High-toughness aluminum alloy and preparation method thereof

Abstract

The invention discloses a high-toughness aluminum alloy and a preparation method thereof, and relates to the technical field of metal materials. When the high-toughness aluminum alloy is prepared, Zn, Mg, Cu, an Al-2Sc intermediate alloy, an Al-5Zr intermediate alloy, Ti, Mn and Y are proportionally added into an aluminum matrix for ingot casting, and precipitation of a strengthening phase, refinement of crystal grains and mechanical properties of the alloy are finely regulated and controlled through homogenizing annealing, hot working, solid solution heat treatment and artificial aging treatment processes; and the treated aluminum alloy is placed in a micro-arc oxidation electrolyte, a ceramic oxidation layer is formed on the surface of the aluminum alloy through the micro-arc oxidation technology in a constant-current mode, and the high-toughness aluminum alloy is prepared. The prepared high-toughness aluminum alloy has excellent mechanical properties including high strength, high toughness and hardness, the surface performance of the high-toughness aluminum alloy is enhanced through the micro-arc oxidation layer, and the high-toughness aluminum alloy is endowed with excellent corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of metal materials, in particular to a high-toughness material and a preparation method thereof. Background Art

[0002] High-strength aluminum alloys are an important type of lightweight structural material with excellent specific strength and processing properties at room temperature. As a traditional structural material, aluminum alloys are widely used in aerospace, transportation and other high-end equipment fields. With their light weight, high strength and excellent forming properties, they play an irreplaceable role in energy conservation, emission reduction and improving energy efficiency. In particular, 7xxx series aluminum alloys have become one of the important basic materials in the aerospace field due to their high strength and good processability, and are widely used in the manufacture of key components such as aircraft fuselages and wings. However, conventional high-strength aluminum alloys still have problems such as insufficient toughness, prone to brittle fracture, and poor corrosion resistance, especially in humid and corrosive environments. They are susceptible to corrosion, resulting in a decrease in material performance and a shortened service life.

[0003] In recent years, with the acceleration of the lightweight process of high-end equipment and the improvement of environmental protection requirements, application scenarios such as aviation structural parts have put forward higher requirements on the fracture toughness, environmental durability and sustainability of the material preparation process. Therefore, the existing aluminum alloy technology urgently needs to be optimized and upgraded to meet increasingly stringent performance standards and environmental protection requirements. In order to take into account ultra-high strength and high toughness and break through the bottleneck of material performance, it is necessary to develop new micro-alloying design, green surface treatment and multi-stage aging synergistic strengthening and toughening high-performance aluminum alloy preparation technology. This can not only effectively solve the problems of insufficient toughness and poor corrosion resistance of aluminum alloys, but also significantly improve the comprehensive performance of materials, and promote the sustainable development of aerospace, transportation and other fields. Summary of the Invention

[0004] The object of the present invention is to provide a high-toughness aluminum alloy and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A high-toughness aluminum alloy is prepared by using an aluminum alloy of a specific component as a matrix, sequentially undergoing melting and casting, step heat treatment, hot extrusion, multi-stage aging and deep cold cycle treatment, and finally in-situ generation of a ceramic oxide layer through a micro-arc oxidation electrolyte.

[0006] As an optimization, the specific components are as follows: 7.0~7.5% Zn, 2.2~2.5% Mg, 1.8~2.0% Cu, 0.08~0.12% Al-2Sc master alloy, 0.05~0.25% Al-5Zr master alloy, 0.08~0.12% Ti, 0.05~0.1% Mn, 0.05~0.15% Y, and the balance is high-purity aluminum ingot.

[0007] As an optimization, the micro-arc oxidation electrolyte is prepared by dispersing graphene oxide in a mixed solution of sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water.

[0008] A method for preparing a high-toughness aluminum alloy comprises the following steps: (1) Weigh the raw materials according to the following mass percentages: 7.0~7.5% Zn, 2.2~2.5% Mg, 1.8~2.0% Cu, 0.08~0.12% Al-2Sc master alloy, 0.05~0.25% Al-5Zr master alloy, 0.08~0.12% Ti, 0.05~0.1% Mn, 0.05~0.15% Y, and the balance is high-purity aluminum ingot; place the high-purity aluminum ingot in a furnace in an argon atmosphere and heat it to 740~7 60℃, stir at 200-400r / min for 10-20min, add Zn, Cu and Mg, and stir at 200-400r / min for 10-20min; heat to 770-790℃, add Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, and stir at 200-400r / min for 10-20min; refine, degas and remove slag, and pour the melt into a metal mold preheated to 180-220℃ for ingot casting; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 380-420°C, keep it warm for 1.5-2.5 hours, then heat it to 450-490°C, keep it warm for 8-12 hours, and air cool it; (3) Heating to 420~450℃, constant temperature for 0.5~1.5h, continuous hot extrusion, and air cooling; (4) Heat the ingot to 460-480°C in an argon atmosphere, heat treat for 2-3 hours, and quench in running water at room temperature; heat to 100-140°C, keep warm for 6-10 hours, air cool and heat to 140-160°C, keep warm for 12-24 hours, air cool and heat to 80-100°C, keep warm for 10-14 hours; cool in liquid nitrogen for 5-15 minutes, return to room temperature and keep for 10 minutes, repeat 2-4 cycles, and dry naturally; (5) The naturally dried aluminum alloy is subjected to pretreatment by degreasing, pickling, water washing and drying; sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water are mixed uniformly in a mass ratio of 1:(0.3~0.7):(0.5~0.7):(0.1~0.15):(70~80), stirred at 40~50°C and 200~400r / min for 30~60min, graphene oxide with a mass of 0.2~0.4 times the amount of sodium silicate added is added, treated at an ultrasonic power of 200~500W for 20~40min, allowed to stand for 20~28h, filtered, and a micro-arc oxidation electrolyte is prepared; the pre-treated aluminum alloy is placed in a micro-arc oxidation electrolyte at 20~35°C, a DC constant current mode is used, the final voltage is controlled at 400~500V, and the treatment is carried out for 20~40min to generate a ceramic oxide layer with a thickness of 20~50μm, thereby obtaining a high-toughness aluminum alloy.

[0009] As an optimization, the refining, degassing and slag removal method in step (1) is as follows: introduce high-purity argon gas for rotary degassing for 10 to 20 minutes, add a sodium-free environmentally friendly refining agent with a mass of 1.5 to 3 times the amount of high-purity aluminum ingot, stir at 200 to 400 r / min for 30 to 60 minutes, and remove the surface slag for 5 to 10 minutes.

[0010] As an optimization, the hot extrusion in step (3) has an extrusion ratio of 10-16:1 and an extrusion speed of 8-12 m / min.

[0011] As an optimization, the graphene oxide in step (5) has a purity of >95%, and the manufacturer is Shanghai Aladdin Biochemical Technology Co., Ltd.

[0012] As an optimization, the pretreatment method of step (5) is as follows: sodium hydroxide, trisodium phosphate and deionized water are mixed uniformly in a mass ratio of 1: (0.5-0.7): (15-25), stirred at 200-400 r / min for 10-20 min, and allowed to stand for 1-3 h to prepare an alkaline degreasing solution; the dried aluminum alloy is placed in the alkaline degreasing solution and treated at 60-70°C and an ultrasonic power of 200-500 W for 5-10 min; 65 % nitric acid, ammonium bifluoride, benzotriazole, and deionized water are uniformly mixed in a mass ratio of 1:(0.15-0.2):(0.001-0.003):(2-4), and stirred at 200-400 r / min for 10-20 min to prepare a pickling solution; the degreased aluminum alloy is placed in the pickling solution, stirred at 25-30°C and 50-150 r / min for 30-60 s; rinsed with running tap water for 1-2 min, and dried.

[0013] Compared with the prior art, the present invention has the following beneficial effects: When preparing a high-toughness aluminum alloy, the present invention adds Zn, Mg, Cu, Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y into an aluminum matrix in proportion to form an ingot. Through homogenization annealing, thermal processing, solution heat treatment and artificial aging treatment processes, the precipitation of strengthening phases, grain refinement and mechanical properties of the alloy are finely controlled. The treated aluminum alloy is placed in a micro-arc oxidation electrolyte, and a ceramic oxide layer is formed on the surface of the aluminum alloy through the micro-arc oxidation technology in a constant current mode to obtain the high-toughness aluminum alloy.

[0014] Firstly, a two-stage homogenization treatment combined with a four-stage aging process is used to construct a "nanocrystalline grain-amorphous interface" bionic brick-mud structure in the matrix. By precisely controlling the homogenization and multi-stage aging process, a nanocrystalline strengthening phase is generated, in which the β'' (Mg2Zn) precipitation phase is dispersed. A liquid nitrogen deep cooling cycle is used to induce the formation of a continuous amorphous phase network at the grain boundaries. In this structure, the nanocrystalline phase provides basic strength through fine grain strengthening and precipitation strengthening. The amorphous phase, with its high elastic limit and multiple shear band deformation capabilities, forces the crack propagation path to be tortuous, dissipating the fracture energy. The two realize efficient stress transfer through the strong bonding interface purified by Sc / Y microalloying, causing passivation, deflection and branching when the crack propagates to the amorphous phase, significantly improving the toughness of the aluminum alloy.

[0015] Secondly, graphene oxide is introduced into the silicate-aluminate electrolyte, and a stable suspension system is constructed through ultrasonic dispersion. Under high-voltage discharge of 400~500V, graphene oxide is driven by electrophoresis to embed into the growing alumina ceramic layer, forming an alternating structure of alumina skeleton and graphene sheets. Its edge carboxyl groups are covalently bonded to alumina through Al-OC bonds, thereby improving the interfacial bonding strength. The graphene sheets block the propagation of microcracks and improve the toughness of the ceramic layer. Finally, through the full-process coordination of Sc / Zr / Y microalloying to inhibit dynamic recrystallization, refining and degassing, and pickling process optimization, the integration of strengthening, toughness, corrosion resistance and functionality is simultaneously achieved within the thickness of the ceramic layer, so that the aluminum alloy can significantly improve its toughness and corrosion resistance while maintaining the strength increase, providing a revolutionary material solution for aerospace precision components. DETAILED DESCRIPTION

[0016] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0017] In order to more clearly illustrate the method provided by the present invention, it is now described in detail through the following examples.

[0018] Example 1: A method for preparing a high-toughness aluminum alloy mainly includes the following preparation steps: (1) Weigh the raw materials according to the following mass percentages: 7.0% Zn, 2.2% Mg, 1.8% Cu, 0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy, 0.1% Ti, 0.07% Mn, 0.1% Y, and the balance is high-purity aluminum ingot; in an argon atmosphere, place the high-purity aluminum ingot in a furnace and heat it to 740°C, stir it at 200 r / min for 10 min, add Zn, Cu, Mg, and stir it at 200 r / min. in stirring for 10 minutes; heating to 770°C, adding Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, stirring at 200r / min for 10 minutes; passing high-purity argon gas for rotary degassing for 10 minutes, adding sodium-free environmentally friendly refining agent with a mass 1.5 times that of high-purity aluminum ingot, stirring at 200r / min for 30 minutes, and scraping off surface scum for 5 minutes; pouring the melt into a metal mold preheated to 180°C for ingot casting; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 380°C, keep it warm for 1.5 hours, then heat it to 450°C, keep it warm for 8 hours, and air cool it; (3) Heating to 420 °C, constant temperature for 0.5 h, continuous hot extrusion, extrusion ratio of 10:1, extrusion speed of 8 m / min, and air cooling; (4) Heat the ingot to 460°C in an argon atmosphere, heat treat for 2 hours, and quench in running water at room temperature; heat to 100°C, keep warm for 6 hours, air cool and heat to 140°C, keep warm for 12 hours, air cool and heat to 80°C, keep warm for 10 hours; cool in liquid nitrogen for 5 minutes, return to room temperature and keep for 10 minutes, repeat 2 cycles, and dry naturally; (5) Sodium hydroxide, trisodium phosphate and deionized water were mixed in a mass ratio of 1:0.5:15, stirred at 200 r / min for 10 min, and allowed to stand for 1 h to prepare an alkaline degreasing solution; the dried aluminum alloy was placed in the alkaline degreasing solution and treated at 60°C and an ultrasonic power of 200 W for 5 min; 65% nitric acid, ammonium bifluoride, benzotriazole and deionized water were mixed in a mass ratio of 1:0.15:0.001:2, and stirred at 200 r / min for 10 min to prepare an acid pickling solution; the degreased aluminum alloy was placed in the acid pickling solution and stirred at 25°C and 50 r / min for 30 s; and rinsed with running tap water. 1min, dried; sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water were mixed in a mass ratio of 1:0.3:0.5:0.1:70, stirred at 40°C and 200r / min for 30min, graphene oxide with a mass 0.3 times that of the sodium silicate addition was added, treated under an ultrasonic power of 200W for 20min, allowed to stand for 20h, and filtered to obtain a micro-arc oxidation electrolyte; at 20°C, the pre-treated aluminum alloy was placed in the micro-arc oxidation electrolyte, a DC constant current mode was adopted, the final voltage was controlled at 400V, and the treatment was carried out for 20min to generate a ceramic oxide layer with a thickness of 20μm, thereby obtaining a high-toughness aluminum alloy.

[0019] Example 2: A method for preparing a high-toughness aluminum alloy mainly includes the following preparation steps: (1) Weigh the raw materials according to the following mass percentages: 7.3% Zn, 2.3% Mg, 1.9% Cu, 0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy, 0.1% Ti, 0.07% Mn, 0.1% Y, and the balance is high-purity aluminum ingot; in an argon atmosphere, place the high-purity aluminum ingot in a furnace and heat it to 750°C, stir it at 300 r / min for 15 min, add Zn, Cu, Mg, and 300 r / min, and stir it for 15 min. min and stir for 15 minutes; heat to 780℃, add Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, and stir at 300r / min for 15 minutes; introduce high-purity argon gas for rotary degassing for 15 minutes, add sodium-free environmentally friendly refining agent with a mass twice that of high-purity aluminum ingot, stir at 300r / min for 45 minutes, and remove surface scum for 7 minutes; pour the melt into a metal mold preheated to 200℃ and cast an ingot; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 400°C, keep it for 2 hours, then heat it to 470°C, keep it for 10 hours, and air cool it; (3) Heating to 435 °C, constant temperature for 1 h, continuous hot extrusion, extrusion ratio of 13:1, extrusion speed of 10 m / min, and air cooling; (4) Heat the ingot to 470 ° C in an argon atmosphere, heat treat for 2.5 hours, quench in running water at room temperature; heat to 120 ° C, keep warm for 8 hours, air cool and heat to 150 ° C, keep warm for 18 hours, air cool and heat to 90 ° C, keep warm for 12 hours; place in liquid nitrogen to cool for 10 minutes, return to room temperature and keep for 15 minutes, repeat 3 cycles, and dry naturally; (5) Sodium hydroxide, trisodium phosphate and deionized water were mixed in a mass ratio of 1:0.6:20, stirred at 300 r / min for 15 min, and allowed to stand for 2 h to prepare an alkaline degreasing solution; the dried aluminum alloy was placed in the alkaline degreasing solution and treated at 65 ° C and an ultrasonic power of 350 W for 7 min; 65% nitric acid, ammonium bifluoride, benzotriazole and deionized water were mixed in a mass ratio of 1:0.17:0.002:3, and stirred at 300 r / min for 15 min to prepare an acid pickling solution; the degreased aluminum alloy was placed in the acid pickling solution and stirred at 27 ° C and 100 r / min for 45 s; the aluminum alloy was rinsed with running tap water for 1 .5min, and dried; sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water were evenly mixed in a mass ratio of 1:0.5:0.6:0.12:75, stirred at 45°C and 300r / min for 45min, graphene oxide with a mass 0.3 times that of the sodium silicate addition was added, and treated under an ultrasonic power of 350W for 30min. The mixture was allowed to stand for 24h and filtered to obtain a micro-arc oxidation electrolyte; at 30°C, the pre-treated aluminum alloy was placed in the micro-arc oxidation electrolyte, and a DC constant current mode was adopted with the final voltage controlled at 450V. The mixture was treated for 30min to generate a ceramic oxide layer with a thickness of 35μm, thereby obtaining a high-toughness aluminum alloy.

[0020] Example 3: A method for preparing a high-toughness aluminum alloy mainly includes the following preparation steps: (1) Weigh the raw materials according to the following mass percentages: 7.5% Zn, 2.5% Mg, 2.0% Cu, 0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy, 0.1% Ti, 0.07% Mn, 0.1% Y, and the balance is high-purity aluminum ingot; in an argon atmosphere, place the high-purity aluminum ingot in a furnace and heat it to 760°C, stir it at 400 r / min for 20 min, add Zn, Cu, Mg, and stir it at 400 r / min. in stirring for 20 minutes; heating to 790°C, adding Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, stirring at 400r / min for 20 minutes; passing high-purity argon gas for rotary degassing for 20 minutes, adding sodium-free environmentally friendly refining agent with a mass three times that of high-purity aluminum ingot, stirring at 400r / min for 60 minutes, and scraping off surface scum for 10 minutes; pouring the melt into a metal mold preheated to 220°C for ingot casting; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 420°C, keep it warm for 2.5 hours, then heat it to 490°C, keep it warm for 12 hours, and air cool it; (3) Heating to 450 °C, constant temperature for 1.5 h, continuous hot extrusion, extrusion ratio of 16:1, extrusion speed of 12 m / min, and air cooling; (4) Heat the ingot to 480 ° C in an argon atmosphere, heat treat for 3 hours, quench in running water at room temperature; heat to 140 ° C, keep warm for 10 hours, air cool and heat to 160 ° C, keep warm for 24 hours, air cool and heat to 100 ° C, keep warm for 14 hours; place in liquid nitrogen to cool for 15 minutes, return to room temperature and keep for 20 minutes, repeat 4 cycles, and dry naturally; (5) Sodium hydroxide, trisodium phosphate and deionized water were mixed in a mass ratio of 1:0.7:25, stirred at 400 r / min for 20 min, and allowed to stand for 3 h to prepare an alkaline degreasing solution; the dried aluminum alloy was placed in the alkaline degreasing solution and treated at 70°C and an ultrasonic power of 500 W for 10 min; 65% nitric acid, ammonium bifluoride, benzotriazole and deionized water were mixed in a mass ratio of 1:0.2:0.003:4, stirred at 400 r / min for 20 min to prepare an acid pickling solution; the degreased aluminum alloy was placed in the acid pickling solution and stirred at 30°C and 150 r / min for 60 s; and rinsed with running tap water. 2min, and dried; sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water were mixed in a mass ratio of 1:0.7:0.7:0.15:80, stirred at 50°C and 400r / min for 60min, graphene oxide with a mass 0.3 times that of the sodium silicate addition was added, and treated under an ultrasonic power of 500W for 40min. The mixture was allowed to stand for 28h and filtered to obtain a micro-arc oxidation electrolyte; at 35°C, the pre-treated aluminum alloy was placed in the micro-arc oxidation electrolyte, and a DC constant current mode was adopted with the final voltage controlled at 500V. The mixture was treated for 40min to generate a ceramic oxide layer with a thickness of 50μm, thereby obtaining a high-toughness aluminum alloy.

[0021] Comparative Example 1: The only difference from Example 2 is that in step (1), “0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy” is adjusted to “0.08% Al-2Sc master alloy, 0.05% Al-5Zr master alloy”.

[0022] Comparative Example 2: The only difference from Example 2 is that in step (1), “0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy” is adjusted to “0.12% Al-2Sc master alloy, 0.25% Al-5Zr master alloy”.

[0023] Comparative Example 3: The only difference from Example 2 is that in step (1), “0.1% Ti” is adjusted to “0.08% Ti”.

[0024] Comparative Example 4: The only difference from Example 2 is that in step (1), “0.1% Ti” is adjusted to “0.12% Ti”.

[0025] Comparative Example 5: The only difference from Example 2 is that in step (1), “0.07% Mn, 0.1% Y” is adjusted to “0.05% Mn, 0.05% Y”.

[0026] Comparative Example 6: The only difference from Example 2 is that in step (1), “0.07% Mn, 0.1% Y” is adjusted to “0.1% Mn, 0.15% Y”.

[0027] Comparative Example 7: The only difference from Example 2 is that in step (5), "the amount of graphene oxide added is 0.3 times the amount of sodium silicate added" is adjusted to "the amount of graphene oxide added is 0.2 times the amount of sodium silicate added".

[0028] Comparative Example 8: The only difference from Example 2 is that in step (5), "the amount of graphene oxide added is 0.3 times the amount of sodium silicate added" is adjusted to "the amount of graphene oxide added is 0.4 times the amount of sodium silicate added".

[0029] Comparative Example 9: A method for preparing a high-toughness aluminum alloy mainly includes the following preparation steps: (1) Weigh the raw materials according to the following mass percentages: 7.3% Zn, 2.3% Mg, 1.9% Cu, 0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy, 0.1% Ti, 0.07% Mn, 0.1% Y, and the balance is high-purity aluminum ingot; in an argon atmosphere, place the high-purity aluminum ingot in a furnace and heat it to 750°C, stir it at 300 r / min for 15 min, add Zn, Cu, Mg, and 300 r / min, and stir it for 15 min. min and stir for 15 minutes; heat to 780℃, add Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, and stir at 300r / min for 15 minutes; introduce high-purity argon gas for rotary degassing for 15 minutes, add sodium-free environmentally friendly refining agent with a mass twice that of high-purity aluminum ingot, stir at 300r / min for 45 minutes, and remove surface scum for 7 minutes; pour the melt into a metal mold preheated to 200℃ and cast an ingot; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 470°C, keep it warm for 10 hours, and then air cool it; (3) Heating to 435 °C, constant temperature for 1 h, continuous hot extrusion, extrusion ratio of 13:1, extrusion speed of 10 m / min, and air cooling; (4) Heat the ingot to 470°C in an argon atmosphere, heat treat for 2.5 hours, quench in running water at room temperature; heat to 90°C and keep warm for 12 hours; cool in liquid nitrogen for 10 minutes, return to room temperature and keep for 15 minutes, repeat 3 cycles, and dry naturally; (5) Sodium hydroxide, trisodium phosphate and deionized water were mixed in a mass ratio of 1:0.6:20, stirred at 300 r / min for 15 min, and allowed to stand for 2 h to prepare an alkaline degreasing solution; the dried aluminum alloy was placed in the alkaline degreasing solution and treated at 65 ° C and an ultrasonic power of 350 W for 7 min; 65% nitric acid, ammonium bifluoride, benzotriazole and deionized water were mixed in a mass ratio of 1:0.17:0.002:3, and stirred at 300 r / min for 15 min to prepare an acid pickling solution; the degreased aluminum alloy was placed in the acid pickling solution and stirred at 27 ° C and 100 r / min for 45 s; the aluminum alloy was rinsed with running tap water for 1 .5min, and dried; sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water were evenly mixed in a mass ratio of 1:0.5:0.6:0.12:75, stirred at 45°C and 300r / min for 45min, graphene oxide with a mass 0.3 times that of the sodium silicate addition was added, and treated under an ultrasonic power of 350W for 30min. The mixture was allowed to stand for 24h and filtered to obtain a micro-arc oxidation electrolyte; at 30°C, the pre-treated aluminum alloy was placed in the micro-arc oxidation electrolyte, and a DC constant current mode was adopted with the final voltage controlled at 450V. The mixture was treated for 30min to generate a ceramic oxide layer with a thickness of 35μm, thereby obtaining a high-toughness aluminum alloy.

[0030] Comparative Example 10: A method for preparing a high-toughness aluminum alloy mainly includes the following preparation steps: (1) Weigh the raw materials according to the following mass percentages: 7.3% Zn, 2.3% Mg, 1.9% Cu, 0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy, 0.1% Ti, 0.07% Mn, 0.1% Y, and the balance is high-purity aluminum ingot; in an argon atmosphere, place the high-purity aluminum ingot in a furnace and heat it to 750°C, stir it at 300 r / min for 15 min, add Zn, Cu, Mg, and 300 r / min, and stir it for 15 min. min and stir for 15 minutes; heat to 780℃, add Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, and stir at 300r / min for 15 minutes; introduce high-purity argon gas for rotary degassing for 15 minutes, add sodium-free environmentally friendly refining agent with a mass twice that of high-purity aluminum ingot, stir at 300r / min for 45 minutes, and remove surface scum for 7 minutes; pour the melt into a metal mold preheated to 200℃ and cast an ingot; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 400°C, keep it for 2 hours, then heat it to 470°C, keep it for 10 hours, and air cool it; (3) Heating to 435 °C, constant temperature for 1 h, continuous hot extrusion, extrusion ratio of 13:1, extrusion speed of 10 m / min, and air cooling; (4) Heating the ingot to 470°C in an argon atmosphere, heat treatment for 2.5 hours, quenching in running water at room temperature; heating to 120°C, holding for 8 hours, air cooling, heating to 150°C, holding for 18 hours, air cooling, heating to 90°C, and air cooling; (5) Sodium hydroxide, trisodium phosphate and deionized water were mixed in a mass ratio of 1:0.6:20, stirred at 300 r / min for 15 min, and allowed to stand for 2 h to prepare an alkaline degreasing solution; the dried aluminum alloy was placed in the alkaline degreasing solution and treated at 65 ° C and an ultrasonic power of 350 W for 7 min; 65% nitric acid, ammonium bifluoride, benzotriazole and deionized water were mixed in a mass ratio of 1:0.17:0.002:3, and stirred at 300 r / min for 15 min to prepare an acid pickling solution; the degreased aluminum alloy was placed in the acid pickling solution and stirred at 27 ° C and 100 r / min for 45 s; the aluminum alloy was rinsed with running tap water for 1 .5min, and dried; sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water were evenly mixed in a mass ratio of 1:0.5:0.6:0.12:75, stirred at 45°C and 300r / min for 45min, graphene oxide with a mass 0.3 times that of the sodium silicate addition was added, and treated under an ultrasonic power of 350W for 30min. The mixture was allowed to stand for 24h and filtered to obtain a micro-arc oxidation electrolyte; at 30°C, the pre-treated aluminum alloy was placed in the micro-arc oxidation electrolyte, and a DC constant current mode was adopted with the final voltage controlled at 450V. The mixture was treated for 30min to generate a ceramic oxide layer with a thickness of 35μm, thereby obtaining a high-toughness aluminum alloy.

[0031] Comparative Example 11: A method for preparing a high-toughness aluminum alloy mainly includes the following preparation steps: (1) Weigh the raw materials according to the following mass percentages: 7.3% Zn, 2.3% Mg, 1.9% Cu, 0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy, 0.1% Ti, 0.07% Mn, 0.1% Y, and the balance is high-purity aluminum ingot; in an argon atmosphere, place the high-purity aluminum ingot in a furnace and heat it to 750°C, stir it at 300 r / min for 15 min, add Zn, Cu, Mg, and 300 r / min, and stir it for 15 min. min and stir for 15 minutes; heat to 780℃, add Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, and stir at 300r / min for 15 minutes; introduce high-purity argon gas for rotary degassing for 15 minutes, add sodium-free environmentally friendly refining agent with a mass twice that of high-purity aluminum ingot, stir at 300r / min for 45 minutes, and remove surface scum for 7 minutes; pour the melt into a metal mold preheated to 200℃ and cast an ingot; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 400°C, keep it for 2 hours, then heat it to 470°C, keep it for 10 hours, and air cool it; (3) Heating to 435 °C, constant temperature for 1 h, continuous hot extrusion, extrusion ratio of 13:1, extrusion speed of 10 m / min, and air cooling; (4) Heat the ingot to 470 ° C in an argon atmosphere, heat treat for 2.5 hours, quench in running water at room temperature; heat to 120 ° C, keep warm for 8 hours, air cool and heat to 150 ° C, keep warm for 18 hours, air cool and heat to 90 ° C, keep warm for 12 hours; place in liquid nitrogen to cool for 10 minutes, return to room temperature and keep for 15 minutes, repeat 3 cycles, and dry naturally; (5) Sodium hydroxide, trisodium phosphate and deionized water were mixed in a mass ratio of 1:0.6:20, stirred at 300 r / min for 15 min, and allowed to stand for 2 h to prepare an alkaline degreasing solution; the dried aluminum alloy was placed in the alkaline degreasing solution and treated at 65 ° C and an ultrasonic power of 350 W for 7 min; 65% nitric acid, ammonium bifluoride, benzotriazole and deionized water were mixed in a mass ratio of 1:0.17:0.002:3, stirred at 300 r / min for 15 min to prepare an acid pickling solution; the degreased aluminum alloy was placed in the acid pickling solution and treated at 27 ° C and 1 00r / min and stirred for 45s; rinsed with running tap water for 1.5min and dried; sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water were mixed in a mass ratio of 1:0.5:0.6:0.12:75, stirred at 45°C and 300r / min for 45min, allowed to stand for 24h, and filtered to obtain a micro-arc oxidation electrolyte; at 30°C, the pre-treated aluminum alloy was placed in the micro-arc oxidation electrolyte, and a DC constant current mode was adopted with the final voltage controlled at 450V. The treatment was carried out for 30min to generate a ceramic oxide layer with a thickness of 35μm to obtain a high-toughness aluminum alloy.

[0032] Comparative Example 12: A method for preparing a high-toughness aluminum alloy mainly includes the following preparation steps: (1) Weigh the raw materials according to the following mass percentages: 7.3% Zn, 2.3% Mg, 1.9% Cu, 0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy, 0.1% Ti, 0.07% Mn, 0.1% Y, and the balance is high-purity aluminum ingot; in an argon atmosphere, place the high-purity aluminum ingot in a furnace and heat it to 750°C, stir it at 300 r / min for 15 min, add Zn, Cu, Mg, and 300 r / min, and stir it for 15 min. min and stir for 15 minutes; heat to 780℃, add Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, and stir at 300r / min for 15 minutes; introduce high-purity argon gas for rotary degassing for 15 minutes, add sodium-free environmentally friendly refining agent with a mass twice that of high-purity aluminum ingot, stir at 300r / min for 45 minutes, and remove surface scum for 7 minutes; pour the melt into a metal mold preheated to 200℃ and cast an ingot; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 400°C, keep it for 2 hours, then heat it to 470°C, keep it for 10 hours, and air cool it; (3) Heating to 435 °C, constant temperature for 1 h, continuous hot extrusion, extrusion ratio of 13:1, extrusion speed of 10 m / min, and air cooling; (4) The ingot was heated to 470°C in an argon atmosphere, heat treated for 2.5 hours, and quenched in running water at room temperature; the temperature was raised to 120°C, kept warm for 8 hours, air-cooled, and then heated to 150°C, kept warm for 18 hours, air-cooled, and then heated to 90°C, kept warm for 12 hours; the ingot was placed in liquid nitrogen for cooling for 10 minutes, returned to room temperature and kept for 15 minutes, and repeated 3 cycles. The ingot was then dried naturally to obtain a high-toughness aluminum alloy.

[0033] Test Example 1: Determination of the optimal ratio of raw materials.

[0034] Test Method: Based on mechanical property analysis, high-toughness aluminum alloys were subjected to tensile testing in accordance with GB / T2281-2021, "Metallic Materials - Tensile Tests - Part 1: Room-Temperature Test Methods." The hardness of high-toughness aluminum alloys was tested in accordance with GB / T231.1, "Metallic Materials - Brinell Hardness Test - Part 1." All specimens were round rods, and the tensile speed was 3 mm / min.

[0035] The results are shown in Table 1.

[0036] Table 1 ; Comparison of Example 2 with Comparative Examples 1 and 2 reveals that the addition of Sc and Zr forms ultrafine phases of Al3Sc and Zr (Al3Zr) in aluminum alloys. These phases significantly improve the material's strength by refining the grain size and inhibiting the formation of coarse grains and eutectic phases in the aluminum alloy. However, when the addition level is too high, oversaturation of Sc forms coarse Al3Sc phases, which can become a crack source. Therefore, the optimal Sc and Zr addition levels are 0.1% for Al-2Sc master alloys and 0.15% for Al-5Zr master alloys.

[0037] Comparison of Example 2 and Comparative Examples 3-4 reveals that the addition of Ti effectively refines grain size and reduces the formation of coarse grains in aluminum alloys. Furthermore, Ti combines with oxygen to form TiO2 particles, which act as nuclei within the alloy, promoting uniform grain distribution and improving the mechanical properties of the material. However, excessive Ti addition can generate TiAl3 lamellae, which can become a source of cracks. Therefore, the optimal Ti addition is controlled to 0.1% Ti.

[0038] Comparing Example 2 with Comparative Examples 3-4 reveals that the addition of Mn and Y effectively reduces brittle phases in the alloy. Mn forms nano-Al6Mn dispersed phases in the aluminum alloy, pinning dislocations and replacing brittle Al3Fe. Y adsorbs O / Si / Fe impurities by segregating at grain boundaries, forming a high-temperature YAl2 phase that pins high-temperature grain boundary slip, thereby improving the aluminum alloy's plasticity and toughness. However, excessive Y addition can lead to Y2O3 nanoclusters, which degrade mechanical properties. The optimal Mn and Y addition levels are 0.07% Mn and 0.1% Y.

[0039] Therefore, the optimal ratio of raw materials is: 7.3% Zn, 2.3% Mg, 1.9% Cu, 0.1% Al-2Sc master alloy, 0.15% Al-5Zr master alloy, 0.1% Ti, 0.07% Mn, 0.1% Y, and the balance is high-purity aluminum ingot, which is the raw material ratio of Example 2.

[0040] Test Example 2: The optimal addition amount of graphene oxide is determined.

[0041] Test method: Through corrosion resistance analysis, high-toughness aluminum alloy was electrochemically tested using a CHI660E electrochemical workstation. The corrosive medium was 3.5wt% sodium chloride solution. A three-electrode system was used, with the sample as the working electrode and an exposed area of ​​1×1cm 2 The reference electrode was a saturated silver chloride electrode, the counter electrode was a platinum electrode, and the scan range was ±0.7 V relative to the open circuit potential at a scan rate of 1 mV / s.

[0042] The microhardness of the ceramic layer was analyzed by using a Vickers hardness tester (HVS-5 / 10 / 30 / 50AT) with a load pressure of 100 N and a dwell time of 15 s.

[0043] The results are shown in Table 2.

[0044] Table 2 ; By comparing Example 2 with Comparative Examples 7-8, it can be found that the addition of graphene oxide effectively improves the hardness and corrosion resistance of the ceramic layer. Graphene oxide refines the grains, inhibits the high-hardness corundum phase α-Al2O3 to γ ​​phase transformation, and fills the pores to achieve structural densification, thereby improving the hardness of the ceramic layer. Graphene oxide sheets are embedded in the Al2O3 ceramic layer, reducing porosity and extending the Cl⁻ diffusion path. At the same time, its edge carboxyl groups form Al-OC covalent bonds with Al³⁺, promoting the regeneration of the passivation film and significantly improving the corrosion resistance of the material. However, when the addition amount exceeds 0.3 times, the π-π stacking between the graphene oxide layers forms an electronic conductive network, accelerating local galvanic corrosion. Therefore, the comprehensive control of the graphene oxide addition amount is 0.3 times the amount of sodium silicate added.

[0045] Test Example 3: Mechanical properties and corrosion resistance tests.

[0046] Mechanical property testing method: The high-toughness aluminum alloy obtained in each embodiment and the aluminum alloys of comparative examples 9 to 12 were subjected to tensile tests in accordance with GB / T2281-2021 "Tensile test of metallic materials Part 1: Room temperature test method". All specimens were round rods, and the tensile speed was 3 mm / min.

[0047] Corrosion resistance test method: The high-toughness aluminum alloy obtained in each example and the aluminum alloys of comparative examples 9 to 12 were electrochemically tested using a CHI660E electrochemical workstation. The corrosive medium was a 3.5 wt% sodium chloride solution. A three-electrode system was used, with the sample as the working electrode and an exposed area of ​​1 × 1 cm. 2 The reference electrode was a saturated silver chloride electrode, the counter electrode was a platinum electrode, and the scan range was ±0.7 V relative to the open circuit potential at a scan rate of 1 mV / s.

[0048] The results are shown in Table 3.

[0049] Table 3 ; From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 9 to 12 in Table 3, it can be found that the high-toughness aluminum alloy prepared in the present invention has good tensile strength, elongation and corrosion resistance.

[0050] By comparing Examples 1 to 3 with Comparative Example 9, it can be found that the two-stage homogenization treatment combined with the four-stage aging process maximizes the synergistic effect of the nano-precipitate phase and the amorphous interface network by precisely controlling the diffusion field stacking and the precipitate phase size. The two-stage homogenization forces the short-range diffusion of Zn / Mg / Cu in the solid solution to avoid dendritic segregation in the cast state, activates the long-range diffusion of Sc / Zr / Y, drives the homogeneous nucleation of the Al3(Sc,Zr) nanophase, and promotes the formation of a continuous purification layer at the Y segregated grain boundary; the four-stage aging process promotes the transformation of the GP zone to β''(MgZn2), generating a rod-shaped β'' phase, significantly improving the tensile strength, while stimulating the viscosity of the amorphous phase and effectively improving the elongation.

[0051] By comparing Examples 1 to 3 with Comparative Example 10, it can be found that the liquid nitrogen cryogenic cycle is a key step in inducing the formation of a continuous amorphous phase network at the grain boundaries. The formed continuous amorphous phase, with its high elastic limit and multiple shear band deformation ability, forces the crack propagation path to be tortuous, dissipates fracture energy, and effectively improves the elongation.

[0052] By comparing Examples 1 to 3 with Comparative Example 11, it can be found that the graphene oxide sheets are embedded in the Al2O3 ceramic layer, which reduces the porosity and prolongs the Cl⁻ diffusion path. At the same time, its edge carboxyl groups form Al-OC covalent bonds with Al³⁺, promoting the regeneration of the passivation film and significantly improving the corrosion resistance of the material.

[0053] By comparing Examples 1 to 3 with Comparative Example 12, it can be found that in-situ construction of a micro-arc oxidation ceramic layer on the outside of the aluminum alloy can significantly improve the corrosion resistance of the high-toughness aluminum alloy.

Claims

1. A high toughness aluminum alloy, characterized in that: The high-toughness aluminum alloy is based on an aluminum alloy with a specific component, and is sequentially subjected to melting and casting, step heat treatment, hot extrusion, multi-stage aging and liquid nitrogen deep-cold cycle treatment, and finally an in-situ ceramic oxide layer is generated by a micro-arc oxidation electrolyte.

2. The high toughness aluminum alloy according to claim 1, characterized in that: The specific components are as follows: 7.0-7.5% Zn, 2.2-2.5% Mg, 1.8-2.0% Cu, 0.08-0.12% Al-2Sc master alloy, 0.05-0.25% Al-5Zr master alloy, 0.08-0.12% Ti, 0.05-0.1% Mn, 0.05-0.15% Y, and the balance is high-purity aluminum ingot.

3. The high toughness aluminum alloy according to claim 1, characterized in that: The micro-arc oxidation electrolyte is prepared by dispersing graphene oxide in a mixed solution of sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water.

4. A method for preparing a high-toughness aluminum alloy, characterized in that: The method comprises the following preparation steps: (1) Weigh the raw materials according to the following mass percentages: 7.0~7.5% Zn, 2.2~2.5% Mg, 1.8~2.0% Cu, 0.08~0.12% Al-2Sc master alloy, 0.05~0.25% Al-5Zr master alloy, 0.08~0.12% Ti, 0.05~0.1% Mn, 0.05~0.15% Y, and the balance is high-purity aluminum ingot; place the high-purity aluminum ingot in a furnace in an argon atmosphere and heat it to 740~7 60℃, stir at 200-400r / min for 10-20min, add Zn, Cu and Mg, and stir at 200-400r / min for 10-20min; heat to 770-790℃, add Al-2Sc master alloy, Al-5Zr master alloy, Ti, Mn and Y, and stir at 200-400r / min for 10-20min; refine, degas and remove slag, and pour the melt into a metal mold preheated to 180-220℃ for ingot casting; (2) Slice the ingot, place it in a muffle furnace in an argon atmosphere, heat it to 380-420°C, keep it warm for 1.5-2.5 hours, then heat it to 450-490°C, keep it warm for 8-12 hours, and air cool it; (3) Heating to 420~450℃, constant temperature for 0.5~1.5h, continuous hot extrusion, and air cooling; (4) Heat the ingot to 460-480°C in an argon atmosphere, heat treat for 2-3 hours, and quench in running water at room temperature; heat to 100-140°C, keep warm for 6-10 hours, air cool and heat to 140-160°C, keep warm for 12-24 hours, air cool and heat to 80-100°C, keep warm for 10-14 hours; cool in liquid nitrogen for 5-15 minutes, return to room temperature and keep for 10-20 minutes, repeat 2-4 cycles, and dry naturally; (5) The naturally dried aluminum alloy is subjected to pretreatment by degreasing, pickling, water washing and drying; sodium silicate, potassium aluminate, trisodium phosphate, potassium hydroxide and deionized water are mixed uniformly in a mass ratio of 1:(0.3~0.7):(0.5~0.7):(0.1~0.15):(70~80), stirred at 40~50°C and 200~400r / min for 30~60min, graphene oxide with a mass of 0.2~0.4 times the amount of sodium silicate added is added, treated at an ultrasonic power of 200~500W for 20~40min, allowed to stand for 20~28h, filtered, and a micro-arc oxidation electrolyte is prepared; the pre-treated aluminum alloy is placed in a micro-arc oxidation electrolyte at 20~35°C, a DC constant current mode is used, the final voltage is controlled at 400~500V, and the treatment is carried out for 20~40min to generate a ceramic oxide layer with a thickness of 20~50μm, thereby obtaining a high-toughness aluminum alloy.

5. The method for preparing a high-toughness aluminum alloy according to claim 4, characterized in that: The refining, degassing and slag removal method in step (1) is as follows: introducing high-purity argon gas for rotary degassing for 10 to 20 minutes, adding a sodium-free environmentally friendly refining agent with a mass of 1.5 to 3 times the amount of high-purity aluminum ingot, stirring at 200 to 400 r / min for 30 to 60 minutes, and removing the surface slag for 5 to 10 minutes.

6. The method for preparing a high-toughness aluminum alloy according to claim 4, characterized in that: In the hot extrusion of step (3), the extrusion ratio is 10-16:1 and the extrusion speed is 8-12 m / min.

7. The method for preparing a high-toughness aluminum alloy according to claim 4, characterized in that: The purity of the graphene oxide in step (5) is >95%.

8. The method for preparing a high-toughness aluminum alloy according to claim 4, characterized in that: The pretreatment method of step (5) is as follows: sodium hydroxide, trisodium phosphate and deionized water are uniformly mixed in a mass ratio of 1: (0.5-0.7): (15-25), stirred at 200-400 r / min for 10-20 min, and allowed to stand for 1-3 h to obtain an alkaline degreasing solution; The dried aluminum alloy is placed in an alkaline degreasing solution and treated at 60-70°C and an ultrasonic power of 200-500W for 5-10 minutes; 65% nitric acid, ammonium bifluoride, benzotriazole, and deionized water are uniformly mixed in a mass ratio of 1:(0.15-0.2):(0.001-0.003):(2-4), and stirred at 200-400 r / min for 10-20 minutes to prepare a pickling solution; the degreased aluminum alloy is placed in the pickling solution and stirred at 25-30°C and 50-150 r / min for 30-60 seconds; the alloy is rinsed with running tap water for 1-2 minutes, and dried.