Aluminum alloy material and preparation process thereof

Abstract

The invention relates to an aluminum alloy material and a preparation process thereof, and relates to the technical field of novel aviation aluminum alloy materials, the aluminum alloy material comprises, by mass, 2.2%-2.8% of Li, 3.0%-3.8% of Cu, 0.6%-1.2% of Mg, 0.5%-1.2% of Zn, 0.08%-0.12% of Zr, 0.3%-0.6% of Ag, 0.08%-0.15% of Sc, 0.1%-0.3% of Er, and the balance Al and impurities, and the total mass of the impurities is not larger than 0.1%. According to the aluminum alloy material, the strength, toughness and corrosion resistance of the aluminum alloy material are kept balanced by adjusting the content ratio of Cu to Li and the proportion of all the elements, and all performance indexes are synergistically improved.

Description

Technical Field

[0001] This invention relates to the field of novel aerospace aluminum alloy materials, and in particular to an aluminum alloy material and its preparation process. Background Technology

[0002] Aluminum alloys are alloys made by adding appropriate amounts of alloying elements to aluminum. They not only possess the basic properties of aluminum, but also exhibit unique properties due to the different alloying elements. They are lightweight, high-strength, have good electrical conductivity, and good corrosion resistance, and are widely used in aerospace, automotive manufacturing, electronic communications, and many other fields.

[0003] Chinese invention patent CN111500901A discloses a high-lithium aluminum-lithium alloy and its preparation method. By mass percentage, the high-lithium aluminum-lithium alloy comprises Cu 3.8–4.2%, Li 4.0–4.8%, Mg 0.3–0.4%, Zn 0.3–0.9%, Ti 0.03–0.07%, and the balance Al. The high-lithium aluminum-lithium alloy provided by this invention optimizes the precipitation of various reinforcing phases in the alloy's microstructure by increasing the mass percentage of lithium and controlling the mass percentage of other elements, thus significantly improving the alloy's mechanical properties.

[0004] Although the lithium content in the aforementioned alloys is high, a low Cu / Li ratio makes it easy for the alloy to form the Al3Li phase, making it difficult to maintain a balance between strength, toughness, and corrosion resistance. Furthermore, lithium is highly reactive in the manufacturing process, easily oxidizing and burning off under conventional smelting conditions, leading to uncontrolled composition and melt contamination. Magnesium is also prone to oxidation and burning off. The aluminum-lithium alloy melt also readily absorbs hydrogen, causing porosity and hydrogen embrittlement in the ingot. Lithium has a low density and is prone to segregation during solidification, such as gravity segregation, resulting in uneven ingot composition and microstructure. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an aluminum alloy material, its preparation process, and the same process. By adjusting the ratio of Cu to Li content and the proportions of each element, the strength, toughness, and corrosion resistance of the aluminum alloy material are balanced, thus synergistically improving the performance indicators of each property.

[0006] In a first aspect, the present invention provides an aluminum alloy material, which, by mass percentage, comprises 2.2-2.8% Li, 3.0-3.8% Cu, 0.6-1.2% Mg, 0.5-1.2% Zn, 0.08-0.12% Zr, 0.3-0.6% Ag, 0.08-0.15% Sc, and 0.1-0.3% Er, with the balance being Al and impurities, wherein the total mass of the impurities is not greater than 0.1%.

[0007] In the above technical solution, Li has a certain solid solubility in Al and can precipitate a coherently ordered Al3Li phase by aging. The content is controlled at 2.2-2.8%. If it is too low, the weight reduction and strengthening effect will be insufficient; if it is too high, the solidification range will widen, the tendency for hot cracking will increase sharply, and because Li has a low density, it will easily float and will also impair toughness.

[0008] Cu can form the Al₂CuLi phase with Li and Al, and Al₂Cu with Al. Cu reduces the corrosion resistance of the alloy and easily forms Cu-rich phases at grain boundaries, leading to electrochemical corrosion. However, the ratio of Cu content to Li content (Cu / Li) is very important, requiring a precise balance between strength and corrosion resistance. A Cu content controlled at 3.0-3.8% provides sufficient Cu to form a high-density Al₂CuLi phase, providing high strength, while matching the Li content to avoid reducing toughness.

[0009] Both Mg and Zn can dissolve in the Al matrix, producing a certain solid solution strengthening effect. The addition of Mg significantly enhances the promoting effect of Ag on the precipitation of the Al₂CuLi phase, increasing the nucleation rate and density of the Al₂CuLi phase, making it finer and more uniform. Zn, together with Mg and Ag, synergistically promotes the precipitation of the Al₂CuLi phase, forming a Mg-Ag-Zn composite synergistic effect, which reduces the interfacial energy. The addition of appropriate amounts of Mg and Zn can adjust the electrode potential of the alloy and improve its resistance to stress corrosion.

[0010] Ag can promote the precipitation of the Al2CuLi phase. Ag atoms combine with vacancies and segregate on the {111} crystal plane, providing heterogeneous nucleation sites for the Al2CuLi phase. This significantly increases the nucleation density of the Al2CuLi phase, making its distribution more uniform and its size smaller, thereby greatly improving the strength of the alloy without significantly impairing its toughness.

[0011] Zr can form Al3Zr in Al, which effectively inhibits recrystallization during hot working and heat treatment, allowing the alloy to maintain an unrecrystallized fibrous structure, thereby improving strength and fatigue resistance.

[0012] Sc in Al can form Al3Sc, which refines the as-cast grains. Al3Sc effectively pins dislocations and grain boundaries, inhibits recrystallization, and maintains an unrecrystallized structure even at high Sc contents, significantly increasing the recrystallization temperature. When Sc and Zr are added together, they form an Al3(Sc, Zr) composite phase. Zr atoms occupy Sc sublattice sites, and this composite has higher thermal stability, stronger resistance to coarsening, and longer-lasting effects compared to Al3Sc or Al3Zr alone.

[0013] Er can form Al3Er in Al. When added together with Sc and Zr, they can form a more complex Al3(Sc,Zr, Er) composite nano-dispersed phase. Er acts similarly to Sc, serving as an effective grain refiner and recrystallization inhibitor. By adding Er, the effect of higher Sc content alone can be achieved with a relatively lower Sc content, thus reducing costs.

[0014] Optionally, the aluminum alloy material further includes 0.05-0.15% Yb by mass.

[0015] In the above technical solution, Yb can form Al3Yb in Al. The atomic radius of Yb is significantly different from that of Sc. The addition of Yb can cause strong lattice distortion, which further delays diffusion and phase coarsening.

[0016] Secondly, the present invention provides a preparation process for an aluminum alloy material, the preparation process comprising the following steps: Raw material preparation and smelting: Prepare the raw materials according to the formula, and put all raw materials except Li into the crucible of the smelting furnace and evacuate to 10°C. -2 -10 -3 Pa, then high-purity argon gas is introduced as a protective atmosphere, heated until completely melted and superheated to 750-780℃, cooled to 700-720℃ and then lithium foil is added and stirred thoroughly; Melt treatment and casting: Under a protective atmosphere, high-purity argon gas is introduced by rotary jetting to remove hydrogen and inclusions from the melt. After the metal is completely melted, it is successively refined, slag removed, and cast into shape to obtain aluminum alloy ingots. Homogenization and hot working: The ingot is subjected to multi-stage homogenization in an air-circulating furnace, and the homogenized ingot is heated to 450-470℃ and extruded to obtain profiles; Solution treatment and quenching: The profile is heated to 530-540℃ in an air-circulating furnace, held at that temperature, and then quickly transferred to a room temperature water bath for rapid quenching. Then, surface treatment is performed to obtain the aluminum alloy material.

[0017] In the above technical solution, lithium oxidizes rapidly in air, and molten aluminum-lithium alloy readily absorbs hydrogen, leading to hydrogen-induced defects. Vacuuming and filling with high-purity argon as a protective atmosphere can prevent lithium oxidation and hydrogen absorption by the melt. Adding lithium last avoids excessive burning; it is added after other elements have melted, at a lower temperature, and with rapid stirring. A rotary jet is used; as tiny bubbles rise in the melt, they carry dissolved hydrogen into the bubbles and expel it, based on the principle of partial pressure at the gas-liquid interface, while simultaneously adsorbing oxide inclusions.

[0018] Casting solidification is a non-equilibrium process, which leads to uneven distribution of elements such as Cu, Li, and Mg in the dendrite trunk and between dendrites. Homogenization treatment, through prolonged high-temperature diffusion, homogenizes the composition. It can also dissolve unbalanced coarse, low-melting-point phases in the as-cast structure and promote the spheroidization of Fe and Si-containing impurity phases, reducing their harmful effects.

[0019] Optionally, the solution treatment and quenching steps also include immediately performing 1.5-3% tensile or compression leveling on the profile after quenching, followed by primary and secondary aging treatments, and finally air cooling to room temperature; the primary aging treatment temperature is 110-120℃ and the treatment time is 6-12h, and the secondary aging treatment temperature is 155-165℃ and the treatment time is 24-36h.

[0020] In the above technical solutions, stretching or compression leveling can eliminate the huge internal stress generated by quenching and prevent deformation during subsequent processing.

[0021] In multi-stage aging treatment, the first-stage low-temperature aging can form high-density GP zones as crystal nuclei, preparing for the subsequent precipitation of the Al2CuLi phase. The second-stage high-temperature aging can promote the fine, uniform, and dense precipitation of the main strengthening phases, such as the Al2CuLi phase, at existing nucleation sites, achieving peak strength. It can also form a wider precipitation-free zone at grain boundaries, improving corrosion resistance.

[0022] Optionally, the surface treatment steps are as follows: activate with sodium citrate at 40-50℃ for 3-5 minutes, then immerse it in a treatment solution with pH 2.5-3.5 at room temperature for 5-10 minutes, and finally immerse it in water at 60-80℃ for 3-5 minutes.

[0023] In the above technical solution, sodium citrate, as a weak alkaline degreasing agent, can remove surface oil stains. Its weak alkaline properties will slightly corrode the surface, making lithium elements easier to dissolve, while preventing metal ions from precipitating on the surface and forming dust.

[0024] By using the alloy's own lithium element as an inducing agent, the alloy is immersed in a mild processing solution to grow an amorphous composite conversion film rich in rare earth and molybdenum elements in situ on the alloy surface, thereby achieving protective performance.

[0025] The warm water sealing process further hydrates the unreacted components in the conversion membrane, making the membrane structure denser and more stable, and removing residual soluble salts.

[0026] Optionally, the treatment solution comprises 5-10 g / L cerium nitrate, 2-5 g / L sodium molybdate, 1-3 mL / L 30% hydrogen peroxide, 0.5-2 g / L ammonium bifluoride, and the balance being water.

[0027] In the above technical solution, cerium nitrate provides Ce. 3+ Ions, under the high pH environment of the micro-region, form Ce(OH)4 precipitate, constituting the main framework of the conversion membrane and endowing the membrane with basic corrosion resistance and self-healing potential. Sodium molybdate provides MoO4. 2- Ions form molybdenum oxides or hydroxides, which intertwine with cerium compounds, filling the gaps in the film layer, making the film denser and further improving corrosion resistance. Hydrogen peroxide can gently oxidize the Al matrix, promoting metal dissolution. Ce... 3+ Oxidized to Ce 4+ This promotes the formation of the more stable and protective Ce(OH)4. Ammonium bifluoride provides F. - Ions can slightly etch the natural oxide film on the surface of aluminum alloys, ensuring contact between the solution and the metal, inducing uniform film formation, and helping to stabilize the pH of the solution.

[0028] Optionally, the preparation steps of the treatment solution are as follows: using water as a solvent, dissolve cerium nitrate, sodium molybdate, and ammonium bifluoride in sequence, stirring thoroughly until completely dissolved after each reagent is added; finally, slowly add hydrogen peroxide dropwise while continuously stirring; and finally, precisely adjust the pH value to 2.5-3.5 with ammonia.

[0029] Thirdly, the application of an aluminum alloy material or an aluminum alloy material preparation process provided by the present invention in the fields of aerospace, machinery manufacturing, medical devices, and sports equipment.

[0030] In summary, the present invention has at least one of the following beneficial technical effects: 1. By adjusting the ratio of Cu to Li content, the corrosion sensitivity caused by Cu and the effect of Li on corrosion resistance are balanced, so that the strength, toughness and corrosion resistance of aluminum alloy materials are balanced, and the performance indicators of each are improved in a synergistic way.

[0031] 2. By adding Er, Al3Er can be formed in Al. When added together with Sc and Zr, they will form a more complex Al3(Sc, Zr, Er) composite nano-dispersed phase, which can be used as an effective grain refiner and recrystallization inhibitor. By adding Er, the effect of high Sc content can be achieved with relatively reduced Sc content, while reducing costs.

[0032] 3. By adding Yb, Al3Yb can be formed in Al. The atomic radius of Yb is significantly different from that of Sc. The addition of Yb can result in strong lattice distortion, which further delays diffusion and phase coarsening.

[0033] 4. Surface treatment is performed using the treatment solution of this application, with Ce provided by cerium nitrate. 3+Ions, in the high pH environment of the micro-region, form Ce(OH)4 precipitate, constituting the main framework of the conversion membrane and endowing the membrane with basic corrosion resistance and self-healing potential; sodium molybdate provides MoO4. 2- Ions form molybdenum oxides or hydroxides, which intertwine with cerium compounds to fill the gaps in the film, making the film denser and further improving corrosion resistance; hydrogen peroxide can gently oxidize the Al matrix, promoting metal dissolution and removing Ce. 3+ Oxidized to Ce 4+ This promotes the formation of a more stable and protective Ce(OH)4; ammonium bifluoride provides F - Ions can slightly etch the natural oxide film on the surface of aluminum alloys, ensuring contact between the solution and the metal, inducing uniform film formation, and helping to stabilize the pH of the solution. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the embodiments.

[0035] All materials used in the following examples are available for purchase on the market.

[0036] Example 1: This example provides an aluminum alloy material and its preparation process.

[0037] The aluminum alloy material comprises, by mass percentage, 2.2% Li, 3.0% Cu, 1.2% Mg, 1.2% Zn, 0.3% Ag, 0.08% Zr, 0.08% Sc, and 0.1% Er, with the balance being Al and impurities, wherein the total amount of impurities is not greater than 0.1%, and the total amount is 100%.

[0038] The preparation process is as follows: S1. Raw Material Preparation and Smelting: Prepare the raw materials according to the formula, and put the high-purity aluminum ingots, high-purity electrolytic copper, Al-Mg, Al-Zn, Al-Ag, Al-Zr, Al-Sc, and Al-Er master alloy ingots into the crucible of the smelting furnace and evacuate to 10°C. -2 Pa, then high-purity argon gas is introduced as a protective atmosphere, heated to complete melting and superheated to 765°C, cooled to 710°C and then lithium foil is added and stirred thoroughly.

[0039] S2. Melt treatment and casting: Under a protective atmosphere, high-purity argon gas is introduced by rotary jetting to remove hydrogen and inclusions from the melt. After the metal is completely melted, it is refined, slag removed, and cast into shape to obtain aluminum alloy ingots.

[0040] S3. Homogenization and Hot Working: The ingot is subjected to multi-stage homogenization in an air-circulating furnace. The homogenized ingot is then heated to 460°C and extruded to obtain the profile.

[0041] S4. Solution treatment and quenching: The profile is heated to 535°C in an air-circulating furnace and held at that temperature. Then it is quickly transferred to a room temperature water bath for rapid quenching. Immediately after quenching, the profile is subjected to 2% tensile or compressive leveling. Then it undergoes first-stage aging and second-stage aging treatments, and finally air-cooled to room temperature. The first-stage aging treatment temperature is 115°C and the treatment time is 9 hours. The second-stage aging treatment temperature is 160°C and the treatment time is 30 hours.

[0042] S5. Surface treatment: After the aluminum alloy casting is placed in boiling water for 30 minutes, it is immersed in octadecyltrimethoxysilane toluene solution for 20 minutes. After treatment, it is dried to obtain the aluminum alloy material.

[0043] Example 2: This example provides an aluminum alloy material and its preparation process.

[0044] The aluminum alloy material comprises, by mass percentage, 2.8% Li, 3.8% Cu, 0.6% Mg, 0.5% Zn, 0.6% Ag, 0.12% Zr, 0.15% Sc, and 0.3% Er, with the balance being Al and impurities, wherein the total amount of impurities is no more than 0.1%, and the total amount is 100%.

[0045] The preparation process is the same as in Example 1.

[0046] Example 3: This example provides an aluminum alloy material and its preparation process.

[0047] The aluminum alloy material comprises, by mass percentage, 2.5% Li, 3.6% Cu, 1.0% Mg, 0.9% Zn, 0.5% Ag, 0.1% Zr, 0.12% Sc, and 0.2% Er, with the balance being Al and impurities, wherein the total amount of impurities is not greater than 0.1%, and the total amount is 100%.

[0048] The preparation process is the same as in Example 1.

[0049] Example 4: This example provides an aluminum alloy material and its preparation process.

[0050] The aluminum alloy material comprises, by mass percentage, 2.5% Li, 3.6% Cu, 1.0% Mg, 0.9% Zn, 0.5% Ag, 0.1% Zr, 0.1% Sc, 0.12% Er, and 0.1% Yb, with the balance being Al and impurities, wherein the total amount of impurities is not greater than 0.1%, and the total amount is 100%.

[0051] The preparation process is as follows: S1. Raw Material Preparation and Smelting: Prepare raw materials according to the formula, and put high-purity aluminum ingots, high-purity electrolytic copper, Al-Mg, Al-Zn, Al-Ag, Al-Zr, Al-Sc, Al-Er, and Al-Yb master alloy ingots into the crucible of the smelting furnace and evacuate to 10°C. -2 Pa, then high-purity argon gas is introduced as a protective atmosphere, heated to complete melting and superheated to 765°C, cooled to 710°C and then lithium foil is added and stirred thoroughly.

[0052] S2. Melt treatment and casting: Under a protective atmosphere, high-purity argon gas is introduced by rotary jetting to remove hydrogen and inclusions from the melt. After the metal is completely melted, it is refined, slag removed, and cast into shape to obtain aluminum alloy ingots.

[0053] S3. Homogenization and Hot Working: The ingot is subjected to multi-stage homogenization in an air-circulating furnace. The homogenized ingot is then heated to 460°C and extruded to obtain the profile.

[0054] S4. Solution treatment and quenching: The profile is heated to 535°C in an air-circulating furnace and held at that temperature. Then it is quickly transferred to a room temperature water bath for rapid quenching. Immediately after quenching, the profile is subjected to 2% tensile or compressive leveling. Then it undergoes first-stage aging and second-stage aging treatments, and finally air-cooled to room temperature. The first-stage aging treatment temperature is 115°C and the treatment time is 9 hours. The second-stage aging treatment temperature is 160°C and the treatment time is 30 hours.

[0055] S5. Surface treatment: After the aluminum alloy casting is placed in boiling water for 30 minutes, it is immersed in octadecyltrimethoxysilane toluene solution for 20 minutes. After treatment, it is dried to obtain the aluminum alloy material.

[0056] Example 5: This example provides an aluminum alloy material and its preparation process.

[0057] The aluminum alloy material comprises, by mass percentage, 2.5% Li, 3.6% Cu, 1.0% Mg, 0.9% Zn, 0.5% Ag, 0.1% Zr, 0.1% Sc, 0.12% Er, and 0.1% Yb, with the balance being Al and impurities, wherein the total amount of impurities is not greater than 0.1%, and the total amount is 100%.

[0058] The preparation process is as follows: S1. Raw Material Preparation and Smelting: Prepare raw materials according to the formula, and put high-purity aluminum ingots, high-purity electrolytic copper, Al-Mg, Al-Zn, Al-Ag, Al-Zr, Al-Sc, Al-Er, and Al-Yb master alloy ingots into the crucible of the smelting furnace and evacuate to 10°C. -2Pa, then high-purity argon gas is introduced as a protective atmosphere, heated to complete melting and superheated to 765°C, cooled to 710°C and then lithium foil is added and stirred thoroughly.

[0059] S2. Melt treatment and casting: Under a protective atmosphere, high-purity argon gas is introduced by rotary jetting to remove hydrogen and inclusions from the melt. After the metal is completely melted, it is refined, slag removed, and cast into shape to obtain aluminum alloy ingots.

[0060] S3. Homogenization and Hot Working: The ingot is subjected to multi-stage homogenization in an air-circulating furnace. The homogenized ingot is then heated to 460°C and extruded to obtain the profile.

[0061] S4. Solution treatment and quenching: The profile is heated to 535°C in an air-circulating furnace and held at that temperature. Then it is quickly transferred to a room temperature water bath for rapid quenching. Immediately after quenching, the profile is subjected to 2% tensile or compression leveling. Then it undergoes first-stage aging and second-stage aging treatments. Finally, it is air-cooled to room temperature. The first-stage aging treatment temperature is 115°C and the treatment time is 9 hours. The second-stage aging treatment temperature is 160°C and the treatment time is 30 hours.

[0062] S5. Surface treatment: S51. Preparation of the treatment solution: Using water as a solvent, dissolve cerium nitrate, sodium molybdate, and ammonium bifluoride in sequence, with the concentration of cerium nitrate being 8 g / L, sodium molybdate being 3 g / L, and ammonium bifluoride being 1 g / L. Each reagent added should be stirred thoroughly until completely dissolved. Finally, under continuous stirring, slowly add 30% hydrogen peroxide with a concentration of 2 mL / L. Finally, use ammonia water to precisely adjust the pH value to 2.5-3.5.

[0063] S52. Surface treatment: Activate with sodium citrate at 45°C for 4 minutes, then immerse in a treatment solution with pH 2.5-3.5 at room temperature for 8 minutes, and finally immerse in water at 60-80°C for 4 minutes. After treatment, dry to obtain the aluminum alloy material.

[0064] Comparative Example 1: This comparative example provides a comparative aluminum alloy material comprising 2.5% Li, 3.6% Cu, 1.0% Mg, 0.9% Zn, 0.5% Ag, with the balance being Al and impurities, wherein the total amount of impurities is no more than 0.1%, and the total amount is 100%.

[0065] The preparation process is the same as in Example 5.

[0066] By varying the amount of transition elements used in the combinations, comparative examples 2-8 were set up, while the remaining raw materials and preparation processes remained the same as in Example 5. The specific combination amounts are shown in Table 1.

[0067] Table 1 The mechanical properties, corrosion resistance, and fracture toughness of the aluminum alloy materials prepared in Examples 1-5 and the comparative aluminum alloy materials obtained in Comparative Examples 1-10 were tested. The test results are shown in Table 2. Wherein: (1) Mechanical properties: Tensile strength, yield strength and elongation are tested using a tensile testing machine. The common standard is ASTM E8 / E8M.

[0068] (2) Corrosion resistance: The corrosion of each alloy sample was tested under a 72-hour salt spray environment using a salt spray test (ASTM B117 standard). The corrosion resistance was quantified by evaluating the area and depth of surface corrosion.

[0069] (3) Fracture toughness: The crack propagation resistance of aluminum alloy materials was tested using the ASTM E399 standard.

[0070] Table 2 The data from Examples 1-3, especially Example 3, show that by using a reasonable ratio of aluminum alloy material components in this application, the resulting aluminum alloy material exhibits superior performance in tensile strength, yield strength, elongation, corrosion resistance, and fracture toughness.

[0071] Compared with Example 3, Example 4 added Yb. The aluminum alloy material obtained in Example 4 showed better performance than the aluminum alloy material obtained in Example 3. This is because Yb can form Al3Yb in Al. The atomic radius of Yb is much different from that of Sc. The addition of Yb can cause strong lattice distortion, which further delays diffusion and phase coarsening.

[0072] Compared to Example 3, Example 5 differs in its surface treatment method and the treatment solution used. The aluminum alloy material obtained in Example 4 exhibits superior performance compared to that obtained in Example 3. This is because sodium citrate, as a weakly alkaline degreasing agent, removes surface oil in the surface treatment process of this application. Its weakly alkaline properties slightly corrode the surface, making lithium elements easier to dissolve, while preventing metal ions from precipitating on the surface and forming a ash residue. Utilizing the alloy's own lithium element as an inducer, it is immersed in a mild treatment solution to grow an amorphous composite conversion film rich in rare earth and molybdenum elements in situ on the alloy surface, thereby achieving protective performance. Sealing with warm water further hydrates unreacted components in the conversion film, making the film structure denser and more stable, and removing residual soluble salts. Cerium nitrate in the treatment solution of this application provides Ce. 3+Ions, under the high pH environment of the micro-region, form Ce(OH)4 precipitate, constituting the main framework of the conversion membrane and endowing the membrane with basic corrosion resistance and self-healing potential. Sodium molybdate provides MoO4. 2- Ions form molybdenum oxides or hydroxides, which intertwine with cerium compounds, filling the gaps in the film layer, making the film denser and further improving corrosion resistance. Hydrogen peroxide can gently oxidize the Al matrix, promoting metal dissolution. Ce... 3+ Oxidized to Ce 4+ This promotes the formation of the more stable and protective Ce(OH)4. Ammonium bifluoride provides F. - Ions can slightly etch the natural oxide film on the surface of aluminum alloys, ensuring contact between the solution and the metal, inducing uniform film formation, and helping to stabilize the pH of the solution.

[0073] Compared to Example 5, Comparative Example 1 lacked the transition elements Zr, Sc, Er, and Yb, resulting in a comparative aluminum alloy material with inferior properties compared to the aluminum alloy material obtained in Example 5. Comparative Examples 2-4, compared to Example 5, lacked the transition elements Zr, Sc, and Er, respectively, resulting in comparative aluminum alloy materials with varying degrees of performance degradation compared to the aluminum alloy material obtained in Example 5. Comparative Examples 5-9, compared to Example 5, lacked two or three of the transition elements Zr, Sc, Er, and Yb, respectively, resulting in comparative aluminum alloy materials with varying degrees of performance degradation compared to the aluminum alloy material obtained in Example 5. This is because Zr can form Al3Zr in Al, effectively suppressing recrystallization during hot working and heat treatment, maintaining an unrecrystallized fibrous structure in the alloy, thereby improving strength and fatigue resistance. Sc can form Al3Sc in Al, refining the as-cast grains. Al3Sc effectively pins dislocations and grain boundaries, suppressing recrystallization, maintaining an unrecrystallized structure even at high Sc contents, and significantly increasing the recrystallization temperature. When Sc and Zr are added together, they form an Al3(Sc, Zr) composite phase. Zr atoms occupy sublattice sites of Sc, and this composite exhibits higher thermal stability, stronger resistance to coarsening, and longer-lasting effects compared to Al3Sc or Al3Zr alone. Er can form Al3Er in Al, and when added together with Sc and Zr, they form a more complex Al3(Sc, Zr, Er) composite nano-dispersed phase. Er functions similarly to Sc, acting as an effective grain refiner and recrystallization inhibitor. By adding Er, the effect of higher Sc content can be achieved with relatively lower Sc content, thus reducing costs.

[0074] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. An aluminum alloy material and its preparation process, characterized in that, The aluminum alloy material comprises, by mass percentage, 2.2-2.8% Li, 3.0-3.8% Cu, 0.6-1.2% Mg, 0.5-1.2% Zn, 0.08-0.12% Zr, 0.3-0.6% Ag, 0.08-0.15% Sc, and 0.1-0.3% Er, with the balance being Al and impurities, wherein the total mass of the impurities is not greater than 0.1%.

2. The aluminum alloy material and its preparation process according to claim 1, characterized in that, The aluminum alloy material also includes Yb with a mass fraction of 0.05-0.15%.

3. A preparation process using the aluminum alloy material and its preparation process as described in any one of claims 1-2, characterized in that, The preparation process includes the following steps: Raw material preparation and smelting: Prepare the raw materials according to the formula, and put all raw materials except Li into the crucible of the smelting furnace and evacuate to 10°C. -2 -10 -3 Pa, then high-purity argon gas is introduced as a protective atmosphere, heated until completely melted and superheated to 750-780℃, cooled to 700-720℃ and then lithium foil is added and stirred thoroughly; Melt treatment and casting: Under a protective atmosphere, high-purity argon gas is introduced by rotary jetting to remove hydrogen and inclusions from the melt. After the metal is completely melted, it is successively refined, slag removed, and cast into shape to obtain aluminum alloy ingots. Homogenization and hot working: The ingot is subjected to multi-stage homogenization in an air-circulating furnace, and the homogenized ingot is heated to 450-470℃ and extruded to obtain profiles; Solution treatment and quenching: The profile is heated to 530-540℃ in an air-circulating furnace, held at that temperature, and then quickly transferred to a room temperature water bath for rapid quenching. Then, surface treatment is performed to obtain the aluminum alloy material.

4. The aluminum alloy material and its preparation process according to claim 3, characterized in that, The solution treatment and quenching steps also include immediately performing 1.5-3% tensile or compression leveling on the profile after quenching, followed by primary aging and secondary aging treatments, and finally air cooling to room temperature; the primary aging treatment temperature is 110-120℃ and the treatment time is 6-12h, and the secondary aging treatment temperature is 155-165℃ and the treatment time is 24-36h.

5. The aluminum alloy material and its preparation process according to claim 4, characterized in that, The surface treatment steps are as follows: activate with sodium citrate at 40-50℃ for 3-5 minutes, then immerse in a treatment solution with pH 2.5-3.5 at room temperature for 5-10 minutes, and finally immerse in water at 60-80℃ for 3-5 minutes.

6. The aluminum alloy material and its preparation process according to claim 5, characterized in that, The treatment solution comprises 5-10 g / L cerium nitrate, 2-5 g / L sodium molybdate, 1-3 mL / L 30% hydrogen peroxide, 0.5-2 g / L ammonium bifluoride, and the balance being water.

7. The aluminum alloy material and its preparation process according to claim 6, characterized in that, The preparation steps of the treatment solution are as follows: using water as a solvent, cerium nitrate, sodium molybdate, and ammonium bifluoride are dissolved in sequence. Each reagent must be stirred thoroughly until completely dissolved. Finally, hydrogen peroxide is slowly added dropwise while continuously stirring. Finally, the pH value is precisely adjusted to 2.5-3.5 with ammonia.

8. An application of an aluminum alloy material in the fields of aerospace, machinery manufacturing, medical devices, and sports equipment, characterized in that, The aluminum alloy material is prepared using the aluminum alloy material as described in any one of claims 1-2, or the aluminum alloy material prepared using the preparation process described in any one of claims 3-7.

Images