Al-zn-based die-cast aluminum alloy and method for manufacturing the same, structural member

Abstract

The application provides an Al-Zn series die-casting aluminum alloy and a preparation method and a structural member thereof. The Al-Zn series die-casting aluminum alloy contains Al, and further contains Zn with a mass percentage of 20-35%, Si with a mass percentage of 0.2-3.5%, Cu with a mass percentage of 0-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Mn with a mass percentage of 0.001-0.3%, Sr with a mass percentage of 0-0.1%, Ti with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, and RE with a mass percentage of 0-0.3%. The Al-Zn series die-casting aluminum alloy has high strength, high toughness and low density, and is suitable for manufacturing thin-wall structural members.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum alloy, and particularly relates to an Al-Zn series die-casting aluminum alloy, a preparation method thereof and a structural member. BACKGROUND

[0002] At present, the 3C, new energy and intelligent machine industries gradually develop in the direction of light weight, and higher requirements are put forward for the strength of aluminum alloy. Due to the requirements of assembly methods and application environments, the toughness of the aluminum alloy is also required to be high in the above-mentioned industries. When the existing Al-Zn series die-casting aluminum alloy is prepared into a thin-walled structural member, the yield strength of the thin-walled structural member can reach 300 MPa, but when the yield strength reaches 300 MPa, the elongation is usually low, not more than 2.5%, and the density is usually greater than 3.5 g / cm 3 . This leads to the fact that the existing Al-Zn series die-casting aluminum alloy cannot simultaneously realize high strength, high toughness and low density.

[0003] Therefore, the market urgently needs an Al-Zn series die-casting aluminum alloy with high strength, high toughness and low density. SUMMARY

[0004] In view of the above defects of the prior art, the present application provides an Al-Zn series die-casting aluminum alloy with high strength, high toughness and low density.

[0005] The present application provides an Al-Zn series die-casting aluminum alloy containing Al, further containing Zn with a mass percentage of 20-35%, Si with a mass percentage of 0.2-3.5%, Cu with a mass percentage of 0-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Mn with a mass percentage of 0.001-0.3%, Sr with a mass percentage of 0-0.1%, Ti with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, and RE with a mass percentage of 0-0.3%.

[0006] Further, the Al-Zn series die-casting aluminum alloy contains Zn with a mass percentage of 20-35%, Si with a mass percentage of 0.5-3%, Cu with a mass percentage of 0.001-3%, Mg with a mass percentage of 0.1-0.3%, Fe with a mass percentage of 0.01-0.3%, Mn with a mass percentage of 0.001-0.2%, Sr with a mass percentage of 0.001-0.1%, Ti with a mass percentage of 0.001-0.3%, V with a mass percentage of 0.001-0.1%, and RE with a mass percentage of 0.001-0.3%.

[0007] Further, the sum of the mass percentage content of Fe and Mn is 0.05-0.6%.

[0008] Further, the sum of the mass percentage content of Sr, Ti, V, Mn, and RE is 0.08-0.6%.

[0009] Further, at least one of the following conditions is met:

[0010] The Al-Zn-based die-casting aluminum alloy further contains B with a mass percentage content of 0-0.1%;

[0011] The Al-Zn-based die-casting aluminum alloy further contains Be with a mass percentage content of 0-0.1%;

[0012] The Al-Zn-based die-casting aluminum alloy further contains Bi with a mass percentage content of 0-0.1%;

[0013] The Al-Zn-based die-casting aluminum alloy further contains Cd with a mass percentage content of 0-0.2%;

[0014] The Al-Zn-based die-casting aluminum alloy further contains Ge with a mass percentage content of 0-0.1%;

[0015] The Al-Zn-based die-casting aluminum alloy further contains Mo with a mass percentage content of 0-0.1%;

[0016] The Al-Zn-based die-casting aluminum alloy further contains Nb with a mass percentage content of 0-0.1%;

[0017] The Al-Zn-based die-casting aluminum alloy further contains Ni with a mass percentage content of 0-0.3%;

[0018] The Al-Zn-based die-casting aluminum alloy further contains Sb with a mass percentage content of 0-0.2%;

[0019] The Al-Zn-based die-casting aluminum alloy further contains Sn with a mass percentage content of 0-0.1%;

[0020] The Al-Zn-based die-casting aluminum alloy further contains In with a mass percentage content of 0-0.1%;

[0021] The Al-Zn-based die-casting aluminum alloy further contains TiC with a mass percentage content of 0-1%;

[0022] The Al-Zn-based die-casting aluminum alloy further contains SiC with a mass percentage content of 0-35%.

[0023] The application also provides a preparation method of the Al-Zn-based die-casting aluminum alloy, comprising the following steps:

[0024] a Zn source, a Si source, a Cu source, a Mg source, a Sr source, a Ti source, a V source, a RE source, and an Al source are provided;

[0025] a heating treatment is performed on the Al source to obtain an aluminum liquid;

[0026] a Zn source, a Si source, a Cu source, a Mg source, a Sr source, a Ti source, a V source, a RE source, and an Al source are provided;

[0027] a die casting treatment and an aging treatment are performed on the mixed liquid to obtain the Al-Zn series die casting aluminum alloy, wherein the Al-Zn series die casting aluminum alloy contains Zn with a mass percentage of 20-35%, Si with a mass percentage of 0.2-3.5%, Cu with a mass percentage of 0-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Mn with a mass percentage of 0.001-0.3%, Sr with a mass percentage of 0-0.1%, Ti with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, and RE with a mass percentage of 0-0.3%.

[0028] Further, the aging treatment is performed at a temperature of 80-150°C for a time of 0.05-30h; or

[0029] The aging treatment includes a first-stage aging treatment, a second-stage aging treatment, a third-stage aging treatment, and a fourth-stage aging treatment, the first-stage aging treatment is performed at a temperature of 40-90°C for a time of 3-20h; the second-stage aging treatment is performed at a temperature of -200~-100°C for a time of 0.5-10h; the third-stage aging treatment is performed at a temperature of 100-130°C for a time of 0.5-5h, and the temperature is adjusted to 100-130°C within 1-5min after the second-stage aging treatment.

[0030] Further, the preparation method of the Al-Zn series die-casting aluminum alloy further comprises the step of adding at least one of a B source, a Be source, a Bi source, a Cd source, a Ge source, a Mo source, a Nb source, a Ni source, a Sb source, a Sn source, an In source, a TiC source and a SiC source into the aluminum liquid, wherein the mass percentage content of B is 0-0.1%, the mass percentage content of Be is 0-0.1%, the mass percentage content of Bi is 0-0.1%, the mass percentage content of Cd is 0-0.2%, the mass percentage content of Ge is 0-0.1%, the mass percentage content of Mo is 0-0.1%, the mass percentage content of Nb is 0-0.1%, the mass percentage content of Ni is 0-0.3%, the mass percentage content of Sb is 0-0.2%, the mass percentage content of Sn is 0-0.1%, the mass percentage content of In is 0-0.1%, the mass percentage content of TiC is 0-1%, and the mass percentage content of SiC is 0-35%.

[0031] The application further provides a structural member made of the Al-Zn series die-casting aluminum alloy or made by the preparation method of the Al-Zn series die-casting aluminum alloy.

[0032] Further, the thickness of the structural member is 1.5-15 mm.

[0033] In the technical scheme, the Al-Zn series die-casting aluminum alloy contains Zn with a mass percentage content of 20-35%, Si with a mass percentage content of 0.2-3.5%, Cu with a mass percentage content of 0-3%, Mg with a mass percentage content of 0-0.3%, Fe with a mass percentage content of 0.001-0.5%, Mn with a mass percentage content of 0.001-0.3%, Sr with a mass percentage content of 0-0.1%, Ti with a mass percentage content of 0-0.3%, V with a mass percentage content of 0-0.3%, and RE with a mass percentage content of 0-0.3%. The elements with the above contents interact and influence each other, so that the Al-Zn series die-casting aluminum alloy has high strength, high toughness and low density, and is suitable for being made into structural members, especially thin-walled structural members, in the 3C, new energy, intelligent machine and other industries. The tensile strength of the Al-Zn series die-casting aluminum alloy is greater than 340 MPa, the yield strength is greater than 300 MPa, the elongation is greater than 4.5%, and the density is less than 3.4 g / cm 3 . DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0035] An Al-Zn series die-casting aluminum alloy is provided in an embodiment of the present application. The Al-Zn series die-casting aluminum alloy has high strength, high toughness and low density, and is suitable for manufacturing structural parts, especially thin-walled structural parts, of the 3C, new energy, intelligent machine and other industries.

[0036] The thickness of the structural part can reach 1.5-15 mm, and can be 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. When the Al-Zn series die-casting aluminum alloy of the present application is used to manufacture a structural part with a thickness of 1.5-15 mm, the surface of the structural part is smooth and no cracking occurs.

[0037] The Al-Zn series die-casting aluminum alloy contains Al, and further contains Zn with a mass percentage of 20-35%, Si with a mass percentage of 0.2-3.5%, Cu with a mass percentage of 0-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Mn with a mass percentage of 0.001-0.3%, Sr with a mass percentage of 0-0.1%, Ti with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, and RE with a mass percentage of 0-0.3%. The RE is at least one of La, Ce, Pr, Nd, Er, Sm, Y, Sc and Gd.

[0038] In an embodiment, the Al-Zn series die-casting aluminum alloy contains Zn with a mass percentage of 20-35%, Si with a mass percentage of 0.5-3%, Cu with a mass percentage of 0.001-3%, Mg with a mass percentage of 0.1-0.3%, Fe with a mass percentage of 0.01-0.3%, Mn with a mass percentage of 0.001-0.2%, Sr with a mass percentage of 0.001-0.1%, Ti with a mass percentage of 0.001-0.3%, V with a mass percentage of 0.001-0.1%, and RE with a mass percentage of 0.001-0.3%.

[0039] The mass percent content of Zn can specifically be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, or 35%.

[0040] The mass percent content of Si can specifically be 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%, 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%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, 3.1%, 3.2%, 3.3%, 3.4%, or 3.5%.

[0041] The mass percent content of Cu can specifically be 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3%.

[0042] The mass percent content of Mg can specifically be 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%.

[0043] The mass percent content of Sr can specifically be 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%.

[0044] The mass percentage content of Ti can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%.

[0045] The mass percentage content of V can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%.

[0046] The mass percentage content of RE can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%.

[0047] The sum of the mass percentage contents of Sr, Ti, V, Mn, and RE is 0.08-0.6%, and can be specifically 0.08%, 0.09%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, or 0.6%. Within this range, Sr, Ti, V, Mn, and RE can cooperate with each other to refine grains, second phases, and precipitated phases, without the addition of one or more elements being excessive and reducing the strength and elongation of the aluminum alloy.

[0048] The Al-Zn-based die-casting aluminum alloy also contains impurities with a total mass percentage content of less than 1%, preferably less than 0.6%, and further preferably less than 0.3%. The aluminum source can be electrolytic aluminum, and of course can also be other types. Bauxite contains Fe impurities, and when bauxite is used as a raw material to obtain electrolytic aluminum through electrolytic treatment, the Al-Zn-based die-casting aluminum alloy inevitably contains Fe impurities, with a mass percentage content of 0.001-0.1%, specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. When recycled aluminum is used as the aluminum source, the mass percentage content of Fe impurities can be 0.001-0.5%, specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0049] Impurities brought by the raw material or the preparation process, especially when recycled aluminum is used as the raw material, also include Mn and / or Cr, with a mass percentage content of 0.001-0.3%. The mass percentage content of Mn and Cr can be 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.15%, 0.2%, 0.25%, or 0.3%. Of course, the content of Mn and / or Cr can also be reduced by using pure aluminum ingots as the aluminum source to reduce the content of impurities.

[0050] The elements and contents in the aluminum alloy can be detected to obtain the content of Mn. When the content of Mn is too high, the content of Mn can be adjusted to 0.001-0.3% through boronization treatment, or the content of Mn can be adjusted to 0.001-0.3% by adding aluminum ingots (such as pure aluminum ingots). When the content of Mn is too low, the content of Mn can also be adjusted to 0.001-0.3% by adding a Mn source. Of course, the content of Mn can also be maintained at a lower level without adding a Mn source.

[0051] In the die-casting aluminum alloy industry, it is generally believed that the sum of the mass percentage contents of Fe and Mn, or the sum of the mass percentage contents of Fe, Mn and Cr is greater than 0.7% to achieve the demolding of the die-casting aluminum alloy. In the Al-Zn series die-casting aluminum alloy of the present application, better demolding performance can be achieved without adding ferrous metals (such as Fe, Mn and Cr), wherein Fe, Mn and Cr come from raw materials. It has been verified through experiments that when Zn and Si within the above content range of the present application are matched, better demolding performance can be achieved, and the affinity and hot corrosion degree of steel molds are greatly reduced. In this way, the present application can achieve better demolding performance without adding at least one of Fe, Mn and Cr to the aluminum liquid. Of course, the present application can add a certain content of Mn to improve the demolding performance.

[0052] The sum of the mass percentage contents of Fe and Mn is 0.05-0.6%, specifically 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55% or 0.6%. The mass percentage contents of Fe and Mn in the aluminum alloy can be adjusted through boronization treatment to make the mass percentage contents of Fe and Mn within an appropriate range.

[0053] The sum of the mass percentage contents of Fe, Mn and Cr is 0.05-0.6%, specifically 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55% or 0.6%. The mass percentage contents of Fe, Mn and Cr in the aluminum alloy can be adjusted through boronization treatment to make the mass percentage contents of Fe, Mn and Cr within an appropriate range.

[0054] In the technical scheme, the Al-Zn series die-casting aluminum alloy contains Zn with a mass percentage of 20-35%, Si with a mass percentage of 0.2-3.5%, Cu with a mass percentage of 0-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Mn with a mass percentage of 0.001-0.3%, Sr with a mass percentage of 0-0.1%, Ti with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, and RE with a mass percentage of 0-0.3%. The elements with the above contents interact and influence each other, so that the Al-Zn series die-casting aluminum alloy has high strength, high toughness and low density, and is suitable for being made into structural parts, especially thin-walled structural parts, of 3C, new energy, intelligent machine and other industries. The tensile strength of the Al-Zn series die-casting aluminum alloy is greater than 340 MPa, the yield strength is greater than 300 MPa, the elongation is greater than 4.5%, and the density is less than 3.4 g / cm 3 . Specifically,

[0055] (1) The mass percentage of Zn is 20-35%, and the Zn in the above content range can improve the fluidity of the aluminum alloy, so that the aluminum alloy is suitable for die-casting forming; the Zn in the above content range can also reduce the solidification temperature of the aluminum alloy, so that the affinity and thermal corrosion degree of the aluminum alloy to the die steel (such as H13 steel) are greatly reduced, thereby improving the service life of the die; with the increase of the content of Zn, the solidus temperature of the aluminum alloy is reduced, causing the melt overheating, and the melt supercooling degree increases with the increase of the melt overheating degree, which can accelerate the nucleation rate and reduce the grain size; the solid solution strengthening of Zn in the aluminum matrix can improve the strength of the aluminum alloy, and the grain boundary of the high-zinc aluminum alloy exists a complex network grain boundary structure composed of fine lamellar α+η phase and η phase, which can hinder the dislocation movement of the alloy, thereby improving the strength and hardness of the aluminum alloy; after aging treatment, the precipitated elemental Zn can further strengthen the aluminum alloy; and the elemental Zn is a non-brittle phase between the grain boundaries, so that the aluminum alloy has a high elongation;

[0056] (2) The mass percentage of Si is 0.2-3.5%, and when the content of Si is too high, the elongation of the aluminum alloy will be sharply reduced, and the Si in the above content range will not significantly reduce the elongation of the aluminum alloy; the Si in the above content range can improve the fluidity of the aluminum alloy, and further improve the forming performance of the aluminum alloy; the Si in the above content range can also reduce the deformation amount of the aluminum alloy due to natural aging, thereby increasing the dimensional stability of the aluminum alloy product;

[0057] (3) The mass percentage content of Cu is not more than 3%, and the solid solution strengthening of Cu in the aluminum matrix can improve the strength of the aluminum alloy; but when the mass percentage content of Cu is too high, such as greater than 3%, the elongation of the aluminum alloy will be sharply reduced, because the coarsened Al2Cu phase can weaken the strength between the alloy dendrites and increase the tendency of cracks between the dendrites;

[0058] (4) The mass percentage content of Mg is not more than 0.3%, and the solid solution strengthening of Mg in the aluminum matrix can improve the strength of the aluminum alloy; the Mg2Si phase formed by Mg and Si is dispersedly distributed in the grain boundary and the grain, but when the mass percentage content of Mg is too high, such as greater than 0.3%, the Mg2Si phase is coarsened, which will sharply reduce the demoulding performance and elongation of the aluminum alloy;

[0059] (5) The mass percentage content of Sr is not more than 0.1%, and Sr as a modifier can change the behavior of intermetallic compound phase in crystallography, and through the heterogeneous nucleation theory or twin valley mechanism, the aluminum alloy is subjected to modification treatment to refine the grains, the second phase and the precipitated phase, so as to improve the elongation of the aluminum alloy, such as refining the Al2Cu phase, the Mg2Si phase and the like to reduce the adverse effect when the contents of Cu and Mg are high;

[0060] (6) The mass percentage content of RE is not more than 0.3%, and RE can provide heterogeneous nucleation points to hinder the growth of grains, so as to refine the grains, the second phase and the precipitated phase, thereby improving the elongation of the aluminum alloy; RE can also promote the precipitation of strengthening phase and dispersion phase, thereby improving the strength of the aluminum alloy;

[0061] (7) The mass percentage content of Ti is not more than 0.3%, and Ti can refine the grains, the second phase and the precipitated phase, thereby improving the elongation of the aluminum alloy;

[0062] (8) The mass percentage content of V is not more than 0.3%, and V in the aluminum alloy forms Al3V, Al 10 V, VAl 11 , Al(VMnTi)Si refractory compounds, which can refine the grains and have the effect of dispersion strengthening, thereby improving the strength and elongation of the aluminum alloy;

[0063] (9) the mass percentage content of Fe is 0.001-0.5%, Fe can reduce the sticking tendency of the aluminum alloy casting and improve the demolding performance of the aluminum alloy; Fe can react with other elements to form a second phase to avoid the adverse effects of Fe and other elements dissolved in the aluminum matrix on the performance of the aluminum alloy; specifically, Fe can react with Al, Si, Mg, Cu, Mn, Ni, B and the like to form Al3Fe, AlFeSi, AlFeMgSi, AlFeSiCu, AlFeSiNi, AlFeMgSiNi, AlFeMnSi, FeNiAl9, AlFeSiB and the like; however, the presence of the beta iron-rich phase in the aluminum matrix can reduce the elongation of the aluminum alloy;

[0064] (10) the mass percentage content of Mn is 0.001-0.3%, Mn reacts with Fe to form a dispersed and fine α-Al(FeMn)Si phase, which can improve the regulation of the beta Fe-rich phase; Mn can significantly refine the recrystallized grains and the second phase, effectively converting the coarse needle-shaped or flaky beta-AlFeSi phase into small particle-shaped α-Al(FeMn)Si dispersed particles to improve the Fe morphology, thereby improving the strength and elongation of the aluminum alloy.

[0065] Zn and Si in the above content range can improve the forming performance, demolding performance, strength, elongation and dimensional stability of the aluminum alloy at the same time, so that the thin-walled structural part made of the Al-Zn series die-casting aluminum alloy of the present application has high strength, high toughness and low density without cracking; Cu and Mg in the above content range can improve the strength of the aluminum alloy; Fe and Mn in the above content range can improve the demolding performance of the aluminum alloy; Sr, RE, Ti, V and Mn in the above content range interact with each other to refine the grains, the second phase and the precipitated phase, thereby significantly improving the elongation of the aluminum alloy, such as refining the Al2Cu phase, the Mg2Si phase and the like to reduce the adverse effects when the content of Cu and Mg is high. In this way, the Al-Zn series die-casting aluminum alloy with high strength, high toughness and low density can be obtained.

[0066] The Al-Zn series die-casting aluminum alloy can further contain B in a mass percentage of 0-0.1%. The mass percentage of B can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. B can refine the grains, the second phase and the precipitated phase, so as to improve the elongation of the aluminum alloy. The boronization of B can also purify the aluminum alloy liquid, further improving the strength and elongation of the aluminum alloy. B can inhibit the segregation of Ti3Al, and therefore, Ti and B are used together for better effect.

[0067] The Al-Zn series die-casting aluminum alloy can further contain Be in a mass percentage of 0-0.1%. The mass percentage of Be can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. Be can refine the Si phase, so as to reduce or eliminate the adverse effects of Si on the performance of the aluminum alloy, thereby improving the strength and elongation of the aluminum alloy.

[0068] The Al-Zn series die-casting aluminum alloy can further contain Bi in a mass percentage of 0-0.1%. The mass percentage of Bi can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. Bi can reduce the surface tension of the aluminum melt, reduce the contact angle between Al and Si, so that the growth front of Si is more easily inhibited by Al, thereby reducing the size of the eutectic silicon, so as to improve the elongation of the aluminum alloy.

[0069] The Al-Zn series die-casting aluminum alloy can also contain Cd in a mass percentage of 0-0.2%. The mass percentage of Cd can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 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, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy.

[0070] The Al-Zn series die-casting aluminum alloy can also contain Ge in a mass percentage of 0-0.1%. The mass percentage of Ge can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. Ge can react with Al and Si to form second phases such as Al9Ge7, Al6Ge5, Al5Ge2, Al3Ge4, SiGe, etc. to improve the strength of the aluminum alloy; Ge can also refine the grains, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy; when the Al-Zn series die-casting aluminum alloy contains both Ge and RE, the mutual cooperation of Ge and RE can significantly refine the grains, the second phase, and the precipitated phase to further improve the elongation of the aluminum alloy.

[0071] The Al-Zn series die-casting aluminum alloy can also contain Mo in a mass percentage of 0-0.1%. The mass percentage of Mo can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. Mo can improve the strength of the aluminum alloy; Mo can also refine the grains to improve the elongation of the aluminum alloy.

[0072] The Al-Zn-based die-casting aluminum alloy can further contain Nb in a mass percentage of 0-0.1%. The mass percentage of Nb can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. Nb can improve the strength of the aluminum alloy; Nb can also refine the grains, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy. When the Al-Zn-based die-casting aluminum alloy contains both Nb and B, strengthening metal compounds such as AlNb3, AlNb, Al3Nb, and NbB2 can be formed to significantly improve the strength of the aluminum alloy.

[0073] The Al-Zn-based die-casting aluminum alloy can further contain Ni in a mass percentage of 0-0.3%. The mass percentage of Ni can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 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%. Ni can improve the strength of the aluminum alloy; Ni can also refine the grains, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy.

[0074] The Al-Zn series die-casting aluminum alloy can also contain Sb in a mass percentage of 0-0.2%. The mass percentage of Sb can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 0.1%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.2%. Sb can improve the strength of the aluminum alloy; Sb can also improve the precipitation of elements such as Cu, Zn, and Ni in the aluminum alloy matrix, further improving the strength of the aluminum alloy; Sb can also be used as a modifier, which can effectively reduce the size of the eutectic silicon flakes, greatly reducing the possibility of the eutectic silicon flakes cutting the aluminum matrix, to improve the strength and elongation of the aluminum alloy.

[0075] The Al-Zn series die-casting aluminum alloy can also contain Te in a mass percentage of 0-0.1%. The mass percentage of Te can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. Te can modify the eutectic silicon, shorten the length of the eutectic silicon, and improve the elongation of the aluminum alloy; when the Al-Zn series die-casting 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.

[0076] The Al-Zn series die-casting aluminum alloy can also contain Sn in a mass percentage of 0-0.1%. The mass percentage of Sn can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. Sn can improve the strength of the aluminum alloy; Sn can also effectively inhibit the growth of the second phase and promote the dispersion distribution of the second phase, to improve the elongation of the aluminum alloy.

[0077] The Al-Zn series die-casting aluminum alloy can also contain In in a mass percentage of 0-0.1%. The mass percentage of In can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. In can improve the strength of the aluminum alloy; In can also refine the grains, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy.

[0078] The Al-Zn series die-casting aluminum alloy can also contain Zr in a mass percentage of 0-0.1%. The mass percentage of Zr can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. Zr can improve the strength of the aluminum alloy; Zr can also form Al3Zr phase in the aluminum alloy, which can refine the grains, the second phase, and the precipitated phase to improve the elongation of the aluminum alloy. When the Al-Zn series die-casting aluminum alloy contains both Zr and B, B can convert Zr from a solid solution state to a precipitated state, and exist in the form of a small plate-shaped second phase particle in the grain interior and at the grain boundary, reduce the lattice distortion, improve the order of the aluminum matrix, and thus improve the tensile strength and yield strength of the aluminum alloy. The Mn-rich phase is distributed at the grain boundary or near the grain boundary to pin the grain boundary, although the coherence of the Mn-rich phase with the Al matrix is low and the size of the Mn-rich phase is large, and the ability to pin dislocations is weak, but the combined addition of Mn and Zr can not only reduce the use amount of each alloying element, but also promote mutual precipitation to form more amounts of Al6(Mn,Zr) phase, Al6(FeMnZr) phase, and Al6(FeMnZr) phase, and the strengthening effect is much greater than that when Mn or Zr is added alone. 3( Zr,Mn) phase and Al6(FeMnZr) phase, and the strengthening effect is much greater than that when Mn or Zr is added alone.

[0079] The Al-Zn series die-casting aluminum alloy also contains TiC with a mass percentage of 0-1% and SiC with a mass percentage of 0-35%. The mass percentage of TiC can be specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, 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%. The mass percentage of SiC can be specifically 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%, 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%.

[0080] TiC, as a grain refiner, has a particle size of about several microns and is not easy to aggregate, and has a better effect of fine-grain strengthening. SiC forms a dispersed phase in the aluminum alloy and forms a strong interface with the aluminum matrix, thereby effectively enhancing the mechanical properties of the alloy, improving the wear resistance, corrosion resistance and thermal stability of the alloy. Both TiC and SiC have a strong effect of fine-grain strengthening, and TiC and SiC can work together with RE to further improve the refining effect.

[0081] The Al-Zn series die-casting aluminum alloy also contains 0-0.1% of AlTiB in terms of mass percentage, specifically 0.001%, 0.005%, 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, 0.05%, 0.055%, 0.06%, 0.065%, 0.07%, 0.075%, 0.08%, 0.085%, 0.09%, 0.095%, or 0.1%. When AlTiB and SiC are used in combination, the mass percentage of SiC can be reduced to 4-10%, thus reducing the cost. In a preferred embodiment, the mass percentage of AlTiB is 0.1-0.8% of AlTiB, and the mass percentage of SiC is 5-8%.

[0082] 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 have a tendency to enhance the adhesion energy of the C-TiB2 / Al interface, so that the originally long strip-shaped TiAl3 is broken and shortened, to avoid the enrichment and growth of TiAl3, greatly enhancing the composite refining effect. And through repeated experiments, it has been verified that when the mass percentage of AlTiB is 0.1-0.8% and the mass percentage of SiC is 4-10%, the strength, elongation, wear resistance, corrosion resistance, and thermal stability of the aluminum alloy can be greatly improved.

[0083] The application also provides a preparation method of the Al-Zn series die-casting aluminum alloy, comprising the following steps:

[0084] providing Zn source, Si source, Cu source, Mg source, Sr source, Ti source, V source, RE source, and Al source;

[0085] heating the Al source to obtain aluminum liquid;

[0086] adjusting the temperature of the aluminum liquid to 750-820°C, adding the Si source into the aluminum liquid to obtain a first mixed liquid;

[0087] adjusting the temperature of the first mixed liquid to 720-740°C, adding the Zn source, Cu source, Mg source, Sr source, Ti source, V source, and RE source into the first mixed liquid to obtain a second mixed liquid;

[0088] performing die-casting treatment and aging treatment on the second mixed liquid to obtain an aluminum alloy roughcast; and

[0089] The aluminum alloy ingot is subjected to aging treatment to obtain the Al-Zn series die-casting aluminum alloy, wherein the aluminum alloy contains Zn in a mass percentage of 20-35%, Si in a mass percentage of 0.2-3.5%, Cu in a mass percentage of 0-3%, Mg in a mass percentage of 0-0.3%, Fe in a mass percentage of 0.001-0.5%, Mn in a mass percentage of 0.001-0.3%, Sr in a mass percentage of 0-0.1%, Ti in a mass percentage of 0-0.3%, V in a mass percentage of 0-0.3%, and RE in a mass percentage of 0-0.3%.

[0090] The elements and contents in the aluminum alloy can be detected to obtain the contents of the elements. When the content of Mn is too high, the content of Mn can be adjusted to 0.001-0.3% by boronization treatment, or the content of Mn can be adjusted to 0.001-0.3% by adding aluminum ingots (such as pure aluminum ingots). When the content of Mn is too low, the content of Mn can also be adjusted to 0.001-0.3% by adding a Mn source. Of course, the content of Mn can also be maintained at a lower level without adding a Mn source.

[0091] The die-casting treatment can be high-pressure casting, the temperature is 590-650ºC, preferably 590-610ºC, the low-speed injection speed is 0.23-0.3m / s, and the high-speed injection speed is 2-2.5m / s. The temperature of the existing die-casting aluminum alloy is about 680ºC, which is relatively high. When the mixed liquid is placed in the mold at this temperature, the erosion of the mixed liquid to the mold is great, which can cause the service life of the mold to be relatively short. The melting point of the Al-Zn series die-casting aluminum alloy of the present application is relatively low, about 590-650ºC, so that the temperature of the die-casting treatment of the present application can be set to be relatively low, the erosion to the mold is relatively small, and the service life of the mold can be improved. The solidification temperature range of the Al-Zn series die-casting aluminum alloy of the present application is very wide, which has excellent die-casting performance and is suitable for being made into structural parts with complex structures. The η-Zn phase in the Al-Zn series die-casting aluminum alloy of the present application has a close-packed hexagonal lattice structure and has good coating performance, so that the Al-Zn series die-casting aluminum alloy of the present application has self-lubricating characteristics. Therefore, the Al-Zn series die-casting aluminum alloy of the present application has better forming performance and demolding performance (20-35wt% of Zn and 0.2-3.5wt% of Si cooperate), which can be suitable for high-pressure casting forming. The preparation method of the Al-Zn series die-casting aluminum alloy has the advantages of low cost and being suitable for large-scale production. The mold used in the die-casting treatment can be a die-casting test mold conforming to the aluminum alloy standard (GB / T13822-2017), and a B-type thin-walled sheet test sample with a thickness of 1.5-15mm can be made. The B-type thin-walled sheet test sample has a smooth surface and does not crack.

[0092] In one embodiment, the temperature of the aging treatment is 80-150 °C and the time is 0.05-30 h. The temperature of the aging treatment can be specifically 80 °C, 90 °C, 100 °C, 110 °C, 120 °C, 130 °C, 140 °C, or 150 °C, and the time can be specifically 0.05 h, 1 h, 5 h, 10 h, 15 h, 20 h, 25 h, or 30 h.

[0093] In yet another embodiment, the aging treatment comprises a first stage aging treatment, a second stage aging treatment, a third stage aging treatment, and a fourth stage aging treatment. The first stage aging treatment has a temperature of 40-90℃, specifically 40℃, 45℃, 50℃, 55℃, 60℃, 65℃, 70℃, 75℃, 80℃, 85℃, or 90℃, and a time of 3-20h, specifically 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h, or 20h; the second stage aging treatment has a temperature of -200~-100℃, specifically -200℃, -190℃, -180℃, -170℃, -160℃, -150℃, -140℃, -130℃, -120℃, -110℃, or -100℃, and a time of 0.5-10h, specifically 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h; the third stage aging treatment has a temperature of 100-130℃, specifically 100℃, 105℃, 110℃, 115℃, 120℃, 125℃, or 130℃, and a time of 0.5-5h, specifically 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, or 5h. The first stage aging treatment has a lower temperature, and in the first stage aging treatment, the atoms in the aluminum alloy ingot obtained by die casting are stabilized to stabilize the morphology of the aluminum alloy ingot, while avoiding rapid precipitation of unsaturated Zn. In the second stage aging treatment, the volume shrinks sharply, generating considerable stress, and in turn generating a large number of dislocations, which interact with the stress in the alloy, the crystal boundary, and themselves to entangle to improve the strength and plasticity of the alloy; in the process of the second stage aging treatment, the crystal structure of the material changes, and in the process of deep cold recovery, recovery recrystallization occurs, causing the grains to rotate, and recrystallization texture is formed by preferred orientation, improving the strength of the aluminum alloy; a large number of supersaturated point defects (such as vacancies) and dislocations obtained by the aluminum alloy in the second stage aging treatment can further promote the segregation of solute atoms such as Zn, Mg, Cu, Ni, and Si, significantly improve the GP zone range, increase the nucleation rate in the third stage aging treatment process, and promote the full precipitation of alloying elements; after the second stage aging treatment is completed, the temperature is adjusted to 100-130℃ within 1-5min, at which time, the large number of supersaturated point defects (such as vacancies) and dislocations obtained by the aluminum alloy at low temperature are retained, and participate in the third stage high-temperature aging under the action of stress and point defects (such as vacancies) and dislocations, and interact with solute atoms, significantly improve the nucleation rate and nucleation speed, refine the precipitated phase, and improve the volume fraction of the precipitated phase, thereby further improving the strength and elongation of the aluminum alloy.

[0094] The aging treatment can further include a fourth stage aging treatment, which can be a natural aging treatment or a water cooling aging treatment. After the fourth stage aging treatment, the elongation of the aluminum alloy is further improved, but the strength is decreased. The natural aging treatment is to place the aluminum alloy billet after the third stage aging treatment at room temperature for 0.5-5h, specifically, 0.5h, 1h, 2h, 3h, 4h, or 5h. The water cooling aging treatment is to place the aluminum alloy billet after the third stage aging treatment in normal temperature water for 0.5-5h, specifically, 0.5h, 1h, 2h, 3h, 4h, or 5h. During the natural aging treatment, the temperature of the aluminum alloy billet decreases rapidly, the fine strengthening phase continues to precipitate but the precipitation rate is also reduced, and the strength and elongation of the aluminum alloy are further improved. During the water cooling aging treatment, the temperature of the aluminum alloy billet decreases more rapidly, the fine strengthening phase continues to precipitate but the precipitation rate is also reduced more rapidly, and the strength and elongation of the aluminum alloy are further improved. The strength and elongation of the aluminum alloy after the water cooling aging treatment are greater than those of the aluminum alloy after the natural aging treatment.

[0095] The aging treatment can further include a fourth stage aging treatment and a fifth stage aging treatment, the fourth stage aging treatment can be a natural aging treatment, and the fifth stage aging treatment can be a water cooling aging treatment. The natural aging treatment is to place the aluminum alloy billet after the third stage aging treatment at room temperature for 0.5-5h, specifically, 0.5h, 1h, 2h, 3h, 4h, or 5h. The water cooling aging treatment is to place the aluminum alloy billet after the natural aging treatment in normal temperature water for 0.5-5h, specifically, 0.5h, 1h, 2h, 3h, 4h, or 5h. During the natural aging treatment, the temperature of the aluminum alloy billet decreases rapidly, the fine strengthening phase continues to precipitate but the precipitation rate is also reduced, and the strength and elongation of the aluminum alloy are further improved. During the water cooling aging treatment, the temperature of the aluminum alloy billet is further decreased, the fine strengthening phase continues to precipitate but the precipitation rate is also further reduced and reduced more rapidly, and the strength and elongation of the aluminum alloy are further improved.

[0096] The Al-Zn series die-casting aluminum alloy contains Zn with a mass percentage of 20-35%, Si with a mass percentage of 0.2-3.5%, Cu with a mass percentage of 0-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Mn with a mass percentage of 0.001-0.3%, Sr with a mass percentage of 0-0.1%, Ti with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, and RE with a mass percentage of 0-0.3%. The elements with the above contents interact with and affect each other, and in combination with the above aging treatment, the Al-Zn series die-casting aluminum alloy with high strength, high toughness and low density can be obtained, which is suitable for being made into structural parts, especially thin-walled structural parts, of 3C, new energy, intelligent machine and other industries. The tensile strength of the Al-Zn series die-casting aluminum alloy is 340 MPa, the yield strength is greater than 300 MPa, the elongation is greater than 4.5%, and the density is less than 3.4 g / cm 3 .

[0097] The preparation method of the Al-Zn series die-casting aluminum alloy further includes the step of adding at least one of a B source, a Be source, a Bi source, a Cd source, a Ge source, a Mo source, a Nb source, a Ni source, a Sb source, a Te source, a Sn source, an In source, an AlTiB source, a TiC source and a SiC source into the first mixed solution. The above elements can at least be used to improve the strength and / or elongation of the aluminum alloy, so as to obtain an Al-Zn series die-casting aluminum alloy with more excellent performance. The raw material of the alloying element can be an aluminum intermediate alloy. For example, the TiC source can be AlTiC. The SiC source can be SiCP / Al-based composite material or intermediate alloy seed.

[0098] Embodiment

[0099] The components and contents of the aluminum alloys of Examples 1-10 are shown in Table 1, and the performance test results are shown in Table 2.

[0100] Table 1 Components and contents of the aluminum alloys of Examples 1-10

[0101]

[0102]

[0103] For simplicity of expression, the contents of trace elements such as impurities in the comparative examples and the examples are not shown.

[0104] Table 2 Performance test results of the aluminum alloys of Examples 1-10

[0105]

[0106] When the aluminum alloys of Examples 1 to 10 are made into thin-walled structural members with a thickness of 2 mm, the surface of the structural members is smooth and no cracking occurs. The tensile strength, yield strength, elongation, and density of the thin-walled structural members are tested. The test results are shown in Table 2.

[0107] Table 2 shows that the aluminum alloys of Examples 1 to 10 have better tensile strength, yield strength, and elongation, and also have lower density. Specifically, the tensile strength of the aluminum alloys of Examples 1 to 10 is not less than 340 MPa, the yield strength is not less than 300 MPa, the elongation is greater than 4.5%, and the density is not higher than 3.4 g / cm 3 .

[0108] The above description is merely preferred embodiments of the present application, and is not intended to limit the patent scope of the present application. Any equivalent structural variations or direct / indirect applications in other related technical fields made by using the content of the present application are included in the patent protection scope of the present application.

Claims

1. An Al-Zn die-cast aluminum alloy, characterized in that, The Al-Zn die-cast aluminum alloy is composed of the following elements by mass percentage: 20-35% Zn, 0.2-3.5% Si, 0.1-3% Cu, 0.01-0.3% Mg, 0.02-0.09% Fe, 0.001-0.15% Mn, 0.02-0.1% Sr, 0.01-0.3% Ti, 0.01-0.3% V, 0.01-0.3% RE, with the balance being Al. The sum of the mass percentages of Fe and Mn is 0.05-0.25%, and the sum of the mass percentages of Sr, Ti, V, Mn, and RE is 0.08-0.6%.

2. The Al-Zn die-cast aluminum alloy according to claim 1, characterized in that, The Al-Zn die-cast aluminum alloy contains 20-35% Zn, 0.5-3% Si, 0.1-3% Cu, 0.1-0.3% Mg, 0.02-0.09% Fe, 0.001-0.15% Mn, 0.02-0.1% Sr, 0.01-0.3% Ti, 0.01-0.1% V, and 0.01-0.3% RE.

3. The Al-Zn die-cast aluminum alloy according to any one of claims 1-2, characterized in that, At least one of the following conditions must be met: The Al-Zn die-cast aluminum alloy also contains 0.001-0.1% B by mass. The Al-Zn die-cast aluminum alloy also contains 0.001-0.1% Be by mass. The Al-Zn die-cast aluminum alloy also contains 0.001-0.1% Bi by mass. The Al-Zn die-cast aluminum alloy also contains 0.001-0.2% Cd by mass. The Al-Zn die-cast aluminum alloy also contains 0.001-0.1% Ge by mass; The Al-Zn die-cast aluminum alloy also contains 0.001-0.1% Mo by mass; The Al-Zn die-cast aluminum alloy also contains 0.001-0.1% Nb by mass. The Al-Zn die-cast aluminum alloy also contains 0.001-0.3% Ni by mass. The Al-Zn die-cast aluminum alloy also contains 0.001-0.2% Sb by mass. The Al-Zn die-cast aluminum alloy also contains 0.001-0.1% Sn by mass. The Al-Zn series die-cast aluminum alloy also contains 0.001-0.1% In by mass; The Al-Zn die-cast aluminum alloy also contains 0.001-1% TiC by mass. The Al-Zn series die-cast aluminum alloy also contains 0.01-35% SiC by mass percentage.

4. A method for preparing the Al-Zn die-cast aluminum alloy as described in any one of claims 1-3, comprising the following steps: It provides Zn, Si, Cu, Mg, Sr, Ti, V, RE, and Al sources; The Al source is heated to obtain molten aluminum; A Zn source, a Si source, a Cu source, a Mg source, a Sr source, a Ti source, a V source, and a RE source are added to the molten aluminum to obtain a mixed solution; and The mixture is subjected to die casting and aging treatment to obtain the Al-Zn die-cast aluminum alloy, wherein the Al-Zn die-cast aluminum alloy contains 20-35% Zn, 0.2-3.5% Si, 0.1-3% Cu, 0.01-0.3% Mg, 0.02-0.09% Fe, 0.001-0.15% Mn, 0.02-0.1% Sr, 0.01-0.3% Ti, 0.01-0.3% V, and other components by mass percentage. The aging treatment comprises 0.01-0.3% RE, 0.05-0.25% Fe and Mn by mass percentage, and 0.08-0.6% Sr, Ti, V, Mn, and RE by mass percentage. The aging treatment includes a first-stage aging treatment, a second-stage aging treatment, a third-stage aging treatment, and a fourth-stage aging treatment. The first-stage aging treatment is performed at a temperature of 40-90°C for 3-20 hours; the second-stage aging treatment is performed at a temperature of -200 to -100°C for 0.5-10 hours; the third-stage aging treatment is performed at a temperature of 100-130°C for 0.5-5 hours; and the fourth-stage aging treatment is either natural aging treatment or water-cooled aging treatment.

5. The method for preparing Al-Zn die-cast aluminum alloy according to claim 4, characterized in that, After the second stage of aging treatment is completed, the temperature is adjusted to 100-130°C within 1-5 minutes.

6. The method for preparing Al-Zn die-cast aluminum alloy according to claim 4 or 5, characterized in that, The preparation method of the Al-Zn die-cast aluminum alloy further includes the step of adding at least one of the following sources to the molten aluminum: B source, Be source, Bi source, Cd source, Ge source, Mo source, Nb source, Ni source, Sb source, Sn source, In source, TiC source, and SiC source, wherein the mass percentage content of B is 0.001-0.1%, the mass percentage content of Be is 0.001-0.1%, the mass percentage content of Bi is 0.001-0.1%, the mass percentage content of Cd is 0.001-0.2%, and the mass percentage content of Ge is 0.001-0.2%. The content is 0.001-0.1%, the mass percentage content of Mo is 0.001-0.1%, the mass percentage content of Nb is 0.001-0.1%, the mass percentage content of Ni is 0.001-0.3%, the mass percentage content of Sb is 0.001-0.2%, the mass percentage content of Sn is 0.001-0.1%, the mass percentage content of In is 0.001-0.1%, the mass percentage content of TiC is 0.001-1%, and the mass percentage content of SiC is 0.01-35%.

7. A structural component, characterized in that, The structural component is made of Al-Zn die-cast aluminum alloy as described in any one of claims 1-3, or Al-Zn die-cast aluminum alloy prepared by the method described in any one of claims 4-6.

8. The structural component according to claim 7, characterized in that, The thickness of the structural component is 1.5-15mm.

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