High-toughness aluminum alloy based on secondary aluminum and preparation method

Abstract

The invention belongs to the technical field of aluminum alloy preparation, and particularly relates to a high-toughness aluminum alloy based on secondary aluminum and a preparation method. Comprising the following steps that secondary aluminum is sequentially subjected to crushing, screening, impurity removal and preheating, the preheated secondary aluminum is heated to be completely molten, and aluminum melt is obtained; an intermediate alloy is added into the aluminum melt, after the alloy is completely melted, the procedures of stirring, refining, degassing and deslagging are sequentially carried out, and an alloy melt is obtained; the alloy melt is subjected to ultrasonic treatment, first ultrasonic treatment is carried out at the power of 50%-60%, then second ultrasonic treatment is carried out at the power of 70%-80%, and finally third ultrasonic treatment is carried out at the power of 50%-60%, so that an aluminum alloy precursor is obtained; and casting the aluminum alloy precursor to obtain the high-toughness aluminum alloy. According to the method, the secondary aluminum is used as a matrix, the strength of the secondary aluminum alloy is improved by adding multiple alloy elements, and the low-cost and high-toughness aluminum alloy is obtained by combining staged ultrasonic melt treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy preparation, and in particular relates to a high-strength and toughness aluminum alloy based on recycled aluminum and a preparation method thereof. Background Art

[0002] Aluminum alloys have a wide range of practical applications. In automobile manufacturing, both traditional fuel-powered and new energy vehicles are increasingly using aluminum alloys to reduce weight, improve fuel economy, and enhance range. Due to its lightweight, corrosion-resistant, and easy-to-process properties, aluminum alloys are widely used in door and window frames, curtain walls, building decoration materials, and structural components. With the advancement of urbanization and the continued development of the real estate market, demand for aluminum in construction is also growing. Aluminum and aluminum alloys are widely used in electronic product casings, heat sinks, electronic components, and the photovoltaic industry.

[0003] Recycled aluminum has a broad market, but its application is still limited by several factors, including purity. Recycled aluminum may contain various impurities, such as iron, copper, and zinc, making it difficult to achieve the high purity of primary aluminum. The presence of impurities can affect aluminum's performance, such as reducing its strength, toughness, and corrosion resistance. It can also reduce the material's density, impacting its pressure resistance and fatigue properties, necessitating careful evaluation when used in applications subject to high pressure or dynamic loads. Unmodified recycled aluminum alloys contain acicular eutectic silicon, which can cause stress concentration and microcracks under external loads, thereby reducing their strength and ductility. Furthermore, the coarse α-Al dendrites in recycled aluminum alloys are susceptible to defects such as casting shrinkage, porosity, and compositional segregation, adversely affecting their performance. Refining α-Al and modifying the eutectic silicon can improve the mechanical properties of hypoeutectic silicon.

[0004] Existing research has used elements such as Cu, Zr, and / or B to enhance the strength of high-strength and tough aluminum alloys based on recycled aluminum. Copper, after aging treatment, forms a secondary nanoscale Al2Cu dispersion, the primary hardening component of the aluminum alloy. This dispersion enhances strength at the expense of ductility and lowers the melting point and eutectic temperature of Al-Si-Mg alloys, leading to an increase in the alloy's solidification range and the formation of porosity. Zr, on the other hand, forms a high-melting-point Al3Zr phase in the aluminum melt, which serves as a heterogeneous nucleation substrate for α-Al, significantly enhancing grain refinement. Furthermore, Zr has a high solid solubility and low diffusion coefficient in the aluminum matrix, allowing it to precipitate into nanoscale Al3Zr dispersions during subsequent heat treatment. These precipitates effectively enhance the alloy's high-temperature mechanical properties by inhibiting recovery and recrystallization and hindering dislocation motion. For hypoeutectic Al-Si alloys with silicon contents exceeding 5%, the eutectic silicon phase exhibits a needle-like morphology, leading to severe matrix fracture and requiring modification. In the aluminum melt, boron combines with titanium to form TiB2 particles, which serve as heterogeneous nucleation cores and refine the grain structure. However, recycled aluminum often contains high levels of iron impurities (such as needle-like FeAl3 phases), which can severely degrade plasticity. Summary of the Invention

[0005] To address the above-mentioned issues, the present invention provides a high-strength and toughness aluminum alloy based on recycled aluminum and its preparation method. Using recycled aluminum as the matrix, the strength of the recycled aluminum alloy is further improved by adding various alloying elements. Combined with staged ultrasonic melt treatment, the alloy is strengthened by thermodynamically reducing dislocation energy or kinetically applying solute drag to reduce dislocation mobility and stabilize low-angle grain boundaries. This simultaneously improves strength and room- and medium-temperature performance, resulting in a low-cost, high-strength and toughness aluminum alloy suitable for a wider range of applications as primary load-bearing aluminum alloy structural components.

[0006] The present invention solves the above technical problems through the following technical solutions.

[0007] The first object of the present invention is to provide a method for preparing a high-strength and tough aluminum alloy based on recycled aluminum, comprising the following steps: S1. The recycled aluminum is crushed, screened, impurity-removed and preheated in sequence, and the preheated recycled aluminum is heated until it is completely melted to obtain an aluminum melt.

[0008] S2. Add Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy into the aluminum melt. After the alloy is completely melted, stirring, refining, degassing and deslagging processes are carried out in sequence to obtain an alloy melt.

[0009] S3. Ultrasonic treatment is performed on the alloy melt. First, ultrasonic treatment is performed for the first time at a power of 50% to 60%, then ultrasonic treatment is performed for the second time at a power of 70% to 80%, and finally ultrasonic treatment is performed for the third time at a power of 50% to 60%. After the ultrasonic treatment is completed, the melt is allowed to stand and heat-insulated to obtain an aluminum alloy precursor.

[0010] S4. Casting the aluminum alloy precursor to obtain a high-strength and tough aluminum alloy.

[0011] Furthermore, the high-strength and toughness aluminum alloy has the following components, calculated by mass percentage: Si: 8wt.%~10wt.%, Mg: 1.5wt.%~2.0wt.%, Cu: 1.0wt.%~2.0wt.%, Ca: 0.55wt.%~0.65wt.%, Zr: 0.1wt.%~0.2wt.%, B: 0.05wt.%~0.1wt.%, V: 0.2wt.%~0.3wt.%, and the remainder is Al and unavoidable impurity elements, totaling 100%.

[0012] Furthermore, the temperature at which the alloy is completely melted is 720°C to 750°C.

[0013] Furthermore, the degassing method is: introducing protective gas for 10 minutes to 15 minutes.

[0014] Furthermore, the power of the ultrasonic treatment is 1000W to 1600W, the time of the first ultrasonic treatment is 5 minutes to 10 minutes, the time of the second ultrasonic treatment is 10 minutes to 15 minutes, and the time of the third ultrasonic treatment is 4 minutes to 6 minutes.

[0015] Furthermore, the standing and heat preservation time is 15 minutes to 20 minutes, and the temperature is 720°C to 730°C.

[0016] Furthermore, before casting, the temperature of the aluminum alloy precursor is 680°C to 720°C.

[0017] Furthermore, during the casting process, the mold temperature is 260°C to 280°C, and the cooling method after casting is air cooling.

[0018] Furthermore, the preheating temperature of the recycled aluminum is 200°C to 300°C, and the Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy are polished to remove the surface oxide layer before being heated and melted, and then preheated to 200°C to 300°C.

[0019] A second object of the present invention is to provide a high-strength and toughness aluminum alloy based on recycled aluminum, which is prepared using the above-mentioned method for preparing a high-strength and toughness aluminum alloy based on recycled aluminum.

[0020] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a high-strength and tough aluminum alloy from recycled aluminum. Using impurity-removed recycled aluminum as a base, the alloy's strength is improved by adding multiple alloying elements. Cu and Ca are used as primary alloying elements to enhance strength, while Zr, B, and V are used as microalloying elements. Al-Si-Mg-Cu-Ca-Zr-BV alloys containing varying Cu and Ca contents are designed. The addition of Cu can significantly improve the strength of aluminum alloys. At the same time, the addition of Ca is also the key to achieving such high strength. Ca segregates to the dislocation core along the small-angle grain boundaries, reduces the dislocation energy by thermodynamics or applies the solute drag effect by kinetically, reduces the dislocation mobility and stabilizes the small-angle grain boundaries for strengthening, which can simultaneously improve the strength and room temperature and medium temperature properties. Combined with staged ultrasonic melt treatment, the first ultrasonic wave is first performed at a power of 50% to 60%, so that the ultrasonic wave propagates evenly in the aluminum liquid, preliminarily refines the grains and promotes impurity agglomeration. Then, the second ultrasonic wave is performed at a power of 70% to 80%, which strengthens the effect on the aluminum liquid, further refines the grains, removes tiny bubbles and impurities, and finally, the third ultrasonic wave is performed at a power of 50% to 60%, stabilizes the alloy melt state, reduces the dislocation energy by thermodynamics or applies the solute drag effect by kinetically, reduces the dislocation mobility and stabilizes the small-angle grain boundaries for strengthening, which can simultaneously improve the strength and room temperature and medium temperature properties, and obtain a low-cost, high-strength and tough aluminum alloy, so that it can be more widely used as the main load-bearing structural parts of aluminum alloys. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a schematic diagram of the process for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to the present invention. DETAILED DESCRIPTION

[0022] The following will provide a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0024] Recycled aluminum has a broad market, but its application remains limited by several factors. First, there are purity issues: Recycled aluminum may contain various impurities, such as iron, copper, and zinc, making it difficult to achieve the high purity of primary aluminum. The presence of impurities can affect aluminum's properties, such as reducing its strength, toughness, and corrosion resistance. Mechanical property fluctuations: Due to the complex raw material sources, the composition and microstructure uniformity of recycled aluminum are difficult to control, resulting in significant fluctuations in its mechanical properties. This limits the use of recycled aluminum in applications requiring stringent mechanical properties, such as aerospace and high-end machinery manufacturing. Internal defects: During the recycling process, internal defects such as pores and inclusions may be generated. These defects reduce the material's density, affecting its pressure resistance and fatigue performance. Therefore, careful evaluation is required before use in applications subject to high pressure or dynamic loads. Second, recycled aluminum alloys contain acicular eutectic silicon, which can cause stress concentration and microcracks under external loads, thereby reducing their strength and ductility. Furthermore, coarse α-Al dendrites in recycled aluminum alloys can easily lead to defects such as casting shrinkage, porosity, and compositional segregation, adversely affecting their performance.

[0025] Although existing research uses elements such as Cu, Zr and / or B to improve the strength of aluminum alloys in the preparation of aluminum alloys based on recycled aluminum, there are still adverse properties such as fluctuations in mechanical properties and internal defects that limit application scenarios.

[0026] Based on this, the present invention proposes a method for preparing a high-strength and tough aluminum alloy based on recycled aluminum, comprising the following steps: S1. The recycled aluminum is crushed, screened, impurity-removed and preheated in sequence, and the preheated recycled aluminum is heated until it is completely melted to obtain an aluminum melt.

[0027] S2. Add Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy into the aluminum melt. After the alloy is completely melted, stirring, refining, degassing and deslagging processes are carried out in sequence to obtain an alloy melt.

[0028] S3. Ultrasonic treatment is performed on the alloy melt. First, ultrasonic treatment is performed for the first time at a power of 50% to 60%, then ultrasonic treatment is performed for the second time at a power of 70% to 80%, and finally ultrasonic treatment is performed for the third time at a power of 50% to 60%. After the ultrasonic treatment is completed, the melt is allowed to stand and heat-insulated to obtain an aluminum alloy precursor.

[0029] S4. Casting the aluminum alloy precursor to obtain a high-strength and tough aluminum alloy.

[0030] The present invention improves upon the base alloy of impurity-removed recycled aluminum alloy by sequentially crushing, screening, and removing impurities from the recycled aluminum. Specifically, after crushing and screening, the recycled aluminum raw material is first passed through the conveyor of an iron magnet, passing through the magnet's magnetic field. The strong magnetic field of the magnetic separator attracts iron impurities in the raw material, separating them from the recycled aluminum. During operation, the magnetic separator's magnetic field strength and conveyor speed are adjusted according to the raw material's flow rate and iron content to ensure effective impurity removal. Ferromagnetic metals (such as iron and nickel) are pre-removed using the magnetic separator to prevent interference with eddy current separation. Furthermore, the material's moisture content is controlled (<10%) to avoid excessive humidity that reduces separation efficiency. The treated raw material is then passed through the conveyor of an eddy current separator. The drum speed, the angle of the separator plate, and the speed of the conveyor belt are adjusted to remove non-magnetic impurities from the recycled aluminum. After preliminary impurity removal by the magnetic and eddy current separators, the recycled aluminum is preheated in a resistance furnace in preparation for the next refining step.

[0031] This invention uses purified recycled aluminum as a base and improves the strength of the aluminum alloy by adding multiple alloying elements. Cu and Ca are used as primary alloying elements to enhance strength, while Zr, B, and V are used as microalloying elements. Al-Si-Mg-Cu-Ca-Zr-BV alloys with varying Cu and Ca contents are designed. The addition of Cu can significantly improve the strength of aluminum alloys. At the same time, the addition of Ca is also the key to achieving such high strength. Ca segregates to the dislocation core along the small-angle grain boundaries, reduces the dislocation energy by thermodynamics or applies the solute drag effect by kinetically, reduces the dislocation mobility and stabilizes the small-angle grain boundaries for strengthening, which can simultaneously improve the strength and room temperature and medium temperature properties. Combined with staged ultrasonic melt treatment, the first ultrasonic wave is first performed at a power of 50% to 60%, so that the ultrasonic wave propagates evenly in the aluminum liquid, preliminarily refines the grains and promotes impurity agglomeration. Then, the second ultrasonic wave is performed at a power of 70% to 80%, which strengthens the effect on the aluminum liquid, further refines the grains, removes tiny bubbles and impurities, and finally, the third ultrasonic wave is performed at a power of 50% to 60%, stabilizes the alloy melt state, reduces the dislocation energy by thermodynamics or applies the solute drag effect by kinetically, reduces the dislocation mobility and stabilizes the small-angle grain boundaries for strengthening, which can simultaneously improve the strength and room temperature and medium temperature properties, and obtain a low-cost, high-strength and tough aluminum alloy, so that it can be more widely used as the main load-bearing structural parts of aluminum alloys.

[0032] In some embodiments, the high-strength and toughness aluminum alloy has the following components, calculated by mass percentage: Si: 8wt.%~10wt.%, Mg: 1.5wt.%~2.0wt.%, Cu: 1.0wt.%~2.0wt.%, Ca: 0.55wt.%~0.65wt.%, Zr: 0.1wt.%~0.2wt.%, B: 0.05wt.%~0.1wt.%, V: 0.2wt.%~0.3wt.%, and the remainder is Al and unavoidable impurity elements, totaling 100%.

[0033] In the present invention, elements such as Cu and Ca are added to an aluminum alloy for modification. The design principles for these element additions are as follows: A Si content of 8 to 10 wt.% results in excellent casting properties, minimal shrinkage, good corrosion resistance and airtightness, and good mechanical and weldability. Mg forms a solid solution in the Al-Cu alloy, improving the alloy's mechanical properties through solid solution strengthening. Mg refines the grain size, forming a stable phase structure during heat treatment, and also improves the alloy's corrosion resistance. Cu in the aluminum alloy improves its mechanical properties, corrosion resistance, and electrical conductivity through solid solution strengthening and precipitation strengthening mechanisms. Ca acts as a modifier, changing the morphology of eutectic silicon from coarse plates or needles to fine fibers or granules. This refinement significantly enhances the alloy's plasticity (e.g., elongation) and fatigue resistance. The Ca modification effect is more stable, with minimal degradation, especially during long melting times or high-temperature conditions, making it suitable for industrial production. Therefore, the Ca content in the present alloy is 0.6 ± 0.05 wt.%. Zr forms a high-melting-point Al3Zr phase in the aluminum melt, serving as a heterogeneous nucleation substrate for α-Al and significantly refining the alloy's grain size. This refined grain structure not only enhances the room-temperature strength of the alloy but also improves its ductility and fatigue resistance. Zr addition indirectly modifies the morphology of eutectic silicon, reduces the coarsening tendency of the eutectic silicon phase, and mitigates the cleavage effect of needle-shaped silicon on the matrix, thereby enhancing the alloy's fracture toughness. Zr also synergizes with elements such as boron and vanadium to create a composite, synergistic strengthening effect. In the aluminum melt, boron combines with titanium to form TiB2 particles, which serve as heterogeneous nucleation cores and refine the grain structure. Furthermore, recycled aluminum often contains high levels of iron impurities (such as needle-shaped FeAl3 phases), which can significantly degrade ductility. Boron reacts with iron to form stable Fe-B compounds (such as Fe2B), mitigating the effects of detrimental iron phases. Vanadium participates in the formation of complex borides (such as TiB2-VC), further enhancing the density of nucleation cores. Furthermore, fine dispersed phases such as Al3V are generated, inhibiting grain growth. The Al3V phase remains stable at high temperatures, improving the material's hot hardness and creep resistance. The addition of V can also form complex phases such as Fe-V-Si with Fe, reducing the brittleness of FeAl3. In summary, the present invention uses elements such as Cu and Ca to add to recycled aluminum to design a new, low-cost, high-strength and tough aluminum alloy, which is then smelted to produce aluminum alloy main load-bearing structural components.

[0034] In some embodiments, the temperature for heating to complete melting is 720°C to 750°C.

[0035] In some embodiments, the degassing method is: introducing a protective gas for 10 to 15 minutes. The present invention uses a protective gas, which is nitrogen or an inert gas, to form a protective atmosphere to reduce oxidation of the aluminum liquid.

[0036] In some embodiments, the ultrasonic treatment power is 1000W to 1600W, the first ultrasonic treatment lasts 5 minutes to 10 minutes, the second ultrasonic treatment lasts 10 minutes to 15 minutes, and the third ultrasonic treatment lasts 4 minutes to 6 minutes. The total duration of the first, second, and third ultrasonic treatments is 15 minutes to 30 minutes, and the power is 1000W to 1600W. The aluminum liquid is treated according to the preset parameters. During the treatment process, the probe position can be appropriately adjusted to ensure uniform treatment of all parts of the aluminum liquid.

[0037] In some embodiments, the holding time is 15 min to 20 min, and the temperature is 720° C. to 730° C.

[0038] In some embodiments, before casting, the temperature of the aluminum alloy precursor is 680°C to 720°C.

[0039] In some embodiments, during the casting process, the mold temperature is 260°C to 280°C, and the cooling method after casting is air cooling. During the casting process, the aluminum alloy precursor is poured into a square mold preheated to 260°C to 280°C and air-cooled. The casting speed should not be too fast to prevent the formation of a deep riser.

[0040] In some embodiments, the preheating temperature of the recycled aluminum is 200°C to 300°C. Before heating and melting the Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy, they are polished to remove the surface oxide layer and then preheated to 200°C to 300°C.

[0041] Polishing is the process of mechanically polishing the surface of pure Al and master alloys until the surface presents a metallic luster and removes the surface oxide layer. After mechanical polishing, the aluminum is placed in a resistance furnace for preheating at 200℃ to 300℃ to evaporate the surface moisture.

[0042] The following is further described through specific examples.

[0043] Example 1 A method for preparing a high-strength and tough aluminum alloy based on recycled aluminum comprises the following steps: S1. High-strength and toughness aluminum alloy: The composition, by mass percentage, is: Si: 8.3 wt.%, Mg: 1.6 wt.%, Cu: 1.1 wt.%, Ca: 0.58 wt.%, Zr: 0.13 wt.%, B: 0.06 wt.%, and V: 0.22 wt.%. The balance is Al and unavoidable impurities, totaling 100%. Recycled aluminum, Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy, and Al-10Ca master alloy were weighed according to the mass percentage of the high-strength and toughness aluminum alloy.

[0044] S2. The recycled aluminum is crushed and sieved in sequence to a particle size of ≤50 mm, and is then passed through a magnetic separator and an eddy current separator to remove magnetic and non-magnetic impurities. After weighing, it is preheated in a resistance furnace at 230°C for 1 hour.

[0045] S3. Set the melting furnace temperature to 730°C. When the melting furnace temperature reaches a predetermined temperature, add the preheated recycled aluminum into the furnace and heat until it is completely melted to obtain an aluminum melt. Add Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy to the aluminum melt. After the alloy is completely melted, refine it and add a refining agent, aluminum chloride, to the melt. The amount of aluminum chloride is 0.55wt.% of the melt. Stir the melt continuously during the addition process. After the addition is completed, heat it to 740°C and keep it at this temperature for 10 minutes.

[0046] S4. After standing still, argon gas was introduced for 15 minutes for degassing. After degassing, the surface was scraped off with a stainless steel spoon to remove the surface scum, and then the alloy was allowed to stand still for 10 minutes to obtain an alloy melt.

[0047] S5. Install the ultrasonic transducer probe on the furnace. The maximum ultrasonic processing power of the ultrasonic transducer is 1200W. Insert it into the molten alloy at a suitable position, generally about one-third of the depth from the liquid surface. Ensure the probe is properly sealed to prevent leakage. When the molten aluminum temperature stabilizes at 720°C, turn on the ultrasonic equipment and treat the molten aluminum according to the preset parameters. During the treatment process, adjust the probe position appropriately to ensure uniform treatment of all parts of the molten aluminum. The treatment should be carried out in stages. Initially, treat at a low power level (55% of the maximum power) for 5 minutes to ensure uniform ultrasonic propagation throughout the molten aluminum, initially refining the grains and promoting impurity agglomeration. Then, increase the power to 75% for 10 minutes to intensify the effect on the molten aluminum, further refine the grains, and remove tiny bubbles and impurities. Finally, treat at 55% power for approximately 5 minutes to stabilize the molten aluminum.

[0048] S6. After the ultrasonic treatment, the aluminum liquid is allowed to stand at 720°C for 15 minutes. When the temperature drops to 680°C, casting is started. The aluminum alloy that has been standing is poured into a square mold preheated to 260°C and air-cooled to obtain a high-strength and tough aluminum alloy based on recycled aluminum.

[0049] Example 2 A method for preparing a high-strength and tough aluminum alloy based on recycled aluminum comprises the following steps: S1. High-strength and toughness aluminum alloy: The composition, by mass percentage, is: Si: 9 wt.%, Mg: 1.8 wt.%, Cu: 1.6 wt.%, Ca: 0.62 wt.%, Zr: 0.15 wt.%, B: 0.07 wt.%, and V: 0.26 wt.%. The balance is Al and unavoidable impurities, totaling 100%. Recycled aluminum, Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy, and Al-10Ca master alloy were weighed according to the mass percentage of the high-strength and toughness aluminum alloy.

[0050] S2. The recycled aluminum is crushed and sieved in sequence to a particle size of ≤50 mm, and is then passed through a magnetic separator and an eddy current separator to remove magnetic and non-magnetic impurities. After weighing, it is preheated in a resistance furnace at 230°C for 1 hour.

[0051] S3. Set the melting furnace temperature to 730°C. When the melting furnace temperature reaches a predetermined temperature, add the preheated recycled aluminum into the furnace and heat until it is completely melted to obtain an aluminum melt. Add Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy to the aluminum melt. After the alloy is completely melted, refine it and add a refining agent, aluminum chloride, to the melt. The amount of aluminum chloride is 0.55wt.% of the melt. Stir the melt continuously during the addition process. After the addition is completed, heat it to 740°C and keep it at this temperature for 10 minutes.

[0052] S4. After standing still, argon gas was introduced for 15 minutes for degassing. After degassing, the surface was scraped off with a stainless steel spoon to remove the surface scum, and then the alloy was allowed to stand still for 10 minutes to obtain an alloy melt.

[0053] S5. Install the ultrasonic transducer probe on the furnace. The maximum ultrasonic processing power of the ultrasonic transducer is 1200W. Insert it into the molten alloy at a suitable position, generally about one-third of the depth from the liquid surface. Ensure the probe is properly sealed to prevent leakage. When the molten aluminum temperature stabilizes at 720°C, turn on the ultrasonic equipment and treat the molten aluminum according to the preset parameters. During the treatment process, adjust the probe position appropriately to ensure uniform treatment of all parts of the molten aluminum. The treatment should be carried out in stages. Initially, treat at a low power level (55% of the maximum power) for 5 minutes to ensure uniform ultrasonic propagation throughout the molten aluminum, initially refining the grains and promoting impurity agglomeration. Then, increase the power to 75% for 10 minutes to intensify the effect on the molten aluminum, further refine the grains, and remove tiny bubbles and impurities. Finally, treat at 55% power for approximately 5 minutes to stabilize the molten aluminum.

[0054] S6. After the ultrasonic treatment, the aluminum liquid is allowed to stand at 720°C for 15 minutes. When the temperature drops to 680°C, casting is started. The aluminum alloy that has been standing is poured into a square mold preheated to 260°C and air-cooled to obtain a high-strength and tough aluminum alloy based on recycled aluminum.

[0055] Example 3 A method for preparing a high-strength and tough aluminum alloy based on recycled aluminum comprises the following steps: S1. High-strength and toughness aluminum alloy: The composition, by mass percentage, is: Si: 9.7 wt.%, Mg: 1.96 wt.%, Cu: 1.92 wt.%, Ca: 0.63 wt.%, Zr: 0.18 wt.%, B: 0.07 wt.%, and V: 0.28 wt.%. The balance is Al and unavoidable impurities, totaling 100%. Recycled aluminum, Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy, and Al-10Ca master alloy were weighed according to the mass percentage of the high-strength and toughness aluminum alloy.

[0056] S2. The recycled aluminum is crushed and sieved in sequence to a particle size of ≤50 mm, and is then passed through a magnetic separator and an eddy current separator to remove magnetic and non-magnetic impurities. After weighing, it is preheated in a resistance furnace at 230°C for 1 hour.

[0057] S3. Set the melting furnace temperature to 730°C. When the melting furnace temperature reaches a predetermined temperature, add the preheated recycled aluminum into the furnace and heat until it is completely melted to obtain an aluminum melt. Add Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy to the aluminum melt. After the alloy is completely melted, refine it and add a refining agent, aluminum chloride, to the melt. The amount of aluminum chloride is 0.55wt.% of the melt. Stir the melt continuously during the addition process. After the addition is completed, heat it to 740°C and keep it at this temperature for 10 minutes.

[0058] S4. After standing still, argon gas was introduced for 15 minutes for degassing. After degassing, the surface was scraped off with a stainless steel spoon to remove the surface scum, and then the alloy was allowed to stand still for 10 minutes to obtain an alloy melt.

[0059] S5. Install the ultrasonic transducer probe on the furnace. The maximum ultrasonic processing power of the ultrasonic transducer is 1200W. Insert it into the molten alloy at a suitable position, generally about one-third of the depth from the liquid surface. Ensure the probe is properly sealed to prevent leakage. When the molten aluminum temperature stabilizes at 720°C, turn on the ultrasonic equipment and treat the molten aluminum according to the preset parameters. During the treatment process, adjust the probe position appropriately to ensure uniform treatment of all parts of the molten aluminum. The treatment should be carried out in stages. Initially, treat at a low power level (55% of the maximum power) for 5 minutes to ensure uniform ultrasonic propagation throughout the molten aluminum, initially refining the grains and promoting impurity agglomeration. Then, increase the power to 75% for 10 minutes to intensify the effect on the molten aluminum, further refine the grains, and remove tiny bubbles and impurities. Finally, treat at 55% power for approximately 5 minutes to stabilize the molten aluminum.

[0060] S6. After the ultrasonic treatment, the aluminum liquid is allowed to stand at 720°C for 15 minutes. When the temperature drops to 680°C, casting is started. The aluminum alloy that has been standing is poured into a square mold preheated to 260°C and air-cooled to obtain a high-strength and tough aluminum alloy based on recycled aluminum.

[0061] Comparative Example 1 A method for preparing a high-strength and tough aluminum alloy based on recycled aluminum comprises the following steps: S1. High-strength and toughness aluminum alloy: The composition, by mass percentage, is: Si: 9 wt.%, Mg: 1.5 wt.%, Cu: 1.2 wt.%, Ca: 0.6 wt.%, and Zr: 0.1 wt.%. The balance is Al and unavoidable impurities, totaling 100%. Weigh recycled aluminum, Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, and Al-10Ca master alloy according to the mass percentage of the high-strength and toughness aluminum alloy.

[0062] S2. The recycled aluminum is crushed and sieved in sequence to a particle size of ≤50 mm, and is then passed through a magnetic separator and an eddy current separator to remove magnetic and non-magnetic impurities. After weighing, it is preheated in a resistance furnace at 230°C for 1 hour.

[0063] S3. Set the melting furnace temperature to 730°C. When the melting furnace temperature reaches a predetermined temperature, add the preheated recycled aluminum into the furnace and heat until it is completely melted to obtain an aluminum melt. Add Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, and Al-10Ca master alloy into the aluminum melt. After the alloy is completely melted, refine it and add a refining agent, aluminum chloride, to the melt. The amount of aluminum chloride is 0.55wt.% of the melt. Stir the melt continuously during the addition process. After the addition is completed, heat it to 740°C and keep it at this temperature for 10 minutes.

[0064] S4. After standing still, argon gas was introduced for 15 minutes for degassing. After degassing, the surface was scraped off with a stainless steel spoon to remove the surface scum, and then the alloy was allowed to stand still for 10 minutes to obtain an alloy melt.

[0065] S5. When the temperature of the alloy melt drops to 680°C, casting begins. The stationary aluminum alloy is poured into a square mold preheated to 260°C and air-cooled to obtain a high-strength and tough aluminum alloy based on recycled aluminum.

[0066] Comparative Example 2 A method for preparing a high-strength and tough aluminum alloy based on recycled aluminum comprises the following steps: S1. High-strength and toughness aluminum alloy: The composition, by mass percentage, is: Si: 9 wt.%, Mg: 1.5 wt.%, Cu: 1.2 wt.%, Ca: 0.6 wt.%, Zr: 0.1 wt.%, B: 0.1 wt.%, and V: 0.2 wt.%. The balance is Al and unavoidable impurities, totaling 100%. Weigh recycled aluminum, Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy, and Al-10Ca master alloy according to the mass percentage of the high-strength and toughness aluminum alloy.

[0067] S2. The recycled aluminum is crushed and sieved in sequence to a particle size of ≤50 mm, and is then passed through a magnetic separator and an eddy current separator to remove magnetic and non-magnetic impurities. After weighing, it is preheated in a resistance furnace at 230°C for 1 hour.

[0068] S3. Set the melting furnace temperature to 730°C. When the melting furnace temperature reaches a predetermined temperature, add the preheated recycled aluminum into the furnace and heat until it is completely melted to obtain an aluminum melt. Add Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy to the aluminum melt. After the alloy is completely melted, refine it and add a refining agent, aluminum chloride, to the melt. The amount of aluminum chloride is 0.55wt.% of the melt. Stir the melt continuously during the addition process. After the addition is completed, heat it to 740°C and keep it at this temperature for 10 minutes.

[0069] S4. After standing still, argon gas was introduced for 15 minutes for degassing. After degassing, the surface was scraped off with a stainless steel spoon to remove the surface scum, and then the alloy was allowed to stand still for 10 minutes to obtain an alloy melt.

[0070] S5. When the temperature of the alloy melt drops to 680°C, casting begins. The stationary aluminum alloy is poured into a square mold preheated to 260°C and air-cooled to obtain a high-strength and tough aluminum alloy based on recycled aluminum.

[0071] The structures and properties of the high-strength and toughness aluminum alloys based on recycled aluminum prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were tested, and the results are as follows: The composition of the high-strength and tough aluminum alloy based on recycled aluminum obtained in Examples 1 to 3 and Comparative Examples 1 to 2 of the present invention was detected using a spectrum analyzer, wherein: In Example 1, the components of the high-strength and toughness aluminum alloy based on recycled aluminum are, by mass percentage: Si: 8.3±0.05wt.%, Mg: 1.6±0.03wt.%, Cu: 1.1±0.02wt.%, Ca: 0.58±0.02wt.%, Zr: 0.13±0.02wt.%, V: 0.22±0.01wt.%, B: 0.06±0.01wt.%, and the remainder is Al and unavoidable impurity elements, of which the total amount of impurity elements Fe and Ni is less than 0.05wt%, totaling 100%.

[0072] In Example 2 and Comparative Example 2, the components of the high-strength and toughness aluminum alloy based on recycled aluminum are, by mass percentage, Si: 9±0.05wt.%, Mg: 1.8±0.05wt.%, Cu: 1.6±0.03wt.%, Ca: 0.6±0.02wt.%, Zr: 0.15±0.02wt.%, V: 0.26±0.01wt.%, B: 0.07±0.01wt.%, and the remainder is Al and unavoidable impurity elements, of which the total amount of impurity elements Fe and Ni is less than 0.05wt%, totaling 100%.

[0073] In Example 3, the components of the high-strength and toughness aluminum alloy based on recycled aluminum are, by mass percentage, Si: 9.7wt.%±0.05wt.%, Mg: 1.96±0.03wt.%, Cu: 1.9±0.02wt.%, Ca: 0.63±0.02wt.%, Zr: 0.18±0.02wt.%, V: 0.28±0.01wt.%, B: 0.07±0.01wt, and the remainder is Al and unavoidable impurity elements, of which the total amount of impurity elements Fe and Ni is less than 0.05wt%, totaling 100%.

[0074] In Comparative Example 1, the components of the high-strength and toughness aluminum alloy based on recycled aluminum are, by mass percentage: Si: 9±0.05wt.%, Mg: 1.8±0.05wt.%, Cu: 1.6±0.03wt.%, Ca: 0.6±0.02wt.%, Zr: 0.15±0.02wt.%, and the remainder is Al and unavoidable impurity elements, of which the total amount of impurity elements Fe and Ni is less than 0.05wt%, totaling 100%.

[0075] The high-strength and tough aluminum alloys based on recycled aluminum prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to mechanical property tests. The high-strength and tough aluminum alloys based on recycled aluminum were processed into tensile performance test specimens for tensile performance tests. The tensile test method complies with the GB / T228.1-2010 standard. The experiment was repeated three times to ensure the accuracy of the data. The results are shown in Table 1.

[0076] Table 1 Mechanical properties of Examples 1 to 3 and Comparative Example 1 As shown in Table 1, the addition of Cu improves the mechanical properties of aluminum alloys through solid solution strengthening and precipitation strengthening mechanisms, significantly increasing their strength. Ca also contributes to strength by segregating along low-angle grain boundaries to dislocation nuclei, reducing dislocation mobility and stabilizing low-angle grain boundaries. Zr refines the alloy grains, and this refined grain structure improves the room-temperature strength of the alloy. Furthermore, Mg forms a solid solution in the Al-Cu alloy, improving the alloy's mechanical properties through solid solution strengthening. The synergistic effect of Zr and BV significantly enhances the grain refinement effect. Combining the strengthening effects of these alloying elements with ultrasonic treatment, and based on a designed alloy derived from a decontaminated recycled aluminum alloy with high room-temperature strength, the tensile strength of this experimental alloy is expected to exceed that of conventional recycled aluminum alloys, potentially reaching a high level, ranging from 280 MPa to 320 MPa. As a modifier, Ca can change the morphology of eutectic silicon, transforming it from coarse plates or needles to fine fibers or particles. This refinement significantly improves the alloy's plasticity and fatigue resistance. Zr can indirectly regulate the morphology of eutectic silicon, reducing the coarsening tendency of the eutectic silicon phase and alleviating the cleavage effect of needle-shaped silicon on the matrix, thereby improving the alloy's fracture toughness. It also synergizes with elements such as B and V to form a composite synergistic strengthening effect, which is beneficial for improving toughness. Considering these elements and the positive effects of ultrasonic treatment on toughness, the toughness of the experimental alloy is expected to be significantly improved compared to conventional recycled aluminum alloys, with the elongation potentially increasing by approximately 10% to 30%, reaching 7% to 9%.

[0077] It should be noted that when numerical ranges are mentioned in the present invention, it should be understood that both endpoints of each numerical range and any value between the two endpoints may be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes preferred embodiments. Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0078] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a high-strength and tough aluminum alloy based on recycled aluminum, characterized in that: The following steps are involved: The recycled aluminum is sequentially crushed, screened, impurity-removed, and preheated, and the preheated recycled aluminum is heated until it is completely melted to obtain aluminum melt; Adding Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy into an aluminum melt, and after the alloy is completely melted, sequentially performing stirring, refining, degassing and deslagging processes to obtain an alloy melt; The alloy melt is ultrasonically treated, firstly performing a first ultrasonic treatment at a power of 50% to 60%, then performing a second ultrasonic treatment at a power of 70% to 80%, and finally performing a third ultrasonic treatment at a power of 50% to 60%. After the ultrasonic treatment, the alloy melt is allowed to stand and heat-insulate to obtain an aluminum alloy precursor. The aluminum alloy precursor is cast to obtain a high-strength and tough aluminum alloy.

2. The method for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The high strength and toughness aluminum alloy is composed of Si: 8wt.%~10wt.%, Mg: 1.5wt.%~2.0wt.%, Cu: 1.0wt.%~2.0wt.%, Ca: 0.55wt.%~0.65wt.%, Zr: 0.1wt.%~0.2wt.%, B: 0.05wt.%~0.1wt.%, V: 0.2wt.%~0.3wt.%, the remainder is Al and unavoidable impurity elements, totaling 100%.

3. The method for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The temperature for heating to complete melting is 720℃~750℃.

4. The method for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The degassing method is: introduce protective gas for 10 minutes to 15 minutes.

5. The method for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The power of ultrasonic treatment is 1000W to 1600W, the time of the first ultrasonic treatment is 5min to 10min, the time of the second ultrasonic treatment is 10min to 15min, and the time of the third ultrasonic treatment is 4min to 6min.

6. The method for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The standing and heat preservation time is 15min to 20min, and the temperature is 720℃ to 730℃.

7. The method for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to claim 1, characterized in that: Before casting, the temperature of the aluminum alloy precursor is 680°C to 720°C.

8. The method for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to claim 1, characterized in that: During the casting process, the mold temperature is 260℃~280℃, and the cooling method after casting is air cooling.

9. The method for preparing a high-strength and tough aluminum alloy based on recycled aluminum according to claim 2, characterized in that: The preheating temperature of the recycled aluminum is 200℃~300℃. Before heating and melting the Al-30Si master alloy, Al-50Cu master alloy, Al-Mn master alloy, Al-10Mg master alloy, Al-5Zr master alloy, Al-5B master alloy, Al-5V master alloy and Al-10Ca master alloy, they are polished to remove the surface oxide layer and then preheated to 200℃~300℃.

10. A high-strength and tough aluminum alloy based on recycled aluminum, characterized in that: The high-strength and toughness aluminum alloy based on recycled aluminum is prepared by the preparation method of any one of claims 1 to 9.

Images