional aluminum alloys, can significantly reduce the structural weight and improve the energy efficiency in the fields of aerospace, transportation, etc. After solution aging treatment, the yield strength of the alloy is ≥350 MPa, the tensile strength is ≥450 MPa, and the elongation is ≥10%, having excellent mechanical properties. At the same time, the welding coefficient is not less than 0.75, ensuring the reliability and stability of the alloy during the welding process. The exfoliation corrosion performance of the alloy is not lower than grade EA, indicating its excellent corrosion resistance and the ability to maintain the integrity and safety of the structure in harsh environments. The preparation method of the present invention includes two-stage homogenization treatment, which helps to eliminate the compositional segregation and intragranular segregation in the ingot and improve the uniformity and performance stability of the alloy. The deformation treatment can further improve the microstructure of the alloy and enhance the mechanical properties and processing performance. The solution treatment and aging treatment achieve the optimal balance between the maximization of the alloy strength and the optimization of toughness by precisely controlling the temperature and time.

[0059] Some exemplary embodiments of the present invention are described above. It can be understood that the above embodiments are only used to explain the present invention and do not constitute a limitation to the protection scope of the present invention. The features in these embodiments can be recombined in a suitable manner, and the obtained solutions are still within the protection scope required by the present invention. Based on the above embodiments, all other embodiments obtained by those skilled in the art without creative efforts, that is, all modifications, equivalent replacements, and improvements made within the spirit and principle of this application, fall within the protection scope required by the present invention.

Claims

1. A high-strength lightweight aluminum alloy, characterized in that: Its chemical composition by weight percentage includes: Mg 3.5-6.5%, Zn 2.5-5.0%, Cu 0.2-1.0%, Mn 0.1-0.4%, Zr 0.05-0.25%, Sc 0.05-0.25%, Fe 0-0.12%, Si 0-0.12%, the balance is Al and unavoidable impurity elements; among which, the Mg / Zn mass ratio = 1.0-2.0, the total content of Mn, Zr and Sc does not exceed 0.5%, the total content of Zr and Sc does not exceed 0.38%, and the Zr / Sc mass ratio = 0.6-1.

5.

2. A high-strength and lightweight aluminum alloy according to claim 1, characterized in that: Its chemical composition includes by weight percentage: Mg 3.8-6.0%, Zn 2.6-4.8%, Cu 0.3-0.9%, Mn 0.15-0.38%, Zr0.08-0.20%, Sc0.08-0.22%, Fe 0.02-0.10%, Si 0.02-0.10%, and the balance is Al and unavoidable impurity elements; among which, the Mg / Zn mass ratio is 1.1-1.9, the total content of Mn, Zr and Sc does not exceed 0.45%, the total content of Zr and Sc does not exceed 0.35%, and the Zr / Sc mass ratio is 0.7-1.

4.

3. The high-strength and lightweight aluminum alloy according to claim 1, characterized in that: Its chemical composition includes by weight percentage: Mg 4.0-5.8%, Zn 2.8-4.5%, Cu 0.35-0.8%, Mn 0.2-0.35%, Zr0.1-0.18%, Sc0.09-0.20%, Fe 0.03-0.09%, Si 0.03-0.08%, and the balance is Al and unavoidable impurity elements; among which, the Mg / Zn mass ratio is 1.2-1.7, the total content of Mn, Zr and Sc does not exceed 0.43%, the total content of Zr and Sc does not exceed 0.32%, and the Zr / Sc mass ratio is 0.8-1.

3.

4. A high-strength and lightweight aluminum alloy according to any one of claims 1 to 3, characterized in that: The alloy density is ≤2.72g / cm 3 The yield strength of the alloy after solution aging treatment is ≥350MPa, the tensile strength is ≥450MPa, the elongation is ≥10%, the welding coefficient is not less than 0.75, and the alloy exfoliation corrosion performance is not lower than EA grade.

5. A method for preparing the high-strength lightweight aluminum alloy according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) melting and casting the alloy according to a certain composition ratio to obtain an aluminum alloy ingot; (2) keeping the aluminum alloy ingot at 280-340° C. for 0.5-10 h to perform a first-stage homogenization treatment; then, keeping the ingot at 460-490° C. for 4-16 h to perform a second-stage homogenization treatment to obtain a homogenized aluminum alloy ingot; (3) subjecting the homogenized aluminum alloy ingot to a deformation process; (4) the deformed aluminum alloy is kept at 465-495° C. for 30-90 min for solution treatment; (5) subjecting the aluminum alloy after the solution treatment to a single-stage or double-stage aging treatment to obtain the high-strength and lightweight aluminum alloy; the single-stage aging treatment comprises keeping the alloy at 110-135° C. for 8-30 hours; the double-stage aging treatment comprises first keeping the alloy at 110-135° C. for 2-8 hours for a first-stage aging treatment, and then keeping the alloy at 155-175° C. for 6-20 hours for a second-stage aging treatment.

6. The method for preparing a high-strength lightweight aluminum alloy according to claim 5, characterized in that: In step (2), the heating rate between the first stage homogenization treatment and the second stage homogenization treatment is 10-50°C / h.

7. The method for preparing a high-strength lightweight aluminum alloy according to claim 5, characterized in that: In step (3), the deformation treatment includes one or more deformation methods of rolling, forging, and extrusion.

8. A flight structure for aerospace use manufactured using the high-strength and lightweight aluminum alloy according to any one of claims 1 to 3.

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