An aluminum alloy and a method for producing the same, and a casting

Abstract

The embodiment of the application provides an aluminum alloy and a preparation method thereof and a casting, and belongs to the field of metal materials. The aluminum alloy comprises, in percentage by weight: Si 6.5%-8.0%, Mg 0.30%-0.50%, Zn 0.25%-3.0%, Mn 0.15%-0.50%, Re 0.15%-0.60%, Sr 0.01%-0.02%, Ti 0.15%-0.20%, B 0.03%-0.04%, V 0.1%-0.2%, Fe 0%-0.12%, impurity elements 0%-0.2%, and the balance is Al; wherein Re comprises La and Ce. The aluminum alloy provided by the application has significantly improved elastic modulus and tensile strength, and the application thickness is less than or equal to 4 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal materials, in particular to an aluminum alloy and a preparation method thereof, and a casting. BACKGROUND

[0002] In order to realize lightweight, high strength and low cost production, integrated casting has become a widely used production technology in the fields of new energy vehicles and aerospace in recent years, and the core is to replace traditional multi-part assembly with integral casting, thereby reducing cost and improving production efficiency. At the same time, the use proportion of aluminum alloy as the main lightweight material in the fields of new energy vehicles and aerospace is rapidly increasing.

[0003] However, as a lightweight material, in order to reduce the application weight of the aluminum alloy structural member, the application wall thickness thereof is generally reduced, but at this time, the elastic modulus and tensile strength thereof will also be poor, so that the aluminum alloy structural member cannot withstand high load.

[0004] Therefore, it is urgent to develop an aluminum alloy which still has excellent performance in elastic modulus and tensile strength on the premise of greatly thinning the wall thickness. SUMMARY

[0005] The embodiments of the present application provide an aluminum alloy and a preparation method thereof, and a casting, so as to obtain an aluminum alloy with small application wall thickness, high elastic modulus and high tensile strength.

[0006] In a first aspect, the embodiments of the present application provide an aluminum alloy, which comprises, in percentage by mass: Si 6.5% to 8.0%, Mg 0.30% to 0.50%, Zn 0.25% to 3.0%, Mn 0.15% to 0.50%, Re 0.15% to 0.60%, Sr 0.01% to 0.02%, Ti 0.15% to 0.20%, B 0.03% to 0.04%, V 0.1% to 0.2%, Fe 0% to 0.12%, impurity elements 0% to 0.2%, and the balance being Al.

[0007] Among them, Re includes La and Ce.

[0008] In a possible implementation, the mass ratio of Si to Mg is (13 to 20): 1.

[0009] And / or, the mass ratio of Ti to V is (1 to 3): 1.

[0010] And / or, in the impurity elements, the mass fraction of any single impurity element is less than or equal to 0.05%.

[0011] In a possible implementation, the mass percentage of Si in the aluminum alloy is 6.5% to 7.5%.

[0012] and / or, the mass ratio of the Si to the Mg is (15-19): 1;

[0013] and / or, the mass ratio of the Ti to the V is (1-1.5): 1.

[0014] In a possible implementation, the aluminum alloy includes, in percentage by mass: Si 6.5%, Mg 0.35%, Zn 0.25%, Mn 0.15%, Re 0.15%, Sr 0.01%, Ti 0.15%, B 0.03%, V 0.1%, Fe 0%-0.12%, impurity elements 0%-0.2%, and the balance being Al;

[0015] or, Si 7.0%, Mg 0.45%, Zn 1.5%, Mn 0.30%, Re 0.30%, Sr 0.015%, Ti 0.20%, B 0.035%, V 0.15%, Fe 0%-0.12%, impurity elements 0%-0.2%, and the balance being Al;

[0016] or, Si 7.5%, Mg 0.50%, Zn 3.0%, Mn 0.50%, Re 0.60%, Sr 0.02%, Ti 0.20%, B 0.04%, V 0.2%, Fe 0%-0.1%, impurity elements 0%-0.2%, and the balance being Al.

[0017] In a second aspect, an embodiment of the present application provides a preparation method of the above aluminum alloy, including: adding a first intermediate alloy to a liquid master alloy to obtain a first transition alloy;

[0018] adding a second intermediate alloy to the first transition alloy to obtain a second transition alloy;

[0019] casting and forming the second transition alloy to obtain a third transition alloy;

[0020] post-processing the third transition alloy to obtain the aluminum alloy;

[0021] the first intermediate alloy includes at least one of an Al-Zn alloy, an Al-Mn alloy, and an Al-V alloy;

[0022] the second intermediate alloy includes at least one of an Al-Ti-B alloy, an Al-La alloy, an Al-Ce alloy, and an Al-Sr alloy.

[0023] In a possible implementation, the temperature of the liquid master alloy is 700-800 °C;

[0024] and / or, the adding of the second intermediate alloy to the first transition alloy includes:

[0025] preheating the second intermediate alloy to 110-180 DEG C, pressing into the bottom of the first transition alloy, stirring until melting;

[0026] And / or, the casting forming comprises:

[0027] pouring the second transition alloy at a temperature of 690-710 DEG C into a mold at a temperature of 200-300 DEG C for casting, and then cooling and solidifying into a shape;

[0028] The casting comprises at least one of gravity casting, low pressure casting, and squeeze casting.

[0029] In a possible implementation, the post-processing comprises solution treatment and aging treatment.

[0030] In a possible implementation, the solution treatment comprises: placing the third transition alloy at 500-540 DEG C for 4-8 hours, and then water quenching the third transition alloy at 25-60 DEG C within less than 10 seconds.

[0031] The aging treatment comprises single-stage aging treatment or double-stage aging treatment.

[0032] The single-stage aging treatment comprises: placing the second transition alloy at 165-190 DEG C for 4-12 hours, and then air cooling after taking out of the furnace.

[0033] The double-stage aging treatment comprises: first placing the second transition alloy at 120-130 DEG C for 4-8 hours, and then placing the second transition alloy at 165-180 DEG C for 4-6 hours, and then air cooling after taking out of the furnace.

[0034] In a possible implementation, before the Re alloy is added into the first transition alloy, the method further comprises:

[0035] The first transition alloy is refined and degassed, so that the hydrogen content of the first transition alloy is less than or equal to 0.5 ml / 100 g.

[0036] In a third aspect, the embodiments of the present application provide an aluminum alloy casting, comprising: the aluminum alloy or the aluminum alloy prepared by the preparation method.

[0037] The aluminum alloy and the preparation method thereof and the casting provided by the embodiment of the present application can achieve excellent strength and elastic modulus when the wall thickness is less than or equal to 4 mm by adding Ti, B, V and Mn, forming Al3V by V and Al, forming Al6Mn by Mn and Al, and forming TiB2 by Ti and B to refine the grains, pin the grain boundaries and dislocations, and cooperatively inhibit recrystallization in the heat treatment process to maintain fine grain structure, adding Sr, La and Ce to modify the lamellar eutectic silicon and reduce the secondary dendrite arm spacing, and adding Zn to increase the nucleation particles of the beta" phase and promote the precipitation of the beta" and the aging response rate. BRIEF DESCRIPTION OF DRAWINGS

[0038] The accompanying drawings, which are incorporated herein and constitute part of the specification, illustrate embodiments consistent with the present application and, together with the description, further serve to explain the principles of the present application.

[0039] Figure 1 A schematic diagram of the crystal structure of the aluminum alloy provided by the present application;

[0040] Figure 2 A schematic diagram of the preparation method of the aluminum alloy provided by the present application.

[0041] The above drawings have shown the specific embodiments of the present application, which will be described in more detail hereinafter. These drawings and the written description are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0042] The exemplary embodiments will be described in detail herein with reference to the accompanying drawings. Unless otherwise indicated, the same numbers on different drawings represent the same or similar elements. The following detailed description does not limit the application as consistent with the application in all respects. Instead, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the appended claims.

[0043] In the prior art in the field of lightweight material application, the aluminum alloy has the technical problems of low strength and elastic modulus and inability to reduce the lightweight wall thickness to 4 mm.

[0044] The preparation method of the aluminum alloy provided by the present application solves the technical problems of inability to reduce the lightweight wall thickness and insufficient strength and elastic modulus of the aluminum alloy by adopting the technical means of adding Ti, Mn, Zn, La, Ce, Sr, V and B to compound modify and refine the Al-Si-Mg alloy.

[0045] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes can not be described again in some examples. The embodiments of the present application will be described below with reference to the drawings.

[0046] The present application provides an aluminum alloy, the crystal structure of which is as shown in Figure 1 Figure 1 In the figure, the white small bright spots are α-Al 15 (Fe, Mn)3Si2 phases formed by Al 15 The network structure formed by the α-Al

[0047] The aluminum alloy includes, by mass percentage: Si 6.5% to 8.0%, Mg 0.30% to 0.50%, Zn 0.25% to 3.0%, Mn 0.15% to 0.50%, Re 0.15% to 0.60%, Sr 0.01% to 0.02%, Ti 0.15% to 0.20%, B 0.03% to 0.04%, V 0.1% to 0.2%, Fe 0% to 0.12%, impurity elements 0% to 0.2%, and the balance being Al.

[0048] The Re includes La and Ce.

[0049] In the aluminum alloy provided by the present application, Si and Mg exist in the form of Mg2Si alloy phase, and the Mg2Si alloy phase is the main strengthening phase therein. By limiting the mass fraction of Si in the obtained aluminum alloy to 6.5% to 8.0% and the mass fraction of Mg to 0.30% to 0.50%, the brittleness of Si phase damaging the plasticity of the aluminum alloy can be avoided, and the influence of solid-solution Mg on the elongation of the aluminum alloy can be avoided, so that the size of the contained Mg2Si alloy phase is small and uniformly distributed, the toughness and strength of the aluminum alloy are improved, and the aluminum alloy still has excellent yield strength, tensile strength and elastic modulus under the premise of a lightweight wall thickness of less than or equal to 4 mm.

[0050] For example, the mass fraction of Si can be 6.5%, 6.8%, 7.0%, 7.2%, 7.5%, 7.8%, 8.0%, or a range formed by any two of them.

[0051] For example, the mass fraction of Mg can be 0.30%, 0.32%, 0.35%, 0.37%, 0.40%, 0.42%, 0.45%, 0.48%, 0.50%, or a range formed by any two of them.

[0052] ​The presence of Zn can form MgZn2 strengthening phase and metastable phase in cooperation with Mg. The nanoscale metastable phase can hinder dislocation movement, greatly improving the yield strength of the aluminum alloy. By limiting the mass fraction of Zn in the aluminum alloy to 0.25% to 3.0%, the segregation of Zn at the grain boundary and the formation of brittle phase can be inhibited, thereby improving the yield strength of the aluminum alloy. In the present application, if the mass fraction of Zn is too large, the excess Zn cannot be completely solid-solved and exists in the form of coarse free zinc particles or "MgZn2 coarse precipitated phase" in the grain boundary or in the grain, which becomes a stress concentration source, resulting in a decrease in the overall strength of the obtained aluminum alloy, unstable tensile properties, and a significant decrease in elongation.

[0053] Exemplarily, the mass fraction of Zn can be 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, or a range of any two of them.

[0054] Mn can form α-Al 15 (Fe, Mn)3Si2 phase with impurity Fe, which can reduce the cathode activity of Fe, improve the corrosion resistance of the aluminum alloy, and more importantly, α-Al 15 (Fe, Mn)3Si2 phase can replace the harmful β phase, thereby improving the plasticity and toughness of the aluminum alloy. In addition, Mn can form Al6Mn particles dispersedly distributed with Al, pin the grain boundary and dislocation, and thereby maintain the fibrous structure of the aluminum alloy. By limiting the mass fraction of Mn in the aluminum alloy to 0.15% to 0.50%, the blocky primary phase Al6Mn is inhibited, and the aluminum alloy has excellent elastic modulus and tensile strength. If the content of Mn is too high, the area of α-Al 15 (Fe, Mn)3Si2 phase will increase, and coarse Al6Mn phase will also be precipitated, which cannot effectively hinder dislocation, thereby reducing the plasticity and toughness of the obtained aluminum alloy.

[0055] Exemplarily, the mass fraction of Mn can be 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, or a range of any two of them.

[0056] La and Ce are added together with rare earth mixed elements Re, which can synergistically refine the a-Al dendrite and inhibit the recrystallization phenomenon in the aluminum alloy. Among them, Ce can also refine the β-Fe phase and reduce the harm of Fe. At the same time, La and Ce can also synergize with Sr to reduce the interface energy between the silicon phase and the aluminum matrix, so that the lamellar eutectic silicon is modified and changes into a coral shape. By limiting the total mass fraction of La and Ce in the aluminum alloy to be 0.15% to 0.60%, and the mass fraction of Sr in the aluminum alloy to be 0.01% to 0.02%, the aspect ratio of eutectic silicon can be reduced from greater than 10 to less than 3, thereby improving the toughness and tensile strength of the aluminum alloy. If only La is added, the number of nucleation points during the forming process of the aluminum alloy is reduced, and the grains are easy to grow into "coarse columnar crystals" or "uneven axis crystals"; if only Ce is added, the binding energy between Ce and Al is slightly lower, and Ostwald ripening is easy to occur (Ostwald ripening: in a dispersed system or solid medium, larger particles will consume smaller particles and gradually grow, and smaller particles will gradually shrink and eventually disappear), and enough small nucleation cores cannot be formed, and the grain size is 20%-50% larger than that of mixed addition, which directly leads to the decrease of the strength and the fluctuation of the plasticity of the obtained aluminum alloy.

[0057] Exemplarily, the mass fraction of Re can be 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, or a range formed by any two of them.

[0058] Ti and B exist in the aluminum alloy in the form of very small and thermodynamically stable TiB2 particles and Al3Ti particles, which can hinder the migration of the grain boundary and limit the increase of the grain size, so that a significantly refined and uniformly distributed equiaxed grain structure is obtained. These small grains can significantly improve the yield strength and tensile strength of the aluminum alloy through grain boundary strengthening mechanism. By limiting the mass fraction of Ti in the aluminum alloy to be 0.15% to 0.20%, and the mass fraction of B in the aluminum alloy to be 0.03% to 0.04%, the grain size can be reduced to 50 μm to 100 μm; and finally the yield strength and tensile strength of the aluminum alloy are improved.

[0059] Exemplarily, the mass fraction of Ti can be 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, or a range formed by any two of them.

[0060] Exemplarily, the mass fraction of B can be 0.03%, 0.031%, 0.032%, 0.033%, 0.034%, 0.035%, 0.036%, 0.037%, 0.038%, 0.039%, 0.040%, or a range formed by any two of them.

[0061] The presence of V can form high-melting-point nano-scale Al3V alloy with Al as a heterogeneous nucleation point, which can refine the grains of the as-cast or heat-treated aluminum alloy together with Ti and B. V can also combine with B to form VB2 in the aluminum alloy. Therefore, the mass fraction of V in the aluminum alloy is limited to 0.1% to 0.2% to balance the consumption rate of B and the generation rate of TiB2, so as to improve the strength and elastic modulus of the aluminum alloy.

[0062] Exemplarily, the mass fraction of V can be 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, or a range formed by any two of them.

[0063] Fe is a kind of impurity, and the solid solubility of Fe in the aluminum alloy is very low. Fe can form needle-shaped Al3Fe or flaky α-AlFeSi with Al. These compounds are very hard and brittle, which can affect the continuity of the aluminum alloy and become "hard points" in the aluminum alloy. Therefore, by limiting the content of Fe in the aluminum alloy to 0% to 0.12%, the existence of "hard points" in the aluminum alloy is reduced, so that the aluminum alloy can obtain good plasticity.

[0064] Exemplarily, the mass fraction of Fe can be 0%, 0.02%, 0.04%, 0.06%, 0.08%, 0.10%, 0.12%, or a range formed by any two of them.

[0065] In the aluminum alloy, some impurity elements inevitably exist, which are brought in by raw materials or introduced in the processing process, including Na, Ca, H, Pb, Sn, Bi, etc. These impurity elements can cause eutectic silicon modification to be invalid, form bubbles, form low-melting eutectic with Al, or cause interdendritic shrinkage and porosity, and finally lead to poor elastic strength of the aluminum alloy. Therefore, by limiting the mass fraction of the impurity elements in the aluminum alloy to 0% to 0.2%, the above situations are avoided as much as possible, so that the aluminum alloy with good elastic strength is obtained.

[0066] In some specific embodiments, the mass ratio of Si to Mg contained in the aluminum alloy is (13-20): 1.

[0067] The aluminum alloy provided in the present application is mainly Al-Si-Mg alloy, and the performance core of the Al-Si-Mg alloy depends on the Mg2Si strengthening phase. In order to avoid the excessive growth of Mg2Si in the aging process affecting the strength of the aluminum alloy, and the excessive solid solution of Mg affecting the elongation of the aluminum alloy, the mass ratio of Si to Mg contained in the aluminum alloy is limited to (13-20): 1, so as to control the generation efficiency of Mg2Si in the aluminum alloy, and further improve the strength and elongation of the aluminum alloy.

[0068] Exemplarily, the mass ratio of Si to Mg can be 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, 20:1, or a range consisting of any two of them.

[0069] In some specific embodiments, the mass ratio of Ti to V contained in the aluminum alloy is (1-3):1.

[0070] In the process of preparing the aluminum alloy, there is a contradiction between the competitive consumption of B by Ti and V and the brittle phase generation with Al. By limiting the mass ratio of Ti to V to be (1-3):1, on the one hand, B can be made to generate TiB2 with Ti as much as possible, strengthening the grain refinement effect, and on the other hand, the aluminum alloy can contain more fine Al3Ti rather than hard brittle phase Al 10 V, thereby making the strength and elastic modulus of the aluminum alloy higher.

[0071] Exemplarily, the mass ratio of Ti to V can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, or a range consisting of any two of them.

[0072] In some specific embodiments, the mass fraction of any single impurity element in the impurity elements is less than or equal to 0.05%.

[0073] By limiting the mass fraction of a single impurity element in the aluminum alloy to be less than or equal to 0.05%, the influence of the impurity elements on the mechanical properties of the aluminum alloy can be further reduced, thereby obtaining an aluminum alloy with better performance.

[0074] Based on the influence of each element on the mechanical properties of the aluminum alloy, in order to obtain an aluminum alloy with more excellent comprehensive performance, in some specific embodiments, the aluminum alloy can include, by mass percentage, Si 6.5%, Mg 0.35%, Zn 0.25%, Mn 0.15%, Re 0.15%, Sr 0.01%, Ti 0.15%, B 0.03%, V 0.1%, Fe 0%-0.12%, impurity elements 0%-0.2%, and the balance being aluminum. In some other specific embodiments, the aluminum alloy includes, by mass percentage, Si 7.0%, Mg 0.45%, Zn 1.5%, Mn 0.30%, Re 0.30%, Sr 0.015%, Ti 0.20%, B 0.035%, V 0.15%, Fe 0%-0.12%, impurity elements 0%-0.2%, and the balance being aluminum. In some other specific embodiments, the aluminum alloy includes, by mass percentage, Si 7.5%, Mg 0.50%, Zn 3.0%, Mn 0.50%, Re 0.60%, Sr 0.02%, Ti 0.20%, B 0.04%, V 0.2%, Fe 0%-0.1%, impurity elements 0%-0.2%, and the balance being aluminum.

[0075] The aluminum alloy provided by the embodiment of the present application takes Al-Si-Mg aluminum alloy as a matrix, and the yield strength, tensile strength and elastic modulus of the obtained aluminum alloy are improved by adopting Ti, Mn, Zn, La, Ce, Sr, V and B elements for composite modification and grain refinement.

[0076] The present application also provides a preparation method of the above-mentioned aluminum alloy, as shown in the formula (I), the preparation method comprises the following steps: Figure 2

[0077] adding a first intermediate alloy into the liquid master alloy to obtain a first transition alloy;

[0078] adding a second intermediate alloy into the first transition alloy to obtain a second transition alloy;

[0079] casting and forming the second transition alloy to obtain a third transition alloy;

[0080] post-processing the third transition alloy to obtain the aluminum alloy;

[0081] The first intermediate alloy comprises at least one of Al-Zn alloy, Al-Mn alloy and Al-V alloy;

[0082] The second intermediate alloy comprises at least one of Al-Ti-B alloy, Al-La alloy, Al-Ce alloy and Al-Sr alloy.

[0083] Since pure Zn metal added into the high-temperature liquid master alloy will be violently volatilized with a high burning loss rate, the dissolution and diffusion rate of pure Mn in the liquid master alloy is very low, which will form coarse needle-like Al6Mn phase and become a crack source, pure Ti has high melting point and large density, which is difficult to dissolve in aluminum liquid, pure B has very low density and is easy to float on the surface of aluminum liquid and be oxidized and burned, pure Sr has high activity and is easy to cause chemical activity out of control, and pure V and rare earth metals La and Ce are easy to be oxidized. Therefore, in order to significantly improve the yield of elements and improve the uniformity of composition distribution, the above-mentioned elements are added in the form of alloy during the preparation of the aluminum alloy.

[0084] ​In addition, for Ti and B, by adding in the form of Al-Ti-B alloy, TiB2heterogeneous nucleation particles (size 0.5-1 μm) and Al3Ti coating layer with good morphology can be provided to the aluminum alloy to refine the α-Al grains. For Sr, by adding in the form of Al-Sr alloy, Sr can be released in the form of Al4Sr phase, adsorbed on the silicon growth front, and promote the transformation of silicon from sheet to fiber. For rare earth metals La and Ce, by adding in the form of Al-La alloy and Al-Ce alloy, Al4(La, Ce) Fe can be formed to replace the needle-like β-Al5FeSi and neutralize the Fe harmful phase, and the thermally stable Al(La, Ce) phase can be generated to inhibit high-temperature grain growth and ensure the dispersion of rare earth metals in the form of nanoscale intermetallic compounds, thereby obtaining an aluminum alloy with excellent yield strength and tensile strength. 11

[0085] In addition, Al-Zn alloy, Al-Mn alloy, and Al-V alloy need a long time of diffusion in the aluminum liquid to ensure homogenization, while the improvement of the performance of the aluminum alloy by the elements involved in the Al-Ti-B alloy, Al-La alloy, Al-Ce alloy, and Al-Sr alloy depends on the nanoscale dispersed phase. Therefore, the present application adds Al-Zn alloy, Al-Mn alloy, and Al-V alloy in the liquid master alloy first to promote their dispersion, so that the first added Mn occupies the aluminum lattice vacancies to form a uniform Al6Mn phase, avoids the subsequent TiB2from being wrapped by Mn, and makes V preferentially occupy the grain boundaries to inhibit recrystallization. The addition of Al-Ti-B alloy, Al-La alloy, Al-Ce alloy, and Al-Sr alloy to the first transition alloy can prevent selective reactions between Mn, V, and TiB2and Sr, and more importantly, can strictly control the residence time of Al-Sr alloy and Al-La alloy in the melt to ensure that the functional alloy phase is "added and used immediately", and the newly exposed (0001) crystal plane of the subsequently formed TiB2can be exposed in the low-Mn melt, greatly improving the nucleation efficiency.

[0086] In order to improve the dispersion uniformity of the first transition alloy in the liquid master alloy, the first transition alloy can be added and then held for 20-40 min, for example, 20 min, 25 min, 30 min, 35 min, 40 min, or a range formed by any two of them.

[0087] In some specific embodiments, the liquid master alloy can be selected from liquid commercial alloy A356, or can be melted from commercial alloy A356, or can be mixed and melted from a certain amount of aluminum, aluminum-silicon alloy, and aluminum-magnesium alloy according to the above-mentioned aluminum alloy formula.

[0088] ​In some embodiments, to avoid the burning and volatilization of key elements when the first intermediate alloy and the second intermediate alloy are added subsequently, resulting in uncontrolled composition, and to regulate the morphology of various alloy phases during synthesis, the temperature of the liquid master alloy is limited to 700-800°C. For example, the temperature can be 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 780°C, 790°C, 800°C, or a range defined by any two of these values.

[0089] In some embodiments, adding the second intermediate alloy to the first transition alloy includes:

[0090] The second intermediate alloy is preheated to 110-180°C, pressed into the bottom of the first transition alloy, and stirred until melted.

[0091] To eliminate the moisture adsorption layer on the surface of the second intermediate alloy and the pre-cracking oxide film, the second intermediate alloy can be preheated to 110-180°C before being added to the first transition alloy. For example, the second intermediate alloy can be preheated to 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, or a range defined by any two of these values.

[0092] It can be understood that by pressing the second intermediate alloy into the bottom of the first transition alloy, the static pressure of the first transition alloy can be used to suppress the volatilization of Sr and the oxidation of La and Ce.

[0093] In some embodiments, the casting forming includes pouring the second transition alloy at a temperature of 690-710°C into a mold at a temperature of 200-300°C, and then cooling and solidifying to form.

[0094] To improve the processing fluidity of the second transition alloy and remove internal bubbles as much as possible, the second transition alloy can be heated to 690-710°C before being poured into the mold. For example, the temperature can be 690°C, 700°C, 710°C, or a range defined by any two of these values.

[0095] To reduce the thermal shock of the mold to the second transition alloy and prolong the service life of the mold, the casting mold can be preheated to 200-300°C. For example, the temperature can be 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, or a range defined by any two of these values.

[0096] In some embodiments, the casting can be at least one of gravity casting, low pressure casting, and squeeze casting. Specifically, the gravity casting can have a pouring speed of 2 kg / s-5 kg / s, and the casting is cooled and solidified by natural heat dissipation of the mold, and then the casting is pushed out by a ejector rod. The low pressure casting is to introduce dry gas into the mold and pressurize to 0.2 MPa-0.4 MPa, and after holding for 30 s-180 s to eliminate shrinkage, the casting is cooled and solidified by exhaust and depressurization, and then the casting is ejected. The squeeze casting is to first fill at a low speed of 110 mm / s-130 mm / s, and then to perform extrusion at a high pressure of greater than 60 MPa, and to hold at the high pressure until solidification, and finally to eject the casting.

[0097] Exemplarily, the filling pressure of the low pressure casting can be 0.2 MPa, 0.3 MPa, 0.4 MPa, or a range formed by any two of them; and the holding time can be 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 120 s, 130 s, 140 s, 150 s, 160 s, 170 s, 180 s, or a range formed by any two of them.

[0098] Exemplarily, the low speed filling speed in the squeeze casting can be 110 mm / s, 120 mm / s, 130 mm / s, or a range formed by any two of them, and the extrusion pressure can be, but not limited to, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, 120 MPa, etc.

[0099] In some embodiments, the post-processing includes solution treatment and aging treatment.

[0100] In order to fully dissolve the strengthening elements of Ti, Mn, Zn, La, Ce, Sr, V and B into the master alloy to form a uniform single-phase solid solution, and to prepare for the subsequent aging treatment, the third transition metal after casting needs to be solution treated before aging treatment.

[0101] Specifically, the solution treatment includes: placing the third transition alloy at 500°C-540°C for 4h-8h, and then water quenching the third transition alloy at 25°C-60°C within less than 10s.

[0102] Exemplarily, the third transition alloy can be placed at 500°C, 510°C, 520°C, 530°C, 540°C, or a range formed by any two of them.

[0103] Exemplarily, the holding time can be 4h, 5h, 6h, 7h, 8h, or a range formed by any two of them.

[0104] Exemplarily, the water quenching time can be 25℃, 30℃, 40℃, 50℃, 60℃ or a range consisting of any two of them.

[0105] In the solid solution treatment process, by water quenching the third transition alloy after holding in less than 10s, it prevents the precipitation of harmful phases due to temperature drop before entering the water quenching, ensuring that the entire third transition alloy can obtain a fast enough cooling rate. At the same time, the rapid water quenching can also inhibit the diffusion of solute atoms during cooling to precipitate coarse equilibrium phases, "freeze" the supersaturated solid solution at high temperature to room temperature, so as to obtain a metastable supersaturated solid solution, and ensure that the subsequent aging treatment can obtain fine and dispersed strengthening phases.

[0106] In order to further reduce the size of the nano-phase precipitated in the aluminum alloy precursor obtained by solid solution treatment, reduce the grain boundary segregation, reduce the hot cracking sensitivity, and further improve the strength and elastic modulus of the aluminum alloy, in some specific embodiments, the aging treatment includes single-stage aging treatment or two-stage aging treatment. Specifically, the single-stage aging treatment includes: taking the aluminum alloy precursor obtained by solid solution treatment out of the furnace and air cooling after holding at 165℃-190℃ for 4h-12h; the two-stage aging treatment includes: taking the aluminum alloy precursor obtained by solid solution treatment out of the furnace and air cooling after holding at 120℃-130℃ for 4h-8h, and then holding at 165℃-180℃ for 4h-6h.

[0107] Exemplarily, the temperature of the single-stage aging treatment can be 165℃, 170℃, 175℃, 180℃, 185℃, 190℃ or a range consisting of any two of them, and the holding time of the single-stage aging treatment can be 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h or a range consisting of any two of them.

[0108] Exemplarily, in the two-stage aging treatment, the temperature of the first holding can be 120℃, 125℃, 130℃ or a range consisting of any two of them, and the holding time can be 4h, 5h, 6h, 7h, 8h or a range consisting of any two of them.

[0109] Exemplarily, in the two-stage aging treatment, the temperature of the second holding can be 165℃, 170℃, 175℃, 180℃ or a range consisting of any two of them, and the holding time can be 4h, 5h, 6h or a range consisting of any two of them.

[0110] In order to eliminate hydrogen pores and non-metallic inclusions in the first transition alloy, improve the purity and fluidity of the alloy melt, and ensure that the finally obtained aluminum alloy has higher density, more excellent mechanical properties (strength, plasticity, toughness, fatigue performance) and good processing formability, the first transition alloy can be refined and degassed before adding the second intermediate alloy, so that the inclusion content is less than or equal to 1.0 mg / kg, and the hydrogen content is less than or equal to 0.5 ml / 100g.

[0111] Specifically, the refining and degassing is achieved by adding a Na-free refining agent and an inert gas into the first transition alloy. After the first transition alloy is melted, the refining agent can react with oxides to generate low-melting-point compounds into the slag phase to remove slag, and can also generate gas to achieve the effect of degassing. The Na-free refining agent can be a fluorosalt-based sodium-free agent Alcoa 722, a rare earth composite agent Lanthanum Clean, a nitrate-graphite-based agent EcoFlux NF, etc.

[0112] The preparation method provided in the embodiment of the present application improves the yield of each element by adding Zn, Mn, V, Ti, B, La, Ce and Sr to the master alloy in batches and reducing the aging treatment temperature and prolonging the aging treatment time, ensures the uniformity of the distribution of each component in the aluminum alloy and the degree of grain refinement, and makes the finally obtained aluminum alloy have excellent toughness, excellent yield strength and tensile strength under the premise of lightweight wall thickness.

[0113] The present application also provides a casting, which comprises the above-mentioned aluminum alloy or the aluminum alloy prepared by the above-mentioned preparation method, and has excellent yield strength, tensile strength and elastic modulus. The casting provided in the embodiment can perform the method provided in the method embodiment, and has similar implementation principles and technical effects, which will not be described here.

[0114] The technical solutions of the present application are further described below by using specific embodiments.

[0115] Embodiment 1

[0116] Batching: according to the element mass percentage Si 6.50%, Mg 0.35%, Zn 0.25%, Mn 0.15%, La 0.075%, Ce 0.075%, Sr 0.01%, Ti 0.15%, B 0.03%, V 0.1%, Fe 0.12%, the balance is Al, configure commercial alloy ingot A356, first intermediate alloy (Al-Zn alloy, Al-Mn alloy, Al-V alloy), second intermediate alloy (Al-Ti-B alloy, Al-La alloy, Al-Ce alloy, Al-Sr alloy), and the first intermediate alloy is uniformly preheated to 150°C; wherein, the mass ratio of Si:Mg = 18.57:1, Ti:V = 1.5:1;

[0117] Melting: after the melting furnace is preheated and dried, the master alloy ingot A356 is put in and heated to 730°C to melt to obtain a liquid master alloy, the preheated first intermediate alloy is added, fully melted and uniformly stirred, then sampled for composition analysis, after the composition meets the standard, it is placed for 20 minutes to obtain a first transition alloy;

[0118] Refining and degassing: the refining agent fluorine salt-based sodium-free agent Alcoa 722 and argon gas are added to the first transition alloy, the argon gas is introduced at a rate of 2m 3 / h, after refining and degassing for 15 min, the slag on the surface of the alloy liquid is quickly removed with a slag spoon, the sample is detected by K mold filtration method and hydrogen content detection, the inclusion content of the alloy liquid is determined to be K mold inspection level 1 (≤1 mg / kg), and the hydrogen content is ≤0.5 ml / 100g;

[0119] Modification treatment: the second intermediate alloy preheated to 110°C is added to the first transition alloy after refining and degassing, the second intermediate alloy is pressed into the bottom of the first transition alloy liquid with a slag spoon and stirred until the second intermediate alloy is fully melted; a second transition alloy is obtained;

[0120] Casting forming: the second transition alloy liquid at 710°C is poured into a mold at 200°C to form a casting, the casting pressure is 65 MPa, and the filling speed is 120 mm / s, so that an integrally formed third transition alloy is obtained by squeeze casting;

[0121] Heat treatment process: the third transition alloy is subjected to solid solution treatment at 525°C for 6h, then quenched in water at room temperature within 5s, then subjected to single-stage aging treatment at 165°C for 8h and air cooled, thereby obtaining the aluminum alloy.

[0122] Example 2

[0123] The aluminum alloy in this example is prepared in the same manner as in Example 1, except that the aluminum alloy comprises, by mass fraction, Si 7.0%, Mg 0.45%, Zn 1.5%, Mn 0.30%, La 0.15%, Ce 0.15%, Sr 0.015%, Ti 0.18%, B 0.036%, V 0.15%, Fe 0.12%, and the balance being aluminum, wherein the mass ratio of Si:Mg = 15.56:1 and Ti:V = 1.2:1.

[0124] Example 3

[0125] The aluminum alloy in this example is prepared in the same manner as in Example 1, except that the aluminum alloy comprises, by mass fraction, Si 7.5%, Mg 0.50%, Zn 3.0%, Mn 0.50%, La 0.30%, Ce 0.30%, Sr 0.02%, Ti 0.20%, B 0.04%, V 0.20%, Fe 0.12%, and the balance being aluminum, wherein the mass ratio of Si:Mg = 15:1 and Ti:V = 1:1.

[0126] Example 4

[0127] The aluminum alloy in this example has the same component content as in Example 1, except that the casting process is gravity casting and the pouring speed is 2 kg / s.

[0128] Example 5

[0129] The aluminum alloy in this example has the same component content as in Example 2, except that the casting process is gravity casting and the pouring speed is 2 kg / s.

[0130] Example 6

[0131] The aluminum alloy in this example has the same component content as in Example 3, except that the casting process is gravity casting and the pouring speed is 2 kg / s.

[0132] Example 7

[0133] The aluminum alloy in this example has the same component content as in Example 1, except that the casting process is low-pressure casting and the pressure is raised to 3 kPa.

[0134] Example 8

[0135] The aluminum alloy in this example has the same component content as in Example 2, except that the casting process is low-pressure casting and the pressure is raised to 3 kPa.

[0136] Example 9

[0137] The aluminum alloy in this example has the same component content as in Example 3, except that the casting process is low-pressure casting and the pressure is raised to 3 kPa.

[0138] Example 10

[0139] The aluminum alloy in this example has the same composition as in Example 1, except that a two-stage aging treatment is used, with the conditions being: 120°C for 6h, and 165°C for 4h.

[0140] Example 11

[0141] The aluminum alloy in this example has the same composition as in Example 2, except that a two-stage aging treatment is used, with the conditions being: 120°C for 6h, and 165°C for 4h.

[0142] Example 12

[0143] The aluminum alloy in this example has the same composition as in Example 3, except that a two-stage aging treatment is used, with the conditions being: 120°C for 6h, and 165°C for 4h.

[0144] Example 13

[0145] The aluminum alloy in this example is prepared in the same way as in Example 1, except that the mass percentage of Mg is 0.5%, and in this case, the mass ratio of Si:Mg is 13:1.

[0146] Example 14

[0147] The aluminum alloy in this example is prepared in the same way as in Example 2, except that the mass percentage of Mg is 0.35%, and in this case, the mass ratio of Si:Mg is 20:1.

[0148] Example 15

[0149] The aluminum alloy in this example is prepared in the same way as in Example 1, except that the mass percentage of Si is 7.5%, and in this case, the mass ratio of Si:Mg is 21.4:1.

[0150] Comparative Example 1

[0151] Commercial aluminum alloy A356, by mass percentage, includes: Si 7.0%, Mg 0.35%, Ti 0.15%, Fe 0.12%, Mn 0.1%, Sr 0.012%, and the balance being aluminum. The pressure for extrusion casting is 145MPa, the temperature for solution treatment is 525°C, the time for solution treatment is 4h, the temperature for aging treatment is 190°C, and the time for aging treatment is 4h.

[0152] Comparative Example 2

[0153] The aluminum alloy in this example is prepared in the same way as in Example 1, except that the mass percentage of Si is 5%, and in this case, the mass ratio of Si:Mg is 14.3:1.

[0154] Comparative Example 3

[0155] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that the mass percentage of V in the aluminum alloy was 0.01%.

[0156] Comparative Example 4

[0157] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that the mass percentage of V in the aluminum alloy was 5%.

[0158] Comparative Example 5

[0159] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that the mass percentage of Ti in the aluminum alloy was 3%.

[0160] Comparative Example 6

[0161] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that the mass percentage of Zn in the aluminum alloy was 5%.

[0162] Comparative Example 7

[0163] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that the aluminum alloy did not contain Mn.

[0164] Comparative Example 8

[0165] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that the aluminum alloy did not contain Zn.

[0166] Comparative Example 9

[0167] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that it did not contain Ce.

[0168] Comparative Example 10

[0169] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that it did not contain La.

[0170] Comparative Example 11

[0171] The aluminum alloy in the present comparative example was prepared by the same process as in Example 1, except that it did not contain La and Ce.

[0172] Comparative Example 12

[0173] The aluminum alloy in the present comparative example was prepared by the same process as in Example 3, except that the mass fraction of La was 0.5% and the mass fraction of Ce was 0.5%.

[0174] The aluminum alloys obtained in Examples 1-15 and Comparative Examples 1-12 were subjected to the following tests:

[0175] Tensile strength: The sample size of 6mm in diameter (4mm in sample thickness at this time) was prepared according to GB / T16865, and then the test method in GB / T228.2021 was used for testing;

[0176] Yield strength: The sample size of 6mm in diameter (4mm in sample thickness at this time) was prepared according to GB / T16865, and then the test method in GB / T228.2021 was used for testing;

[0177] Plastic elongation: The sample size of 6mm in diameter (4mm in sample thickness at this time) was prepared according to GB / T16865, and then the test method in GB / T228.2021 was used for testing;

[0178] Elastic modulus: The sample size of 6mm in diameter (4mm in sample thickness at this time) was tested according to GB / T22315-2008;

[0179] Strength plastic product: The product was calculated according to the tensile strength and plastic elongation.

[0180] The test results are shown in Table 1:

[0181] Table 1

[0182]

[0183] According to the test data in Table 1, it can be seen that the aluminum alloy provided by the application still has high elastic modulus and strength plastic product under the condition of 4mm wall thickness.

[0184] In Examples 1-3, the aluminum alloy subjected to extrusion casting and single-stage aging treatment has a tensile strength greater than or equal to 350MPa, a yield strength greater than or equal to 270MPa, and an elastic modulus greater than or equal to 80Mpa.

[0185] In Examples 4-6, the aluminum alloy subjected to gravity casting and single-stage aging treatment has a tensile strength greater than or equal to 260MPa, a yield strength greater than or equal to 220MPa, and an elastic modulus greater than or equal to 70Mpa.

[0186] In Examples 7-9, the aluminum alloy subjected to low-pressure casting and single-stage aging treatment has a tensile strength greater than or equal to 310MPa, a yield strength greater than or equal to 260MPa, and an elastic modulus greater than or equal to 72Mpa.

[0187] In Examples 10-12, the aluminum alloy subjected to squeeze casting and two-stage aging treatment has a tensile strength greater than or equal to 320 MPa, a yield strength greater than or equal to 270 MPa, and an elastic modulus greater than or equal to 82 MPa.

[0188] Compared with Example 15, the aluminum alloy obtained in Example 1 has higher tensile strength, yield strength, and elastic modulus, and also has higher strength-ductility product. This shows that the aluminum alloy with the mass ratio of Si to Mg in the range of (13-20): 1 has better mechanical properties and can be applied to a wall thickness of 4 mm.

[0189] Compared with Comparative Example 1, the aluminum alloy obtained in Example 1 has higher tensile strength, yield strength, and elastic modulus, and also has higher strength-ductility product. This shows that the aluminum alloy provided in the present application has better mechanical properties than the existing commercial aluminum alloy A356 and can be applied to lightweight applications with a wall thickness of 4 mm.

[0190] Compared with Comparative Example 2, the aluminum alloy obtained in Example 1 has higher tensile strength, yield strength, and strength-ductility product under the condition of squeeze casting, which shows that, under the premise that the mass ratio of Si to Mg meets (13-20): 1, the aluminum alloy with the mass percentage of Si between 6.5% and 8.0% can have excellent tensile strength, yield strength, and strength-ductility product when the wall thickness is 4 mm.

[0191] Compared with Comparative Examples 3 and 4, the aluminum alloy obtained in Example 1 has higher tensile strength, yield strength, and strength-ductility product under the condition of squeeze casting, which shows that the aluminum alloy with the content of V between 0.1% and 0.2% can have excellent tensile strength, yield strength, and strength-ductility product when the wall thickness is 4 mm.

[0192] Compared with Comparative Example 5, the aluminum alloy obtained in Example 1 has higher tensile strength, elastic modulus, and strength-ductility product under the condition of squeeze casting, which shows that the aluminum alloy with the content of Ti between 0.15% and 0.2% can have excellent tensile strength, elastic modulus, and strength-ductility product when the wall thickness is 4 mm.

[0193] Compared with Comparative Example 6, the aluminum alloy obtained in Example 1 has higher strength-ductility product under the condition of squeeze casting, which shows that although increasing the addition amount of Zn is beneficial to improving the tensile strength and yield strength of the aluminum alloy as well as the elastic modulus, the strength-ductility product will decrease, making it impossible to achieve lightweight applications with a wall thickness of less than or equal to 4 mm. It can be seen that the aluminum alloy with the content of Zn between 0.25% and 0.30% can have higher strength-ductility when the wall thickness is 4 mm.

[0194] Compared with Comparative Example 7 and Comparative Example 8, the tensile strength, yield strength, elastic modulus and strength-ductility product of the aluminum alloy obtained in Example 1 are higher under the condition of squeeze casting, which indicates that the presence of Mn and Zn is conducive to improving the mechanical strength of the obtained aluminum alloy, making it suitable for lightweight applications with a wall thickness of 4 mm.

[0195] Compared with Comparative Example 9, Comparative Example 10 and Comparative Example 11, the tensile strength, elastic modulus and strength-ductility product of the aluminum alloy obtained in Example 1 are higher under the condition of squeeze casting, which indicates that La and Ce are indispensable for improving the mechanical properties of the obtained aluminum alloy.

[0196] Compared with Comparative Example 12, the tensile strength and strength-ductility product of the aluminum alloy obtained in Example 3 are higher under the condition of squeeze casting, which indicates that the total amount of La and Ce added in the range of 0.15% to 0.60% can obtain an aluminum alloy with higher strength-ductility product when the wall thickness is 4 mm.

[0197] Finally, it should be noted that: after considering the specification and practicing the invention disclosed herein, those skilled in the art will easily think of other embodiments of the present application. The present application is intended to cover any variations, uses or adaptations of the present application which follow the general principles of the present application and include common knowledge or conventional technical means in the art which are not disclosed in the present application, and is not limited to the precise structure described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is only limited by the appended claims.

Claims

1. An aluminum alloy characterized by, According to the mass percentage, it comprises: Si 6.5%-8.0%, Mg 0.30%-0.50%, Zn 0.25%-3.0%, Mn 0.15%-0.50%, Re 0.15%-0.60%, Sr 0.01%-0.02%, Ti 0.15%-0.20%, B 0.03%-0.04%, V 0.1%-0.2%, Fe 0%-0.12%, impurity elements 0%-0.2%, and the balance is Al; Wherein, Re includes La and Ce; The preparation method of the aluminum alloy comprises: Adding a first intermediate alloy to a liquid master alloy to obtain a first transition alloy; Adding a second intermediate alloy to the first transition alloy to obtain a second transition alloy; Casting and forming the second transition alloy to obtain a third transition alloy; Post-processing the third transition alloy to obtain the aluminum alloy; The first intermediate alloy comprises at least one of Al-Zn alloy, Al-Mn alloy and Al-V alloy; The second intermediate alloy comprises at least one of Al-Ti-B alloy, Al-La alloy, Al-Ce alloy and Al-Sr alloy.

2. The aluminum alloy of claim 1, wherein The mass ratio of Si to Mg is (13-20):1; And / or, the mass ratio of Ti to V is (1-3):1; And / or, in the impurity elements, the mass fraction of any single impurity element is less than or equal to 0.05%.

3. The aluminum alloy of claim 2, wherein, The mass percentage of Si in the aluminum alloy is 6.5%-7.5%; And / or, the mass ratio of Si to Mg is (15-19):1; And / or, the mass ratio of Ti to V is (1-1.5):

1.

4. The aluminum alloy of claim 3, wherein According to the mass percentage, it comprises: Si 6.5%, Mg 0.35%, Zn 0.25%, Mn 0.15%, Re 0.15%, Sr 0.01%, Ti 0.15%, B 0.03%, V 0.1%, Fe 0%-0.12%, impurity elements 0%-0.2%, and the balance is Al; Or, Si 7.0%, Mg 0.45%, Zn 1.5%, Mn 0.30%, Re 0.30%, Sr 0.015%, Ti 0.20%, B 0.035%, V 0.15%, Fe 0%-0.12%, impurity elements 0%-0.2%, and the balance is Al; Or, Si 7.5%, Mg 0.50%, Zn 3.0%, Mn 0.50%, Re 0.60%, Sr 0.02%, Ti 0.20%, B 0.04%, V 0.2%, Fe 0%-0.1%, impurity elements 0%-0.2%, and the balance is Al.

5. The aluminum alloy of claim 1, wherein: The temperature of the liquid master alloy is 700-800°C; And / or, the adding of the second intermediate alloy to the first transition alloy comprises: Preheating the second intermediate alloy to 110-180°C, pressing it into the bottom of the first transition alloy, and stirring until it melts; And / or, the casting and forming comprises: casting the second transition alloy at a temperature of 690-710 DEG C into a mold at a temperature of 200-300 DEG C, and then cooling and solidifying to form a shape; the casting includes at least one of gravity casting, low pressure casting, and squeeze casting.

6. The aluminum alloy of claim 1, wherein the post-treatment includes solution treatment and aging treatment.

7. The aluminum alloy of claim 6, wherein, the solution treatment includes: placing the third transition alloy at 500-540 DEG C for 4-8 hours, and then water quenching the third transition alloy at 25-60 DEG C in less than 10 seconds to obtain an aluminum alloy precursor; the aging treatment includes single-stage aging treatment or double-stage aging treatment; the single-stage aging treatment includes: placing the aluminum alloy precursor at 165-190 DEG C for 4-12 hours, and then furnace cooling and air cooling; the double-stage aging treatment includes: first placing the aluminum alloy precursor at 120-130 DEG C for 4-8 hours, and then placing the aluminum alloy precursor at 165-180 DEG C for 4-6 hours, and then furnace cooling and air cooling.

8. The aluminum alloy of claim 1, wherein, before the adding of the second intermediate alloy into the first transition alloy, further comprising: refining and degassing the first transition alloy, so that the hydrogen content of the first transition alloy is less than or equal to 0.5 ml / 100 g.

9. A casting, characterized in that an aluminum alloy according to any one of claims 1-8.

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