Al-Zn-Cu series die-casting aluminum alloy, preparation method thereof and structural part

Abstract

The invention provides an Al-Zn-Cu series die-casting aluminum alloy, a preparation method thereof and a structural part. The Al-Zn-Cu series die casting aluminum alloy contains Al, the invention discloses a high-strength aluminum alloy, which comprises the following components in percentage by mass: 20 to 35 percent of Zn, 0.2 to 3.5 percent of Si, 0.01 to 3 percent of Cu, 0 to 0.3 percent of Mg, 0.001 to 0.5 percent of Fe, 0 to 1 percent of Co, 0 to 0.3 percent of Te, 0 to 0.3 percent of V, 0 to 0.1 percent of Sr and the balance of Al. The mass percent content of Zr is 0-0.3%, and the mass percent content of Mn is 0.001-0.3%.

Description

[0001] This application is a divisional application of the invention patent application with the application number 202510300653.X, the application date of March 14, 2025, and the invention name of "Al-Zn-Cu series die-casting aluminum alloy and its preparation method and structural part". TECHNICAL FIELD

[0002] The present application relates to the technical field of aluminum alloy, and particularly relates to an Al-Zn-Cu series die-casting aluminum alloy and its preparation method and structural part. BACKGROUND

[0003] With the increasing demand for energy saving and emission reduction of automobiles, die-casting aluminum alloys are widely used in 3C, new energy, intelligent machines and other industries due to their integration, lightweight, high toughness and other advantages. However, the existing Al-Si series die-casting aluminum alloy has a high die-casting temperature of above 600 DEG C, and has a large energy loss. In addition, the existing Al-Si series die-casting aluminum alloy has low mechanical properties, and cannot perfectly solve the sticking problem, and has a large damage to the mold. Moreover, when the existing Al-Si series die-casting aluminum alloy is made into a structural part of 3C, new energy, intelligent machines and other industries, especially when it is made into a thin-walled structural part, it is prone to cracking, resulting in low mechanical properties.

[0004] Therefore, there is an urgent need for a die-casting aluminum alloy with better mechanical properties and demolding performance, and suitable for making thin-walled structural parts. SUMMARY

[0005] In view of the above defects of the prior art, the present application provides an Al-Zn-Cu series die-casting aluminum alloy, which has better mechanical properties and demolding performance, and is not prone to cracking when made into a structural part, especially a thin-walled structural part.

[0006] The present application provides an Al-Zn-Cu series die-casting aluminum alloy, which 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 0.01-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Co with a mass percentage of 0-1%, Te with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, Sr with a mass percentage of 0-0.1%, Zr with a mass percentage of 0-0.3%, and Mn with a mass percentage of 0.001-0.3%.

[0007] Further, the Al-Zn-Cu series die-casting aluminum alloy contains Zn with a mass percentage of 20-30%, Si with a mass percentage of 1-3%, Cu with a mass percentage of 1-2.5%, Mg with a mass percentage of 0.1-0.3%, Fe with a mass percentage of 0.001-0.3%, Co with a mass percentage of 0.1-0.5%, Te with a mass percentage of 0.001-0.2%, V with a mass percentage of 0.001-0.2%, Sr with a mass percentage of 0.001-0.1%, Zr with a mass percentage of 0.001-0.2%, and Mn with a mass percentage of 0.001-0.2%.

[0008] Further, the ratio of the sum of the mass percentages of Co, Te, V, and Zr to the mass percentage of Cu is 0.01-10:1.

[0009] Further, the Al-Zn-Cu series die-casting aluminum alloy further contains Cr, wherein the mass percentage of Cr is 0.001-0.3%, and the sum of the mass percentages of Fe, Mn, and Cr is 0.05-0.6%.

[0010] Further, the Al-Zn-Cu series die-casting aluminum alloy further contains B, Be, Bi, Cd, Ge, Mo, Nb, Ni, Sb, Sn, In, TiC, and SiC, wherein the mass percentage of B is 0-0.05%, the mass percentage of Be is 0-0.1%, the mass percentage of Bi is 0-0.1%, the mass percentage of Cd is 0-0.2%, the mass percentage of Ge is 0-0.1%, the mass percentage of Mo is 0-0.1%, the mass percentage of Nb is 0-0.1%, the mass percentage of Ni is 0-0.3%, the mass percentage of Sb is 0-0.2%, the mass percentage of Sn is 0-0.1%, the mass percentage of In is 0-0.1%, the mass percentage of TiC is 0-1%, and the mass percentage of SiC is 0-35%.

[0011] The application further provides a preparation method of the Al-Zn-Cu series die-casting aluminum alloy, comprising the following steps: providing a Zn source, a Si source, a Cu source, a Mg source, a Co source, a Te source, a Zr source, a V source, a Sr source, and an Al source; subjecting the Al source to a heating treatment to obtain aluminum liquid; adding the Zn source, the Si source, the Cu source, the Mg source, the Co source, the Te source, the Zr source, the Sr source, and the V source into the aluminum liquid to obtain a mixed liquid; and The mixed solution is subjected to die casting treatment and aging treatment to obtain the Al-Zn-Cu series die casting aluminum alloy, wherein the Al-Zn-Cu 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 0.01-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Co with a mass percentage of 0-1%, Te with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, Sr with a mass percentage of 0-0.1%, Zr with a mass percentage of 0-0.3%, and Mn with a mass percentage of 0.001-0.3%.

[0012] Further, the temperature of the die casting treatment is 590-650ºC, the low-speed injection speed is 0.23-0.3m / s, and the high-speed injection speed is 2-2.5m / s.

[0013] Further, the temperature of the aging treatment is 80-150ºC, and the time is 0.05-30h; or The aging treatment includes first-stage aging treatment, second-stage aging treatment, and third-stage aging treatment, the temperature of the first-stage aging treatment is 40-90ºC, and the time is 3-20h; the temperature of the second-stage aging treatment is -200~-100ºC, and the time is 0.5-10h; the temperature of the third-stage aging treatment is 100-130ºC, and the time is 0.5-5h.

[0014] The aging treatment includes first-stage aging treatment, second-stage aging treatment, third-stage aging treatment, and fourth-stage aging treatment, the temperature of the first-stage aging treatment is 40-90ºC, and the time is 3-20h; the temperature of the second-stage aging treatment is -200~-100ºC, and the time is 0.5-10h; the temperature of the third-stage aging treatment is 100-130ºC, and the time is 0.5-5h, the temperature is adjusted to 100-130ºC within 1-5min after the second-stage aging treatment; the fourth-stage aging treatment is natural aging treatment or water cooling aging treatment.

[0015] Further, the preparation method of the Al-Zn-Cu series die-casting aluminum alloy further comprises the step of adding at least one of B, Be, Bi, Cd, Ge, Mo, Nb, Ni, Sb, Sn, In, TiC, and SiC into the aluminum liquid, wherein the mass percentage of B is 0-0.05%, the mass percentage of Be is 0-0.1%, the mass percentage of Bi is 0-0.1%, the mass percentage of Cd is 0-0.2%, the mass percentage of Ge is 0-0.1%, the mass percentage of Mo is 0-0.1%, the mass percentage of Nb is 0-0.1%, the mass percentage of Ni is 0-0.3%, the mass percentage of Sb is 0-0.2%, the mass percentage of Sn is 0-0.1%, the mass percentage of In is 0-0.1%, the mass percentage of TiC is 0-1%, and the mass percentage of SiC is 0-35%.

[0016] The present application further provides a structural member made of the Al-Zn-Cu series die-casting aluminum alloy or the Al-Zn-Cu series die-casting aluminum alloy prepared by the preparation method of the Al-Zn-Cu series die-casting aluminum alloy.

[0017] Further, the thickness of the structural member is 1.5-15 mm.

[0018] In the technical scheme of the present application, the Al-Zn-Cu 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 0.01-3%, Mg with a mass percentage of 0-0.3%, Fe with a mass percentage of 0.001-0.5%, Co with a mass percentage of 0-1%, Te with a mass percentage of 0-0.3%, V with a mass percentage of 0-0.3%, Sr with a mass percentage of 0-0.1%, Zr with a mass percentage of 0-0.3%, and Mn with a mass percentage of 0.001-0.3%. The elements with the above contents interact and influence each other, so that the Al-Zn-Cu series die-casting aluminum alloy has better demolding performance and mechanical properties, and when it is made into a structural member, such as a thin-walled structural member with a wall thickness of 1.5-15 mm, it will not crack. DETAILED DESCRIPTION

[0019] The technical scheme in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0020] An embodiment of the present application provides an Al-Zn-Cu series die-casting aluminum alloy. The Al-Zn-Cu series die-casting aluminum alloy has better mechanical properties and demolding properties, and is suitable for manufacturing structural parts in the 3C, new energy, intelligent machine and other industries. When manufactured as a structural part, such as a thin-walled structural part with a wall thickness of 1.5-15 mm, cracking does not occur.

[0021] The thickness of the structural part 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.

[0022] The Al-Zn-Cu series die-casting aluminum alloy contains Al, and also 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 0.01-3%, Mg with a mass percentage content of 0-0.3%, Fe with a mass percentage content of 0.001-0.5%, Co with a mass percentage content of 0-1%, Te with a mass percentage content of 0-0.3%, V with a mass percentage content of 0-0.3%, Sr with a mass percentage content of 0-0.1%, Zr with a mass percentage content of 0-0.3%, and Mn with a mass percentage content of 0.001-0.3%.

[0023] In an embodiment, the Al-Zn-Cu series die-casting aluminum alloy contains Zn with a mass percentage content of 20-30%, Si with a mass percentage content of 1-3%, Cu with a mass percentage content of 1-2.5%, Mg with a mass percentage content of 0.1-0.3%, Fe with a mass percentage content of 0.001-0.3%, Co with a mass percentage content of 0.1-0.5%, Te with a mass percentage content of 0.001-0.2%, V with a mass percentage content of 0.001-0.2%, Sr with a mass percentage content of 0.001-0.1%, Zr with a mass percentage content of 0.001-0.2%, and Mn with a mass percentage content of 0.001-0.2%.

[0024] The ratio of the sum of the mass percentage content of Co, Te, V, Zr to the mass percentage content of Cu is 0.01-10:1, preferably 0.01-0.3:1, and specifically can be 0.01:1, 0.02:1, 0.03:1, 0.04:1, 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, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1. Within this range, the Al-Zn-Cu series die-casting aluminum alloy can have better strength and elongation.

[0025] The mass percentage content of Zn specifically can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, or 35%.

[0026] The mass percentage content of Si specifically can 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%.

[0027] The mass percentage content of Cu specifically can be 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%, 0.25%, 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%, or 3%.

[0028] 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 %.

[0029] The mass percent content of Co 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 %, 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 %.

[0030] 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 %.

[0031] The mass percent content of Te, V, and Zr 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 %.

[0032] The Al-Zn-Cu series 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 of the present application 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-Cu series die-casting aluminum alloy inevitably contains Fe impurities, and the mass percentage content of Fe impurities can be 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%.

[0033] 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, and the mass percentage content of Mn and Cr can be 0.001-0.3%, 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%. 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.

[0034] 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.

[0035] 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, should be greater than 0.7% to achieve die-casting of the aluminum alloy. In the Al-Zn-Cu series die-casting aluminum alloy of the present application, better die-casting 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 combined, better die-casting performance can be achieved, and the affinity and hot corrosion degree of the steel mold are greatly reduced. In this way, the present application can achieve better die-casting performance without adding at least one of Fe, Mn and Cr to the aluminum liquid. Of course, a certain content of Mn can be added to improve the die-casting performance.

[0036] In the present application, no Fe material, Mn material and Cr material are added to the aluminum alloy, and 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.

[0037] In the technical solution of the present application, the Al-Zn-Cu 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 0.01-3%, Mg with a mass percentage content of 0-0.3%, Fe with a mass percentage content of 0.001-0.5%, Co with a mass percentage content of 0-1%, Te with a mass percentage content of 0-0.3%, V with a mass percentage content of 0-0.3%, Sr with a mass percentage content of 0-0.1%, Zr with a mass percentage content of 0-0.3%, and Mn with a mass percentage content of 0.001-0.3%. The elements within the above contents interact and influence each other, so that the Al-Zn-Cu series die-casting aluminum alloy has better mechanical properties and die-casting performance, and the density is less than 3.4 g / cm 3When being made into structural parts, such as thin-walled structural parts with a wall thickness of 1.5-15 mm, no cracking occurs, and the mechanical properties are not reduced. Specifically: (1) The mass percentage content of Zn is 20-35%. Zn in the above content range can improve the fluidity of the aluminum alloy, so that the aluminum alloy is suitable for die casting; Zn in the above content range can also reduce the solidification temperature of the aluminum alloy, greatly reduce the affinity and hot corrosion degree of the aluminum alloy to the die steel (such as H13 steel), and improve 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 to be overheated, and the melt supercooling degree increases with the increase of the melt superheating 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; the grain boundary of 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, and improve 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, which can make the aluminum alloy have a high elongation; (2) The mass percentage content of Si is 0.2-3.5%. Si in the above content range can improve the fluidity of the aluminum alloy, and further improve the forming performance of the aluminum alloy; Si in the above content range can also reduce the deformation amount of the material due to natural aging, thereby increasing the dimensional stability of the aluminum alloy product; when the content of Si is less than 3%, the hard and brittle Si phase is finely and uniformly distributed between the dendrites, which can increase the strength and hardness of the aluminum alloy, and the strength and hardness of the alloy increase with the increase of the content of Si; when the content of Si in the alloy is greater than 3%, the fine granular Si phase formed by eutectic reaction becomes large and produces microsegregation, thereby producing cracking tendency and leading to the decrease of the strength of the alloy; (3) The mass percentage content of Cu is 0.01-3%. The solid solution strengthening of Cu in the aluminum matrix can improve the strength of the aluminum alloy; Cu can reduce the interfacial energy between the Al phase and the Zn phase in the aluminum-zinc alloy, and at the same time improve the strength and elongation of the aluminum alloy; the Al2Cu phase formed by Cu and Al is dispersedly distributed in the grain boundary and the grain, but when the mass percentage content of Cu is too high, such as greater than 3%, the Al2Cu phase coarsens, which can sharply reduce the elongation of the aluminum alloy; and Cu can increase the solidification temperature range of the aluminum alloy, which can cause the aluminum alloy structural part to be prone to cracking; (4) The mass percentage content of Mg is not greater than 0.3%. 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 coarsens, which can sharply reduce the demolding performance and elongation of the aluminum alloy; (5) The mass percentage content of Fe is 0.001-0.5%. Fe can reduce the sticking tendency of aluminum alloy castings and improve the demolding performance of aluminum alloys. Fe can react with other elements to form a second phase, so as to avoid the adverse effects of Fe and other elements dissolved in the aluminum matrix on the performance of aluminum alloys. Specifically, Fe can react with Al, Si, Mg, Cu, Mn, Ni, B and other elements to form second phases such as Al3Fe, AlFeSi, AlFeMgSi, AlFeSiCu, AlFeSiNi, AlFeMgSiNi, AlFeMnSi, FeNiAl9, AlFeSiB. However, the presence of β-iron-rich phase in the aluminum matrix will reduce the elongation of aluminum alloys. (6) The mass percentage content of Co is not greater than 1%. Co can react with Al, Fe, Si, etc. to form Al3Co, Al3FeCo, Al 15 (Fe,Co)3Si2 and other phases can improve the morphology of Fe and increase the strength of aluminum alloys; Co can also refine the grains, second phase and precipitated phase to improve the elongation of aluminum alloys; at the same time, Co can also narrow the solidification temperature range of aluminum alloys, avoiding the increase in the solidification temperature range caused by the addition of Cu, and avoiding cracking of aluminum alloy structural parts. (7) The mass percentage of Te is not greater than 0.3%. Te can modify eutectic silicon, causing the eutectic silicon to shorten along the length direction, thereby increasing the elongation of the aluminum alloy. Te can also narrow the solidification temperature range of the aluminum alloy, avoiding the increase in the solidification temperature range caused by the addition of Cu. (8) The mass percentage content of V is not greater than 0.3%, and V forms Al3V and Al in the aluminum alloy. 10 V, Al 11 Refractory compounds such as V and Al(VMnTi)Si can refine grains and disperse and strengthen, thereby improving the strength and elongation of aluminum alloys. (9) The mass percentage content of Zr is not greater than 0.3%. Zr can improve the strength of aluminum alloy. Zr can also form Al3Zr phase in aluminum alloy. Al3Zr phase can refine grains, second phase and precipitated phase to improve the elongation of aluminum alloy. When the Al-Zn-Cu die-cast aluminum alloy contains both Zr and V, Zr and V can cooperate to narrow the solidification temperature range of aluminum alloy and avoid the increase in solidification temperature range caused by the addition of Cu. (10) The mass percentage content of Sr is not greater than 0.1%. As a modifier, Sr can change the behavior of intermetallic compound phases in crystallography. By modifying aluminum alloys through heterogeneous nucleation theory or twin valley mechanism, the grains, second phase and precipitated phases can be refined to improve the elongation of aluminum alloys. For example, it can refine Al2Cu phase, Mg2Si phase, etc. to reduce the adverse effects when Cu and Mg content is high. (11) The mass percentage content of Mn is 0.001-0.3%, Mn can form independent Al6Mn and Al6FeMn hardening phases in high-zinc aluminum alloy, the Mn-rich phase is distributed in 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, the ability of pinning 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 the precipitation of each other to form more Al6(Mn,Zr) phase, Al 3( Zr,Mn) phase and Al6(FeMnZr) phase, the strengthening effect is much greater than when Mn or Zr is added alone.

[0038] 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 when the aluminum alloy of the present application is made into a thin-walled structural part (such as a structural part with a wall thickness of 1.5-15mm), the thin-walled structural part will not crack. Cu and Mg in the above content range can improve the strength of the aluminum alloy. Fe, Mn and Co in the above content range can improve the demolding performance of the aluminum alloy. The mutual cooperation of Co, Te, V, Zr, Sr and Mn in the above content range can further improve the strength and elongation of the aluminum alloy, and an Al-Zn-Cu series die-casting aluminum alloy with high strength and high elongation is obtained. The mutual cooperation of Co, Te, V and Zr in the above content range can also narrow the solidification temperature range of the aluminum alloy, offsetting the defect of increased solidification temperature range caused by Cu. The solidification temperature range of the Al-Zn-Cu series die-casting aluminum alloy of the present application is 520-550°C, which is relatively narrow, so that the Al-Zn-Cu series die-casting aluminum alloy of the present application is not prone to cracking.

[0039] The Al-Zn-Cu series die-casting aluminum alloy can also contain Ti in a mass percentage of 0-0.3% and B in a mass percentage of 0-0.05%. The mass percentage 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%. 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%, or 0.05%. Both Ti and 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, the effect of Ti and B is better when used together.

[0040] The Al-Zn-Cu series die-casting aluminum alloy can also 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, so as to improve the elongation of the aluminum alloy. When the Al-Zn-Cu series die-casting 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.

[0041] The Al-Zn-Cu series die-casting aluminum alloy can also 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.

[0042] The Al-Zn-Cu series die-casting aluminum alloy also contains 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 Si growth front is more easily inhibited by Al, thereby reducing the size of the eutectic silicon, so that the elongation of the aluminum alloy can be improved.

[0043] The Al-Zn-Cu 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, second phases and precipitates to improve the elongation of the aluminum alloy.

[0044] The Al-Zn-Cu 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, second phases and precipitates to improve the elongation of the aluminum alloy; when the Al-Zn-Cu series die-casting aluminum alloy contains both Ge and RE, the mutual cooperation of Ge and RE can further refine the grains, second phases and precipitates, further improving the elongation of the aluminum alloy.

[0045] The Al-Zn-Cu 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.

[0046] The Al-Zn-Cu series die-casting aluminum alloy can also 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%, 0.15%, 0.2%, 0.25%, 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.

[0047] The Al-Zn-Cu 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 Cu, Zn, Ni, etc. in the aluminum alloy matrix, further improving the strength of the aluminum alloy; Sb can also act 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. When the Al-Zn-Cu 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.

[0048] The Al-Zn-Cu series die-casting aluminum alloy can further 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, promote the dispersed distribution of the second phase, and improve the elongation of the aluminum alloy.

[0049] The Al-Zn-Cu series die-casting aluminum alloy can further 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, and improve the elongation of the aluminum alloy.

[0050] The Al-Zn-Cu series die-casting aluminum alloy can further contain RE in a mass percentage of 0-0.3%. The RE is at least one of La, Ce, Pr, Nd, Er, Sm, Y, Sc, and Gd. The mass percentage 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%. RE can provide heterogeneous nucleation particles, hinder the growth of the grains, refine the grains, the second phase, and the precipitated phase, and improve the elongation of the aluminum alloy; RE can also promote the precipitation of the strengthening phase and the dispersed phase, and improve the strength of the aluminum alloy.

[0051] The Al-Zn-Cu series die-casting aluminum alloy further contains AlTiB with a mass percentage of 0-1% and SiC with a mass percentage of 0-35%, and the mass percentage of AlTiB 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%. The mass percentage of SiC 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%, 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%.

[0052] When AlTiB and SiC are used in combination, the mass percentage of SiC can be reduced to 4-10%, which can reduce the cost. In a preferred embodiment, the mass percentage of AlTiB is 0.3-0.8% and the mass percentage of SiC is 5-8%.

[0053] 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, the originally long strip-shaped TiAl3 is broken and shortened, so as to avoid the enrichment and growth of TiAl3, and the refining effect of the combination is greatly enhanced. And it has been verified through multiple experiments that when the mass percentage of AlTiB is 0.3-0.8% 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.

[0054] The Al-Zn system die-casting aluminum alloy further contains TiC in a mass percentage of 0-1%. The mass percentage of TiC 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%, 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%. As a grain refiner, TiC has a particle size of several microns and is not easy to aggregate, and has a better effect of fine-grain strengthening, so that the strength, elongation, wear resistance, corrosion resistance and thermal stability of the aluminum alloy can be improved.

[0055] The application further provides a preparation method of the Al-Zn-Cu system die-casting aluminum alloy, which comprises the following steps: providing Zn source, Si source, Cu source, Mg source, Co source, Te source, Zr source, Sr source, V source, and Al source; heating the Al source to obtain aluminum liquid; adjusting the temperature of the aluminum liquid to 750-820°C, adding the Si source into the aluminum liquid to obtain first mixed liquid; adjusting the temperature of the first mixed liquid to 720-740°C, adding the Zn source, Cu source, Mg source, Co source, Te source, Zr source, Sr source, and V source into the first mixed liquid to obtain second mixed liquid; performing die-casting treatment on the second mixed liquid to obtain aluminum alloy roughcast; and performing aging treatment on the aluminum alloy roughcast to obtain the Al-Zn-Cu system die-casting aluminum alloy, wherein the Al-Zn-Cu system die-casting 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 0.01-3%, Mg in a mass percentage of 0-0.3%, Fe in a mass percentage of 0.001-0.5%, Co in a mass percentage of 0-1%, Te in a mass percentage of 0-0.3%, V in a mass percentage of 0-0.3%, Sr in a mass percentage of 0-0.1%, Zr in a mass percentage of 0-0.3%, and Mn in a mass percentage of 0.001-0.3%.

[0056] The elements and contents in the aluminum alloy can be detected to obtain the contents of each element. When the content of Mn is too high, the content of Mn can be adjusted to 0.001-0.3% by boronizing 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.

[0057] The die casting process can be high-pressure casting, the temperature is 590-650°C, preferably 590-610°C, 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 die casting process is about 680°C, 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-Cu series die casting aluminum alloy of the present application is relatively low, about 590-650°C, so that the temperature of the die casting process of the present application can be set 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-Cu series die casting aluminum alloy of the present application is very narrow, and has excellent die casting performance, which is suitable for being made into structural parts with complex structure. The η-Zn phase in the Al-Zn-Cu series die casting aluminum alloy of the present application has a close-packed hexagonal lattice structure, has good smearing performance, and makes the Al-Zn-Cu series die casting aluminum alloy of the present application have self-lubricating characteristics. Therefore, the Al-Zn-Cu 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 are matched), which can be suitable for high-pressure casting forming. The preparation method of the Al-Zn-Cu series die casting aluminum alloy has the advantages of low cost and being suitable for large-scale mass production. Among them, the mold used in the die casting process 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.

[0058] In an embodiment, the temperature of the aging treatment is 80-150°C, and the time is 0.05-30h. 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 0.05h, 1h, 5h, 10h, 15h, 20h, 25h, or 30h.

[0059] 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, a 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.

[0060] 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.

[0061] 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.

[0062] The Al-Zn-Cu series die-casting 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 0.01-3%, Mg in a mass percentage of 0-0.3%, Fe in a mass percentage of 0.001-0.5%, Co in a mass percentage of 0-1%, Te in a mass percentage of 0-0.3%, V in a mass percentage of 0-0.3%, Sr in a mass percentage of 0-0.1%, Zr in a mass percentage of 0-0.3%, and Mn in a mass percentage of 0.001-0.3%. The elements interact with and affect each other, so that the Al-Zn-Cu series die-casting aluminum alloy has better mechanical properties and demolding properties. When the Al-Zn-Cu series die-casting aluminum alloy is made into a structural part, such as a thin-walled structural part with a wall thickness of 1.5-15 mm, cracking does not occur.

[0063] The preparation method of the Al-Zn-Cu series die-casting aluminum alloy further includes the step of adding at least one of a Ti source, 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, AlTiB, and a SiC source to 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-Cu 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 a SiCP / Al-based composite material or an intermediate alloy seed crystal.

[0064] Examples and comparative examples The components and contents of the aluminum alloys of examples one to ten are shown in Table 1, and the performance test results are shown in Table 2.

[0065] Table 1 Components and contents of the aluminum alloys of examples one to ten For simplicity of expression, the contents of trace elements such as impurities in the comparative examples and examples are not shown.

[0066] Table 2 Performance test results of the aluminum alloys of examples one to ten When the aluminum alloys of examples one to ten are made into thin-walled structural parts with a thickness of 2 mm, the surfaces of the structural parts are smooth and cracking does not occur. The tensile strength, yield strength, elongation, and density of the thin-walled structural parts are tested. The test results are shown in Table 2.

[0067] Table 2 shows that the aluminum alloys of Examples 1-10 have better tensile strength, yield strength, elongation, and flowability. Specifically, the tensile strength of the aluminum alloys of Examples 1-10 is not less than 330 MPa, the yield strength is not less than 290 MPa, the elongation is not less than 4%, and the density is not higher than 3.4 g / cm 3 .

[0068] The above merely provides the preferred embodiments of the present application, but does not limit the patent scope of the present application. Any equivalent structure transformation based on the content of the present application, or direct / indirect application in other related technical fields, all fall within the patent protection scope of the present application.

Claims

1. An Al-Zn-Cu die-cast aluminum alloy containing Al, characterized in that, The Al-Zn-Cu die-cast aluminum alloy further contains 20-35% Zn, 0.2-3.5% Si, 0.01-3% Cu, 0-0.3% Mg, 0.001-0.5% Fe, 0-1% Co, 0-0.3% Te, 0-0.3% V, 0-0.1% Sr, 0-0.3% Zr, and 0.001-0.3% Mn by mass.

2. The Al-Zn-Cu die-cast aluminum alloy according to claim 1, characterized in that, The Al-Zn-Cu die-cast aluminum alloy contains 20-30% Zn, 1-3% Si, 1-2.5% Cu, 0.1-0.3% Mg, 0.001-0.3% Fe, 0.1-0.5% Co, 0.001-0.2% Te, 0.001-0.2% V, 0.001-0.1% Sr, 0.001-0.2% Zr, and 0.001-0.2% Mn by mass.

3. The Al-Zn-Cu die-cast aluminum alloy according to claim 1, characterized in that, The mass percentage content of Si is 2.5-3.5%; The Fe content is 0.001-0.1% by mass; The mass percentage content of Mn is 0.001-0.1%; The solidification temperature range of the Al-Zn-Cu die-cast aluminum alloy is 520-550°C; The ratio of the sum of the mass percentage contents of Co, Te, V, and Zr to the mass percentage content of Cu is 0.01-10:

1.

4. The Al-Zn-Cu die-cast aluminum alloy according to any one of claims 1-3, characterized in that, The Al-Zn-Cu die-cast aluminum alloy also contains Cr, wherein the mass percentage content of Cr is 0.001-0.3%, and the sum of the mass percentage contents of Fe, Mn and Cr is 0.05-0.6%.

5. The Al-Zn-Cu die-cast aluminum alloy according to claim 4, characterized in that, The sum of the mass percentage contents of Fe, Mn, and Cr is 0.05-0.2%.

6. The Al-Zn-Cu die-cast aluminum alloy according to any one of claims 1-3, characterized in that, The Al-Zn-Cu die-cast aluminum alloy further contains B, Be, Bi, Cd, Ge, Mo, Nb, Ni, Sb, Sn, In, TiC, and SiC, wherein the mass percentage content of B is 0-0.05%, 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%.

7. A method for preparing an Al-Zn-Cu die-cast aluminum alloy, comprising the following steps: It provides Zn source, Si source, Cu source, Mg source, Co source, Te source, Zr source, V source, Sr source, and Al source; The Al source is heated to obtain molten aluminum; A Zn source, a Si source, a Cu source, a Mg source, a Co source, a Te source, a Zr source, a Sr source, and a V 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-Cu die-cast aluminum alloy, wherein the Al-Zn-Cu die-cast aluminum alloy contains 20-35% Zn, 0.2-3.5% Si, 0.01-3% Cu, 0-0.3% Mg, 0.001-0.5% Fe, 0-1% Co, 0-0.3% Te, 0-0.3% V, 0-0.1% Sr, 0-0.3% Zr, and 0.001-0.3% Mn by mass.

8. The method for preparing Al-Zn-Cu die-cast aluminum alloy according to claim 7, characterized in that, The aging treatment is performed at a temperature of 80-150℃ for a time of 0.05-30 hours; or The aging process includes a first-level aging process, a second-level aging process, and a third-level aging process. The temperature of the first-level aging process is 40-90°C, and the time is 3-20 hours. The temperature of the second-level aging process is -200 to -100°C, and the time is 0.5-10 hours. The temperature of the third-level aging process is 100-130°C, and the time is 0.5-5 hours.

9. The method for preparing Al-Zn-Cu die-cast aluminum alloy according to claim 7 or 8, characterized in that, The preparation method of the Al-Zn-Cu die-cast aluminum alloy further includes the step of adding at least one of B, Be, Bi, Cd, Ge, Mo, Nb, Ni, Sb, Sn, In, TiC, and SiC to the molten aluminum, wherein the mass percentage content of B is 0-0.05%, 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%.

10. A structural component, characterized in that, The structural component is made of Al-Zn-Cu die-cast aluminum alloy as described in any one of claims 1-6, or Al-Zn-Cu die-cast aluminum alloy prepared by the method described in any one of claims 7-9.

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