Heat-treatment-free die-casting aluminum alloy based on secondary aluminum and preparation method and structural part thereof

Abstract

The invention provides a preparation method of a heat-treatment-free die-casting aluminum alloy based on secondary aluminum. The preparation method comprises the following steps: testing secondary aluminum liquid; calculating the adding amounts of Si, Cu, Mn, Mg, Zn, Ti, RE, Sr and B; si, Cu, Mn, Mg, Zn, Ti and B are added into the regenerated aluminum liquid, and alloy liquid is obtained; refining, electromagnetic stirring, slagging-off and die-casting treatment are conducted, and the aluminum alloy parts are obtained; the aluminum alloy is obtained through low-temperature quenching treatment, the aluminum alloy contains 6 wt%-9 wt% of Si, 0.1 wt%-0.6 wt% of Fe, 0.01 wt%-0.4 wt% of Cu, 0.01 wt%-0.8 wt% of Mn, 0.01 wt%-0.5 wt% of Mg, 0.01 wt%-0.5 wt% of Zn, 0.01 wt%-0.2 wt% of Ti, 0-0.1 wt% of RE, 0-0.05 wt% of Sr and 0-0.01 wt% of B. The low-temperature quenching treatment temperature ranges from-150 DEG C to 0 DEG C, and the time ranges from 0.1 h to 10 h. The invention also provides the aluminum alloy and the structural member prepared by the method.

Description

[0001] This invention is a divisional application, the original application number is 202410672817.7, the application date is May 28, 2024, and the name is heat-treatment-free die-cast aluminum alloy based on recycled aluminum and its preparation method and structural parts. Technical Field

[0002] The present invention relates to the technical field of aluminum alloys, and in particular to a method for preparing a heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the heat-treatment-free die-cast aluminum alloy prepared by the preparation method, and a structural part. Background Art

[0003] To improve demolding performance, Fe needs to be added to heat-treatment-free die-cast aluminum alloys (such as Al-Si-based heat-treatment-free die-cast aluminum alloys). The Fe addition level must be greater than 0.6wt%. However, excessive Fe can easily form needle-shaped or flaky β-AlFeSi phases, reducing the plasticity of the aluminum alloy. When the Fe addition level is reduced, an appropriate amount of Mn can be added to ensure that the aluminum alloy has good anti-sticking properties while avoiding the formation of needle-shaped or flaky β-AlFeSi phases. Due to the low Fe content required, the industry currently primarily uses electrolytic aluminum ingots to directly formulate heat-treatment-free die-cast aluminum alloys. Recycled aluminum (high in Fe content) cannot be used, which results in higher costs.

[0004] Therefore, there is an urgent need to develop a heat-treatment-free die-cast aluminum alloy with low cost and excellent tensile strength, yield strength, and elongation. Summary of the Invention

[0005] In response to the above-mentioned defects of the prior art, the present invention provides a heat-treatment-free die-cast aluminum alloy based on recycled aluminum, aiming to ensure that the heat-treatment-free die-cast aluminum alloy based on recycled aluminum has lower cost and better tensile strength, yield strength, and elongation.

[0006] The present invention also provides a method for preparing a heat-treatment-free die-cast aluminum alloy based on recycled aluminum, comprising the following steps: Providing recycled aluminum; heating the recycled aluminum to obtain recycled aluminum liquid; Performing chemical analysis on the regenerated aluminum liquid to obtain the elements and contents of the regenerated aluminum liquid; Calculate the amounts of Si, Cu, Mn, Mg, Zn, Ti, Sr, RE, and B to be added to the recycled aluminum liquid based on the elements and contents of the recycled aluminum liquid and the elements and contents of the preset heat-treatment-free die-casting aluminum alloy based on the recycled aluminum; adding Si, Cu, Mn, Mg, Zn, Ti, Sr, RE and B to the regenerated aluminum liquid and performing a second heating treatment to obtain an alloy liquid; The alloy liquid is subjected to refining treatment, electromagnetic stirring, slag removal treatment, and die casting treatment to obtain aluminum alloy parts; and The aluminum alloy parts are subjected to low-temperature quenching treatment to obtain the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, wherein the heat-treatment-free die-cast aluminum alloy based on recycled aluminum contains Al, and also contains Si with a mass percentage content of 6-9%, Fe with a mass percentage content of 0.1-0.6%, Cu with a mass percentage content of 0.01-0.4%, Mn with a mass percentage content of 0.01-0.8%, Mg with a mass percentage content of 0.01-0.5%, Zn with a mass percentage content of 0.01-0.5%, Ti with a mass percentage content of 0.01-0.2%, RE with a mass percentage content of 0-0.1%, Sr with a mass percentage content of 0-0.05%, and B with a mass percentage content of 0-0.01%. The temperature of the low-temperature quenching treatment is -150~0°C, and the time is 0.1~10h.

[0007] Furthermore, the temperature of the low-temperature quenching treatment is -140~0°C, and the time is 0.1~10h.

[0008] Furthermore, the heat-treatment-free die-cast aluminum alloy based on recycled aluminum contains 7-9% Si by mass, 0.2-0.5% Fe by mass, 0.1-0.3% Cu by mass, 0.3-0.7% Mn by mass, 0.2-0.4% Mg by mass, 0.2-0.4% Zn by mass, 0.1-0.2% Ti by mass, 0-0.1% RE by mass, 0.005-0.05% Sr by mass, and 0.005-0.01% B by mass.

[0009] Furthermore, in the regenerated aluminum liquid, the mass ratio of Mn to Fe is 0.5-2:1.

[0010] Furthermore, the preparation method further comprises the step of adding at least one of Co, Be, and Ca to the regenerated aluminum liquid, wherein at least one of the following conditions is met: In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Co is 0-0.1%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Be is 0-0.1%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Ca is 0-0.1%.

[0011] Furthermore, in the regenerated aluminum liquid, the mass ratio of Co to Fe is 0.2-1:1.

[0012] Furthermore, the preparation method also includes the step of adding C to the recycled aluminum liquid, wherein the mass percentage content of C in the heat treatment-free die-casting aluminum alloy based on recycled aluminum is 0-0.05%.

[0013] Furthermore, the preparation method further comprises the step of adding at least one of Nb, Ni, Te, In, Mo, Ag, Cd, V, Sn, Zr, Sb, and Bi to the regenerated aluminum liquid, wherein at least one of the following conditions is met: In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Nb is 0-0.1%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Ni is 0-0.2%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Te is 0-0.1%; In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of In is 0-0.1%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Mo is 0-0.2%; In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Ag is 0-0.1%; In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Cd is 0-0.05%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage of V is 0-0.2%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Sn is 0-0.08%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Zr is 0-0.2%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Sb is 0-0.2%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Bi is 0-0.2%.

[0014] The present invention provides a heat treatment-free die-casting aluminum alloy based on recycled aluminum prepared by the preparation method.

[0015] The present invention also provides a structural component, at least part of which is made of the heat-treatment-free die-cast aluminum alloy based on recycled aluminum.

[0016] In the technical solution of the present invention, the preparation method of the heat-treatment-free die-cast aluminum alloy based on recycled aluminum uses recycled aluminum as raw material to reduce costs. Unlike primary aluminum, the Fe content range in recycled aluminum is relatively wide, and the types of impurity elements are too many and the content is relatively high. In order to improve the utilization rate of recycled aluminum, on the one hand, it is necessary to have a large tolerance for high Fe content. The higher the Fe content, the worse the overall performance. It is necessary to regulate the Fe content / Fe morphology to reduce the Fe damage; on the other hand, it is also necessary to have a strong tolerance for the characteristics of the recycled aluminum alloy with more impurity element types and a higher impurity element composition range to reduce the impact of impurity elements on the alloy performance.

[0017] Si, Cu, Mn, Mg, Zn, Ti, Sr, and B are added to the recycled aluminum liquid. Si, Cu, Mn, Mg, Zn, Ti, Sr, and B influence and interact with each other, which solves the shortcomings of high Fe content, many types of impurity elements, and high content in recycled aluminum, and obtains a heat-treatment-free die-cast aluminum alloy with a tensile strength greater than 260 MPa, a yield strength greater than 120 MPa, and an elongation greater than 10%. The heat-treatment-free die-cast aluminum alloy based on recycled aluminum contains 6-9% Si by mass, 0.1-0.6% Fe by mass, 0.01-0.4% Cu by mass, 0.01-0.8% Mn by mass, 0.01-0.5% Mg by mass, 0.01-0.5% Zn by mass, 0.01-0.2% Ti by mass, 0-0.05% Sr by mass, and 0-0.01% B by mass. Specifically: (1) Si can improve the process flow properties of aluminum alloys, but when the content is too high, it will reduce the elongation. Si can also react with Al, Fe, Mg, Cu, B, etc. to form second phases such as Mg2Si, AlFeSi, AlFeSiCu, AlFeMgSi, AlCuMgSi, AlFeSiB, etc., to improve the tensile strength and yield strength of aluminum alloys; (2) Mg can react with Al, Fe, Si, Cu, Zn, etc. to form second phases such as AlFeMgSi, (CuMg)Al2, AlCuMgSi, Mg2Si, Mg2Zn, Mg2SiZn, etc., to improve the tensile strength and yield strength of aluminum alloys. Among them, Mg forms (CuMg)Al2 phase and AlFeSiMg phase when it is solid-dissolved in CuAl2 phase and AlFeSi phase; (3) Cu can react with Al, Fe, Si, Mg, Zn, etc. to form second phases such as CuAl2, AlFeSiCu, AlCuMgSi, Al2CuZn, (CuMg)Al2, etc., to improve the tensile strength and yield strength of aluminum alloys. It can also promote the precipitation of second phases such as Mg2Si, Mg2Zn, Mg2SiZn, etc., and increase the volume fraction and dispersion of the precipitated phases. Subsequent natural aging treatment or vehicle paint baking heat treatment (referred to as T85 treatment) can further improve the aging strengthening effect of Cu and Mg. (4) Zn can react with Al, Mg, Cu and Si to form second phases such as MgZn2, Mg2SiZn, Al2CuZn, etc., to improve the tensile strength and yield strength of aluminum alloys. Zn can eliminate elemental Si to reduce the effect of Si on the properties of aluminum alloys. It can also promote the precipitation of phases such as Mg2Si, Mg2Zn, Mg2SiZn, Al2Cu, etc., and increase the volume fraction and dispersion of the precipitated phases. (5) Fe can improve demolding performance and react with Al, Si, Mg, Cu, and B to form second phases such as Al3Fe, AlFeSi, AlFeMgSi, AlFeSiCu, and AlFeSiB, thereby increasing the tensile strength and yield strength of aluminum alloys. However, the Fe content and / or Fe morphology need to be controlled; (6) Mn can react with Al, Fe, Si, and Cu to form MnAl2, MnAl6, α-(Fe, Mn)Al6, Al 12 CuMn2, α-Al(FeMn)Si, τ(Cu2Mn3Al 20) and other second phases to improve the tensile strength and yield strength of aluminum alloys; Mn can significantly refine the grain size by lattice distortion produced by solid solution in the matrix and MnAl6 dispersed particles produced by reaction with Al to improve elongation, and MnAl6 can also dissolve Fe to form α-(Fe,Mn)Al6 phase to reduce Fe content and reduce Fe damage; Mn forms spherical granular or Chinese character-shaped AlFeMnSi compound phases with Al, Fe, Mn and Si to avoid the formation of long needle-shaped Fe phase to reduce Fe damage, and improve the tensile strength and yield strength of aluminum alloys while improving the demoulding properties of aluminum alloys; Mn can transform coarse needle-shaped β-AlFeSi phase into small granular α-Al(FeMn)Si phase dispersed particles to improve Fe morphology and eliminate Fe damage. Specifically, Mn can replace part of the Fe in the coarse needle-shaped β-AlFeSi phase to form small granular dispersed β- The formation and growth shape of the Al(FeMn)Si phase and β phase are improved, thereby reducing Fe damage. Mn also promotes the transformation of the needle-shaped β-Al(FeMn)Si phase into small granular α-Al(FeMn)Si dispersed phase. The resulting α-Al(FeMn)Si phase dispersed particles are distributed in the aluminum matrix and strongly pinned to the subgrain boundaries of the aluminum alloy. This is mainly because the Mn-containing α phase dispersed particles in the aluminum alloy can serve as heterogeneous nucleation sites for the β′ phase during aging, inducing its nucleation, thereby accelerating the precipitation of the β′ phase. Mn can also react with impurities in the recycled aluminum liquid to form Al-Mn-X phases (X is an impurity element, including but not limited to transition metal elements such as Fe, Cr, Sn, Pb, Cd, etc.), thereby purifying the recycled aluminum liquid. These phases can serve as grain nucleation sites to increase the nucleation rate and refine the grains. Purification can improve the alloy's tensile strength, yield strength, elongation, and fluidity. (7) Sr preferentially combines with Fe to form dispersion strengthening, reducing the solid solubility of Fe in recycled aluminum, thereby improving the yield strength and tensile strength of aluminum alloys; Sr can change the behavior of intermetallic compound phases in crystallography and can be used as a modifier to refine grains and second phases by modifying aluminum alloys through heterogeneous nucleation theory or twin valley mechanism. For example, Sr can change the morphology of eutectic silicon phase through modification, thereby improving the elongation of aluminum alloys and reducing the tendency of die sticking during die casting; Sr can transform the coarse needle-shaped β-AlFeSi and β-AlFeMnSi phases in the ingot into small granular Chinese character-shaped α-AlFeSi and α-Al(FeMn)Si phases, reducing the ingot homogenization time and improving the yield strength, tensile strength and elongation of aluminum alloys; (8) The TiAl2 phase generated by the reaction of Ti and Al acts as a non-spontaneous core during crystallization, which can refine the grains, second phases and precipitated phases to improve the tensile strength, yield strength and elongation of the aluminum alloy; (9) B can undergo boronization reaction with transition metal elements (including Fe and other transition metal elements) to generate compounds such as boron iron compounds that can be separated from the regenerated aluminum liquid, thereby reducing the content of transition metal elements such as Fe and purifying the regenerated aluminum liquid; B is easily adsorbed on the surface of the iron-rich phase, inhibiting the growth of the iron-rich phase, playing a role in controlling the size of the iron-rich phase, and also preventing the formation of the iron-rich phase in the regenerated aluminum liquid; B can inhibit the segregation of Ti3Al, therefore, the effect is better when Ti and B are used together; B can also refine the grains and the second phase to improve the elongation of the aluminum alloy.

[0018] The combination of B, Mn, and Sr within the above content range can regulate the Fe content and improve the Fe morphology to eliminate the Fe hazards, thereby overcoming the defect of a wide and high Fe content range in recycled aluminum; the combined effect of Si, Cu, Mn, Mg, Zn, Ti, Sr, and Fe within the above content range can improve the tensile strength and yield strength of the aluminum alloy; the combined effect of Mn, B, Ti, and Sr within the above content range can refine the grains, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy; Cu and Zn within the above content range can promote the precipitation of the second phase, increase the volume fraction and dispersion of the precipitated phase, and further improve the tensile strength, yield strength, and elongation of the aluminum alloy; B and Mn within the above content range can also purify the recycled aluminum liquid, remove impurity elements, and cooperate with refining treatment and slag skimming treatment to remove as many impurity elements as possible. In addition, the present invention maximizes the range of Mn and Ti content. The combination of Mn, B, and Ti effectively regulates Fe, purifies the recycled aluminum liquid, promotes the precipitation of precipitated phases, and refines grains, secondary phases, and precipitated phases. To increase the raw material source for alloy smelting and fully utilize recycled aluminum resources, the content range of at least one of the main elements Fe, Cu, Mn, Mg, Zn, and Ti is increased. By maintaining a reasonable ratio of these elements, even if the recycled aluminum alloy contains too many impurity elements and too high a content, the combination of these elements can produce a heat-treatment-free die-cast aluminum alloy with excellent performance.

[0019] The present invention uses recycled aluminum as raw material, which has significant advantages in energy conservation and emission reduction. The production energy consumption of recycled aluminum is only 4.9% of that of primary aluminum, and the carbon emissions are only 4.2% of that of primary aluminum. Compared with using primary aluminum as raw material, the present invention is relatively low in cost. Moreover, under the combined action of Si, Cu, Mn, Mg, Zn, Ti, Sr, Fe, and B within the above-mentioned content ranges, combined with refining treatment, electromagnetic stirring, and slag removal, the Fe content and Fe morphology in the recycled aluminum are effectively regulated, and the types and content ranges of impurity elements are expanded, resulting in a heat-treatment-free die-cast aluminum alloy with excellent comprehensive performance. In addition, the prices of Si, Cu, Mn, Mg, Zn, Ti, Sr, and B are all relatively low, and the Si content is no more than 9%, which can further reduce costs.

[0020] Since the mechanical properties of the heat-treatment-free die-cast aluminum alloy cannot be improved by aging heat treatment, most of the solute atoms of the heat-treatment-free die-cast aluminum alloy based on recycled aluminum of the present invention are usually present in the aluminum matrix in the form of solid solution. In addition to grain refinement, the strength increase of the heat-treatment-free die-cast aluminum alloy mainly comes from the pinning of dislocations by the lattice volume mismatch and elastic mismatch caused by the solid solution atoms, that is, solid solution strengthening.

[0021] Heat-treatment-free die-cast aluminum alloys undergo natural aging during storage and transportation after die-casting, meaning their strength increases with extended storage time. This natural aging is attributed to the aggregation of solute atoms in the aluminum alloy, known as solute atom clusters. Solute atom clusters are disordered aggregations of solute atoms within the aluminum matrix, measuring several nanometers in size and typically consisting of a few to dozens of randomly distributed atoms with no clear crystal structure.

[0022] The change in the strength of the heat-treatment-free die-cast aluminum alloy is mainly related to the size and volume fraction of the solute atomic clusters. During the natural aging process, the formation and growth of the clusters are closely related to the change in the concentration of supersaturated quenching vacancies. Vacancies are thermal defects, and their concentration has an exponential function relationship with temperature. The present invention performs a low-temperature quenching treatment on the aluminum alloy parts after the die-casting treatment to produce supersaturated vacancies, thereby improving the mechanical properties of the heat-treatment-free die-cast aluminum alloy. Specifically, during the die-casting process, the equilibrium vacancy concentration is relatively large; during the subsequent quenching treatment, some vacancies at high temperature are retained, thereby producing supersaturated vacancies; moreover, the low-temperature quenching treatment can also cause the aluminum alloy to shrink, produce plastic deformation, and reduce the solubility of elements in aluminum, increase the nucleation points of the clusters, and refine the α-Al phase and eutectic Si phase structure to improve the yield strength, tensile strength and elongation of the heat-treatment-free die-cast aluminum alloy.

[0023] The addition of Cu, Mn, Mg, Zn, Ti, Sr, Fe, and B can also regulate the clustering behavior of solute atoms in aluminum alloys, such as affecting the formation of existing clusters and the formation of new clusters by regulating vacancies. After adding Mg (0.01-0.5wt%) and Cu (0.01-0.4wt%) elements within a certain content range to the recycled aluminum liquid of the present invention, the Mg atoms activate the diffusion of vacancies and promote the formation of Mg-Si clusters and Cu-Mg clusters, significantly strengthening the clusters. The atomic radius of Mn and Sr is much larger than that of Al. The Mn and Sr atoms within the above content range form lattice distortion in the aluminum matrix. In addition, the pinning vacancies and Mg-Si clusters and Cu-Mg clusters added to the heat-treatment-free aluminum alloy promote the growth of clusters, further promoting the natural aging effect, thereby improving the yield strength, tensile strength, and elongation of the heat-treatment-free aluminum alloy.

[0024] In summary, under the combined action of Si, Cu, Mn, Mg, Zn, Ti, Sr, Fe and B within the above-mentioned content range, a heat-treatment-free die-cast aluminum alloy based on recycled aluminum is obtained with excellent demolding performance, tensile strength, yield strength, and elongation. DETAILED DESCRIPTION

[0025] The following is a clear and complete description of 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 them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0026] The present invention provides a method for preparing a heat-treatment-free die-cast aluminum alloy based on recycled aluminum, comprising the following steps: Providing recycled aluminum; Heating the recycled aluminum at a temperature of 680-720° C. to obtain recycled aluminum liquid; Performing chemical analysis on the regenerated aluminum liquid to obtain the elements and contents of the regenerated aluminum liquid; Designing the amounts of Si, Cu, Mn, Mg, Zn, Ti, and B to be added to the recycled aluminum liquid based on the elements and contents of the recycled aluminum liquid and the elements and contents of the preset heat-treatment-free die-casting aluminum alloy based on the recycled aluminum; Adding B to the regenerated aluminum liquid at a temperature of 710-740°C and stirring with electromagnetic stirring; Adding Si, Cu, Mn, Mg, Zn, and Ti to the regenerated aluminum liquid at a temperature of 740-780° C., heating the liquid and subjecting it to electromagnetic stirring to obtain an alloy liquid; and The alloy liquid is subjected to refining treatment, electromagnetic stirring, slag removal treatment, and die casting treatment to obtain aluminum alloy parts; and The aluminum alloy parts are subjected to low-temperature quenching treatment to obtain the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, which contains Al, and also contains Si with a mass percentage content of 6-9%, Fe with a mass percentage content of 0.1-0.6%, Cu with a mass percentage content of 0.01-0.4%, Mn with a mass percentage content of 0.01-0.8%, Mg with a mass percentage content of 0.01-0.5%, Zn with a mass percentage content of 0.01-0.5%, Ti with a mass percentage content of 0.01-0.2%, Sr with a mass percentage content of 0-0.05%, B with a mass percentage content of 0-0.01%, and unavoidable impurities.

[0027] Recycled aluminum is aluminum alloy extracted by remelting scrap aluminum, scrap aluminum alloy, or aluminum-containing waste.

[0028] It is understood that the preset heat-treatment-free die-cast aluminum alloy based on recycled aluminum contains 6-9% Si by mass, 0.1-0.6% Fe by mass, 0.01-0.4% Cu by mass, 0.01-0.8% Mn by mass, 0.01-0.5% Mg by mass, 0.01-0.5% Zn by mass, 0.01-0.2% Ti by mass, 0-0.05% Sr by mass, 0-0.01% B by mass, and unavoidable impurities. After the alloy liquid is subjected to refining, electromagnetic stirring, and slag removal, the elements and contents of the alloy liquid can be tested again. If the elements and contents of the detected alloy liquid are inconsistent with the elements and contents of the preset heat-treatment-free die-cast aluminum alloy based on recycled aluminum, a certain amount of elements are added accordingly; if the two are consistent, die casting is carried out.

[0029] In one embodiment, the heat-treatment-free die-casting aluminum alloy based on recycled aluminum contains 7-9% Si by mass, 0.2-0.5% Fe by mass, 0.1-0.3% Cu by mass, 0.3-0.7% Mn by mass, 0.2-0.4% Mg by mass, 0.2-0.4% Zn by mass, 0.1-0.2% Ti by mass, 0.005-0.05% Sr by mass, and 0.005-0.01% B by mass.

[0030] Ice water or liquid nitrogen can be used for low-temperature quenching. The temperature of the low-temperature quenching treatment is -200~0°C, specifically -200°C, -190°C, -180°C, -170°C, -160°C, -150°C, -140°C, -130°C, -120°C, -110°C, -100°C, -90°C, -80°C, -70°C, -60°C, -50°C, -40°C, -30°C, -20°C, -10°C, -9°C, -8°C, -7°C, -6°C, -5°C, -4°C, -3°C, -2°C, -1°C, or 0°C. The low-temperature quenching treatment time is 0.1 to 10 hours, specifically 0.1 hour, 0.5 hour, 1 hour, 5 hours, or 10 hours. It is understood that ice / ice water and liquid nitrogen can be added in a timely manner to maintain the low-temperature quenching temperature at no more than 0°C, retain as many vacancies as possible, and ensure the generation of supersaturated vacancies.

[0031] Electromagnetic stirring accelerates the dissolution of Mn and allows more elements, such as Mn, to react evenly with Fe, resulting in a more dispersed and fine α-Al(FeMn)Si phase, thus enhancing the Fe modification effect. The electromagnetic stirring frequency ranges from 10 to 30 Hz, and the duration ranges from 1 to 10 minutes. This electromagnetic stirring process can refine grains and alter the morphology of the Fe phase (for example, transforming long, needle-like or massive Al(FeMn)Si phases into dispersed, nanoscale, spherical Al(MnFe)Cu phases).

[0032] Before the recycled aluminum undergoes its initial heat treatment, it can undergo pretreatment, such as sorting, crushing, magnetic separation for iron removal, and cleaning. The recycled aluminum can also undergo an initial test of its composition and content, perhaps using a photoelectric direct-reading spectrometer or chemical analysis. This allows recycled aluminum with similar composition and content to be blended based on the test results, avoiding situations where the blended recycled aluminum has an overly complex composition, excessive or substandard content of certain elements. Before testing the recycled aluminum liquid, it can undergo a refining process to remove impurities such as surface scum.

[0033] In one embodiment, the refining process is performed at a temperature of 690-750°C for 10-20 minutes. The refining agent may include the following raw materials in parts by weight: 60-70 parts KF, 50-60 parts NaCl, 40-60 parts LiCl, 20-25 parts cryolite, 10-25 parts AIF3, 10-15 parts CaF2, 5-10 parts light calcium carbonate, 15-20 parts graphite powder, 10-20 parts talc, 20-30 parts MgCl2, and 10-30 parts rare earth salt. The rare earth salt may be a combination of one or more of a light rare earth chloride, fluoride, or nitric acid compound. The rare earth salt may be a combination of one or more of a heavy rare earth chloride, fluoride, or nitric acid compound. The mass ratio of the refining agent to the recycled aluminum liquid is 0.0013-0.0018:1.

[0034] In another embodiment, the alloy liquid is subjected to a refining treatment at a temperature of 710-735°C for 10-30 minutes, wherein the mass ratio of the refining agent to the alloy liquid is 0.01-0.05:1, and the refining agent comprises a metal salt and hexachloroethane at a mass ratio of 0.5-1.5:1, wherein the metal salt is at least one of aluminum fluoride, sodium fluoride, sodium nitrate, aluminum nitrate, manganese chloride, zinc chloride, and sodium chloride. In one embodiment, the mass ratio of the fluoride salt, nitrate salt, and chloride salt is 1:0.5-1.5:0.5-1.5.

[0035] The molten alloy is die-casted at a temperature of 660-700°C, with the die-casting machine operating at a speed of 0.23-2.5 m / s. It is understood that the die-casting process of the present invention is conventional die-casting, but vacuum die-casting can also be used to die-cast the molten alloy. The strength (e.g., yield strength and tensile strength) and elongation of the aluminum alloy after vacuum die-casting are higher than those of the aluminum alloy after conventional die-casting.

[0036] The mass ratio of Mn to Fe in the recycled aluminum liquid and the alloy liquid can be 0.5-2:1, preferably 0.6-1.5:1, and specifically 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.14:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, or 2:1. During the die-casting process, the cooling rate is high, and Fe forms a small, short rod-like or block-like Al-Fe phase or Al-Fe-Si phase, preventing Fe from affecting elongation.

[0037] The mass percentage content of Si may be 6%, 6.2%, 6.4%, 6.6%, 6.7%, 6.8%, 6.9%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, 8.2%, 8.4%, 8.6%, 8.8%, or 9%. The mass percentage content of Fe may be 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.42%, 0.44%, 0.46%, 0.48%, 0.5%, 0.52%, 0.54%, 0.56%, 0.58%, or 0.6%. The mass percentage content of Cu can specifically be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.22%, 0.24%, 0.26%, 0.28%, 0.3%, 0.32%, 0.34%, 0.36%, 0.38%, or 0.4%. The mass percentage content of Mn can be specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.40%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, 0.50%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58%, 0.59%, 0.60%, 0.61%, 0.62%, 0.63%, 0.64%, 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.70%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.80%, 0.81%, 0.82%, 0.83%, 0.84 9%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.42%, 0.44%, 0.46%, 0.48%, 0.5%, 0.52%, 0.54%, 0.56%, 0.58%, 0.6%, 0.62%, 0.64%, 0.66%, 0.68%, 0.7%, 0.72%, 0.74%, 0.76%, 0.78%, or 0.8%.The mass percentage content of Mg can be specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.42%, 0.44%, 0.46%, 0.48%, or 0.5%. The mass percentage content of Zn can specifically be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.2%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.3%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, 0.39%, 0.4%, 0.42%, 0.44%, 0.46%, 0.48%, or 0.5%. The mass percentage content of Ti may be 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.2%. The mass percentage content of B may be 0-0.01%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, or 0.01%. The mass percentage content of Sr can be 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, or 0.05%. Si, Cu, Mn, Mg, Zn, Ti, Sr, and B can be added in the form of simple elements or alloys. The intermediate alloy has good dispersibility and is easily dissolved in the recycled aluminum liquid. In the heat-treatment-free die-casting aluminum alloy based on recycled aluminum, the content of a single impurity does not exceed 0.05%, and the total impurity content does not exceed 0.15%.

[0038] When the Si content is high (>7%), the fluidity of the aluminum alloy melt is significantly improved, and the hardness and strength of the alloy are also correspondingly increased. However, high Si content can significantly reduce the alloy's plasticity. The presence and micromorphology of Si in the matrix have a significant impact on the alloy's properties. Through the combined application of methods such as elemental modification and electromagnetic stirring, the morphology and distribution of the Si phase can be significantly improved, minimizing the detrimental effects of Si on the alloy's properties. The main function of Si is to increase the fluidity of the aluminum alloy while also improving its strength within a certain range.

[0039] Mg has a significant effect on strengthening Al. If added together with less than 1% Mn, a composite strengthening effect can be produced. Therefore, adding Mn can reduce the Mg content and reduce the tendency to hot cracking. In addition, Mn can also precipitate Mg5Al8 compounds, improving corrosion resistance and welding properties. When the Mg content is less than 0.5wt.%, the yield strength is linearly related to the increase in Mg content. When the Mg content is greater than 0.5wt.%, the linear relationship is broken, and the strengthening response of the Al-Si-Mg alloy is reduced. This is related to the formation of the AlFeMgSi phase, which occupies a large number of Mg atoms, making it difficult to precipitate and strengthen.

[0040] Adding a small amount of Zn can produce a strong solid solution strengthening effect, significantly improving the strength of aluminum alloys. Zn can promote the precipitation of primary Si, reduce the solid solubility of Si in Al, enhance the precipitation strengthening effect of aluminum alloys, promote the aging precipitation kinetics of aluminum alloys, and increase the density of precipitated phases in the matrix. Zn can improve fluidity, increase hot brittleness, and reduce corrosion resistance in die-cast aluminum alloys.

[0041] In the technical solution of the present invention, the preparation method of the heat-treatment-free die-cast aluminum alloy based on recycled aluminum uses recycled aluminum as raw material to reduce costs. Unlike primary aluminum, the Fe content range in recycled aluminum is relatively wide, and the types of impurity elements are too many and the content is relatively high. In order to improve the utilization rate of recycled aluminum, on the one hand, it is necessary to have a large tolerance for high Fe content. The higher the Fe content, the worse the overall performance. It is necessary to regulate the Fe content / Fe morphology to reduce the Fe damage; on the other hand, it is also necessary to have a strong tolerance for the characteristics of the recycled aluminum alloy with more impurity element types and a higher impurity element composition range to reduce the impact of impurity elements on the alloy performance.

[0042] Si, Cu, Mn, Mg, Zn, Ti, Sr, and B are added to the recycled aluminum liquid. Si, Cu, Mn, Mg, Zn, Ti, Sr, and B influence and interact with each other, which solves the shortcomings of high Fe content, many types of impurity elements, and high content in recycled aluminum, and obtains a heat-treatment-free die-cast aluminum alloy with a tensile strength greater than 260 MPa, a yield strength greater than 120 MPa, and an elongation greater than 10%. The heat-treatment-free die-cast aluminum alloy based on recycled aluminum contains 6-9% Si by mass, 0.1-0.6% Fe by mass, 0.01-0.4% Cu by mass, 0.01-0.8% Mn by mass, 0.01-0.5% Mg by mass, 0.01-0.5% Zn by mass, 0.01-0.2% Ti by mass, 0-0.05% Sr by mass, and 0-0.01% B by mass. Specifically: (1) Si can improve the process flow properties of aluminum alloys, but when the content is too high, it will reduce the elongation. Si can also react with Al, Fe, Mg, Cu, B, etc. to form second phases such as Mg2Si, AlFeSi, AlFeSiCu, AlFeMgSi, AlCuMgSi, AlFeSiB, etc., to improve the tensile strength and yield strength of aluminum alloys; (2) Mg can react with Al, Fe, Si, Cu, Zn, etc. to form second phases such as AlFeMgSi, (CuMg)Al2, AlCuMgSi, Mg2Si, Mg2Zn, Mg2SiZn, etc., to improve the tensile strength and yield strength of aluminum alloys. Among them, Mg forms (CuMg)Al2 phase and AlFeSiMg phase when it is solid-dissolved in CuAl2 phase and AlFeSi phase; (3) Cu can react with Al, Fe, Si, Mg, Zn, etc. to form second phases such as CuAl2, AlFeSiCu, AlCuMgSi, Al2CuZn, (CuMg)Al2, etc., to improve the tensile strength and yield strength of aluminum alloys. It can also promote the precipitation of second phases such as Mg2Si, Mg2Zn, Mg2SiZn, etc., and increase the volume fraction and dispersion of the precipitated phases. Subsequent natural aging treatment or vehicle paint baking heat treatment (referred to as T85 treatment) can further improve the aging strengthening effect of Cu and Mg. (4) Zn can react with Al, Mg, Cu and Si to form second phases such as MgZn2, Mg2SiZn, Al2CuZn, etc., to improve the tensile strength and yield strength of aluminum alloys. Zn can eliminate elemental Si to reduce the effect of Si on the properties of aluminum alloys. It can also promote the precipitation of phases such as Mg2Si, Mg2Zn, Mg2SiZn, Al2Cu, etc., and increase the volume fraction and dispersion of the precipitated phases. (5) Fe can improve demolding performance and react with Al, Si, Mg, Cu, and B to form second phases such as Al3Fe, AlFeSi, AlFeMgSi, AlFeSiCu, and AlFeSiB, thereby increasing the tensile strength and yield strength of aluminum alloys. However, the Fe content and / or Fe morphology need to be controlled; (6) Mn can react with Al, Fe, Si, and Cu to form MnAl2, MnAl6, α-(Fe, Mn)Al6, Al 12 CuMn2, α-Al(FeMn)Si, τ(Cu2Mn3Al 20 ) and other second phases to improve the tensile strength and yield strength of aluminum alloys; Mn can significantly refine the grain size by lattice distortion produced by solid solution in the matrix and MnAl6 dispersed particles produced by reaction with Al to improve elongation, and MnAl6 can also dissolve Fe to form α-(Fe,Mn)Al6 phase to reduce Fe content and reduce Fe damage; Mn forms spherical granular or Chinese character-shaped AlFeMnSi compound phases with Al, Fe, Mn and Si to avoid the formation of long needle-shaped Fe phase to reduce Fe damage, and improve the tensile strength and yield strength of aluminum alloys while improving the demoulding properties of aluminum alloys; Mn can transform coarse needle-shaped β-AlFeSi phase into small granular α-Al(FeMn)Si phase dispersed particles to improve Fe morphology and eliminate Fe damage. Specifically, Mn can replace part of the Fe in the coarse needle-shaped β-AlFeSi phase to form small granular dispersed β- The formation and growth shape of the Al(FeMn)Si phase and β phase are improved, thereby reducing Fe damage. Mn also promotes the transformation of the needle-shaped β-Al(FeMn)Si phase into small granular α-Al(FeMn)Si dispersed phase. The resulting α-Al(FeMn)Si phase dispersed particles are distributed in the aluminum matrix and strongly pinned to the subgrain boundaries of the aluminum alloy. This is mainly because the Mn-containing α phase dispersed particles in the aluminum alloy can serve as heterogeneous nucleation sites for the β′ phase during aging, inducing its nucleation, thereby accelerating the precipitation of the β′ phase. Mn can also react with impurities in the recycled aluminum liquid to form Al-Mn-X phases (X is an impurity element, including but not limited to transition metal elements such as Fe, Cr, Sn, Pb, Cd, etc.), thereby purifying the recycled aluminum liquid. These phases can serve as grain nucleation sites to increase the nucleation rate and refine the grains. Purification can improve the alloy's tensile strength, yield strength, elongation, and fluidity. (7) Sr preferentially combines with Fe to form dispersion strengthening, reducing the solid solubility of Fe in recycled aluminum, thereby improving the yield strength and tensile strength of aluminum alloys; Sr can change the behavior of intermetallic compound phases in crystallography and can be used as a modifier to refine grains and second phases by modifying aluminum alloys through heterogeneous nucleation theory or twin valley mechanism. For example, Sr can change the morphology of eutectic silicon phase through modification, thereby improving the elongation of aluminum alloys and reducing the tendency of die sticking during die casting; Sr can transform the coarse needle-shaped β-AlFeSi and β-AlFeMnSi phases in the ingot into small granular Chinese character-shaped α-AlFeSi and α-Al(FeMn)Si phases, reducing the ingot homogenization time and improving the yield strength, tensile strength and elongation of aluminum alloys; (8) The TiAl2 phase generated by the reaction of Ti and Al acts as a non-spontaneous core during crystallization, which can refine the grains, second phases and precipitated phases to improve the tensile strength, yield strength and elongation of the aluminum alloy; (9) B can undergo boronization reaction with transition metal elements (including Fe and other transition metal elements) to generate compounds such as boron iron compounds that can be separated from the regenerated aluminum liquid, thereby reducing the content of transition metal elements such as Fe and purifying the regenerated aluminum liquid; B is easily adsorbed on the surface of the iron-rich phase, inhibiting the growth of the iron-rich phase, playing a role in controlling the size of the iron-rich phase, and also preventing the formation of the iron-rich phase in the regenerated aluminum liquid; B can inhibit the segregation of Ti3Al, therefore, the effect is better when Ti and B are used together; B can also refine the grains and the second phase to improve the elongation of the aluminum alloy.

[0043] The combination of B, Mn, and Sr within the above content range can regulate the Fe content and improve the Fe morphology to eliminate the Fe hazards, thereby overcoming the defect of a wide and high Fe content range in recycled aluminum; the combined effect of Si, Cu, Mn, Mg, Zn, Ti, Sr, and Fe within the above content range can improve the tensile strength and yield strength of the aluminum alloy; the combined effect of Mn, B, Ti, and Sr within the above content range can refine the grains, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy; Cu and Zn within the above content range can promote the precipitation of the second phase, increase the volume fraction and dispersion of the precipitated phase, and further improve the tensile strength, yield strength, and elongation of the aluminum alloy; B and Mn within the above content range can also purify the recycled aluminum liquid, remove impurity elements, and cooperate with refining treatment and slag skimming treatment to remove as many impurity elements as possible. In addition, the present invention maximizes the range of Mn and Ti content. The combination of Mn, B, and Ti effectively regulates Fe, purifies the recycled aluminum liquid, promotes the precipitation of precipitated phases, and refines grains, secondary phases, and precipitated phases. To increase the raw material source for alloy smelting and fully utilize recycled aluminum resources, the content range of at least one of the main elements Fe, Cu, Mn, Mg, Zn, and Ti is increased. By maintaining a reasonable ratio of these elements, even if the recycled aluminum alloy contains too many impurity elements and too high a content, the combination of these elements can produce a heat-treatment-free die-cast aluminum alloy with excellent performance.

[0044] The present invention uses recycled aluminum as raw material, which has significant advantages in energy conservation and emission reduction. The production energy consumption of recycled aluminum is only 4.9% of that of primary aluminum, and the carbon emissions are only 4.2% of that of primary aluminum. Compared with using primary aluminum as raw material, the present invention is relatively low in cost. Moreover, under the combined action of Si, Cu, Mn, Mg, Zn, Ti, Sr, Fe, and B within the above-mentioned content ranges, combined with refining treatment, electromagnetic stirring, and slag removal, the Fe content and Fe morphology in the recycled aluminum are effectively regulated, and the types and content ranges of impurity elements are expanded, resulting in a heat-treatment-free die-cast aluminum alloy with excellent comprehensive performance. In addition, the prices of Si, Cu, Mn, Mg, Zn, Ti, Sr, and B are all relatively low, and the Si content is no more than 9%, which can further reduce costs.

[0045] Since the mechanical properties of the heat-treatment-free die-cast aluminum alloy cannot be improved by aging heat treatment, most of the solute atoms of the heat-treatment-free die-cast aluminum alloy based on recycled aluminum of the present invention are usually present in the aluminum matrix in the form of solid solution. In addition to grain refinement, the strength increase of the heat-treatment-free die-cast aluminum alloy mainly comes from the pinning of dislocations by the lattice volume mismatch and elastic mismatch caused by the solid solution atoms, that is, solid solution strengthening.

[0046] Heat-treatment-free die-cast aluminum alloys undergo natural aging during storage and transportation after die-casting, meaning their strength increases with extended storage time. This natural aging is attributed to the aggregation of solute atoms in the aluminum alloy, known as solute atom clusters. Solute atom clusters are disordered aggregations of solute atoms within the aluminum matrix, measuring several nanometers in size and typically consisting of a few to dozens of randomly distributed atoms with no clear crystal structure.

[0047] The change in the strength of the heat-treatment-free die-cast aluminum alloy is mainly related to the size and volume fraction of the solute atomic clusters. During the natural aging process, the formation and growth of the clusters are closely related to the change in the concentration of supersaturated quenching vacancies. Vacancies are thermal defects, and their concentration has an exponential function relationship with temperature. The present invention performs a low-temperature quenching treatment on the aluminum alloy parts after the die-casting treatment to produce supersaturated vacancies, thereby improving the mechanical properties of the heat-treatment-free die-cast aluminum alloy. Specifically, during the die-casting process, the equilibrium vacancy concentration is relatively large; during the subsequent quenching treatment, some vacancies at high temperature are retained, thereby producing supersaturated vacancies; moreover, the low-temperature quenching treatment can also cause the aluminum alloy to shrink, produce plastic deformation, and reduce the solubility of elements in aluminum, increase the nucleation points of the clusters, and refine the α-Al phase and eutectic Si phase structure to improve the yield strength, tensile strength and elongation of the heat-treatment-free die-cast aluminum alloy.

[0048] The addition of Cu, Mn, Mg, Zn, Ti, Sr, Fe, and B can also regulate the clustering behavior of solute atoms in aluminum alloys, such as affecting the formation of existing clusters and the formation of new clusters by regulating vacancies. After adding Mg (0.01-0.5wt%) and Cu (0.01-0.4wt%) elements within a certain content range to the recycled aluminum liquid of the present invention, the Mg atoms activate the diffusion of vacancies and promote the formation of Mg-Si clusters and Cu-Mg clusters, significantly strengthening the clusters. The atomic radius of Mn and Sr is much larger than that of Al. The Mn and Sr atoms within the above content range form lattice distortion in the aluminum matrix. In addition, the pinning vacancies and Mg-Si clusters and Cu-Mg clusters added to the heat-treatment-free aluminum alloy promote the growth of clusters, further promoting the natural aging effect, thereby improving the yield strength, tensile strength, and elongation of the heat-treatment-free aluminum alloy.

[0049] In summary, under the combined action of Si, Cu, Mn, Mg, Zn, Ti, Sr, Fe and B within the above-mentioned content range, a heat-treatment-free die-cast aluminum alloy based on recycled aluminum is obtained with excellent demolding performance, tensile strength, yield strength, and elongation.

[0050] When adding Mn to the regenerated aluminum liquid, at least one of Cr, RE, Co, Be and Ca may be added to the regenerated aluminum liquid at the same time, and electromagnetic stirring may be performed.

[0051] Electromagnetic stirring accelerates the dispersion of elements such as Cr, RE, Co, Be, and Ca in the solution, preventing them from agglomerating and growing. It also allows more elements like Cr, RE, Co, Be, Ca, and Fe to react evenly, generating more dispersed and fine secondary phases such as α-Al(FeMn)Si. This improves the effectiveness of Fe modification and refines the secondary phase. The electromagnetic stirring frequency is 20 to 40 Hz, and the duration is 5 to 15 minutes. This electromagnetic stirring process can refine grains and alter the morphology of the Fe phase (for example, transforming long, needle-like or massive Al(FeMn)Si phases into dispersed, nanoscale, spherical Al(MnFe)Cu phases).

[0052] After adding Mn to the regenerated aluminum liquid, at least one of C, Nb, Ni, Te, In, Mo, Ag, Cd, V, Sn, Zr, Sb, and Bi may be added to the regenerated aluminum liquid at a temperature of 700-760°C and electromagnetically stirred.

[0053] Electromagnetic stirring accelerates the dispersion of elements such as C, Nb, Ni, Te, In, Mo, Ag, Cd, V, Sn, Zr, Sb, and Bi in the solution, preventing them from agglomerating and growing. Furthermore, it allows more elements such as C, Nb, Ni, Te, In, Mo, Ag, Cd, V, Sn, Zr, Sb, In, Bi, Cr, RE, Co, Be, Ca, and Fe to react uniformly, generating a more dispersed and fine second phase, improving the effect of Fe modification and refining the second phase. The electromagnetic stirring frequency is 20 to 40 Hz, and the duration is 5 to 15 minutes. This electromagnetic stirring treatment can refine grains and change the morphology of the Fe phase (for example, it can transform long, needle-like or massive Al(FeMn)Si phases into dispersed, nanoscale, spherical Al(MnFe)Cu phases).

[0054] Cr, RE, Co, Be, Ca, C, Nb, Ni, Te, In, Mo, Ag, Cd, V, Sn, Zr, Sb, and Bi can be added as single elements or alloys. Master alloys have excellent dispersibility and are easily dissolved in the recycled aluminum liquid. The amounts of Cr, RE, Co, Be, Ca, C, Nb, Ni, Te, In, Mo, Ag, Cd, V, Sn, Zr, Sb, and Bi to be added to the recycled aluminum liquid can be calculated based on the elements and contents of the recycled aluminum liquid and the elements and contents of the predetermined heat-treatment-free die-cast aluminum alloy based on the recycled aluminum.

[0055] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the total mass percentage content of at least one element selected from Cr, RE, Co, Be, Ca, C, Nb, Ni, Te, In, Mo, Ag, Cd, V, Sn, Zr, Sb, and Bi is not more than 0.4%, preferably not more than 0.3%, and specifically can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, or 0.4%.

[0056] RE is at least one of La, Ce, Pr, Nd, Er, Sm, Y, Gd, and Sc. In one embodiment, RE is La, Y, and Sm in a ratio of 0.01-0.03:0.02-0.05:1. In another embodiment, RE is Pr, Er, and Nd in a ratio of 0.02-0.05:0.03-0.08:1. In yet another embodiment, RE is Sm, Y, and Gd in a ratio of 0.06-0.08:0.1-0.2:1. The combined addition of multiple rare earth elements achieves a better refinement effect.

[0057] In the regenerated aluminum liquid and the aluminum alloy liquid, the mass ratio of Cr to Fe is 0.2-1:1, preferably 0.5-1:1, and specifically 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1:1.

[0058] In the regenerated aluminum liquid and the aluminum alloy liquid, the mass ratio of Co to Fe is 0.2-1:1, preferably 0.5-1:1, and specifically 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1:1.

[0059] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Cr is 0-0.1%, specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Cr can transform the needle-shaped β-Fe phase into the α-Fe phase to improve the Fe morphology and eliminate the harmful effects of Fe. It is also easy to form a dispersed phase with Fe to reduce the Fe content and reduce the harmful effects of Fe. Cr forms (CrFe)Al7 and (CrMn)Al in the recycled aluminum liquid. 12Intermetallic compounds such as Cr can hinder the nucleation and growth of recrystallization, thereby improving the tensile strength, yield strength, and elongation of aluminum alloys and reducing their susceptibility to stress corrosion cracking. Cr forms various fine chromium-containing compounds in aluminum alloys that dissolve back into the α phase during the solution stage and disperse and precipitate various Cr-containing phases, such as α-AlCrSi dispersed phases, during the aging stage. These Cr-containing phases serve as nuclei for the heterogeneous nucleation of β" and θ" phases, accelerating their formation and thus improving the tensile strength and yield strength of the aluminum alloy. Furthermore, the dispersed precipitation of Cr-containing phases in the matrix inevitably delays the formation of the θ' phase at grain boundaries. Furthermore, Mn and Cr can combine with Fe and Si to form a dispersed α-Al(FeMnCr)Si phase. This α-Al(FeMnCr)Si phase has a high bulk density and strong thermal stability. Pinning grain boundaries effectively controls the growth of the recycled aluminum grains, thereby controlling grain size. When Cr and Mo are added in combination, a multi-phase rich in Cr and rich in Mo can be generated, which can significantly improve the tensile strength of the aluminum alloy.

[0060] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of RE is 0-0.1%, specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. RE is consistent with the distribution area of the Fe phase, and can form a rare earth active film on the surface of the iron-containing phase or combine with atoms such as Al, Fe, and Ti to form rare earth compounds such as AlFeRE, preventing the formation of hard and brittle β-AlFeSi phases on grain boundaries, effectively reducing the solid solution of harmful elements in the aluminum matrix, and thus improving the tensile strength and yield strength of the aluminum alloy. RE can transform the elongated β-Fe phase into a spherical α-Fe phase and modify the elemental Si. RE can also promote the precipitation of dispersed phases such as CuAl2 and (CuMg)Al2, further improving the tensile strength and yield strength of the aluminum alloy. RE is a surface-active element with a radius larger than that of Al. It cannot enter the α-Al lattice, but it can segregate at grain boundaries or adsorb at the solid-liquid interface, causing partial supercooling. This increases the chance of dendrite melting, thereby refining grains, secondary phases, and precipitated phases (for example, Al3Fe, Al3ScZr, AlSiMo, and Mg2Si phases), further improving the tensile strength, yield strength, and elongation of aluminum alloys. The combination of Ca and RE can significantly refine grains and secondary phases, thereby improving tensile strength, yield strength, and elongation.

[0061] After adding RE (0-0.1wt%) and Zr (0-0.2wt%) within a certain content range to the recycled aluminum liquid, and when the mass ratio of RE to Zr is 0.1-1:1, the high-distortion coherent solid solution elements can promote the formation of atomic clusters such as high-density Mg-Si clusters and Cu-Mg clusters, and significantly inhibit the diffusion of atoms in the atomic clusters, improve the stability of the atomic clusters, and thus improve the yield strength, tensile strength and elongation of the aluminum alloy.

[0062] The mass ratio of RE to Zr is 0.1-1:1, preferably 0.5-1:1, specifically 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, or 1:1.

[0063] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Co is 0-0.1%, specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Co can promote the formation of Fe spherical phase, generate small-grained Al3(Fe,Co) phase that can improve the mechanical properties of the aluminum alloy, and can also transform coarse needle-shaped and flaky Al3Fe phase into α-Al 15 (Fe, Co) 3 Si 2 (its shape can be granular, small flower-shaped or small strips), and has a refining effect on the Al 3 Fe phase, further improving the tensile strength, yield strength, and elongation of the aluminum alloy. Adding Ce and Co at the same time can not only improve the thermal stability of recycled aluminum, but also promote <001> and <111> The mechanical properties of aluminum alloys can be improved by forming orientation.

[0064] In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Be is 0-0.1%, specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Be can react with Al, Fe, Si, etc. to form secondary phases such as Be-Fe (Al8Fe2SiBe)2, thereby improving the tensile strength and yield strength of aluminum alloys. It can transform the eutectic Si phase from a lamellar phase to a fine phase to refine the Si phase, thereby reducing or eliminating the adverse effects of Si on the properties of aluminum alloys. It can transform the plate-like β intermediate phase into the relatively harmless Chinese character-shaped Be-Fe (Al8Fe2SiBe) phase and prevent the formation of the needle-like β-Fe phase, thereby reducing or eliminating the adverse effects of Fe on the properties of aluminum alloys. It can also promote the formation and precipitation of phases such as Mg2Si, Mg2Zn, Mg2SiZn, and Al2Cu, thereby reducing the solid solubility of the above elements in the aluminum matrix. Be can also form an active film on the surface of impurity element phases such as Fe, preventing the growth of impurity elements, and can segregate at grain boundaries or adsorb at the solid-liquid interface, forming partial supercooling, which increases the chance of dendrite melting and thus refines the grains. Among them, the refining effect of Be increases with the increase of Be content.

[0065] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage of Ca is 0-0.1%, specifically 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Ca can improve the β-Fe phase to reduce Fe damage, and can also react with Al, Cu, Zn, and Si to form secondary phases such as Al4Ca, Al2Ca3, AlCa2, AlCaCu, CaZn, CaAlZn, and Al2CaSi2, thereby improving the tensile strength and yield strength of the aluminum alloy. Ca can also refine the eutectic structure, improve the β-Fe phase, and has a modificatory effect on Al-Si alloys.

[0066] The addition of elements such as Cr, RE, Co, Be, and Sr not only further promotes the reaction between Mn and Fe by reducing their maximum solid solubility in the matrix, but also occupies the positions of Mn and Fe elements in the second phase. By controlling the second phase structure, the Fe-containing phase becomes more dispersed and fine, further promoting the effect of modifying Fe. Therefore, when the mass ratio of Mn to Fe is greater than 1.2:1, the α-Al(MnFeX)Si phase (where X is any one or more of the elements Cr, RE, Co, Be, and Sr) can still remain fine and dispersed, and there is no excess Mn and Al forming a coarse AlMn phase.

[0067] When Ti, B and RE are used together, the effective action time of Ti and B can be extended. This is because RE improves the wettability of aluminum alloy liquid to boride, and TiB2 is not easy to coagulate and precipitate, thus ensuring the effective amount of TiB2.

[0068] The combined effect of Mn, Cr and RE can effectively improve the Fe morphology, reduce the Fe content and refine the grain size, thus obtaining an aluminum alloy with better tensile strength, yield strength and elongation. Specifically, Mn can significantly refine the recrystallized grains and the second phase, effectively transforming the coarse needle-shaped or flaky β-AlFeSi phase into small granular α-Al(FeMn)Si dispersed particles to improve the Fe morphology, and can also react with Fe to form α-(Fe,Mn)Al6 phase to reduce the Fe content. Obviously, Mn can reduce the Fe content, improve the Fe morphology, and refine the grains and the second phase; Cr can effectively transform the needle-shaped β-Fe phase into the α-Fe phase to improve the Fe morphology, and can also react with Fe to form (CrFe)Al7 and (CrMn)Al 12 Cr also reacts with Al, Si, and Mg to form dispersed phases such as AlCrSi and Mg2(SiCr), increasing the precipitation volume fraction and uniform distribution of the dispersed phases. Cr also hinders grain growth, refines grains and secondary phases, and increases the alloy's tensile strength, yield strength, and elongation. RE is distributed in the same region as the Fe phase, forming a rare earth active film on the Fe phase surface, preventing the formation of a hard and brittle β-AlFeSi phase at the grain boundaries. The combined addition of Mn, Cr, and RE effectively improves the Fe morphology. When Mn and Cr are added together, they react with Fe and Si to form dispersed α-Al(FeMnCr)Si and α-Al(FeMnCr)Si phases. These phases have high bulk density and strong thermal stability. With extended standing time, these phases partially sink to the bottom and partially pin grain boundaries, effectively refining and controlling grain size. Mn, Cr, and RE can also react with trace impurities in recycled aluminum to form Al-Cr-X, Al-Mn-X, and Al-RE-X phases (X represents an impurity element, including but not limited to transition metals such as Fe, Cr, Sn, Pb, and Cd). This purifies the aluminum alloy and improves its elongation. These phases serve as grain nucleation sites, increasing the nucleation rate and refining the grains, thereby improving the alloy's tensile strength, yield strength, and fluidity. In summary, the synergistic effect of Mn, Cr, and RE within the aforementioned content ranges improves Fe morphology, reduces Fe content, and refines grains, resulting in an aluminum alloy with excellent overall performance.

[0069] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage of C is 0-0.05%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, or 0.05%. C acts as a refiner, significantly refining the grain size and secondary phase to improve the elongation of the aluminum alloy. It also acts as a highly effective modifier, reacting with Fe during heat treatment to form carbides, thereby improving the tensile strength and yield strength of the aluminum alloy.

[0070] Ti, C, B, and Sr work together to effectively refine grains and secondary phases. Specifically, B inhibits the segregation of Ti3Al. When used together, Ti and B effectively reduce the Fe content and refine the grains and secondary phases. When RE, Ti, and B are combined, TiB2 is less likely to aggregate and precipitate, ensuring the effective TiB2 quantity. The TiAl3 phase formed by the reaction of Ti and Al serves as a non-spontaneous nucleus during crystallization, refining the grains and secondary phases. Sr, as a modifier, refines the grains and secondary phases and can also transform the coarse, needle-shaped β-AlFeSi and β-AlFeMnSi phases into small, granular, Chinese character-shaped α-AlFeSi and α-Al(FeMn)Si phases. When used together, these four elements effectively reduce the Fe content, improve Fe morphology, and refine the grains and secondary phases.

[0071] When B, Mn, Cr, and RE are combined, they can prevent the formation of iron-rich phases. This allows the amount of B, Mn, Cr, or RE added to the recycled aluminum liquid to be calculated in advance based on the Fe content in the recycled aluminum, without having to worry about the difficulty in effectively removing the β-Fe phase due to the continued formation of the iron-rich phase in the recycled aluminum. At least one of Ti, C, and Sr can assist B, Mn, Cr, and RE, further refining the grains and secondary phases and further reducing the size of the α-Fe phase. Specifically, Sr can preferentially combine with elements such as Fe, Cu, and Si to form dispersion strengthening, reducing the distribution of elements such as Cr, Mn, and Cu toward grain boundaries and reducing the solid solubility of these elements in the alloy, thereby improving the overall performance of the alloy. The above-mentioned content ranges of Mn, Cr, RE, B, Ti, C, and Sr act synergistically to improve Fe morphology and reduce Fe content while also refining grains and secondary phases, resulting in an aluminum alloy with excellent overall performance.

[0072] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the Nb content is 0-0.01% by mass, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, or 0.01%. Nb reacts with Al and B to form high-temperature strengthening metal compounds such as AlNb3, AlNb, Al3Nb, and NbB2. Some Nb may be dispersed in the matrix grain boundaries, significantly improving the yield strength and tensile strength of the aluminum alloy. Nb refines grains and secondary phases, thereby increasing the elongation of the aluminum alloy. The lattice mismatch constant between NbB2 and Al (30.6%) is smaller than the lattice mismatch constant between TiB2 and Al (34.0%). Considering only its interaction with Al, NbB2 is more likely to serve as a potential heterogeneous nucleation site than TiB2.

[0073] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Ni is 0-0.02%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, or 0.02%. Ni can refine the grains, promote the precipitation of the second phase, increase the volume fraction and dispersion of the precipitated phase, and react with Al, Fe, Mg, Si, etc. to form second phases such as AlFeSiNi, AlFeMgSiNi, and FeNiAl9, thereby reducing the Fe content.

[0074] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage of Te is 0-0.01%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, or 0.01%. Te can narrow the solidification temperature range of the aluminum alloy, forming fine petal-shaped primary crystals instead of dendritic primary crystals, reducing or eliminating microshrinkage, thereby improving the mechanical properties and thermal conductivity of the aluminum alloy. When Sb is added in combination with Te, fine petal-shaped primary crystals can be formed, thereby improving the tensile strength and elongation of the aluminum alloy.

[0075] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage of Ag is 0-0.01%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, or 0.01%. Ag promotes the precipitation of secondary phases (such as Al2Cu, Mg2Si, Mg3Sb2, and Mg3Bi2), refines the precipitated phases, increases the density of the precipitated phases, and enhances the precipitation strengthening effect of the aluminum alloy, thereby improving the tensile strength, yield strength, and elongation of the aluminum alloy.

[0076] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage of In is 0-0.01%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, or 0.01%. In reacts with Al and Cu to form secondary phases such as AlIn and CuIn, thereby increasing the tensile strength and yield strength of the aluminum alloy. In also refines the grain size, thereby increasing the elongation of the aluminum alloy. Ag, In, and Nb interact with each other to promote the precipitation of secondary phases and refine the grain size and precipitated phases. Specifically, In can react with Al and Cu to form secondary phases such as AlIn and CuIn; Nb, Ti and Al can form TiAl-Nb phase; Ag can promote the precipitation of the secondary phase and refine the precipitated phase, and Nb and In can also refine the grains and the secondary phase, thereby achieving the purpose of improving the tensile strength, yield strength and elongation of the aluminum alloy at the same time.

[0077] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage of Mo is 0-0.02%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, or 0.02%. Mo can also react with Al, Si, Fe, etc. to form secondary phases such as AlMo, AlSiMo, and AlSiFeMo, which are dispersed at the grain boundaries of the aluminum matrix. Mo can also refine grains and improve the morphology of Fe-containing intermetallic compounds, further improving the tensile strength, yield strength, and elongation of the aluminum alloy.

[0078] In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Cd is 0-0.05%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, or 0.05%. Cd can refine α-Al and react with Al, RE, Cu, Mg, Si, Fe, Sb, Bi, etc. in the melt to form strengthening phases such as REAl2Cd3, Al3Cd, Al2Cd3, (CuCd)Al2, Mg2(SiCdREFe), Mg3(SbCd)2, and Mg3(BiCd)2 to improve the tensile strength and yield strength of aluminum alloys and reduce the Fe content. Cd will form a large number of Cd-vacancy clusters in the aging stage, which will promote and accelerate the precipitation of CuAl2 phase, thereby reducing the solid solubility of the above elements in the aluminum matrix.

[0079] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of V is 0-0.02%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, or 0.02%. V can react with Al to form VAl 11 Refractory compounds such as V can refine the grains during the casting process; V can also refine the recrystallization structure and increase the recrystallization temperature to improve the tensile strength, yield strength and elongation of the aluminum alloy; during the die-casting process, the temperature cooling rate is relatively large, and the non-steady-state phase Al3V obtained by the rapid cooling method will form a large number of fine and dispersed ellipsoidal Al(VCrTi)Si phases with Cr, Si and Ti in the aluminum alloy, which can prevent dislocation movement and recrystallization nucleation and growth, and significantly improve the tensile strength and yield strength of the aluminum alloy.

[0080] In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Sn is 0-0.08%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, or 0.08%. Sn can react with Al, Mg, Sc, etc. to generate second phases such as Al9Sn7, Al6Sn5, Al5Sn2, Al3Sn4, Mg2Sn, Mg2ScSn, etc., to improve the tensile strength and yield strength of aluminum alloys; Sn can promote the precipitation of second phases such as Mg2Si, Mg2Zn, Mg2SiZn, Al2Cu, etc., to reduce the solid solubility of the above elements in the aluminum matrix; Sn can also effectively inhibit the growth of MgSi2 phase and promote its dispersed distribution, thereby improving the tensile strength and yield strength of the alloy.

[0081] In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Zr is 0-0.02%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, or 0.02%. Zr can react with Al, RE, etc. to form second phases such as Al3ScZr and (Zr,RE)Al3 to improve the tensile strength and yield strength of aluminum alloys; Zr can also promote the precipitation of phases such as Mg2Sn, Mg2Si, Mg3Sb2 and CuAl2 to reduce the solid solubility of the above elements in the aluminum matrix; Zr can also refine the grains and further improve the elongation of aluminum alloys; the addition of B can transform Zr from a solid solution state to a precipitation state, and exist in the form of fine plate-like second phase particles inside the grains and at the grain boundaries, reducing lattice distortion, improving the orderliness of the aluminum matrix, and enhancing the tensile strength and yield strength of the aluminum alloy; the combined action of Er and Zr can promote the precipitation of β″ phase and make the β″ phase finer and more dispersed. The synergistic effect of Er and Zr can significantly inhibit the recrystallization of Al-Fe alloys.

[0082] The mass ratio of Er to Zr may be 0.5-5:1, preferably 1-3:1, specifically 0.5:1, 1:1, 2:1, 3:1, 4:1, or 5:1.

[0083] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the Sb content by mass is 0-0.02%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, or 0.02%. Sb reacts with Mg and other elements to form secondary phases such as Mg3Sb2, which can improve the tensile strength and yield strength of the aluminum alloy. When Sb is added in combination with Te, it can form fine, petal-shaped primary crystals, thereby improving the tensile strength and elongation of the aluminum alloy.

[0084] In the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Bi is 0-0.02%, specifically 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, or 0.02%. Bi can react with Mg and Cd to form secondary phases such as Mg3Bi2 and Mg3(BiCd)2, thereby increasing the tensile strength and yield strength of the aluminum alloy.

[0085] The present invention also provides a structural component, at least partially made of the aforementioned heat-treatment-free die-cast aluminum alloy based on recycled aluminum, or the heat-treatment-free die-cast aluminum alloy based on recycled aluminum produced by the aforementioned preparation method. This structural component can be used in new energy vehicles, including automotive structural components such as the vehicle body, rear wheelhouse inner panels, rear longitudinal beams, floor connecting plates, rear floor panels, beam inner reinforcement plates, hoods, fenders, doors, rear compartments, and roofs.

[0086] Of course, the structural member of the present invention can also be used in other fields, such as aerospace, high-speed rail, ships, mobile devices, household appliances, chemical industry, daily necessities, construction and other fields.

[0087] Examples and Comparative Examples Please refer to Table 1 for the components and contents of the heat treatment-free die-cast aluminum alloys based on recycled aluminum in Examples 1 to 5 and Comparative Examples 1 to 2, and please refer to Table 2 for the performance test results.

[0088] Table 1 Composition and content of aluminum alloys of Examples 1 to 5 and Comparative Examples 1 to 2 To simplify the description, the contents of trace elements such as impurities in the comparative examples and examples are not shown.

[0089] A domestically produced CSS-44100 electronic universal tensile tester was used for processing and tensile testing according to the "Method for Tensile Testing of Metal Materials at Room Temperature" (GB / T228-2002) and the "Method for Tensile Testing of Metal Materials at High Temperature" (GB4338-2006-T). The processed specimens were polished using 800# and 1500# water-abrasive sandpaper, respectively. The tensile force of the tensile tester was 2kN, and the tensile speed was 2mm / min. Three specimens were tested under the same conditions, and the average value was calculated.

[0090] Table 2 Performance test results of aluminum alloys of Examples 1 to 5 and Comparative Examples 1 to 2 The tensile strength, yield strength, and elongation of the heat-treatment-free die-cast aluminum alloys based on recycled aluminum in Examples 1 to 5 are significantly greater than those of the heat-treatment-free die-cast aluminum alloys based on recycled aluminum in Comparative Examples 1 and 2. This indicates that the heat-treatment-free die-cast aluminum alloys based on recycled aluminum of the present invention exhibit superior properties. Specifically, the Mn content of Examples 1 to 5 is higher than that of Comparative Examples 1 and 2, the Zn content of Examples 1 to 5 is higher than that of Comparative Examples 1 and 2, and the Ti content of Examples 1 to 5 is higher than that of Comparative Examples 1 and 2. This demonstrates that when the Mn, Zn, and Ti contents are increased in Examples 1 to 5, the interaction of these elements can produce heat-treatment-free die-cast aluminum alloys based on recycled aluminum with superior performance.

[0091] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for preparing a heat-treatment-free die-cast aluminum alloy based on recycled aluminum, comprising the following steps: Providing recycled aluminum; heating the recycled aluminum to obtain recycled aluminum liquid; Performing chemical analysis on the regenerated aluminum liquid to obtain the elements and contents of the regenerated aluminum liquid; Calculate the amounts of Si, Cu, Mn, Mg, Zn, Ti, Sr, RE, and B to be added to the recycled aluminum liquid based on the elements and contents of the recycled aluminum liquid and the elements and contents of the preset heat-treatment-free die-casting aluminum alloy based on the recycled aluminum; adding Si, Cu, Mn, Mg, Zn, Ti, Sr, RE and B to the regenerated aluminum liquid and performing a second heating treatment to obtain an alloy liquid; The alloy liquid is subjected to refining treatment, electromagnetic stirring, slag removal treatment, and die casting treatment to obtain aluminum alloy parts; and The aluminum alloy parts are subjected to low-temperature quenching treatment to obtain the heat-treatment-free die-cast aluminum alloy based on recycled aluminum, wherein the heat-treatment-free die-cast aluminum alloy based on recycled aluminum contains Al, and also contains Si with a mass percentage content of 6-9%, Fe with a mass percentage content of 0.1-0.6%, Cu with a mass percentage content of 0.01-0.4%, Mn with a mass percentage content of 0.01-0.8%, Mg with a mass percentage content of 0.01-0.5%, Zn with a mass percentage content of 0.01-0.5%, Ti with a mass percentage content of 0.01-0.2%, RE with a mass percentage content of 0-0.1%, Sr with a mass percentage content of 0-0.05%, and B with a mass percentage content of 0-0.01%. The temperature of the low-temperature quenching treatment is -150~0°C, and the time is 0.1~10h.

2. The method for preparing heat-treatment-free die-cast aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The temperature of the low-temperature quenching treatment is -140~0°C, and the time is 0.1~10h.

3. The method for preparing heat-treatment-free die-cast aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The heat-treatment-free die-cast aluminum alloy based on recycled aluminum contains 7-9% Si by mass, 0.2-0.5% Fe by mass, 0.1-0.3% Cu by mass, 0.3-0.7% Mn by mass, 0.2-0.4% Mg by mass, 0.2-0.4% Zn by mass, 0.1-0.2% Ti by mass, 0-0.1% RE by mass, 0.005-0.05% Sr by mass, and 0.005-0.01% B by mass.

4. The method for preparing heat-treatment-free die-cast aluminum alloy based on recycled aluminum according to claim 1, characterized in that: In the regenerated aluminum liquid, the mass ratio of Mn to Fe is 0.5-2:

1.

5. The method for preparing heat-treatment-free die-cast aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The process further includes adding at least one of Co, Be, and Ca to the regenerated aluminum liquid, wherein at least one of the following conditions is met: In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Co is 0-0.1%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Be is 0-0.1%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Ca is 0-0.1%.

6. The method for preparing heat-treatment-free die-cast aluminum alloy based on recycled aluminum according to claim 5, characterized in that: In the regenerated aluminum liquid, the mass ratio of Co to Fe is 0.2-1:

1.

7. The method for preparing heat-treatment-free die-cast aluminum alloy based on recycled aluminum according to claim 1, characterized in that: The method further includes adding C to the recycled aluminum liquid, wherein the mass percentage content of C in the heat treatment-free die-casting aluminum alloy based on recycled aluminum is 0-0.05%.

8. The method for preparing a heat treatment-free die-cast aluminum alloy based on recycled aluminum according to any one of claims 1 to 7, characterized in that: The method further includes adding at least one of Nb, Ni, Te, In, Mo, Ag, Cd, V, Sn, Zr, Sb, and Bi to the regenerated aluminum liquid, wherein at least one of the following conditions is met: In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Nb is 0-0.1%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Ni is 0-0.2%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Te is 0-0.1%; In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of In is 0-0.1%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Mo is 0-0.2%; In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Ag is 0-0.1%; In the heat treatment-free die-cast aluminum alloy based on recycled aluminum, the mass percentage content of Cd is 0-0.05%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage of V is 0-0.2%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Sn is 0-0.08%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Zr is 0-0.2%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Sb is 0-0.2%; In the heat treatment-free die-casting aluminum alloy based on recycled aluminum, the mass percentage content of Bi is 0-0.2%.

9. A heat-treatment-free die-casting aluminum alloy based on recycled aluminum produced by the method for producing a heat-treatment-free die-casting aluminum alloy based on recycled aluminum according to any one of claims 1 to 8.

10. A structural member, characterized in that: At least part of the structural member is made of a heat-treatment-free die-cast aluminum alloy based on recycled aluminum obtained by the preparation method described in any one of claims 1 to 8 or a heat-treatment-free die-cast aluminum alloy based on recycled aluminum as described in claim 9.

Images