High-strength high-elongation al-si-mg series die-casting aluminum alloy and preparation method and structural member thereof

Abstract

The application provides a high-strength and high-elongation Al-Si-Mg series die-casting aluminum alloy, a preparation method thereof and a structural member. The high-strength and high-elongation Al-Si-Mg series die-casting aluminum alloy contains 6-8% of Si in terms of mass percentage, 1.2-1.8% of Mg in terms of mass percentage, 0.001-2.5% of Zn in terms of mass percentage, 0.01-0.4% of Fe in terms of mass percentage, 0.001-0.5% of Cr in terms of mass percentage, 0.001-0.15% of Ti in terms of mass percentage, 0-0.05% of Sr in terms of mass percentage, 0-0.3% of Mn in terms of mass percentage, 0-0.3% of Zr in terms of mass percentage, 0-0.5% of Li in terms of mass percentage, 0-1% of AlTiB in terms of mass percentage, 0-35% of SiC in terms of mass percentage, and 0-0.1% of Cu in terms of mass percentage, and the balance is Al.

Description

[0001] This invention is a divisional application. The original application number is 2025105115688, the application date is April 22, 2025, and the title is High-strength and High-elongation Al-Si-Mg die-cast aluminum alloy and its preparation method and structural parts. Technical Field

[0002] This invention relates to the field of aluminum alloy technology, and in particular to a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, its preparation method, and structural components. Background Technology

[0003] Die-cast aluminum alloys possess excellent comprehensive properties, including high strength, low density, good mechanical properties, and ease of machining. They are widely used in aerospace and military industries, new energy vehicles, consumer electronics, household and industrial appliances, and high-rise buildings. For aluminum-silicon die-cast aluminum alloys, the addition of silicon does not significantly improve strength; therefore, alloying elements that can enhance strength, such as magnesium (Mg), need to be added. However, the addition of Mg drastically reduces the elongation of aluminum-silicon die-cast aluminum alloys. Therefore, there is an urgent need to provide an aluminum-silicon die-cast aluminum alloy that combines superior tensile strength, yield strength, and elongation. Summary of the Invention

[0004] To address the aforementioned deficiencies in the prior art, this invention provides a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy that combines excellent tensile strength, yield strength, and elongation.

[0005] This invention provides a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, containing Al, and also containing 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, 0-0.5% Li, and 0-0.1% Cu.

[0006] Furthermore, the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains -8% Si, 1.2-1.8% Mg, 0.001-2% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0.001-0.05% Sr, 0.001-0.3% Mn, 0.001-0.3% Zr, 0.001-0.5% Li, and 0.001-0.1% Cu.

[0007] Furthermore, the mass ratio of Mg to Zn is 0.1-10:1.

[0008] Furthermore, the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains at least one of Sb, Sn, Co, Bi, Ca, Be, V, Ge, Mo, Nb, Te, Ag, In, AlTiB, SiC, BN, and AlTiC, wherein the mass percentage content of Sb is 0-0.3%, the mass percentage content of Sn is 0-0.3%, the mass percentage content of Co is 0-0.3%, the mass percentage content of Bi is 0-0.3%, the mass percentage content of Ca is 0-0.2%, and the mass percentage content of Be is 0- 0.2%, V by mass percentage is 0-0.2%, Ge by mass percentage is 0-0.1%, Mo by mass percentage is 0-0.2%, Nb by mass percentage is 0-0.1%, Te by mass percentage is 0-0.1%, Ag by mass percentage is 0-0.1%, In by mass percentage is 0-0.2%, AlTiB by mass percentage is 0-1%, SiC by mass percentage is 0-35%, BN by mass percentage is 0-1%, and AlTiC by mass percentage is 0-1%.

[0009] This invention also provides a method for preparing a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, comprising the following steps: It provides Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, Cu, and Al sources; The Al source is heated to obtain molten aluminum; Adding Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, and Cu sources to the molten aluminum yields a mixed solution; and The mixture is subjected to die casting and aging treatment to obtain the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, wherein the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy contains 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, 0-0.5% Li, and 0-0.1% Cu.

[0010] Furthermore, the preparation method of the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also includes a step of surface treatment of the mold, wherein the surface treatment is to form a boron carbide layer on the parting surface of the mold.

[0011] Furthermore, the die-casting process is high-pressure casting, in which the temperature is 600-670ºC, the low-speed injection velocity is 0.23-0.3m / s, and the high-speed injection velocity is 2-2.5m / s; or The die casting process is a semi-solid die casting process. In the semi-solid die casting process, the temperature of the mixture is 580-610℃, the stirring speed is 550-700 r / min, the stirring time is 4-10min, the solid phase rate is 35-50%, the injection speed is 0.4-1.5m / s, the mold temperature is 220-240℃, and the air pressure in the mold cavity is 30-50kPa.

[0012] Furthermore, the aging treatment is performed at a temperature of 170-250℃ for a time of 0.05-30 hours; or The aging process includes a first-level aging process, a second-level aging process, a third-level aging process, and a fourth-level aging process. The first-level aging process is carried out at a temperature of 80-120°C for 3-20 hours; the second-level aging process is carried out at a temperature of -200 to -100°C for 0.5 to 10 hours; the third-level aging process is carried out at a temperature of 170-250°C for 0.05 to 5 hours. After the second-level aging process is completed, the temperature is adjusted to 170-250°C within 1-5 minutes; the fourth-level aging process is either natural aging or water-cooled aging; or... The aging treatment includes a first-stage low-temperature electric field aging treatment and a second-stage high-temperature aging treatment. The first-stage low-temperature electric field aging treatment is performed at a temperature of 50-130℃ for a time of 0.1-100h, with an electric field strength of 2-50kV / cm. The second-stage high-temperature aging treatment is performed at a temperature of 170-250℃ for a time of 0.05-30h.

[0013] Furthermore, the preparation method of the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy further includes the step of adding at least one of the following sources to the molten aluminum: Sb source, Sn source, Co source, Bi source, Ca source, Be source, V source, Ge source, Mo source, Nb source, Te source, Ag source, In source, AlTiB source, SiC source, BN source, and AlTiC source, wherein the mass percentage content of Sb is 0-0.3%, the mass percentage content of Sn is 0-0.3%, the mass percentage content of Co is 0-0.3%, the mass percentage content of Bi is 0-0.3%, and the mass percentage content of Ca is 0-0. 2%, Be (by mass) 0-0.2%, V (by mass) 0-0.2%, Ge (by mass) 0-0.1%, Mo (by mass) 0-0.2%, Nb (by mass) 0-0.1%, Te (by mass) 0-0.1%, Ag (by mass) 0-0.1%, In (by mass) 0-0.2%, AlTiB (by mass) 0-1%, SiC (by mass) 0-35%, BN (by mass) 0-1%, and AlTiC (by mass) 0-1%.

[0014] The present invention also provides a structural component, the material of which is the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, or a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy prepared by the preparation method of the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy.

[0015] In the technical solution of this invention, the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy contains 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, and 0-0.1% Cu. The interaction and mutual influence of these elements result in the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy possessing excellent yield strength, tensile strength, and elongation. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] One embodiment of the present invention provides a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy. This high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy possesses excellent tensile strength, yield strength, and elongation, making it suitable for manufacturing various structural components. The thickness of the structural components can be 1.5-15 mm, specifically 1.5 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm.

[0018] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy contains Al, and also contains 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, 0-0.5% Li, and 0-0.1% Cu.

[0019] The specific percentage content of Si by mass can be 6%, 6.1%, 6.2%, 6.3%, 6.4%, 6.5%, 6.6%, 6.7%, 6.8%, 6.9%, 7%, 7.1%, 7.2%, 7.3%, 7.4%, 7.5%, 7.6%, 7.7%, 7.8%, 7.9%, or 8%.

[0020] The specific percentage content of Mg by mass can be 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, or 1.8%.

[0021] The Zn content by mass percentage 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%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0. 3%, 0.35%, 0.4%, 0.45%, 0.45%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.78%, 0.85%, 0.9%, 0.95%, 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, or 2.5%. The mass percentage content of Mg and Zn can be directly proportional. When the Mg content is high, the Zn content can also be set higher to generate more MgZn2 dispersed second phase, thereby significantly improving the strength of the aluminum alloy. The mass ratio of Mg to Zn is 0.1-10:1, specifically 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1.

[0022] The specific percentage of Fe content by mass can 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%, or 0.4%.

[0023] The specific mass percentage contents of Cr and Li 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%, 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. 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%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, or 0.5%.

[0024] The specific percentage content of Ti by mass 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%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15%.

[0025] The specific mass percentage content of Mn and Zr 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%, 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%, or 0.3%.

[0026] The specific percentage content of Sr by mass 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%.

[0027] The specific percentage content of Cu by mass 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%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%.

[0028] In one embodiment, the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy further comprises 6-8% Si, 1.2-1.8% Mg, 0.001-2% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0.001-0.05% Sr, 0.001-0.3% Mn, 0.001-0.3% Zr, and 0.001-0.1% Cu.

[0029] It is understood that the Al-Si-Mg series die-cast aluminum alloy also contains impurities, wherein the mass percentage content of a single impurity is less than 0.02%, and the sum of the mass percentage contents of the impurities is less than 0.1%.

[0030] In the technical solution of this invention, the Al-Si-Mg system high thermal conductivity aluminum alloy contains 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, and 0-0.1% Cu by mass. The Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, and Cu within the above content ranges act as a whole, interacting and influencing each other to ensure that the Al-Si-Mg system has a better elongation. Specifically: (1) When the mass percentage content of Si is 6-8%, Si can improve the fluidity and density of aluminum alloy, thereby improving the forming performance and mechanical properties of aluminum alloy. When the mass percentage content of Si is 6-8%, the improvement of strength is not obvious. When the Si content exceeds 8%, coarse elemental Si will appear, which will drastically reduce the elongation of aluminum alloy. (2) The mass percentage content of Mg is 1.2-1.8%. Mg can significantly improve the mechanical properties of aluminum alloys. Mg can react with other elements to form a second phase, avoiding adverse effects on the elongation of aluminum alloys. Mg can react with Al, Fe, Si, Cu, Zn, B, Ni and other elements to form second phases such as MgB, Mg2Sn, Mg2Si, Mg2Zn, Mg2SiZn, (CuMg)Al2, AlFeMgSi, AlFeMgSiNi. However, a mass percentage content of 1.2-1.8% of Mg will drastically reduce the elongation of aluminum alloys. (3) The mass percentage content of Zn is 0.01-2.5%. Zn can be dissolved in the aluminum matrix to greatly improve the strength of aluminum alloy through solid solution strengthening. After aging treatment, the precipitated elemental Zn can further improve the strength of aluminum alloy. Moreover, elemental Zn is a non-brittle phase between grain boundaries, which can improve the elongation of aluminum alloy. Zn can increase the eutectic structure of aluminum alloy and improve the fluidity of aluminum alloy, making the aluminum alloy suitable for die casting. Zn can eliminate elemental Si to reduce the adverse effect of elemental Si on the performance of aluminum alloy. Zn can also promote the precipitation of phases such as Mg2Si and Al2Cu to improve mechanical properties. In addition, Zn can react with other elements to generate a second phase to avoid the adverse effect of Zn dissolved in the aluminum matrix on the elongation of aluminum alloy. Specifically, Zn can react with Al, Mg, Cu and Si to generate second phases such as MgZn2, Mg2SiZn and Al2CuZn. (4) The mass percentage content of Fe is 0.01-0.4%. On the one hand, Fe can reduce the tendency of aluminum alloy castings to stick to the mold and improve the mechanical properties of aluminum alloys. On the other hand, Fe can react with other elements as much as possible to form a second phase, so as to avoid the adverse effect of Fe dissolved in the aluminum matrix on the elongation of aluminum alloys. Specifically, Fe can react with Al, Si, Mg, Cu, Mn, Ni, etc. to form Al3Fe, AlFeSi, AlFeMgSi, AlFeSiCu, AlFeSiNi, AlFeMgSiNi, AlFeMnSi, (CrFe)Al7, (CrMn)Al 12 Second phases such as AlFeSiB and FeNiAl9; (5) The mass percentage content of Cr is 0.001-0.5%. Cr can form (CrFe)Al7 and (CrMn)Al in aluminum. 12Intermetallic compounds such as Cr have a certain strengthening effect on aluminum alloys; Cr can also improve the toughness of aluminum alloys and reduce the susceptibility to stress corrosion cracking; Cr can also improve the morphology of Fe, turning the β-Fe phase into the α-Fe phase, reducing the cutting effect on the aluminum matrix when the β-Fe phase cannot be dissolved, thereby improving the elongation of aluminum alloys; an appropriate amount of Cr forms a variety of fine chromium-containing compounds in cast aluminum alloys, which can dissolve in the α phase during the die casting stage and disperse and precipitate a variety of Cr-containing phases during the aging stage. These Cr-containing phases can act as the nucleation core for the heterogeneous formation of the β" phase, thereby accelerating the formation of the β" phase. The dispersed precipitation of these Cr-containing phases in the aluminum matrix will inevitably have a certain delaying effect on the formation of metastable phases at grain boundaries, thereby improving the elongation of aluminum alloys; Cr can also significantly improve the microstructure and phase distribution of the original alloy, forming some Cr-rich multi-component phases. The changes in these phases and their distribution can improve the strength of aluminum alloys. (6) The mass percentage content of Ti is 0.001-0.15%. Ti can improve the strength and elongation of aluminum alloys. Specifically, the TiAl3 phase generated by the reaction of Ti and Al can serve as a non-spontaneous nucleus during crystallization, which can refine the grains, the second phase and the precipitated phase, thereby improving the strength and elongation of aluminum alloys. (7) The mass percentage content of Sr is 0-0.05%. Sr can be modified by heterogeneous nucleation theory or twin valley mechanism to refine the second phase such as eutectic silicon and improve the strength and elongation of aluminum alloy. Sr can also turn the β-Fe phase in the ingot into the α-Fe phase, reduce the cutting effect of the β-Fe phase on the aluminum matrix when it cannot be dissolved, and improve the elongation of aluminum alloy. Sr can preferentially combine with elements such as Fe, Cu, Mn, Cr, and Si to form dispersion strengthening, so as to avoid the adverse effect of Sr dissolved in the aluminum matrix on the elongation of aluminum alloy. Sr can also promote the precipitation of phases such as CuAl2 and Mg2Si to reduce the solid solubility of these alloying elements in the aluminum matrix and improve the elongation of aluminum alloy. (8) The mass percentage content of Mn is 0-0.3% and the mass percentage content of Mn is 0.001-0.3%. Mn reacts with Fe to generate a finely dispersed α-Al(FeMn)Si phase, which can improve the regulation of the β-Fe-rich phase. Mn can significantly refine the recrystallized grains and the second phase, effectively transforming the coarse needle-like or plate-like β-AlFeSi phase into small granular α-Al(FeMn)Si dispersed particles to improve the morphology of Fe and thus improve the strength and elongation of the aluminum alloy. (9) The mass percentage content of Zr is 0-0.3%. Zr can improve the strength of aluminum alloys. Zr can also form Al3Zr phase in aluminum alloys. Al3Zr phase can refine grains, second phase and precipitated phase to improve the elongation of aluminum alloys. Mn can form independent Al6Mn and Al6FeMn manganese-rich hardening phases in aluminum alloys. Mn-rich phase is distributed at or near grain boundaries and pins grain boundaries. Although Mn-rich phase has low coherence with Al matrix and its size is large, and its ability to pin dislocations is weak, the combined addition of Mn and Zr can not only reduce the amount of each alloying element used, but also promote mutual precipitation and form more Al6(Mn,Zr) phase and Al 3( The strengthening effect of Zr,Mn) phase and Al6(FeMnZr) phase is much greater than the strengthening effect of adding Mn or Zr alone; (10) The mass percentage content of Li is 0-0.5%. The solid solution strengthening of Li in the aluminum matrix can improve the strength of aluminum alloy; and increase the fraction of the aging precipitate δ′ phase (Al3Li) to improve the precipitation strengthening effect; in addition, the addition of Li greatly reduces the maximum solubility of elements such as Mg, Cu, and Zr in Al solid solution, reduces the stacking fault energy, promotes the formation of {111}Al stacking defects, and the {111}Al stacking defects are conducive to nucleation; large-angle grain boundaries and small-angle grain boundaries are conducive to the formation of lamellar T1 phase (Al2CuLi); vacancies or vacancy groups can provide nucleation sites, with dispersed particles as nucleation cores, forming phase pinning grain boundaries such as Mg2Si, which improves the strength and elongation of aluminum alloy; (11) The mass percentage content of Cu is 0-0.1%. The solid solution strengthening of Cu in the aluminum matrix can improve the strength of aluminum alloy. When the mass percentage content of Cu is not greater than 0.1%, the elongation of aluminum alloy can be significantly improved. Trace amounts of Cu can also reduce the natural aging rate, thereby mitigating the adverse effects of the storage effect on the alloy.

[0031] To avoid the adverse effect of Si on elongation, this invention sets the Si mass percentage content to 6-8% (preferably 6-7.5%). However, a Si mass percentage content of 6-8% does not significantly improve the strength of the aluminum alloy. Accordingly, this invention sets the Mg mass percentage content to 1.2-1.8% (preferably 1.4-1.6%), the Zn mass percentage content to 0.01-2.5% (preferably 0.5-2%), and the Li mass percentage content to 0-0.5% (preferably 0.1-0.5%). Through Mg... While Mg (Fe) can significantly improve the strength of aluminum alloys, a Mg content of 1.2-1.8% by mass can significantly reduce the elongation of the aluminum alloy. Zn and Li can mitigate the effect of high Mg content on the elongation of the aluminum alloy. To improve the elongation of the aluminum alloy, this invention sets the Fe and Cu content at relatively low mass percentages, namely 0.01-0.4% (preferably 0.05-0.2%) and 0-0.1% (preferably 0.001-0.05%), respectively, to avoid the impact of high Fe content on the elongation of the aluminum alloy. This invention also adds a Mg content of 0% by mass. The invention incorporates 0.001-0.5% (preferably 0.01-0.2%) of Cr and 0.3% (preferably 0.01-0.2%) of Mn by mass percentage to compensate for the impact of low Fe content on demolding performance, thereby ensuring the demolding performance of the aluminum alloy. The combination of Cr, Mn, and Li can also simultaneously improve the strength and elongation of the aluminum alloy. Furthermore, the invention adds 0-0.3% (preferably 0.01-0.2%) of Zr by mass percentage. The combined addition of Mn and Zr not only reduces the amount of each alloying element used but also promotes mutual precipitation, thus improving the overall performance. This invention achieves a high-strength effect in one step. It also incorporates 0.001-0.15% (preferably 0.01-0.1%) Ti and 0-0.05% (preferably 0.01-0.05%) Sr by mass percentage, which refines the grains, second phase, and precipitated phases, thereby improving the strength and elongation of the aluminum alloy. Sr and Zr also promote the precipitation of Mg2Si, MgB, (CuMg)Al2, etc., further improving the elongation of the aluminum alloy. These elements can also react with each other to form a second phase, preventing them from dissolving in the aluminum matrix and affecting the elongation of the aluminum alloy. Thus, Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, and Cu within the above content range interact and influence each other as a whole, giving the aluminum alloy better strength, elongation, and mold release properties.Furthermore, under the further effects of subsequent refining, aging, and die-casting processes, the solid solubility of each element in the aluminum matrix is ​​further reduced, as are the impurity elements. This can minimize the adverse effects of alloying and impurity elements on the elongation of the aluminum alloy. The second phase (such as Al3Fe, Mg2Si, Al2Cu, MgZn2, AlMnSi, etc.) can also be refined within or at the grain boundaries of the aluminum matrix, greatly improving the strength and elongation of the aluminum alloy.

[0032] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0.01-0.3% Sb, 0.01-0.3% Sn, 0.01-0.5% Ni, and 0.01-0.3% Bi by mass.

[0033] The specific mass percentage contents of Sb, Sn, and Bi can 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%, or 0.3%.

[0034] The specific mass percentage content of Ni can 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%, or 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%, 0.41%, 0.42%, 0.43%, 0.44%, 0.45%, 0.46%, 0.47%, 0.48%, 0.49%, or 0.5%.

[0035] The sum of the mass percentage contents of Sn, Sb, Ni, Fe, and Bi is 0.05-1%. Specifically, the sum of the mass percentage contents of Sn, Sb, Fe, and Bi can be 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%.

[0036] The mass ratio of the sum of the mass percentage contents of Sn, Sb, Ni, Fe, and Bi to the mass percentage content of Mg is 0.05-1:1. Specifically, this mass ratio can be 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 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.

[0037] Sn, Sb, Fe, and Bi can all react with Mg to form a second phase. Mg preferentially reacts with Si to form the Mg2Si phase, and then reacts with Sn, Sb, Fe, and Bi to form second phases such as Mg2Sn, AlFeMgSiNi, Mg3Sb2, and Mg3Bi2. This avoids the adverse effects of Mg dissolved in the aluminum matrix on the elongation of the aluminum alloy. Setting the total mass percentage of Sn, Sb, Ni, Fe, and Bi to 0.05-1%, and the mass ratio of the sum of the mass percentages of Sn, Sb, Ni, Fe, and Bi to the mass percentage of Mg to 0.05-1:1, ensures that all or almost all of Mg forms a second phase with other alloying elements, avoiding Mg dissolved in the aluminum matrix and also preventing the addition of excessive elements from affecting the elongation of the aluminum alloy. Specifically: Fe can react with other elements to form a second phase, thus avoiding the adverse effects of Fe dissolved in the aluminum matrix on the elongation of aluminum alloys. Specifically, Fe can react with Al, Si, Mg, Cu, Mn, Ni, etc., to form Al3Fe, AlFeSi, AlFeMgSi, AlFeSiCu, AlFeSiNi, AlFeMgSiNi, AlFeMnSi, (CrFe)Al7, (CrMn)Al, etc. 12 Second phases such as AlFeSiB and FeNiAl9.

[0038] Sb can be used as a modifier in aluminum alloys to effectively reduce the size of eutectic silicon layers and significantly reduce the possibility of Si cutting the matrix, thereby improving the mechanical properties of the alloy. Sb can react with other elements such as Mg to form the second phase Mg3Sb2, which can also improve the mechanical properties of the alloy. In addition, the addition of Sb can also increase the mutual precipitation of elements such as Cu, Zn, and Ni in the alloy matrix with high solid solubility, further improving the mechanical properties of the alloy.

[0039] Sn can react with Mg to form a rounded, spherical, dispersed Mg2Sn strengthening phase, which can reduce the solid solubility of Mg and Sn in the aluminum matrix. Sn can also react with other elements to form a second phase, thereby improving the mechanical properties of aluminum alloys. Specifically, Sn can react with Al to form various high-temperature strengthening phases such as Al9Sn7, Al6Sn5, Al5Sn2, and Al3Sn4.

[0040] Bi expands during solidification, which is beneficial for feeding. It can also form strengthening phases such as Mg3Bi2 and Mg3(BiCd)2 with Mg and Cd, thereby improving the mechanical properties of the alloy.

[0041] Ni can improve the mechanical properties of aluminum alloys. Ni can also react with other elements to form a second phase, thus avoiding the adverse effects of Ni dissolved in the aluminum matrix on the elongation of the aluminum alloy. Specifically, Ni can react with Al, Fe, Mg, Si, etc., to form second phases such as Al3Ni, AlFeSiNi, AlFeMgSiNi, and FeNiAl9, promoting the precipitation of Cu, Mg, Zn, Si, Fe, and other elements dissolved in the alloy. Ni can also refine grains, promote the precipitation of strengthening phases such as CuAl2, (CuMg)Al2, and Mg2Si, and increase the volume fraction and dispersion of the precipitated phases, thereby reducing the solid solubility of alloying elements in the aluminum matrix. Cu with a mass percentage content of 0-0.1% can work together with Mg with a mass percentage content of 1.2-1.8% and Ni with a mass percentage content of 0.01-0.5% to form a composite strengthening effect, reducing the solid solubility of each other in the matrix and improving the mechanical strength and elongation of the aluminum alloy.

[0042] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-0.2% RE, 0-0.2% Mo, 0-0.3% Co, and 0-0.2% Be by mass. RE is at least one of La, Ce, Pr, Nd, Er, Sm, Y, and Gd.

[0043] The specific percentage content of RE, Mo, and Be by mass 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%, 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%.

[0044] Co can react with other elements to form a second phase, thereby improving the mechanical properties of aluminum alloys. Specifically, Co can react with Al, Fe, Si, etc., to form Al. 15 Secondary phases include (Fe,Co)3Si2 and Al3(Fe,Co); Co can refine grains and also refine the Al3Fe phase, transforming coarse needle-like and plate-like β-Al3Fe phases into small flower-like and fine strip-like α-Al3Fe phases. 15 The (Fe,Co)3Si2 phase, with Co also promoting α-Al 15 The precipitation of the (Fe,Co)3Si2 phase further improves the strength and elongation of the aluminum alloy.

[0045] To avoid the influence of Fe on the elongation of aluminum alloys, the mass percentage content of Fe can be set relatively low. To ensure the demolding performance of aluminum alloys, the sum of the mass percentage contents of Fe, Cr, Co, and Mn should be 0.04-1%, specifically 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1%. When the mold undergoes surface treatment to form a boron carbide layer on the parting surface, the mass percentage content of Fe can be 0.01-0.1% (preferably 0.01-0.06%), and the sum of the mass percentage contents of Fe and Mn can be 0.02-0.1%, specifically 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%; the sum of the mass percentage contents of Fe, Cr, and Mn can be 0.04-0.1%, specifically 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%; the sum of the mass percentage contents of Fe, Cr, Co, and Mn can be 0.04-0.5%, preferably 0.05-0.3%, and more preferably 0.05-0.1%. This achieves better demolding performance and avoids the impact of excessive element addition on elongation.

[0046] The interaction of Mn, Cr, RE, Mo, Co, Be, and Sr elements not only reduces their maximum solid solubility in the aluminum matrix, thereby increasing elongation, but also promotes the reaction between Mn and Fe. Mn can occupy the positions of Fe in the second phase, making the Fe-containing phase more dispersed and finer, thus promoting the effect of modified Fe. Mn, Cr, RE, Mo, Co, Be, and Sr elements can also form a finely dispersed α-Al(MnFeX)Si phase (where X is at least one of Cr, RE, Mo, Co, Be, and Sr), further improving the elongation of the aluminum alloy.

[0047] The combined addition of 0.01-0.5% Ni and 0.01-0.5% Co by mass can effectively modify Fe and transform free Fe into a second phase, thereby improving the mechanical properties of aluminum alloys. The combination of 0.001-0.04% Cu with 0.001-0.2% RE and 0.001-0.3% Zr by mass can significantly improve the dispersion of Mg2Si, while preventing the formation of coarse AlSiFe, Mg3Sb2, Mg2Si, and Al3Zr phases, and reducing the solid solubility of various elements in the matrix, ensuring uniform precipitation during solidification. The addition of trace amounts of Cu can also reduce the anisotropy that occurs after the addition of Mn to the alloy.

[0048] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-0.2% Ca by mass. The specific mass percentage of Ca 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%, 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%. Ca can refine the eutectic structure and improve the β-Fe phase, thereby improving the alloy's strength and heat treatment performance. It can also form Al4Ca, Al2Ca3, AlCa2, and AlCaCu strengthening phases with Cu and Al, significantly improving the strength, heat resistance, and fatigue resistance of aluminum alloys.

[0049] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-0.2% V by mass. The specific mass percentage of V 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%, 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%. V can refine grains, second phases, and precipitated phases, thereby reducing grain boundary area and lowering corrosion susceptibility at grain boundaries, thus improving the corrosion resistance and elongation of the aluminum alloy.

[0050] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-0.2% In by mass. The specific mass percentage of In 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%, 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%. In can improve the strength of the aluminum alloy; In can also refine the grains, second phase, and precipitated phases, thereby improving the elongation of the aluminum alloy.

[0051] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-0.1% Ge by mass. The specific mass percentage of Ge 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%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Ge can improve the mechanical properties of aluminum alloys; Ge can react with other elements to form a second phase, further improving the mechanical properties of the alloy. Specifically, Ge can react with Al and Si to form second phases such as Al9Ge7, Al6Ge5, Al5Ge2, Al3Ge4, and SiGe. In addition, Ge can promote the precipitation of second phases such as Mg2Si and CuAl2, refine the precipitated phases, and reduce the solid solubility of the above elements in the aluminum matrix. Ge can also replace some Si atoms in metastable precipitated phases. The Si-Ge phase precipitated in the early stage of aging provides nucleation sites for the main precipitated phases such as β" and θ", increasing the density of β" and θ" phases, thereby further improving the mechanical properties of aluminum alloys.

[0052] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-0.1% Nb by mass. The specific mass percentage of Nb 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%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Nb can improve the strength of the aluminum alloy; Nb can also refine the grains, second phase, and precipitated phases, thereby improving the elongation of the aluminum alloy. When the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy contains both Nb and B, strengthening metal compounds such as AlNb3, AlNb, Al3Nb, and NbB2 can be formed, which can significantly improve the strength of the aluminum alloy.

[0053] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-0.1% Te by mass. The specific mass percentage of Te 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%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Te can modify eutectic silicon, causing it to shorten along its length, thereby increasing the elongation of the aluminum alloy. When the aluminum alloy contains both Sb and Te, fine, petal-shaped primary crystals can be formed, further improving the strength and elongation of the aluminum alloy.

[0054] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-0.1% Ag by mass. The specific mass percentage of Ag 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%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Ag can refine the second phase to improve the elongation of the aluminum alloy. Ag can promote the precipitation of second phases (such as Al2Cu, Mg2Si, Mg2Sb, Mg3Sn2, and Mg3Bi2), refine the precipitated phases and increase the density of the precipitated phases, thereby improving the precipitation strengthening effect of the aluminum alloy. It can also refine the second phase to improve the elongation and strength of the aluminum alloy.

[0055] The high-strength Al-Si-Mg die-cast aluminum alloy also contains 0-0.2% Cd by mass. The specific mass percentage of Cd 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%, 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%. Cd can improve the strength of the aluminum alloy; Cd can also refine the grains, second phase, and precipitated phases, thereby improving the elongation of the aluminum alloy. Cd can refine α-Al and form strengthening phases such as Al2Cd3, Al3Cd, Al2Cd3, (CuCd)Al2, Mg2(SiCdREFe), and Mg3(BiCd)2 with Al, RE, Cu, Mg, Si, Fe, and Bi. These phases reduce the solid solubility of each other in the aluminum matrix and increase the volume fraction of precipitated phases, thereby improving the strength of aluminum alloys. Furthermore, during the aging stage, Cd forms numerous Cd-vacancy clusters, promoting and accelerating the precipitation of phases such as CuAl2 and Mg2Si, further reducing the solid solubility of these elements in the aluminum matrix and enhancing the strength of the aluminum alloy.

[0056] The high-strength Al-Si-Mg die-cast aluminum alloy also contains 0-0.1% B by mass. The specific mass percentage of B 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%, 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%. Boron (B) can refine grains, second phases, and precipitates to improve the elongation of aluminum alloys. B can react with Al, Fe, Si, Mg, and Cu to form second phases such as AlFeSiB, MgB, and CuB, which reduces the solid solubility of these elements in the matrix and mitigates their adverse effects on elongation and thermal conductivity. Furthermore, B can refine grains, modifying and refining elemental Si to reduce the adverse effects of coarse elemental Si on aluminum alloy properties. It can also transform the β-AlFeSi phase into a Chinese character-shaped α-AlFeSi phase to eliminate the adverse effects of iron-rich phases on aluminum alloy properties and inhibit the segregation of TiAl3. Therefore, the combined use of Ti and B yields better results. The borination effect of B can also purify the molten aluminum alloy, further improving its strength and elongation.

[0057] The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 0-1% AlTiB, 0-35% SiC, 0-1% BN, and 0-1% AlTiC by mass.

[0058] The specific mass percentage content of AlTiB, BN, and AlTiC can be 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, or 1%.

[0059] The specific percentage content of SiC by mass can be 0.01%, 0.05%, 0.1%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, or 17%. 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 20.5%, 21%, 21.5%, 22%, 22.5%, 23%, 23.5%, 24%, 24.5%, 25%, 25.5%, 26%, 26.5%, 27%, 27.5%, 28%, 28.5%, 29%, 29.5%, 30%, 30.5%, 31%, 31.5%, 32%, 32.5%, 33%, 33.5%, 34%, 34.5%, or 35%.

[0060] When AlTiB and SiC are used in combination, the mass percentage content of SiC can be reduced to 4-10%, thus lowering costs. In a preferred embodiment, the mass percentage content of AlTiB is 0.3-0.8%, and the mass percentage content of SiC is 5-8%. Specifically, when AlTiB and SiC are used in combination, a C-TiB2 particle complex is formed at the SiC-Al interface. The C atoms in SiC tend to enhance the adhesion energy of the C-TiB2 / Al interface, causing the originally elongated TiAl3 to break down and shorten, thus preventing the enrichment and growth of TiAl3 and greatly enhancing the composite refining effect. Furthermore, multiple experiments have verified that when AlTiB with a mass percentage of 0.1-0.5% and SiC with a mass percentage of 4-10% are combined, the strength, elongation, wear resistance, corrosion resistance, and thermal stability of the aluminum alloy can be significantly improved.

[0061] AlTiB, SiC, AlTiC, and BN all exhibit excellent grain refinement effects. When used in combination, reducing the content of each compound can achieve a better grain refinement effect. When SiC is combined with Ti and B, a C-TiB2 particle complex is formed at the SiC-Al interface. The C atoms in SiC tend to enhance the adhesion energy of the C-TiB2 / Al interface, causing the originally elongated TiAl3 to break down and shorten, thus preventing the enrichment and growth of TiAl3 and greatly enhancing the composite grain refinement effect. BN disperses AlB2 and AlN nanonuclei at the aluminum matrix interface and grain boundaries, which can refine the grains and promote uniform grain nucleation to improve the elongation of aluminum alloys. Under the action of SiC, Ti, B, and BN, AlTiC is less prone to aggregation and has a better grain refinement strengthening effect.

[0062] This invention also provides a method for preparing a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, comprising the following steps: It provides Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, Cu, and Al sources; The Al source is heated to obtain molten aluminum; The temperature of the molten aluminum is adjusted to 750-820ºC, and a Si source is added to the molten aluminum to obtain a first mixed solution; The temperature of the first mixture is adjusted to 720-740ºC, and Si source, Mg source, Zn source, Fe source, Cr source, Ti source, Sr source, Mn source, Li source, Zr source and Cu source are added to the first mixture to obtain the second mixture; The second mixture is subjected to degassing, refining, and die-casting processes to obtain aluminum alloy parts; and The aluminum alloy parts are subjected to aging treatment to obtain the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, wherein the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy contains 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, 0-0.5% Li, and 0-0.1% Cu.

[0063] Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, and Cu sources can be used as aluminum master alloys.

[0064] In one embodiment, the die-casting process can be high-pressure casting at a temperature of 600-670ºC, a low-speed injection velocity of 0.23-0.3 m / s, and a high-speed injection velocity of 2-2.5 m / s. Existing die-casting aluminum alloys are processed at temperatures of approximately 680ºC, which is relatively high. At this temperature, when the mixture is placed into the mold, the erosion of the mold by the mixture is significant, leading to a short mold lifespan. The Al-Si-Mg die-casting aluminum alloy of this invention has a lower melting point, allowing the die-casting temperature to be set lower, resulting in less erosion of the mold and improving its lifespan.

[0065] In another embodiment, the die casting process can be a semi-solid die casting process to obtain a semi-solid die-cast aluminum alloy. In the semi-solid die casting process, a device that can enhance the "flow + stirring" effect is used to improve the uniformity of the second mixture to obtain a semi-solid slurry. Combined with vacuum-assisted technology, the air pressure in the mold cavity is reduced to 30-50 kPa, and then the semi-solid slurry is injected into the mold for semi-solid die casting. In the semi-solid die casting process, the temperature of the second mixture is 580-610℃, the stirring speed is 550-700 r / min, the stirring time is 4-10 min, the solid fraction is controlled at 35-50%, the injection speed is 0.4-1.5 m / s, and the mold temperature is 220-240℃.

[0066] When the die-casting process is a semi-solid die-casting process, the refining process can be as follows: mixing potassium titanate whiskers and aluminum powder to obtain a mixture; pulverizing the mixture using a low-energy ball mill under an argon protective atmosphere; adding the mixture of potassium titanate whiskers and aluminum powder to the second mixture while mechanically or electromagnetically stirring it. The addition of aluminum powder can improve the wettability of the mixture with the molten aluminum and prevent agglomeration. During the pulverization process, the ball-to-material ratio is 6:1, the ball milling time is 30-100 minutes, and the rotation speed is 150-300 rpm. The specific gravity of the added mixture is 3-10% of the mass of the second mixture, specifically 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%. Utilizing the crystal orientation relationship between potassium titanate whiskers and α-Al, by controlling the temperature and holding time of the second mixture, a titanium-rich transition layer is formed on the surface of the potassium titanate whiskers, reducing interfacial mismatch and enhancing heterogeneous nucleation ability. Potassium titanate whiskers, acting as a heterogeneous nucleation substrate, preferentially induce the nucleation of α-Al grains during aluminum alloy solidification, significantly increasing the nucleation rate and thus refining the grain size. Potassium titanate whiskers also inhibit grain growth; the dispersed whiskers limit abnormal grain growth through physical inhibition, while simultaneously reducing dendrite spacing and improving the uniformity of the aluminum alloy microstructure. This enhances the strength, wear resistance, and machinability of aluminum alloys, making them suitable for manufacturing precision components such as engine cylinder liners and bearings.

[0067] In the high-pressure casting or semi-solid die casting process, the mold used includes a moving mold and a fixed mold. Both the moving mold and the fixed mold have parting surfaces. The two parting surfaces together form a cavity to accommodate the mixed molten material, forming an aluminum alloy product with a certain shape. Before die casting, both parting surfaces can undergo surface treatment. The surface treatment involves forming a boron carbide layer on the parting surface. The boron carbide layer not only improves the demolding performance but also enhances the wear resistance of the mold and resists the corrosion of chemicals such as acids, alkalis, and salts, as well as the thermal erosion of the aluminum alloy, thereby extending the service life of the mold. The thickness of the boron carbide layer can be 1-10 mm, specifically 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, or 10 mm. Through the surface treatment, the Fe content, the sum of the mass percentages of Fe and Cr, or the sum of the mass percentages of Fe, Cr, and Mn, or the sum of the mass percentages of Fe, Cr, Co, and Mn can be set to a lower value.

[0068] The surface treatment can be performed by mixing a boron-containing gas (such as BCl3) and a carbon-containing gas (such as CH4) to obtain a mixed gas; introducing the mixed gas into a cavity, and using chemical vapor deposition (CVD), the boron-containing gas and the carbon-containing gas react chemically and deposit on the parting surface to form a boron carbide layer. The CVD temperature is 900-1200°C, the deposition pressure is 200-500 Pa, and the carrier gas flow rate is 100-200 sccm. The boron carbide layer can increase the hardness of the mold steel to 3000-4000 Hv; the boron carbide layer can reduce the affinity of the mixed melt to the mold surface, improve the demolding performance of the aluminum alloy, and allow for smooth demolding even with low Fe, Cr, Co, or Mn content, greatly improving the elongation of the aluminum alloy; the boron carbide layer can resist the corrosion of chemicals such as acids, alkalis, and salts, improving the corrosion resistance of the aluminum alloy; the boron carbide layer can maintain good physical and chemical properties at high temperatures, improving the thermal stability of the aluminum alloy; the boron carbide layer has an extremely low coefficient of friction, improving the surface smoothness of the aluminum alloy, and significantly reducing wear and energy consumption caused by mechanical friction in aluminum alloy products; the boron carbide layer also has high heat transfer properties, allowing heat to be quickly conducted away during aluminum alloy forming, increasing the heat transfer rate of the mold by 2-4 times compared to ordinary molds, enabling the formed aluminum alloy to cool faster and have a finer microstructure, thereby improving the strength and elongation of the aluminum alloy.

[0069] The degassing process involves adjusting the temperature of the second mixture to 700-740℃ and introducing an inert gas such as argon into the mixture using a degassing machine. The specific temperature for the degassing process can be 700℃, 710℃, 720℃, 730℃, or 740℃. The degassing process takes 10-30 minutes, specifically 10 minutes, 15 minutes, 20 minutes, 25 minutes, or 30 minutes.

[0070] In another embodiment, the refining process involves introducing an inert gas such as argon into the second mixture using a degasser, while simultaneously adding a refining agent. The vortex formed by the degasser's rotating disc in the second mixture allows the refining agent to be evenly dispersed and mixed into the mixture. This refining agent refines the alloy microstructure to improve the strength and elongation of the aluminum alloy, offering advantages such as good dispersibility and low cost. The refining process takes 10-30 minutes, specifically 10, 15, 20, 25, or 30 minutes, and the refining temperature is 700-740°C, specifically 700°C, 710°C, 720°C, 730°C, or 740°C. The refining agent contains: 5-10 parts potassium fluoroaluminate, 6-20 parts AlTi5B1 metal powder, 8-25 parts potassium titanate whisker powder, 20-40 parts sodium chloride + potassium chloride, 5-10 parts potassium nitrate, 5-10 parts potassium carbonate, and 0.5-3 parts potassium silicate. Understandably, this refining process is suitable for semi-solid die casting and high-pressure casting.

[0071] In one embodiment, the aging treatment temperature is 170-250℃, and the time is 0.05-30h. Specifically, the aging treatment temperature can be 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, or 250℃, and the time can be 0.05h, 1h, 5h, 10h, 15h, 20h, 25h, or 30h.

[0072] In another embodiment, the aging process includes a first-level aging process, a second-level aging process, and a third-level aging process. The first-level aging process is performed at a temperature of 80-120℃, specifically 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, or 120℃, for a time of 3-20 hours, specifically 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, or 20 hours. The second-level aging process is performed at a temperature of -200℃ to -100℃, specifically -200℃, -190℃, -180℃, -170℃, -160℃, -150℃, -140℃, or -130℃. The temperature for the third-stage aging treatment is 170-250℃, specifically 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, or 250℃, and the time is 0.05-5h, specifically 0.05h, 0.1h, 0.5h, 1h, 5h, 10h, 15h, 20h, 25h, or 30h. The first stage of aging treatment has a low temperature. In the first stage of aging treatment, the solute atoms in the die-cast aluminum alloy parts are stabilized and a dense GP zone is formed. At the same time, the rapid precipitation of unsaturated Zn is avoided. Thus, the Zn content can be set to a higher level.In the second-stage aging treatment, the volume shrinks rapidly, generating considerable stress, which in turn produces a large number of dislocations. These dislocations interact with the stress and grain boundaries within the alloy, and their own entanglement enhances the alloy's yield strength, tensile strength, and elongation. During this second-stage aging process, the material's crystal structure changes. Cryogenic recovery leads to recrystallization, causing grain rotation and preferential orientation to form a recrystallization texture, further improving the aluminum alloy's tensile strength and yield strength. The numerous supersaturation point defects (such as vacancies) and dislocations obtained in this second-stage aging treatment can further promote the growth of Si, Mg, Zn, Fe, Cr, and Li. The segregation of solute atoms such as Ti, Sr, Mn, and Zr significantly increases the GP zone size, which can increase the nucleation rate during the third-stage aging process and promote more complete precipitation of alloying elements. After the second-stage aging process, the temperature is adjusted to 170-250℃ within 1-5 minutes to ensure that all or almost all supersaturated point defects (such as vacancies) and dislocations formed in the second-stage aging process are retained in the third-stage aging process. At this time, the GP zone gradually transforms into a precipitate phase with a smaller size but a larger volume fraction, precipitating all or almost all alloying elements dissolved in the alloy, increasing the pinning effect on dislocations, and greatly improving the strength and elongation of the aluminum alloy. The composite addition of Si, Mg, Zn, Fe, Cr, Li, Ti, Sr, Mn, and Zr allows the alloy to disperse and precipitate various dispersed phases containing Si, Mg, Zn, Fe, Cr, Li, Ti, Sr, Mn, and Zr during the aging stage. These dispersed phases themselves can refine the grains, improving the alloy's strength and elongation; they can also act as nuclei for the heterogeneous nucleation of the β" phase, thereby accelerating the formation of the β" phase and further improving strength and elongation. The aging treatment may further include a fourth-stage aging treatment, which can be natural aging or water-cooled aging. After the fourth-stage aging treatment, the elongation of the aluminum alloy is further improved, but the strength decreases. The natural aging treatment involves placing the aluminum alloy parts that have undergone the third-stage aging treatment at room temperature for 0.5-5 hours, specifically 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours. The water-cooled aging treatment involves immersing the aluminum alloy parts, which have undergone the third-stage aging treatment, in room-temperature water for 0.5-5 hours, specifically 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, or 5 hours. During the natural aging process, the temperature of the aluminum alloy parts drops rapidly, and fine strengthening phases continue to precipitate, but the precipitation rate decreases, further improving the strength and elongation of the aluminum alloy. During the water-cooled aging treatment, the temperature of the aluminum alloy parts drops even more rapidly, and fine strengthening phases continue to precipitate, but the precipitation rate decreases even faster, further improving the strength and elongation of the aluminum alloy. The strength and elongation of the aluminum alloy after the water-cooled aging treatment are greater than those of the aluminum alloy after natural aging treatment.

[0073] In another embodiment, the aging treatment includes a primary low-temperature electric field aging treatment and a secondary high-temperature aging treatment. The primary low-temperature electric field aging treatment is performed at a temperature of 50-130℃ for a duration of 0.1-100 hours, with an electric field strength of 2-50 kV / cm. Specifically, the primary low-temperature electric field aging treatment temperature can be 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, or 130℃, and the specific duration can be 0.1h, 0.5h, 1h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, or 40h. The duration of the high-temperature aging treatment is 45h, 50h, 55h, 60h, 65h, 70h, 75h, 80h, 85h, 90h, 95h, or 100h, with specific electric field strengths of 2kV / cm, 5kV / cm, 10kV / cm, 15kV / cm, 20kV / cm, 25kV / cm, 30kV / cm, 35kV / cm, 40kV / cm, 45kV / cm, or 50kV / cm. The secondary high-temperature aging treatment is performed without an electric field, with a temperature of 170-250℃ and a duration of 0.05-30h. The specific temperatures for the secondary high-temperature aging treatment can be 170℃, 180℃, 190℃, 200℃, 210℃, 220℃, 230℃, 240℃, or 250℃, and the specific times can be 0.05h, 0.1h, 0.5h, 1h, 5h, 10h, 15h, 20h, 25h, or 30h. During the primary low-temperature electric field aging treatment, the low temperature of 50-130℃ can suppress the segregation of atoms such as Si, Mg, Zn, Fe, Cr, Li, Ti, Sr, Mn, and Zr, while simultaneously increasing the supercooling of the alloy, significantly expanding the GP region, facilitating increased nucleation rate in subsequent high-temperature processes, and allowing for more complete precipitation of alloying elements. Furthermore, because applying an electric field at low temperatures reduces the precipitation activation energy of phases in the alloy, the low-temperature electric field aging can accelerate the precipitation nucleation rate of precipitated phases during the aging process, increasing the volume fraction of nucleation sites. The alloy exhibits a significant increase in hardness during the initial stage of electric field aging. In the subsequent secondary high-temperature aging treatment, the time required for the alloy to reach peak hardness is shortened, the volume fraction of precipitated phases is increased, and the size of the precipitated phases is refined. With the increase of the electric field strength during the primary low-temperature electric field aging treatment, the number of nucleation sites for the strengthening phases in the alloy increases dramatically. This indicates that increasing the electric field strength can improve the nucleation and precipitation rate of the precipitated phases, and it has no significant impact on the growth of the phases during the secondary high-temperature aging treatment without an electric field, thus preventing phase coarsening and improving the elongation of the aluminum alloy.

[0074] In the technical solution of this invention, the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy contains 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, 0-0.5% Li, and 0-0.1% Cu. The interaction and mutual influence of these elements result in the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy possessing excellent yield strength, tensile strength, and elongation.

[0075] In this invention, to avoid the adverse effect of Si on elongation, the mass percentage content of Si is set to 6-8% (preferably 6-7.5%). However, a Si mass percentage content of 6-8% does not significantly improve the strength of the aluminum alloy. Correspondingly, the mass percentage content of Mg is set to 1.2-1.8% (preferably 1.4-1.6%), the mass percentage content of Zn is set to 0.01-2.5% (preferably 0.5-2%), and the mass percentage content of Li is set to 0-0.5% (preferably 0.1-0.5%). The strength of aluminum alloys is significantly improved by using Mg, Zn, and Li. However, setting the Mg content to 1.2-1.8% by mass significantly reduces the elongation of the aluminum alloy. Zn and Li can reduce the reduction in elongation caused by high Mg content. To improve the elongation of the aluminum alloy, the present invention sets the Fe and Cu content to be relatively low, at 0.01-0.4% (preferably 0.05-0.2%) and 0-0.1% (preferably 0.001-0.05%), respectively, to avoid the impact of high Fe content on the elongation of the aluminum alloy. The present invention also adds a mass percentage of... The invention incorporates 0.001-0.5% (preferably 0.01-0.2%) of Cr and 0.3% (preferably 0.01-0.2%) of Mn by mass percentage to compensate for the impact of low Fe content on demolding performance, thereby ensuring the demolding performance of the aluminum alloy. The combination of Cr, Mn, and Li can also simultaneously improve the strength and elongation of the aluminum alloy. Furthermore, the invention adds 0.3% (preferably 0.01-0.2%) of Zr by mass percentage. The combined addition of Mn and Zr not only reduces the amount of each alloying element used but also promotes mutual precipitation. Furthermore, this invention incorporates 0.001-0.15% (preferably 0.01-0.1%) Ti and 0-0.05% (preferably 0.01-0.05%) Sr by mass percentage, which refines the grains, second phase, and precipitated phases, thereby improving the strength and elongation of the aluminum alloy. Sr and Zr also promote the precipitation of Mg2Si, MgB, and (CuMg)Al2, further enhancing the elongation of the aluminum alloy. These elements can also react with each other to form a second phase, preventing them from dissolving in the aluminum matrix and affecting the elongation of the aluminum alloy. Thus, Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, and Cu within the aforementioned content range interact and influence each other as a whole, resulting in aluminum alloys with superior strength, elongation, and mold release properties.Furthermore, under the further effects of subsequent refining, aging, and die-casting processes, the solid solubility of each element in the aluminum matrix is ​​further reduced, as are the impurity elements. This can minimize the adverse effects of alloying and impurity elements on the elongation of the aluminum alloy. The second phase (such as Al3Fe, Mg2Si, Al2Cu, MgZn2, AlMnSi, etc.) can also be refined within or at the grain boundaries of the aluminum matrix, greatly improving the strength and elongation of the aluminum alloy.

[0076] The method for preparing the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy further includes the step of adding at least one of the following sources to the first mixture: Sb source, Sn source, Bi source, Ni source, RE source, Mo source, Be source, Ca source, V source, In source, Ge source, Nb source, Te source, Ag source, Co source, Cd source, B source, AlTiB source, SiC source, BN source, and AlTiC source. These elements can at least be used to improve the strength or elongation of the aluminum alloy, resulting in a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy with superior performance. The raw materials for these alloying elements can be aluminum master alloys. For example, the RE source can be an Al-RE alloy.

[0077] Example Please refer to Table 1 for the composition and content of the aluminum alloys in Examples 1 to 10, and Table 2 for the performance test results.

[0078] Table 1. Composition and content of aluminum alloys in Examples 1 to 10 For the sake of simplicity, not all impurity elements and their contents are shown.

[0079] Table 2. Performance test results of aluminum alloys in Examples 1 to 10. The aluminum alloys from Examples 1 to 10 were used to fabricate structural components, and the tensile strength, yield strength, and elongation of these components were tested. The test results are shown in Table 2. In Examples 6 to 10, the mold underwent surface treatment, forming a 2mm boron carbide layer on the mold's parting surface.

[0080] Table 2 shows that the aluminum alloys of Examples 1 to 10 have better tensile strength, yield strength, and elongation. Specifically, the aluminum alloys of Examples 1 to 10 have a tensile strength of not less than 400 MPa, a yield strength of not less than 310 MPa, and an elongation of not less than 5%.

[0081] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the content of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, characterized in that, The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy also contains 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, 0-0.5% Li, 0-1% AlTiB, 0-35% SiC, and 0-0.1% Cu, with the balance being Al.

2. The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy according to claim 1, characterized in that, The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy contains 6-8% Si, 1.2-1.8% Mg, 0.01-1.5% Zn, 0.01-0.4% Fe, 0.001-0.5% Cr, 0.001-0.15% Ti, 0.001-0.05% Sr, 0.01-0.25% Mn, 0.001-0.25% Zr, 0-0.5% Li, 0.1-1% AlTiB, 0.01-35% SiC, and 0.01-0.08% Cu, with the balance being Al.

3. The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy according to claim 1, characterized in that, The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy further contains at least one of Sb, Sn, Co, Bi, Ca, Be, V, Ge, Mo, Nb, Te, Ag, In, Ni, BN, and AlTiC, wherein the mass percentage content of Sb is 0-0.3%, the mass percentage content of Sn is 0-0.3%, the mass percentage content of Co is 0-0.3%, the mass percentage content of Bi is 0-0.3%, the mass percentage content of Ca is 0-0.2%, the mass percentage content of Be is 0-0.2%, the mass percentage content of V is 0-0.2%, the mass percentage content of Ge is 0-0.1%, the mass percentage content of Mo is 0-0.2%, the mass percentage content of Nb is 0-0.1%, the mass percentage content of Te is 0-0.1%, the mass percentage content of Ag is 0-0.1%, the mass percentage content of In is 0-0.2%, the mass percentage content of Ni is 0.001-0.5%, the mass percentage content of BN is 0-1%, and the mass percentage content of AlTiC is 0-1%.

4. The high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy according to claim 3, characterized in that, At least one of the following conditions must be met: The Sb content is 0.01-0.3% by mass; The Sn content is 0.15-0.3% by mass; The percentage content of Co is 0.15-0.3% by mass; The mass percentage content of Bi is 0.01-0.3%; The Ca content is 0.15-0.2% by mass; The Be content is 0.15-0.2% by mass; The mass percentage content of V is 0.001-0.2%; The mass percentage content of Ge is 0.001-0.1%; The mass percentage content of Mo is 0.001-0.2%; The Nb content is 0.001-0.1% by mass; The Te content is 0.001-0.1% by mass; The mass percentage content of Ag is 0.001-0.1%; The mass percentage content of In is 0.001-0.2%; The mass percentage content of Ni is 0.2-0.5%; The mass percentage content of BN is 0.1-1%; The AlTiC content is 0.1-1% by mass.

5. A method for preparing a high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, comprising the following steps: It provides Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, Cu, and Al sources; The Al source is heated to obtain molten aluminum; Adding Si, Mg, Zn, Fe, Cr, Ti, Sr, Mn, Li, Zr, AlTiB, SiC, and Cu sources to the molten aluminum yields a mixed solution; and The mixture is subjected to die casting and aging treatment to obtain the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy, wherein the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy contains 6-8% Si, 1.2-1.8% Mg, 0.001-2.5% Zn, 0.01-0.4% Fe, and 0.001- 0.5% Cr, 0.001-0.15% Ti, 0-0.05% Sr, 0-0.3% Mn, 0-0.3% Zr, 0-0.5% Li, 0-1% AlTiB, 0-35% SiC, and 0-0.1% Cu, with the balance being Al.

6. The method for preparing high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy according to claim 5, characterized in that, The preparation method of the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy further includes a step of surface treatment of the mold, wherein the surface treatment is to form a boron carbide layer on the parting surface of the mold.

7. The method for preparing high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy according to claim 5, characterized in that, The die-casting process is high-pressure casting, in which the temperature is 600-670ºC, the low-speed injection velocity is 0.23-0.3m / s, and the high-speed injection velocity is 2-2.5m / s; or The die casting process is a semi-solid die casting process. In the semi-solid die casting process, the temperature of the mixture is 580-610℃, the stirring speed is 550-700 r / min, the stirring time is 4-10min, the solid phase rate is 35-50%, the injection speed is 0.4-1.5m / s, the mold temperature is 220-240℃, and the air pressure in the mold cavity is 30-50kPa.

8. The method for preparing high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy according to claim 5, characterized in that, The aging treatment is performed at a temperature of 170-250℃ for a time of 0.05-30 hours; or The aging process includes a first-level aging process, a second-level aging process, a third-level aging process, and a fourth-level aging process. The first-level aging process is carried out at a temperature of 80-120°C for 3-20 hours; the second-level aging process is carried out at a temperature of -200 to -100°C for 0.5 to 10 hours; the third-level aging process is carried out at a temperature of 170-250°C for 0.05 to 5 hours; and the fourth-level aging process is either natural aging or water-cooled aging; or... The aging treatment includes a first-stage low-temperature electric field aging treatment and a second-stage high-temperature aging treatment. The first-stage low-temperature electric field aging treatment is performed at a temperature of 50-130℃ for a time of 0.1-100h, with an electric field strength of 2-50kV / cm. The second-stage high-temperature aging treatment is performed at a temperature of 170-250℃ for a time of 0.05-30h.

9. The method for preparing high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy according to claim 5, characterized in that, The preparation method of the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy further includes the step of adding at least one of the following sources to the molten aluminum: Sb source, Sn source, Co source, Bi source, Ca source, Be source, V source, Ge source, Mo source, Nb source, Te source, Ag source, In source, Ni source, BN source, and AlTiC source, wherein the mass percentage content of Sb is 0-0.3%, the mass percentage content of Sn is 0-0.3%, the mass percentage content of Co is 0-0.3%, the mass percentage content of Bi is 0-0.3%, and the mass percentage content of Ca is 0-0.3%. 0.2%, Be (mass percentage) 0-0.2%, V (mass percentage) 0-0.2%, Ge (mass percentage) 0-0.1%, Mo (mass percentage) 0-0.2%, Nb (mass percentage) 0-0.1%, Te (mass percentage) 0-0.1%, Ag (mass percentage) 0-0.1%, In (mass percentage) 0-0.2%, Ni (mass percentage) 0.1-0.5%, BN (mass percentage) 0-1%, AlTiC (mass percentage) 0-1%.

10. A structural component, characterized in that, The material of the structural component is the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy as described in any one of claims 1-4, or the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy prepared by the preparation method of the high-strength, high-elongation Al-Si-Mg die-cast aluminum alloy as described in any one of claims 5-9.

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