Aluminum-lithium alloy with high strength and high exfoliation corrosion resistance, preparation process and application thereof

Abstract

The application discloses an aluminum-lithium alloy with high strength and high exfoliation corrosion resistance, a preparation process and application thereof, and belongs to the technical field of aluminum-lithium alloy materials.The aluminum-lithium alloy comprises the following components in percentage by mass: Cu 3.0%-4.2%, Li 0.6%-1.5%, Mn 0.1%-0.6%, Zr 0.05%-0.4%, and Zn and Ag, and the balance of Al and inevitable impurities, wherein the mass ratio of Zn / Ag is 2.0-6.0, and the Zn addition amount is 0.2%-1.2%; or the Ag is replaced by Mg, the mass ratio of Zn / Mg is 0.8-3.0, and the Zn addition amount is 0.4%-1.2%. The preparation process comprises the following steps: batching and smelting, two-stage homogenization treatment, hot rolling, controlled temperature annealing, cold rolling, solid solution quenching and stepwise aging temperature control treatment. The application breaks through the technical bottleneck that the strength and corrosion resistance of the aluminum-lithium alloy are difficult to be simultaneously improved by optimizing the Zn / Mg or Zn / Ag ratio and the stepwise aging process.

Description

Technical Field

[0001] This invention relates to the field of metallurgical processing technology, specifically to a high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, its preparation process, and its applications. Background Technology

[0002] Compared to traditional aluminum alloys, Al-Cu-Li alloys are widely used in the aerospace field due to their advantages such as light weight, high strength, high modulus, and excellent fatigue performance. It is generally believed that adding 1 wt.% Li to an aluminum alloy can reduce its density by 3% and increase its elastic modulus by 6%. However, due to the chemical reactivity of Li, the alloy's corrosion susceptibility increases, thus affecting the safety, reliability, and normal service life of aircraft. Therefore, studying the corrosion mechanism of Al-Cu-Li alloys is imperative.

[0003] Currently, commercially available high-strength Al-Cu-Li alloys typically contain magnesium (Mg). Mg is a crucial element for achieving high strength in Al-Cu-Li alloys, promoting the nucleation and dispersed precipitation of the main strengthening phase. In Al-Cu-Li alloys, the main strengthening phase is the T1 phase (…). The precipitation density and uniformity of CuLi directly determine the strength of the alloy. However, when only magnesium is added, the corrosion resistance of the alloy is often insufficient. To address this, existing technologies have attempted to add zinc to improve corrosion resistance. However, in alloy systems where magnesium is present, the potential difference between the zinc-containing precipitates and the non-precipitated zone (PFZ) remains significant, making it difficult to effectively suppress exfoliation corrosion, a concern in the aerospace field. Further research has attempted to replace magnesium with silver, which improves corrosion resistance but leads to a significant decrease in strength. Adding Ag alone results in a double decrease in both strength and exfoliation corrosion resistance. Therefore, existing alloy systems struggle to balance high strength and high corrosion resistance, failing to meet the comprehensive performance requirements of the aerospace industry. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the above-mentioned technologies.

[0005] Therefore, the purpose of this invention is to propose a high-strength, high-resistance aluminum-lithium alloy, its preparation process, and its application. By adding a specific Zn at a specific Zn to Mg mass ratio or a Zn to Ag mass ratio, the aluminum-lithium alloy acquires high strength and high resistance to exfoliation corrosion. By employing a step-by-step aging temperature control method, the precipitation of the precipitated phase is precisely controlled, thereby achieving a target alloy strength ≥530MPa and an exfoliation corrosion resistance level higher than PC, overcoming the technical challenge that alloy strength and plasticity cannot be improved simultaneously with exfoliation corrosion resistance.

[0006] The technical solution of the present invention is a high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, comprising the following components by mass percentage: Cu 3.0%–4.2%, Li 0.6%–1.5%, Mn 0.1%–0.6%, Zr 0.05%–0.4%, Zn and Ag, with the balance being Al and unavoidable impurities. The mass ratio of Zn / Ag is 2.0–6.0, and the amount of Zn added is 0.2%–1.2%.

[0007] Furthermore, the Ag is replaced with Mg, the Zn / Mg mass ratio is 0.8 to 3.0, and the Zn addition amount is 0.4% to 1.2%.

[0008] A preparation process for a high-strength, highly resistant-to-exfoliation corrosion aluminum-lithium alloy material includes the following steps: According to the composition ratio of aluminum-lithium alloy material, the ingredients are batched, and the batched ingredients are smelted, refined and cast to obtain ingots; The ingot is homogenized to obtain a homogenized alloy ingot. The homogenized alloy ingot is subjected to hot working, temperature-controlled annealing, and cold working to obtain a shaped blank. After solution treatment and quenching of the formed blank, aging treatment is performed using a stepped aging temperature control method to obtain the aluminum-lithium alloy material. The stepped aging temperature control method includes: The first step involves increasing the temperature at a rate of 5℃ / min to 15℃ / min to the first temperature plateau of 30℃ to 60℃, and holding the temperature for 20min to 40min. The second step involves increasing the temperature at a rate of 10℃ / min to 20℃ / min to the second temperature plateau of 80℃ to 100℃, and holding the temperature for 30min to 60min. The third step involves increasing the temperature at a rate of 20℃ / min to 30℃ / min until reaching the third temperature plateau of 130℃ to 160℃, and then holding the temperature for 4 hours to 156 hours.

[0009] Furthermore, the homogenization process is a bipolar homogenization process, including a first-stage treatment at a temperature of 440℃~480℃ for 6h~12h and a second-stage treatment at a temperature of 500℃~550℃ for 18h~36h.

[0010] Furthermore, the temperature-controlled annealing temperature is 400℃~490℃, and after holding at that temperature for 1.8h~3.2h, it is air-cooled. The cold working is room temperature cold rolling, and the deformation amount is 20%~90%.

[0011] Furthermore, the stepped aging temperature control method can be replaced with: The first step involves increasing the temperature at a rate of 5℃ / min to 15℃ / min to the first temperature plateau of 50℃ to 80℃, and holding the temperature for 20min to 40min. The second step involves increasing the temperature at a rate of 20℃ / min to 40℃ / min to the second temperature plateau of 130℃ to 160℃, and holding the temperature for 4 hours to 156 hours.

[0012] Furthermore, the smelting is carried out under argon protection, and during the casting process, the order in which different samples are added is determined according to the different melting points of the different alloys to prevent the loss of the set elements during casting.

[0013] Furthermore, the hot working is hot rolling, the initial rolling temperature is 450℃~500℃, the billet temperature during the hot rolling process is 350℃~370℃, and the deformation is 30%~90%.

[0014] Furthermore, the solution treatment temperature is 500℃~530℃, and the temperature is maintained for 1h~3h.

[0015] Application of a high-strength, high-resistance aluminum-lithium alloy in the manufacture of aerospace vehicles.

[0016] The advantages of this invention compared to existing technologies are: 10. This invention provides a high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, its preparation process, and its applications. When adding Zn and Ag, in an alloy system where Ag is already present, the Zn / Ag mass ratio is controlled to be 2.0–6.0, and the Zn addition amount is 0.2%–1.2%. By controlling the addition ratio of Zn and Ag, a microalloying synergistic effect is formed during solid solution and aging processes, promoting precipitation kinetics and enhancing the main strengthening phase, T1 phase (…). By adjusting the interlayer microstructure of the T1 phase, the precipitation density and distribution uniformity of CuLi are improved, and a passivation layer with fine and dispersed distribution at the precipitation phase boundary corrosion electrochemistry is formed, thereby achieving a synergistic improvement in high strength and good corrosion resistance. 11. This invention provides a high-strength, high-resistance aluminum-lithium alloy, its preparation process, and its application. When Zn is added, in an alloy system where Mg is already present, by controlling the Zn / Mg mass ratio to be 0.8–3.0 and the Zn addition amount to be 0.4%–1.2%, the synergistic effect of Zn and Mg can be fully utilized, enabling them to form a microalloying synergistic effect during solid solution and aging processes. This regulates the type and distribution of grain boundary precipitates, significantly reducing the electrochemical potential difference between the Zn-containing precipitates and the non-precipitated zone (PFZ), thereby effectively blocking the intergranular corrosion propagation path. This improves both strength and corrosion resistance, achieving a good balance between high strength and high corrosion resistance. 12. This invention provides a high-strength, high-resistance aluminum-lithium alloy, its preparation process, and its application. A stepped aging temperature control method is employed, first raising the temperature at 5℃ / min to 15℃ / min to a first temperature plateau of 30℃ to 60℃, holding for 20min to 40min; then raising the temperature at 10℃ / min to 20℃ / min to a second temperature plateau of 80℃ to 100℃, holding for 30min to 60min; finally, raising the temperature at 20℃ / min to 30℃ / min to a third temperature plateau of 130℃ to 160℃, holding for 4h to 156h. This method achieves precise control of the T1 phase and other strengthening phases, resulting in an alloy yield strength ≥530MPa and a higher resistance to exfoliation corrosion than PC, breaking through the technical bottleneck of simultaneously improving the strength and corrosion resistance of traditional alloys. Attached Figure Description

[0017] Figure 1 These are the yield strength mechanical property curves of Embodiments 2 and 10 of the present invention and Comparative Example 1 under different aging times.

[0018] Figure 2 These are the tensile strength mechanical property curves of Embodiments 2 and 10 of the present invention and Comparative Example 1 under different aging times.

[0019] Figure 3 The results of the peeling corrosion of the samples obtained under different aging regimes in Examples 2, 4, and 10 of the present invention after being immersed for different times are shown. Detailed Implementation

[0020] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] This embodiment proposes a high-strength, high-resistance-to-exfoliation-corrosion-resistant aluminum-lithium alloy, which comprises the following components by mass percentage: Cu 3.0%–4.2%, Li 0.6%–1.5%, Mn 0.1%–0.6%, Zr 0.05%–0.4%, Zn and Ag, with the balance being Al and unavoidable impurities. The Zn / Ag mass ratio is 2.0–6.0, and the Zn addition amount is 0.2%–1.2%.

[0023] To clearly illustrate the previous embodiment, in one embodiment of the present invention, Ag is replaced with Mg, the mass ratio of Zn / Mg is 0.8 to 3.0, and the amount of Zn added is 0.4% to 1.2%.

[0024] This embodiment proposes a preparation process for a high-strength, highly resistant-to-exfoliation corrosion aluminum-lithium alloy, comprising the following steps: According to the composition ratio of aluminum-lithium alloy, the ingredients are batched, smelted, refined and cast to obtain ingots; The ingot is homogenized to obtain a homogenized alloy ingot; The homogenized alloy ingot is subjected to hot working, temperature-controlled annealing and cold working to obtain a shaped blank; After solution treatment and quenching of the formed blank, an aluminum-lithium alloy material is obtained by aging treatment using a stepped aging temperature control method. The stepped aging temperature control method includes: The first step involves increasing the temperature at a rate of 5℃ / min to 15℃ / min to the first temperature plateau of 30℃ to 60℃, and holding the temperature for 20min to 40min. The second step involves increasing the temperature at a rate of 10℃ / min to 20℃ / min to the second temperature plateau of 80℃ to 100℃, and holding the temperature for 30min to 60min. The third step involves increasing the temperature at a rate of 20℃ / min to 30℃ / min until reaching the third temperature plateau of 130℃ to 160℃, and then holding the temperature for 4 hours to 156 hours.

[0025] Furthermore, the smelting is carried out under argon protection. During the casting process, the order in which different samples are added is determined according to the different melting points of the different alloys to prevent the loss of the set elements during casting.

[0026] Furthermore, the homogenization process is a bipolar homogenization process, including a first-stage treatment at a temperature of 440℃~480℃ for 6h~12h and a second-stage treatment at a temperature of 500℃~550℃ for 18h~36h.

[0027] Furthermore, the hot working is hot rolling, with an initial rolling temperature of 450℃~500℃, a billet temperature of 350℃~370℃ during hot rolling, and a deformation of 30%~90%.

[0028] Furthermore, the temperature-controlled annealing temperature is 400℃~490℃, and after holding at that temperature for 1.8h~3.2h, it is air-cooled. The cold working is room temperature cold rolling, and the deformation is 20%~90%.

[0029] Furthermore, the solution treatment temperature is 500℃~530℃, and the temperature is maintained for 1h~3h.

[0030] In one embodiment of the present invention, the stepped aging temperature control method can be replaced by: The first step involves increasing the temperature at a rate of 5℃ / min to 15℃ / min to the first temperature plateau of 50℃ to 80℃, and holding the temperature for 20min to 40min. The second step involves increasing the temperature at a rate of 20℃ / min to 40℃ / min to the second temperature plateau of 130℃ to 160℃, and holding the temperature for 4 hours to 156 hours.

[0031] This embodiment proposes the application of a high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy in the manufacture of aerospace vehicles.

[0032] It should be noted that the applications in the manufacture of aerospace vehicles include core components such as the fuselage, wings, cabin, load-bearing structure, and power system components.

[0033] Example 1 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Mg 0.18%, Mn 0.32%, Zn 0.34%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Mg mass ratio of 1.89.

[0034] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0035] The obtained ingot was subjected to a two-stage homogenization treatment. The first stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingot. The homogenized ingot was then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling between 360℃ and 370℃, deformation of 80%), temperature-controlled annealing (specifically, annealing temperature of 450℃, holding for 2 hours, followed by air cooling), and cold rolling (room temperature cold rolling, deformation of...). 80%) to obtain a shaped blank; the shaped blank is then subjected to solution treatment (solution temperature of 510℃, holding time of 1h), quenching and aging treatment in sequence (the aging treatment adopts a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30min, then heating to 150℃ at 25℃ / min, holding for 26h, or setting three heating platforms, first heating to 50℃ at 10℃ / min, holding for 30min, then heating to 80℃ at 20℃ / min, holding for 45min, and finally heating to 150℃ at 25℃ / min, holding for 26h), to obtain a high-strength and high-resistance to exfoliation corrosion aluminum-lithium alloy.

[0036] Example 2 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Mg 0.4%, Mn 0.32%, Zn 0.74%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Mg mass ratio of 1.85.

[0037] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0038] The obtained ingot was subjected to a two-stage homogenization treatment. The first stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingot. The homogenized ingot was then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling between 360℃ and 370℃, deformation of 80%), temperature-controlled annealing (specifically, annealing temperature of 450℃, holding for 2 hours, followed by air cooling), and cold rolling (room temperature cold rolling, deformation of...). 80%) to obtain a shaped blank; the shaped blank is then subjected to solution treatment (solution temperature of 510℃, holding time of 1h), quenching and aging treatment in sequence (the aging treatment adopts a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30min, then heating to 150℃ at 25℃ / min, holding for 26h, or setting three heating platforms, first heating to 50℃ at 10℃ / min, holding for 30min, then heating to 80℃ at 20℃ / min, holding for 45min, and finally heating to 150℃ at 25℃ / min, holding for 26h), to obtain a high-strength and high-resistance to exfoliation corrosion aluminum-lithium alloy.

[0039] Example 3 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Mg 0.61%, Mn 0.32%, Zn 1.12%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Mg mass ratio of 1.84.

[0040] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0041] The obtained ingot was subjected to a two-stage homogenization treatment. The first stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingot. The homogenized ingot was then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling between 360℃ and 370℃, deformation of 80%), temperature-controlled annealing (specifically, annealing temperature of 450℃, holding for 2 hours, followed by air cooling), and cold rolling (room temperature cold rolling, deformation of...). 80%) to obtain a shaped blank; the shaped blank is then subjected to solution treatment (solution temperature of 510℃, holding time of 1h), quenching and aging treatment in sequence (the aging treatment adopts a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30min, then heating to 150℃ at 25℃ / min, holding for 26h, or setting three heating platforms, first heating to 50℃ at 10℃ / min, holding for 30min, then heating to 80℃ at 20℃ / min, holding for 45min, and finally heating to 150℃ at 25℃ / min, holding for 26h), to obtain a high-strength and high-resistance to exfoliation corrosion aluminum-lithium alloy.

[0042] Example 4 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Mg 0.42%, Mn 0.32%, Zn 0.34%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Mg mass ratio of 0.81.

[0043] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0044] The obtained ingot was subjected to a two-stage homogenization treatment. The first stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingot. The homogenized ingot was then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling between 360℃ and 370℃, deformation of 80%), temperature-controlled annealing (specifically, annealing temperature of 450℃, holding for 2 hours, followed by air cooling), and cold rolling (room temperature cold rolling, deformation of...). 80%) to obtain a shaped blank; the shaped blank is then subjected to solution treatment (solution temperature of 510℃, holding time of 1h), quenching and aging treatment in sequence (the aging treatment adopts a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30min, then heating to 150℃ at 25℃ / min, holding for 26h, or setting three heating platforms, first heating to 50℃ at 10℃ / min, holding for 30min, then heating to 80℃ at 20℃ / min, holding for 45min, and finally heating to 150℃ at 25℃ / min, holding for 26h), to obtain a high-strength and high-resistance to exfoliation corrosion aluminum-lithium alloy.

[0045] Example 5 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Mg 0.81%, Mn 0.32%, Zn 0.74%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Mg mass ratio of 0.81.

[0046] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0047] The obtained ingot was subjected to a two-stage homogenization treatment. The first stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingot. The homogenized ingot was then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling between 360℃ and 370℃, deformation of 80%), temperature-controlled annealing (specifically, annealing temperature of 450℃, holding for 2 hours, followed by air cooling), and cold rolling (room temperature cold rolling, deformation of...). 80%) to obtain a shaped blank; the shaped blank is then subjected to solution treatment (solution temperature of 510℃, holding time of 1h), quenching and aging treatment in sequence (the aging treatment adopts a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30min, then heating to 150℃ at 25℃ / min, holding for 26h, or setting three heating platforms, first heating to 50℃ at 10℃ / min, holding for 30min, then heating to 80℃ at 20℃ / min, holding for 45min, and finally heating to 150℃ at 25℃ / min, holding for 26h), to obtain a high-strength and high-resistance to exfoliation corrosion aluminum-lithium alloy.

[0048] Example 6 A high-strength, high-resistance-to-exfoliation corrosion aluminum-lithium alloy, specifically, by mass percentage, comprises Cu 3.6%, Li 1.0%, Mg 1.23%, Mn 0.32%, Zn 1.12%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Mg mass ratio of 0.81.

[0049] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0050] The obtained ingot was subjected to a two-stage homogenization treatment. The first stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingot. The homogenized ingot was then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling between 360℃ and 370℃, deformation of 80%), temperature-controlled annealing (specifically, annealing temperature of 450℃, holding for 2 hours, followed by air cooling), and cold rolling (room temperature cold rolling, deformation of...). 80%) to obtain a shaped blank; the shaped blank is then subjected to solution treatment (solution temperature of 510℃, holding time of 1h), quenching and aging treatment in sequence (the aging treatment adopts a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30min, then heating to 150℃ at 25℃ / min, holding for 26h, or setting three heating platforms, first heating to 50℃ at 10℃ / min, holding for 30min, then heating to 80℃ at 20℃ / min, holding for 45min, and finally heating to 150℃ at 25℃ / min, holding for 26h), to obtain a high-strength and high-resistance to exfoliation corrosion aluminum-lithium alloy.

[0051] Example 7 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Ag 0.13%, Mn 0.32%, Zn 0.42%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Ag mass ratio of 3.2.

[0052] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0053] The obtained ingots were subjected to a two-stage homogenization treatment. The first-stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second-stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in homogenized ingots. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingots. The homogenized ingots were then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling of 360℃~370℃, deformation of 80%) and temperature-controlled annealing (specifically, annealing temperature of 4...). The blank is obtained by cold rolling (at 50℃ for 2 hours, followed by air cooling) and cold rolling (at room temperature with a deformation of 80%). The blank is then subjected to solution treatment (solution temperature of 510℃ for 1 hour), quenching, and aging treatment (gradient aging temperature control method with three heating platforms: first, heating to 50℃ at 10℃ / min and holding for 30 minutes; then heating to 80℃ at 20℃ / min and holding for 45 minutes; finally, heating to 150℃ at 25℃ / min and holding for 26 hours) to obtain a high-strength aluminum-lithium alloy with high resistance to exfoliation corrosion.

[0054] Example 8 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Ag 0.31%, Mn 0.32%, Zn 0.98%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Ag mass ratio of 3.2.

[0055] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0056] The obtained ingots were subjected to a two-stage homogenization treatment. The first-stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second-stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in homogenized ingots. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingots. The homogenized ingots were then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling of 360℃~370℃, deformation of 80%) and temperature-controlled annealing (specifically, annealing temperature of 4...). The blank is obtained by cold rolling (at 50℃ for 2 hours, followed by air cooling) and cold rolling (at room temperature with a deformation of 80%). The blank is then subjected to solution treatment (solution temperature of 510℃ for 1 hour), quenching, and aging treatment (gradient aging temperature control method with three heating platforms: first, heating to 50℃ at 10℃ / min and holding for 30 minutes; then heating to 80℃ at 20℃ / min and holding for 45 minutes; finally, heating to 150℃ at 25℃ / min and holding for 26 hours) to obtain a high-strength aluminum-lithium alloy with high resistance to exfoliation corrosion.

[0057] Example 9 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Ag 0.08%, Mn 0.32%, Zn 0.42%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Ag mass ratio of 5.3.

[0058] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0059] The obtained ingots were subjected to a two-stage homogenization treatment. The first-stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second-stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in homogenized ingots. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingots. The homogenized ingots were then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling of 360℃~370℃, deformation of 80%) and temperature-controlled annealing (specifically, annealing temperature of 4...). The blank is obtained by cold rolling (at 50℃ for 2 hours, followed by air cooling) and cold rolling (at room temperature with a deformation of 80%). The blank is then subjected to solution treatment (solution temperature of 510℃ for 1 hour), quenching, and aging treatment (gradient aging temperature control method with three heating platforms: first, heating to 50℃ at 10℃ / min and holding for 30 minutes; then heating to 80℃ at 20℃ / min and holding for 45 minutes; finally, heating to 150℃ at 25℃ / min and holding for 26 hours) to obtain a high-strength aluminum-lithium alloy with high resistance to exfoliation corrosion.

[0060] Example 10 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Ag 0.20%, Mn 0.32%, Zn 0.98%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, with a Zn / Ag mass ratio of 4.9.

[0061] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0062] The obtained ingots were subjected to a two-stage homogenization treatment. The first-stage homogenization treatment was carried out at a temperature of 460℃ for 8 hours, and the second-stage homogenization treatment was carried out at a temperature of 520℃ for 24 hours, resulting in homogenized ingots. The two-stage homogenization treatment was preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure in the alloy ingots. The homogenized ingots were then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling of 360℃~370℃, deformation of 80%) and temperature-controlled annealing (specifically, annealing temperature of 4...). The blank is obtained by cold rolling (at 50℃ for 2 hours, followed by air cooling) and cold rolling (at room temperature with a deformation of 80%). The blank is then subjected to solution treatment (solution temperature of 510℃ for 1 hour), quenching, and aging treatment (gradient aging temperature control method with three heating platforms: first, heating to 50℃ at 10℃ / min and holding for 30 minutes; then heating to 80℃ at 20℃ / min and holding for 45 minutes; finally, heating to 150℃ at 25℃ / min and holding for 26 hours) to obtain a high-strength aluminum-lithium alloy with high resistance to exfoliation corrosion.

[0063] Comparative Example 1 A high-strength, high-resistance-to-exfoliation corrosion aluminum-lithium alloy, specifically comprising, by mass percentage: Cu 3.6%, Li 1.0%, Mg 0.4%, Mn 0.32%, unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al.

[0064] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0065] The obtained ingot is subjected to a two-stage homogenization treatment. The first-stage homogenization treatment is carried out at a temperature of 460℃ for 8 hours, and the second-stage homogenization treatment is carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment is preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure distribution in the alloy ingot. The homogenized ingot is then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling is 360℃~370℃, deformation is 80%), controlled rolling, and controlled rolling processes. The aluminum-lithium alloy was obtained by warm annealing (specifically, annealing temperature 450℃, holding temperature for 2 hours, followed by air cooling) and cold rolling (using room temperature cold rolling with a deformation of 80%). The formed blank was then subjected to solution treatment (solution temperature 510℃, holding time 1 hour), quenching and aging treatment (the aging treatment adopted a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30 minutes, and then heating to 150℃ at 25℃ / min, holding for 26 hours) to obtain a high-strength aluminum-lithium alloy with high resistance to exfoliation corrosion.

[0066] Comparative Example 2 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising Cu 3.7%, Li 1.2%, Mg 0.6% by mass percentage, with unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al.

[0067] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0068] The obtained ingot is subjected to a two-stage homogenization treatment. The first-stage homogenization treatment is carried out at a temperature of 460℃ for 8 hours, and the second-stage homogenization treatment is carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment is preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure distribution in the alloy ingot. The homogenized ingot is then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling is 360℃~370℃, deformation is 80%), controlled rolling, and controlled rolling processes. The aluminum-lithium alloy was obtained by warm annealing (specifically, annealing temperature 450℃, holding temperature for 2 hours, followed by air cooling) and cold rolling (using room temperature cold rolling with a deformation of 80%). The formed blank was then subjected to solution treatment (solution temperature 510℃, holding time 1 hour), quenching and aging treatment (the aging treatment adopted a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30 minutes, and then heating to 150℃ at 25℃ / min, holding for 26 hours) to obtain a high-strength aluminum-lithium alloy with high resistance to exfoliation corrosion.

[0069] Comparative Example 3 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising Cu 1.8%, Li 1.7%, Mg 0.41%, Zn 0.6% by mass, with unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al, and a Zn / Mg mass ratio of 1.46.

[0070] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0071] The obtained ingot is subjected to a two-stage homogenization treatment. The first-stage homogenization treatment is carried out at a temperature of 460℃ for 8 hours, and the second-stage homogenization treatment is carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment is preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure distribution in the alloy ingot. The homogenized ingot is then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling is 360℃~370℃, deformation is 80%), controlled rolling, and controlled rolling processes. The aluminum-lithium alloy was obtained by warm annealing (specifically, annealing temperature 450℃, holding temperature for 2 hours, followed by air cooling) and cold rolling (using room temperature cold rolling with a deformation of 80%). The formed blank was then subjected to solution treatment (solution temperature 510℃, holding time 1 hour), quenching and aging treatment (the aging treatment adopted a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30 minutes, and then heating to 150℃ at 25℃ / min, holding for 26 hours) to obtain a high-strength aluminum-lithium alloy with high resistance to exfoliation corrosion.

[0072] Comparative Example 4 A high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy, specifically comprising Cu 1.8%, Li 1.7%, Mg 0.41% by mass, with unavoidable impurities <0.05%, of which iron ≤0.02%, silicon ≤0.02%, and the balance being Al.

[0073] The preparation method of the aluminum-lithium alloy in this embodiment is as follows: The raw materials are prepared according to the composition of the high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy described above. The preparation process has no special requirements; a well-known process in the art can be used. The prepared raw materials are then sequentially smelted, refined, and cast. Smelting is preferably carried out under argon protection. The smelting, refining, and casting processes have no special requirements and can be well-known in the art to obtain an ingot. The specific smelting and casting steps are as follows: preheating of the molten material, primary feeding, degassing and slag removal, secondary feeding, degassing and slag removal, lithium addition under protective gas, stirring, settling, and casting. The preheating temperature of the molten material is 300℃~400℃, and the holding time is 2h~3h. During the smelting and casting process, the order of adding different samples is determined according to the different melting points of the added alloys to ensure sufficient melting of the added molten material and prevent loss of the set elements. For high-melting-point intermediate alloys such as Al-Mn and Al-Zr, the temperature needs to be appropriately increased and the melting time extended, with a sufficient melting time of not less than 0.5h. The melting and casting temperature is 760℃~780℃, and the holding time is 30min~40min. The lithium addition process should be carried out under sufficient high-purity argon protection. Use a special bell jar for lithium addition to place the lithium into the high-temperature melt, while maintaining a relatively low furnace temperature, which should be set to 710℃~730℃. During the addition process, a miscibility time of 5min~10min should be maintained to ensure that the Li element is fully dissolved. After the lithium is added, stir for 3min, then maintain a temperature of 730℃~750℃ and let it stand for 12min before pouring the melt. When using the high-temperature melt of aluminum-lithium alloy for casting, it is necessary to guide the flow. The pouring process should be carried out smoothly, under the protection of high-purity argon atmosphere, and the water flow rate at the outlet of the water-cooled mold should be controlled. The flow rate should be controlled at 0.1m / s~0.4m / s to achieve the ideal cooling effect of heating first and then cooling later in the casting ingot.

[0074] The obtained ingot is subjected to a two-stage homogenization treatment. The first-stage homogenization treatment is carried out at a temperature of 460℃ for 8 hours, and the second-stage homogenization treatment is carried out at a temperature of 520℃ for 24 hours, resulting in a homogenized ingot. The two-stage homogenization treatment is preferably carried out under normal air atmosphere to promote the homogenization of chemical composition and grain structure distribution in the alloy ingot. The homogenized ingot is then subjected to hot rolling (initial rolling temperature of 480℃, billet temperature during hot rolling is 360℃~370℃, deformation is 80%), controlled rolling, and controlled rolling processes. The aluminum-lithium alloy was obtained by warm annealing (specifically, annealing temperature 450℃, holding temperature for 2 hours, followed by air cooling) and cold rolling (using room temperature cold rolling with a deformation of 80%). The formed blank was then subjected to solution treatment (solution temperature 510℃, holding time 1 hour), quenching and aging treatment (the aging treatment adopted a gradient aging temperature control method, setting two heating platforms, first heating to 70℃ at 10℃ / min, holding for 30 minutes, and then heating to 150℃ at 25℃ / min, holding for 26 hours) to obtain a high-strength aluminum-lithium alloy with high resistance to exfoliation corrosion.

[0075] Table 1. Composition (wt.%) of aluminum-lithium alloys in Examples 1-10 and Comparative Examples 1-4 Table 2 shows the test results of mechanical properties and exfoliation corrosion resistance of Examples 1-6 and Comparative Examples 1-4 under an aging regime of T ~ 10℃ / min × 70℃ × 30min + 25℃ / min × 150℃ × 26h, and of Examples 7-10 under an aging regime of T ~ 10℃ / min × 50℃ × 30min + 20℃ / min × 80℃ × 45min + 25℃ / min × 150℃ × 26h. Where YS represents the yield strength of the material, UTS represents the tensile strength of the material, Elongation represents the elongation of the material, and The results of the exfoliation corrosion represent the exfoliation corrosion level of the material. (See Table 2.) Figure 1 and Figure 2 As shown, the high-strength, high-resistance aluminum-lithium alloy material provided by the present invention, through a reasonable metal element ratio, has excellent strength and resistance to exfoliation corrosion.

[0076] The aluminum-lithium alloy materials obtained in Examples 2, 4, and 10 were subjected to exfoliation corrosion resistance tests for different durations using different processing techniques and heat treatments. The results are shown in Tables 3 and 4. Figure 3 As shown.

[0077] Table 3 shows the exfoliation corrosion results of samples obtained from Examples 2, 4, and 10 under different aging regimes after immersion for different times. Table 4 shows the mechanical properties and 72-hour exfoliation corrosion results of Examples 2 and 4 under different stepped heat treatment schemes. From Table 3, Table 4 and Figure 3 As shown, the high-strength aluminum-lithium alloy material with resistance to exfoliation corrosion provided by the present invention has excellent resistance to exfoliation corrosion through reasonable heat treatment scheme design and composition design. In Table 4, Temper refers to tempering.

[0078] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0079] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0080] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A high-strength, highly resistant-to-exfoliation corrosion aluminum-lithium alloy, characterized in that, The composition comprises, by mass percentage: Cu 3.0%–4.2%, Li 0.6%–1.5%, Mn 0.1%–0.6%, Zr 0.05%–0.4%, Zn and Ag, with the balance being Al and unavoidable impurities. The Zn / Ag mass ratio is 2.0–6.0, and the Zn addition amount is 0.2%–1.2%.

2. The high-strength, high-resistance-to-exfoliation-corrosion-resistant aluminum-lithium alloy according to claim 1, characterized in that: The Ag is replaced with Mg, the Zn / Mg mass ratio is 0.8 to 3.0, and the Zn addition amount is 0.4% to 1.2%.

3. A preparation process for a high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy according to claim 1 or 2, characterized in that, Includes the following steps: According to the composition ratio of aluminum-lithium alloy, the ingredients are batched, and the batched ingredients are smelted, refined and cast to obtain ingots; The ingot is homogenized to obtain a homogenized alloy ingot. The homogenized alloy ingot is subjected to hot working, temperature-controlled annealing, and cold working to obtain a shaped blank. After solution treatment and quenching of the formed blank, aging treatment is performed using a stepped aging temperature control method to obtain the aluminum-lithium alloy material. The stepped aging temperature control method includes: The first step involves increasing the temperature at a rate of 5℃ / min to 15℃ / min to the first temperature plateau of 30℃ to 60℃, and holding the temperature for 20min to 40min. The second step involves increasing the temperature at a rate of 10℃ / min to 20℃ / min to the second temperature plateau of 80℃ to 100℃, and holding the temperature for 30min to 60min. The third step involves increasing the temperature at a rate of 20℃ / min to 30℃ / min until reaching the third temperature plateau of 130℃ to 160℃, and then holding the temperature for 4 hours to 156 hours.

4. The preparation process of the high-strength, high-resistance-to-exfoliation-corrosion-resistant aluminum-lithium alloy according to claim 3, characterized in that: The smelting is carried out under argon protection. During the casting process, the order in which different samples are added is determined according to the different melting points of the different alloys to prevent the loss of the set elements during casting.

5. The preparation process of the high-strength, high-resistance-to-exfoliation-corrosion-resistant aluminum-lithium alloy according to claim 3, characterized in that: The homogenization process is a bipolar homogenization process, which includes a first-stage treatment at a temperature of 440℃~480℃ for 6h~12h and a second-stage treatment at a temperature of 500℃~550℃ for 18h~36h.

6. The preparation process of the high-strength, high-resistance-to-exfoliation-corrosion-resistant aluminum-lithium alloy according to claim 3, characterized in that: The hot working is hot rolling, the initial rolling temperature is 450℃~500℃, the billet temperature during the hot rolling process is 350℃~370℃, and the deformation is 30%~90%.

7. The preparation process of a high-strength, high-resistance-to-exfoliation-corrosion-resistant aluminum-lithium alloy according to claim 3, characterized in that: The temperature-controlled annealing temperature is 400℃~490℃, and the temperature is held for 1.8h~3.2h before air cooling. The cold working is room temperature cold rolling, and the deformation amount is 20%~90%.

8. The preparation process of a high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy according to claim 3, characterized in that: The solution treatment temperature is 500℃~530℃, and the temperature is maintained for 1h~3h.

9. The preparation process of a high-strength, high-resistance-to-exfoliation-corrosion-resistant aluminum-lithium alloy according to claim 3, characterized in that, The stepped aging temperature control method can be replaced by: The first step involves increasing the temperature at a rate of 5℃ / min to 15℃ / min to the first temperature plateau of 50℃ to 80℃, and holding the temperature for 20min to 40min. The second step involves increasing the temperature at a rate of 20℃ / min to 40℃ / min to the second temperature plateau of 130℃ to 160℃, and holding the temperature for 4 hours to 156 hours.

10. The application of a high-strength, high-resistance-to-exfoliation-corrosion aluminum-lithium alloy according to any one of claims 1 to 2 in the manufacture of aerospace vehicles.

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