Aluminum alloy and preparation method therefor, and aluminum alloy die casting

Abstract

The present application provides an aluminum alloy and a preparation method therefor, and an aluminum alloy die casting. On the basis of 100% of the total mass of the aluminum alloy, the aluminum alloy comprises the following components: 6.5-8.5% of Si; less than or equal to 0.3% of Fe; less than or equal to 0.3% of Cu; less than or equal to 0.5% of Mn; less than or equal to 0.5% of Mg; less than or equal to 0.2% of Cr; 0.002-0.02% of V; 10-100 ppm of Nb; 0.01-0.03% of Sr; 10-100 ppm of a rare earth element, wherein the rare earth element is La and / or Ce; and the aluminum alloy further includes Al and inevitable impurities.

Description

[0001] The present application claims priority to Chinese patent application No. 202410324467.5, entitled "ALUMINUM ALLOY AND PREPARATION METHOD THEREFOR, AND ALUMINUM ALLOY DIE CASTING", filed before the China National Intellectual Property Administration (CNIPA) on March 21, 2024, the entire contents of which are incorporated herein by reference.TECHINCAL FIELD

[0002] This application relates to the technical field of aluminum alloys, and in particular to an aluminum alloy, a preparation method for the aluminum alloy, and an aluminum alloy die casting.BACKGROUND

[0003] With the rapid development of new energy vehicles and the continuously increasing demand for lightweighting, large-scale integrated thin-walled structural components (such as shock absorber towers, rear vehicle bodies, longitudinal beams, and front compartments) have experienced rapid development. Currently, aluminum alloy die castings, which are made from die-cast aluminum alloys, are commonly used for thin-walled structural components in vehicles.

[0004] However, traditional Al-Si series die-cast aluminum alloys only possess moderate strength and also have low plasticity and toughness, making it difficult to meet the requirements for thin-walled structural components in vehicles. Therefore, the traditional processing technology for aluminum alloy die castings usually includes heat treatment (solid solution treatment and aging) to improve the mechanical properties of cast aluminum alloys. However, this not only increases the complexity of the process and consumes a significant amount of energy, but also causes deformation of the aluminum alloy castings due to heating and cooling effects, affecting assembly accuracy and even leading to the scrapping of the aluminum alloy castings. Additionally, in order to facilitate demolding during the production of aluminum alloy die castings, a certain amount of Fe is added to the die-cast aluminum alloy. The addition of Fe leads to a decrease in the plasticity, toughness, corrosion resistance, and flow formability of the die-cast aluminum alloy. These factors collectively restrict the further application of die-cast aluminum alloys and aluminum alloy die castings.

[0005] Therefore, there is an urgent need to optimize the alloy material composition to develop an aluminum alloy, a preparation method for the same, and aluminum alloy die castings. This aluminum alloy should possess high strength, excellent plasticity and toughness, corrosion resistance, and flow formability. Furthermore, the aluminum alloy does not require heat treatment and exhibits good mechanical properties in the as-cast state. Therefore, aluminum alloy die castings made from such aluminum alloy can fully meet the requirements for thin-walled structural components in vehicles.SUMMARY

[0006] The present application aims to solve at least one of the technical problems in the related art to a certain extent. In view of this, embodiments of the present application provide an aluminum alloy, a preparation method therefor, and an aluminum alloy die casting. This aluminum alloy possesses high strength, excellent plasticity and toughness, corrosion resistance, and flow formability. Moreover, it does not require heat treatment and exhibits good mechanical properties in the as-cast state, which can provide support for the application of large-scale integrated aluminum alloy die castings.

[0007] An embodiment of the present application provides an aluminum alloy, including components: Si, Fe, Cu, Mn, Mg, Cr, V, Nb, Sr and Rare earth elements, based on 100% of a total mass of the aluminum alloy, a content of Si is 6.5~8.5%; a content of Fe is less than and equal to 0.3%; a content of Cu is less than and equal to 0.3%; a content of Mn is less than and equal to 0.5%; a content of Mg is less than and equal to 0.5%; a content of Cr is less than and equal to 0.2%; a content of V is 0.002~0.02%; a content of Nb is 10~100 ppm; a content of Sr is 0.01~0.03%; a content of rare earth elements is 10~100 ppm, wherein the rare earth elements are selected from La and Ce; in addition to these components, the aluminum alloy further includes Al and unavoidable impurities.

[0008] The advantages and technical effects brought about by the aluminum alloy of the embodiments of the present application are as follows: (1) The addition of an appropriate amount of vanadium can, on one hand, produce a grain refinement strengthening effect, and on the other hand, promote the precipitation of fine AlV phases in the aluminum matrix, resulting in precipitation strengthening. These two effects collectively enhance the strength and toughness of the aluminum alloy. Moreover, the added V can combine with Fe to form AlSiVFe phases, consuming a portion of the impurity Fe and mitigating negative effects of Fe, thereby improving the plasticity and toughness, the corrosion resistance, and the flow formability of the aluminum alloy. (2) The addition of an appropriate amount of rare earth elements (La and / or Ce) can form intermetallic compounds with aluminum and other alloying elements, thereby improving the strength and toughness of the aluminum alloy. Moreover, the added rare earth elements (La and / or Ce) act as surface-active elements, reducing the surface tension of the alloy melt, and further improving the flow formability of the aluminum alloy. (3) The addition of an appropriate amount of Nb can refine the metallographic structure of the Al-Si alloy, thereby improving the strength and toughness of the aluminum alloy. (4) To sum up, through the optimized design of the aluminum alloy composition in this embodiment, particularly by adding appropriate amounts of the V element, the rare earth elements (La and / or Ce), and the Nb element, compared with traditional Al-Si series die-cast aluminum alloys, the aluminum alloy according to the embodiments of the present application exhibits high strength while maintaining excellent plasticity, toughness, corrosion resistance, and flow formability, meeting the requirements for automotive thin-walled structural components. Furthermore, the aluminum alloy of the present application does not require heat treatment in subsequent process, which effectively simplifies the processing technology of aluminum alloy die castings, avoids deformation issues, and the product yield of aluminum alloy die castings is improved.

[0009] In some embodiments, the content of Si is 6.5~7.5%; and / or the content of Fe is less than and equal to 0.15%; and / or the content of Cu is 0.001~0.3%; and / or the content of Mn is 0.3~0.5%; and / or the content of Mg is 0.1~0.5%; and / or the content of Cr is 0.1~0.2%; and / or the content of V is 0.005~0.02%; and / or the content of Nb is 30~80 ppm; and / or the content of Sr is 0.02~0.03%; and / or the content of the rare earth elements is 20~80 ppm.

[0010] In some embodiments, the content of V is 0.005~0.01%.

[0011] In some embodiments, the content of Nb is 40~60 ppm.

[0012] In some embodiments, the content of the rare earth elements is 20~50 ppm.

[0013] The present application also provides a preparation method for the aluminum alloy, including steps of: obtaining an aluminum melt by placing and melting an aluminum raw material in a smelting furnace, then adding Si raw material, Cu raw material, Mn raw material, Cr raw material, V raw material, and rare earth raw material to the aluminum melt and performing a first smelting process, and obtaining a first alloy melt; adding a deslagging agent to the first alloy melt, performing a first deslagging treatment, then adding Mg raw material, Nb raw material and Sr raw material and performing a second smelting process, leaving the first alloy melt standing for a first standing period and then performing a second deslagging treatment, and obtaining a second alloy melt; introducing an inert gas mixed with a refining agent into the second alloy melt, performing degassing and refining, and obtaining a third alloy melt; testing contents of the compositions of the third alloy melt, and when a test result meets specifications, leaving the third alloy melt standing for a second standing period, then performing a third deslagging treatment to obtain a fourth alloy melt; and pouring the fourth alloy melt into a mold, waiting for the alloy melt to take shape upon solidification, and obtaining an aluminum alloy ingot.

[0014] The advantages and technical effects brought about by the preparation method for the aluminum alloy of the embodiments of the present application are as follows: Through the preparation method for the aluminum alloy according to the embodiment of the present application, an aluminum alloy with excellent comprehensive properties is yielded. Aluminum alloy die castings can be manufactured without performing heat treatment in subsequent process, simplifying the processing technology. Moreover, the problem of deformation in aluminum alloy die castings caused by heat treatment can also be solved, and the product yield of aluminum alloy die castings is improved.

[0015] In some embodiments, the V raw material is an Al-V master alloy, the Nb raw material is an Al-Nb-B refiner, the rare earth raw material is an Al-rare earth master alloy.

[0016] In some embodiments, a temperature for the first smelting process is above 760°C, and a duration of the first smelting process is not less than 20 minutes.

[0017] In some embodiments, the temperature for the first deslagging treatment is above 730°C, the temperature for the second smelting process is above 720°C, and the duration of the second smelting process is not less than 10 minutes.

[0018] In some embodiments, the temperature of the degassing and refining is above 720°C, and the duration of the degassing and refining is not less than 10 minutes.

[0019] In some embodiments, the temperature during the pouring is 690~720°C.

[0020] The present application also provides an aluminum alloy die casting made from the aluminum alloy of the embodiments of the present application.

[0021] The advantages and technical effects brought about by the aluminum alloy die casting of the embodiments of the present application are as follows: By utilizing the aluminum alloy of the embodiments of this application, the aluminum alloy die casting of the embodiments possesses high strength while exhibiting excellent plasticity and toughness as well as excellent corrosion resistance. Therefore, the aluminum alloy die casting can meet the requirements for automotive thin-walled structural components such as shock absorber towers, rear vehicle bodies, longitudinal beams, and front compartments. Moreover, the aluminum alloy die casting can be obtained without performing heat treatment, which simplifies the processing of the aluminum alloy die casting, and avoids the deformation problem, thereby improving the product yield of the aluminum alloy die casting.

[0022] The above description is only a general overview of solutions of the present disclosure. In order to learn technical means of the present disclosure more clearly and allow the technical means to be implemented based on the disclosure of the description, and in order to make the above and other objects, features and advantages of the present disclosure more apparent and understandable, specific embodiments of the present disclosure are illustrated below.BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to describe technical solutions of the embodiments of the present disclosure or the related art more clearly, the accompanying drawings used in the illustration of the embodiments or the related art will be briefly introduced. Apparently, the accompanying drawings in the following explanation illustrate merely some embodiments of the present disclosure, and those skilled in the art may obtain other accompanying drawings based on these accompanying drawings without paying any creative effort. FIG. 1 is a schematic flowchart of a preparation method for an aluminum alloy according to an embodiment of the present application.DETAILED DESCRIPTION

[0024] To make objectives, technical solutions, and advantages of embodiments of the present disclosure clearer, a clear and thorough description for solutions in the embodiments of the present disclosure will be given below in conjunction with the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are a part of embodiments of the present disclosure, not all the embodiments. All other embodiments obtained, based on the embodiments in the present disclosure, by those skilled in the art without paying creative effort fall within the protection scope of the present disclosure.

[0025] The embodiments of the present application are described in detail below. Examples of the embodiments are illustrated in the accompanying drawings. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application, but should not be construed as limiting the present application.

[0026] An embodiment of the present application provides an aluminum alloy. Based on a total mass of the aluminum alloy being 100%, the aluminum alloy includes the following components: Si: 6.5~8.5%; Fe: ≤0.3%; Cu: ≤0.3%; Mn: ≤0.5%; Mg: ≤0.5%; Cr: ≤0.2%; V: 0.002~0.02%; Nb: 10~100 ppm; Sr: 0.01~0.03%; Rare earth elements: 10~100 ppm, the rare earth elements are La and / or Ce; the aluminum alloy further includes Al and unavoidable impurities.

[0027] Through the optimized design of the aluminum alloy composition in this embodiment, particularly by adding appropriate amounts of the V element, the rare earth elements (La and / or Ce), and the Nb element, an aluminum alloy with excellent comprehensive properties, such as excellent strength (the tensile strength being greater than 240 MPa, the yield strength being greater than 120 MPa), plasticity and toughness (the elongation being greater than 10%, the bending angle being greater than 30 ° ), and corrosion resistance (corrosion pit depth ≤ 150 µm after experiencing 240 hours of salt spray corrosion), is obtained. Furthermore, the aluminum alloy of this embodiment does not require heat treatment in subsequent process, which can effectively simplify the processing technology of aluminum alloy die castings, avoid the deformation problem, thereby improving the product yield of the aluminum alloy die castings.

[0028] It should be noted that ppm means parts per million, i.e., 1%=10,000 ppm.

[0029] In the aluminum alloy provided by the embodiment of the present application, the content of Si is 6.5~8.5%, for example, 6.5%, 6.8%, 7%, 7.2%, 7.4%, 7.6%, 7.8%, 8%, 8.2%, 8.8%, etc. Si is a main element of the aluminum alloy. The strength and flow formability of the aluminum alloy can be improved by adding an appropriate amount of Si. When the content of Si is less than 6.5%, the fluidity and die-casting performance of the aluminum alloy are poor. When the content of Si is too high, the toughness of the aluminum alloy degrades. Preferably, the content of Si is 6.5~7.5%. When the content of Si is too high, it is not conducive to improving the toughness of the aluminum alloy.

[0030] In the aluminum alloy provided by the embodiment of the present application, the content of Fe is ≤0.3%, for example, 0%, 0.05%, 0.1%, 0.2%, 0.25%, 0.3%, etc. In the embodiment of the present application, Fe element is an impurity in the aluminum alloy, so the content of Fe in the aluminum alloy should be minimized. When the content of Fe is greater than 0.3%, the plasticity and toughness, the corrosion resistance, and the flow formability of the aluminum alloy degrade. Preferably, the content of Fe is ≤0.15%. When the content of Fe is too high, it is not conducive to improving the plasticity and toughness of the aluminum alloy.

[0031] In the aluminum alloy provided by the embodiment of the present application, the content of Cu is ≤0.3%, for example, 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, etc. Cu is a strengthening element. An appropriate amount of Cu is added to provide solid solution strengthening and precipitation strengthening, thereby improving the strength of the aluminum alloy. When the content of Cu is greater than 0.3%, the corrosion resistance of the aluminum alloy degrades. Preferably, the content of Cu is 0.001~0.3%. When the content of Cu is too low, it is not conducive to improving the strength of the aluminum alloy.

[0032] In the aluminum alloy provided by the embodiment of the present application, the content of Mn is ≤0.5%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc. The addition of appropriate amount of Mn facilitates demolding and subsequent die casting. When the content of Mn is greater than 0.5%, the toughness of the aluminum alloy degrades. Preferably, the content of Mn is 0.3~0.5%. When the content of Mn is too low, it is not conducive to improving the die-casting performance of the aluminum alloy.

[0033] In the aluminum alloy provided by the embodiment of the present application, the content of Mg is ≤0.5%, for example, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc. The addition of an appropriate amount of Mg can improve the strength of the aluminum alloy. When the content of Mg is greater than 0.5%, the toughness of the aluminum alloy is poor. Preferably, the content of Mg is 0.1~0.5%. When the content of Mg is too low, it is not conducive to improving the strength of the aluminum alloy.

[0034] In the aluminum alloy provided by the embodiment of the present application, the content of Cr is ≤ 0.2%. On one hand, the addition of an appropriate amount of Cr can refine the metallographic structure of the Al-Si alloy, thereby improving the toughness of the aluminum alloy. On the other hand, the addition of an appropriate amount of Cr facilitates demolding and subsequent die casting. When the content of Cr is greater than 0.2%, the toughness of the aluminum alloy degrades. Preferably, the content of Cr is 0.1~0.2%. When the content of Cr is too low, it is not conducive to improving the toughness of the aluminum alloy.

[0035] In the aluminum alloy provided by the embodiment of the present application, the content of V is 0.002~0.02%, for example, 0.002%, 0.004%, 0.006%, 0.008%, 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, etc. The addition of an appropriate amount of vanadium can, on one hand, produce a grain refinement strengthening effect, and on the other hand, promote the precipitation of fine AlV phases in the aluminum matrix, resulting in precipitation strengthening. These two effects collectively enhance the strength and toughness of the aluminum alloy. Moreover, the added V can combine with Fe to form AlSiVFe phases, consuming a portion of the impurity Fe and mitigating negative effects of Fe, thereby improving the plasticity and toughness, the corrosion resistance, and the flow formability of the aluminum alloy. When the content of V is less than 0.002%, the strength and toughness, the plasticity, the corrosion resistance, and the flow formability of the aluminum alloy are all poor. When the content of V is greater than 0.02%, coarse compounds form, resulting in poor strength of the aluminum alloy.

[0036] Preferably, the content of V is 0.005~0.02%. More preferably, the content of V is 0.005~0.01%. When the content of V is too low, it is not conducive to improving the strength, the toughness, the plasticity, and other properties of the aluminum alloy. When the content of V is too high, it is not conducive to maintaining high strength in the aluminum alloy.

[0037] In the aluminum alloy provided by the embodiment of the present application, the content of Nb is 10~100 ppm, for example, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, etc. The addition of an appropriate amount of Nb can refine the metallographic structure of the Al-Si alloy, thereby improving the strength and toughness of the aluminum alloy. When the content of Nb is less than 10 ppm, the alloy coarsens, resulting in poor strength and toughness of the aluminum alloy. When the content of Nb is greater than 100 ppm, Nb agglomeration occurs, failing to refine the structure and thus leading to poor strength and toughness of the aluminum alloy. Preferably, the content of Nb is 30~80 ppm; more preferably, the content of Nb is 40~60 ppm. When the content of Nb is too low or too high, it is not conducive to improving the strength and toughness of the aluminum alloy.

[0038] In the aluminum alloy provided by the embodiment of the present application, the content of Sr is 0.01~0.03%, for example, 0.01%, 0.012%, 0.014%, 0.016%, 0.018%, 0.02%, 0.022%, 0.024%, 0.026%, 0.028%, 0.03%, etc. The addition of an appropriate amount of Sr can refine the metallographic structure of the Al-Si alloy, thereby improving the strength and toughness of the aluminum alloy. When the content of Sr is less than 0.01%, the alloy structure coarsens, leading to a degradation in the strength and toughness of the aluminum alloy. When the content of Sr is greater than 0.03%, the alloy melt tends to absorb H, leading to increased internal porosity and a corresponding degradation in strength and toughness. Preferably, the content of Sr is 0.02~0.03%. When the content of Sr is too low, it is not conducive to improving the strength and toughness of the aluminum alloy.

[0039] In the aluminum alloy provided by the embodiment of the present application, the content of rare earth elements (La and / or Ce) is 10~100 ppm, for example, 10 ppm, 20 ppm, 30 ppm, 40 ppm, 50 ppm, 60 ppm, 70 ppm, 80 ppm, 90 ppm, 100 ppm, etc. The addition of an appropriate amount of rare earth elements (La and / or Ce) can form intermetallic compounds with aluminum and other alloying elements, thereby improving the strength and toughness of the aluminum alloy. Moreover, the added rare earth elements (La and / or Ce) act as surface-active elements, reducing the surface tension of the alloy melt, and further improving the flow formability of the aluminum alloy. However, when rare earth elements other than La and / or Ce are used, the above effects cannot be achieved. When the content of rare earth elements (La and / or Ce) is less than 10 ppm, the strength and toughness, and the flow formability of the aluminum alloy are poor. When the content of rare earth elements (La and / or Ce) is greater than 100 ppm, rare earth element agglomeration occurs, leading to poor toughness of the aluminum alloy.

[0040] Preferably, the content of rare earth elements is 20~80 ppm. More preferably, the content of rare earth elements is 20~50 ppm. When the content of rare earth elements is too low, it is not conducive to improving the strength and toughness of the aluminum alloy. When the content of rare earth elements is too high, it is not conducive to improving the toughness of the aluminum alloy.

[0041] In the aluminum alloy provided by the embodiment of the present application, when the rare earth element is a mixture of La and Ce, the mass ratio of La to Ce can be set arbitrarily.

[0042] In the aluminum alloy provided by the embodiment of the present application, the unavoidable impurities are P, S, and O. The content of a single impurity is less than or equal to 0.05%, and a total content of these impurities is less than or equal to 0.15%.

[0043] Furthermore, an embodiment of the present application also provides a preparation method for an aluminum alloy. As shown in FIG. 1, the method includes steps described below.

[0044] In step S1, an aluminum melt is obtained by placing and melting aluminum raw material in a smelting furnace, then Si raw material, Cu raw material, Mn raw material, Cr raw material, V raw material and rare earth raw material are added to the aluminum melt and a first smelting process is performed on the aluminum melt, and a first alloy melt is obtained.

[0045] In step S2, a first deslagging treatment is performed after a deslagging agent is added to the first alloy melt, then Mg raw material, Nb raw material and Sr raw material are added and a second smelting process is performed; after the first alloy melt is left for standing for a first standing period, a second deslagging treatment is performed to obtain a second alloy melt.

[0046] In step S3, the second alloy melt is subjected to degassing and refining by introducing an inert gas mixed with a refining agent into the second alloy melt, and a third alloy melt is obtained.

[0047] In step S4, contents of compositions of the third alloy melt are tested; if the test result meets specifications, the third alloy melt is left for standing for a second standing, then it is subjected to a third deslagging treatment, and a fourth alloy melt is obtained; if the test result does not meet specifications, the compositions are adjusted and the deslagging treatment is performed until the test result meets specifications.

[0048] In step S5, the fourth alloy melt is poured into a mold, and an aluminum alloy ingot is obtained after the alloy melt takes shape upon solidification.

[0049] Through the preparation method for the aluminum alloy according to the embodiment of the present application, an aluminum alloy with excellent comprehensive properties is yielded. Aluminum alloy die castings can be manufactured without performing heat treatment in subsequent process, simplifying the processing technology. Moreover, the problem of deformation in aluminum alloy die castings caused by heat treatment can also be solved, and the product yield of aluminum alloy die castings is improved.

[0050] In the preparation method for the aluminum alloy according to the embodiment of the present application, raw materials that are refractory and not easily burnt out are added first in step S1. After they are melted into the aluminum melt, raw materials that are easily melted and prone to burning out are added in step S2. This effectively reduces the burning loss of the elements added in step S2.

[0051] In some embodiments, the V raw material is an Al-V master alloy, the Nb raw material is an Al-Nb-B refiner, and the rare earth raw material is an Al-rare earth master alloy. If these elements were added in forms of elementary substance, a higher temperature is required, which could easily lead to the burning loss of other elements prone to burning out. Therefore, these elements are preferably added in the form of master alloys. As for the addition methods of other elements, they can be added either in forms of elementary substance or master alloys formed with Al.

[0052] Based on the aforementioned addition methods of various raw materials, in some embodiments, the temperature for the first smelting is above 760°C, and the duration of the first smelting is no less than 20 minutes. If the temperature of the alloy melt is too low or the duration of the first smelting is too short in this step, it may result in incomplete melting of the added raw materials. Preferably, the temperature for the first smelting ranges from 760°C to 800°C, such as 760°C, 770°C, 780°C, 790°C, 800°C, and the duration of the first smelting ranges from 20 to 40 minutes, such as 20 minutes, 30 minutes, 40 minutes. If the temperature of the alloy melt is too high or the duration of the first smelting is too long in this step, it can easily cause burning loss of the added raw materials.

[0053] Based on the aforementioned addition methods of various raw materials, in some embodiments, the temperature for the first deslagging treatment is above 730°C. If the temperature of the alloy melt in this step is too low, it can easily lead to insufficient deslagging. Preferably, the temperature for the first deslagging treatment ranges from 730°C to 750°C, for example, 730°C, 735°C, 740°C, 745°C, 750°C, etc. If the temperature of the alloy melt in this step is too high, it can easily cause burning loss of the added elements.

[0054] Based on the aforementioned addition methods of various raw materials, in some embodiments, the temperature for the second smelting is above 720°C, and the duration of the second smelting is not less than 10 minutes. If the temperature of the alloy melt is too low or the duration of the second smelting is too short in this step, it can easily lead to incomplete melting of the added raw materials. Preferably, the temperature for the second smelting ranges from 720°C to 750°C, for example, 720°C, 725°C, 730°C, 735°C, 740°C, 745°C, 750°C, etc., and the duration of the second smelting ranges from 10 to 20 minutes, for example, 10 min, 15 min, 20 min, etc. If the temperature of the alloy melt is too high or the duration of the second smelting is too long in this step, it can easily cause burning loss of the added elements.

[0055] The temperature for the second smelting is higher than that for the first smelting, and the duration of the second smelting is longer than that of the first smelting. This is because the raw materials added in step S1 are more refractory, while the elements added in step S2 are relatively easier to melt and more prone to burning off.

[0056] In some embodiments, the temperature of the degassing and refining is above 720°C, and the duration of the degassing and refining is not less than 10 minutes. If the temperature of the alloy melt is too low or the duration of the degassing and refining is too short in this step, it is not conducive to sufficient degassing. Preferably, the temperature for the degassing and refining ranges from 720°C to 730°C, for example, 720°C, 722°C, 724°C, 726°C, 728°C, 730°C, etc., and the duration of the degassing and refining ranges from 10 to 20 minutes, for example, 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, etc. If the temperature of the alloy melt is too high or the duration of the degassing and refining is too long in this step, it can easily cause burning loss of the elements in the alloy melt.

[0057] In some embodiments, the durations of the first standing and the second standing are both in a range of 5 to 15 minutes, for example, 5 min, 8 min, 10 min, 12 min, 14 min, 15 min, etc. The purpose of standing is to allow the slag in the alloy melt to float to the surface, which is beneficial for purifying the alloy melt.

[0058] In some embodiments, the fourth alloy melt is poured into a mold at a casting temperature of 690 to 720°C, for example, 690°C, 695°C, 700°C, 705°C, 710°C, 715°C, 720°C, etc. After the alloy melt takes shape upon solidification, an aluminum alloy ingot is obtained. If this casting temperature is too low, it can lead to defects such as cold shuts on the surface of the aluminum alloy. If the casting temperature is too high, it can result in increased hydrogen content and severe shrinkage porosity within the aluminum alloy.

[0059] Furthermore, an embodiment of the present application further provides an aluminum alloy die casting that is made from the aluminum alloy of the embodiments of this application.

[0060] By utilizing the aluminum alloy of the embodiments of this application, the aluminum alloy die casting of this embodiment possesses high strength while exhibiting excellent plasticity and toughness as well as excellent corrosion resistance. Therefore, the aluminum alloy die casting can meet the requirements for automotive thin-walled structural components such as shock absorber towers, rear vehicle bodies, longitudinal beams, and front compartments. Moreover, aluminum alloy die castings with qualified properties can be obtained without performing heat treatment in subsequent process, which simplifies the processing of the aluminum alloy die castings, and avoids the deformation problems caused by heat treatment, thereby improving the product yield of aluminum alloy die castings.

[0061] Furthermore, an embodiment of the present application further provides a method for preparing an aluminum alloy die casting, including: obtaining an aluminum alloy melt by melting the aluminum alloy of the embodiments of this application; then subjecting the aluminum alloy melt to die casting and trimming to obtain the aluminum alloy die casting.

[0062] Alternatively, the method for preparing the aluminum alloy die casting includes steps described below.

[0063] In S1, an aluminum melt is obtained by placing and melting aluminum raw material in a smelting furnace, then Si raw material, Cu raw material, Mn raw material, Cr raw material, V raw material and rare earth raw material are added to the aluminum melt and a first smelting is performed on the aluminum melt, and a first alloy melt is obtained.

[0064] In S2, a first deslagging treatment is performed after a deslagging agent is added to the first alloy melt, then Mg raw material, Nb raw material and Sr raw material are added and a second smelting is performed; after the first alloy melt is left for standing for a first standing period, a second deslagging treatment is performed to obtain a second alloy melt.

[0065] In S3, the second alloy melt is subjected to degassing and refining by introducing an inert gas mixed with a refining agent into the second alloy melt, and a third alloy melt is obtained.

[0066] In S4, contents of compositions of the third alloy melt are tested; if the test result meets specifications, the third alloy melt is left for standing for a second standing, then it is subjected to a third deslagging treatment, and a fourth alloy melt is obtained; if the test result does not meet specifications, the compositions are adjusted and the deslagging treatment is performed until the test result meets specifications.

[0067] In S5, the fourth alloy melt is directly poured into a die-casting mold for die casting, then trimming is performed to obtain the aluminum alloy die casting.

[0068] Both of the above methods can be used to prepare the aluminum alloy die casting. The former is suitable when the final shape of the casting is not predetermined, as it is first cast into ingots for ease of transportation. The latter is suitable when the final shape of the casting is known in advance. When using the latter method to prepare the aluminum alloy die casting, the specific conditions in steps S1-S5 can refer to the preparation method of the aluminum alloy.

[0069] The present application is described in detail below with reference to examples and accompanying drawings.Example 1

[0070] A die-cast aluminum alloy, a total mass of the die-cast aluminum alloy being 100%, includes Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, Re (with a mass ratio of La to Ce of 1:1). The specific contents are shown in Table 1. The die-cast aluminum alloy further includes Al and unavoidable impurities P, S, O, where a content of a single impurity is less than or equal to 0.05%, and a total content of impurities is less than or equal to 0.15%.

[0071] The preparation method for the die-cast aluminum alloy includes steps described below.

[0072] In S1, the aluminum raw material is placed in a smelting furnace and melted at 720°C to obtain an aluminum melt. Then, the temperature of the aluminum melt is raised to 760°C. Al-Si master alloy, Al-Cu master alloy, Al-Mn master alloy, Al-Cr master alloy, Al-V master alloy, and Al-rare earth master alloy are added to the aluminum melt, and the aluminum melt is stirred at this temperature for 20 minutes to obtain a first alloy melt.

[0073] In S2, a deslagging agent is added to the first alloy melt, with the temperature of the alloy melt controlled at 730°C. After the process of deslagging, the surface dross is completely removed. Then, Mg, Al-Nb-B refiner, and Al-Sr master alloy are added, with the temperature of the alloy melt controlled at 720°C, and the mixture is stirred at this temperature for 10 minutes. Then, the mixture is left for standing for a first standing period of 5 minutes to obtain the second alloy melt.

[0074] In S3, argon gas mixed with a refining agent is introduced into the second alloy melt, with the alloy melt temperature controlled at 720°C. The alloy melt is subjected to degassing and refining for 10 minutes, and a third alloy melt is obtained.

[0075] In S4, contents of compositions of the third alloy melt are tested. If the test result meets specifications, the third alloy melt is left for standing for a second standing for 5 minutes, then it is subjected to a third deslagging treatment, and a fourth alloy melt is obtained.

[0076] In S5, the fourth alloy melt is poured into a mold. After the alloy melt takes shape upon solidification, a die-cast aluminum alloy ingot is obtained.Example 2

[0077] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La) in the die-cast aluminum alloy of this example are shown in Table 1. Other conditions are the same as those in Example 1.

[0078] The preparation method for such die-cast aluminum alloy includes steps described below.

[0079] In S1, the aluminum raw material is placed in a smelting furnace and melted at 740°C to obtain an aluminum melt. Then, the temperature of the aluminum melt is raised to 780°C, Si, Cu, Mn, Al-Cr master alloy, Al-V master alloy, and mixed rare earth (La and Ce) are added to the aluminum melt, and the mixture is stirred at this temperature for 30 minutes to obtain a first alloy melt.

[0080] In S2, a deslagging agent is added to the first alloy melt, with the temperature of the alloy melt controlled at 750°C. After the deslagging process, the surface dross is completely removed from the alloy melt. Then, Mg, Al-Nb-B refiner, and Al-Sr master alloy are added, with the alloy melt temperature controlled at 750°C, and the mixture is stirred at this temperature for 20 minutes. Then, the mixture is left for standing for a first standing period of 15 minutes to obtain the second alloy melt.

[0081] In S3, argon gas mixed with a refining agent is introduced into the second alloy melt, with the alloy melt temperature controlled at 730°C. The alloy melt is subjected to degassing and refining for 20 minutes, and a third alloy melt is obtained.

[0082] In S4, contents of compositions of the third alloy melt are tested. If the test result meets specifications, the third alloy melt is left for standing for a second standing for 15 minutes, and a fourth alloy melt is obtained.

[0083] In S5, the fourth alloy melt is poured into a mold. After the alloy melt takes shape upon solidification, a die-cast aluminum alloy ingot is obtained.Example 3

[0084] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (Ce) in the die-cast aluminum alloy of this example are shown in Table 1. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Example 4

[0085] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this example are shown in Table 1. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Example 5

[0086] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this example are shown in Table 1. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Example 6

[0087] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this example are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Example 7

[0088] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this example are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Example 8

[0089] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this example are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Example 9

[0090] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this example are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Example 10

[0091] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this example are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Example 11

[0092] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this example are shown in Table 2. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this example is the same as that in Example 1.Comparative Example 1

[0093] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 2

[0094] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 3

[0095] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 4

[0096] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 5

[0097] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 3. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 6

[0098] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 7

[0099] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 8

[0100] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 9

[0101] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 10

[0102] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 11

[0103] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.Comparative Example 12

[0104] The contents of Si, Fe, Cu, Mn, Mg, Cr, V, Sr, Nb, and Re (La and Ce) in the die-cast aluminum alloy of this comparative example are shown in Table 4. Other conditions are the same as those in Example 1. The preparation method for the die-cast aluminum alloy in this comparative example is the same as that in Example 1.

[0105] Mechanical property tests were conducted on the die-cast aluminum alloy ingots according to various examples and comparative examples. The yield strength, the tensile strength, and the elongation were tested according to the standard GB / T 228 for tensile mechanical properties of metallic materials; the bending angle was tested according to the standard VDA-238 for bending angle of metallic materials. The mechanical property test results for the die-cast aluminum alloy ingots of various examples and comparative examples are shown in Tables 1-4. Table 1. Chemical Compositions and Mechanical Properties of Die-Cast Aluminum Alloys in Examples 1-5Chemical CompositionsMechanical Properties(wt.%)ppmSiFeCuMnMgCrVSrNbReYield Strength / MPaTensile Strength / MPaElongation / %Bending Angle / °Ex.16.50.130.0010.40.20.10.0050.02505012324713.537Ex.27.50.130.0010.40.20.10.0050.0250501362591336Ex.38.50.130.0010.40.20.10.0050.0250501452681234Ex.47.50.130.0010.30.20.10.0050.0250501292531335Ex.57.50.130.0010.50.20.10.0050.0250501402621133 Table 2. Chemical Compositions and Mechanical Properties of Die-Cast Aluminum Alloys in Examples 6-11 Chemical CompositionsMechanical Properties(wt.%)ppmSiFeCuMnMgCrVSrNbReYield Strength / MPaTensile Strength / MPaElongation / %Bending Angle / °Ex.67.50.130.0010.40.10.10.0050.0250501252491438Ex.77.50.130.0010.40.50.10.0050.0250501432661132Ex.87.50.130.0010.40.20.10.0020.02505012925112.533Ex.97.50.130.0010.40.20.10.020.0250501422631232Ex.107.50.130.0010.40.20.10.0050.02502013125014.535Ex.117.50.130.0010.40.20.10.0050.02508015227111.533 Table 3. Chemical Compositions and Mechanical Properties of Die-Cast Aluminum Alloys in Comparative Examples 1-5 Chemical CompositionsMechanical Properties(wt.%)ppmSiFeCuMnMgCrVSrNbReYield Strength / MPaTensile Strength / MPaElongation / %Bending Angle / °Comp. Ex. 16.00.130.0010.40.20.10.0050.0250501142261641Comp. Ex. 29.00.130.0010.40.20.10.0050.02505015227510.528Comp. Ex. 37.50.130.0010.60.20.10.0050.0250501422669.526Comp. Ex. 47.50.130.0010.40.60.10.0050.025050147271927Comp. Ex. 57.50.130.0010.40.20.100.0250501162311030 Table 4. Chemical Compositions and Mechanical Properties of Die-Cast Aluminum Alloys in Comparative Examples 6-11 Chemical CompositionsMechanical Properties(wt.%)ppmSiFeCuMnMgCrVSrNbREYield Strength / MPaTensile Strength / MPaElongation / %Bending angle / °Comp. Ex.67.50.130.0010.40.20.10.050.02505010922310.532Comp. Ex.77.50.130.0010.40.20.10.0050.025001132341332Comp. Ex.87.50.130.0010.40.20.10.0050.02505001332548.527Comp. Ex.97.50.50.0010.130.200.0050.025080150270620Comp. Ex.107.50.130.0010.40.20.10.0050.02080151269928Comp. Ex.117.50.130.0010.40.20.10.0050.02200801522719.528Comp. Ex.127.50.130.0010.40.20.10.020.025050140260927

[0106] As can be seen from Tables 1 and 2, mechanical properties the die-cast aluminum alloys of Examples 1-11 simultaneously meet the following requirements: yield strength ≥ 120 MPa, tensile strength≥240 MPa, elongation≥10%, and bending angle≥30° . Therefore, the die-cast aluminum alloys of Examples 1-11 are qualified materials that can meet the needs of automotive thin-walled structural components.

[0107] Based on the comparison between Example 1 and Comparative Example 1, it can be seen that the silicon content in Comparative Example 1 is 6.0%, which is below the lower limit specified in the embodiments of the present application. This results in lower yield strength and tensile strength of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards.

[0108] Based on the comparison between Example 1 and Comparative Example 2, it can be seen that the Si content in Comparative Example 2 is 9.0%, which exceeds the upper limit specified in the embodiments of the present application. This results in a lower bending angle of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards and indicating poor toughness of the die-cast aluminum alloy.

[0109] Based on the comparison between Example 5 and Comparative Example 3, it can be seen that the Mn content in Comparative Example 3 is 0.6%, which exceeds the upper limit specified in the embodiments of the present application. This results in reduced elongation and bending angle of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards and indicating poor plasticity and toughness of the die-cast aluminum alloy.

[0110] Based on the comparison between Example 7 and Comparative Example 4, it can be seen that the Mg content in Comparative Example 4 is 0.6%, which exceeds the upper limit specified in the embodiments of this application. This results in reduced elongation and bending angle of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards and indicating poor plasticity and toughness of the die-cast aluminum alloy.

[0111] Based on the comparison between Examples 8, 9 and Comparative Example 5, it can be seen that the V content in Comparative Example 5 is 0%, which is below the lower limit specified in the embodiments of the present application. This results in lower yield strength and tensile strength of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards.

[0112] Based on the comparison between Examples 8, 9 and Comparative Example 6, it can be seen that the V content in Comparative Example 6 is 0.05%, which exceeds the upper limit specified in the embodiments of the present application. This results in lower yield strength and tensile strength of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards.

[0113] Based on the comparison between Examples 10,11 and Comparative Example 7, it can be seen that the rare earth element content in Comparative Example 7 is 0%, which is below the lower limit specified in the embodiments of the present application. This results in lower yield strength and tensile strength of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards.

[0114] Based on the comparison between Examples 10, 11 and Comparative Example 8, it can be seen that the rare earth element content in Comparative Example 8 is 500 ppm, which exceeds the upper limit specified in the embodiments of the present application. This results in reduced elongation and bending angle of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards and indicating poor plasticity and toughness of the die-cast aluminum alloy.

[0115] Based on the comparison between Example 11 and Comparative Example 9, it can be seen that the Fe content in Comparative Example 9 is 0.5%, which exceeds the upper limit specified in the embodiments of the present application. This results in reduced elongation and bending angle of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards and indicating poor plasticity and toughness of the material.

[0116] Based on the comparison between Example 11 and Comparative Example 10, it can be seen that the Nb content in Comparative Example 10 is 0, which is below the lower limit specified in the embodiments of the present application. This results in reduced elongation and bending angle of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards and indicating poor plasticity and toughness of the die-cast aluminum alloy.

[0117] Based on the comparison between Example 11 and Comparative Example 11, it can be seen that the Nb content in Comparative Example 11 is 200 ppm, which exceeds the upper limit specified in the embodiments of the present application. This leads to reduced elongation and bending angle of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards and indicating poor plasticity and toughness of the die-cast aluminum alloy.

[0118] Based on the comparison between Example 9 and Comparative Example 12, it can be seen that Comparative Example 12 uses Y element instead of La and / or Ce as the rare earth element, resulting in reduced elongation and bending angle of the die-cast aluminum alloy, failing to meet the aforementioned qualification standards and indicating poor plasticity and toughness of the material.

[0119] In the present application, terms "an embodiment," "some embodiments," "example," "specific example," or "some examples" mean that specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the specification, schematic references to the above terms do not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials, or characteristics may be combined in a suitable manner in any one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0120] Although the embodiments of the present application have been shown and described above, it is understood that the foregoing embodiments are illustrative and are not to be construed as limiting the application. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. An aluminum alloy, comprising components: Si, Fe, Cu, Mn, Mg, Cr, V, Nb, Sr and Rare earth elements, characterized in that, based on 100% of a total mass of the aluminum alloy, a content of Si is 6.5~8.5%; a content of Fe is less than and equal to 0.3%; a content of Cu is less than and equal to 0.3%; a content of Mn is less than and equal to 0.5%; a content of Mg is less than and equal to 0.5%; a content of Cr is less than and equal to 0.2%; a content of V is 0.002~0.02%; a content of Nb is 10~100 ppm; a content of Sr is 0.01~0.03%; a content of rare earth elements is 10~100 ppm, wherein the rare earth elements are selected from La and Ce; in addition to these components, the aluminum alloy further comprises Al and unavoidable impurities.

2. The aluminum alloy according to claim 1, wherein the content of Si is 6.5~7.5%; and / or the content of Fe is less than and equal to 0.15%; and / or the content of Cu is 0.001~0.3%; and / or the content of Mn is 0.3~0.5%; and / or the content of Mg is 0.1~0.5%; and / or the content of Cr is 0.1~0.2%; and / or the content of V is 0.005~0.02%; and / or the content of Nb is 30~80 ppm; and / or the content of Sr is 0.02~0.03%; and / or the content of the rare earth elements is 20~80 ppm.

3. The aluminum alloy according to claim 2, wherein the content of V is 0.005~0.01%.

4. The aluminum alloy according to claim 2, wherein the content of Nb is 40~60 ppm.

5. The aluminum alloy according to claim 2, wherein the content of the rare earth elements is 20~50 ppm.

6. The aluminum alloy according to any one of claims 1 to 5, wherein a tensile strength of the aluminum alloy is greater than or equal to 240 MPa, a yield strength of the aluminum alloy is greater than or equal to 120 MPa, an elongation of the aluminum alloy is greater than or equal to 10%, and a bending angle of the aluminum alloy is greater than or equal to 30°.

7. A preparation method for the aluminum alloy according to any one of claims 1 to 6, <b>characterized by comprising steps of: obtaining an aluminum melt by placing and melting an aluminum raw material in a smelting furnace, then adding Si raw material, Cu raw material, Mn raw material, Cr raw material, V raw material, and rare earth raw material to the aluminum melt and performing a first smelting process, and obtaining a first alloy melt; adding a deslagging agent to the first alloy melt, performing a first deslagging treatment, then adding Mg raw material, Nb raw material and Sr raw material and performing a second smelting process, leaving the first alloy melt standing for a first standing period and then performing a second deslagging treatment, and obtaining a second alloy melt; introducing an inert gas mixed with a refining agent into the second alloy melt, performing degassing and refining, and obtaining a third alloy melt; testing contents of the compositions of the third alloy melt, and when a test result meets specifications, leaving the third alloy melt standing for a second standing period, then performing a third deslagging treatment to obtain a fourth alloy melt; and pouring the fourth alloy melt into a mold, waiting for the alloy melt to take shape upon solidification, and obtaining an aluminum alloy ingot.

8. The preparation method according to claim 7, wherein the V raw material is an Al-V master alloy, the Nb raw material is an Al-Nb-B refiner, the rare earth raw material is an Al-rare earth master alloy.

9. The preparation method according to claim 7 or 8, wherein a temperature for the first smelting process is above 760°C, and a duration of the first smelting process is not less than 20 minutes; and / or the temperature for the first deslagging treatment is above 730°C, the temperature for the second smelting process is above 720°C, and the duration of the second smelting process is not less than 10 minutes; and / or the temperature of the degassing and refining is above 720°C, and the duration of the degassing and refining is not less than 10 minutes; and / or the temperature during the pouring is 690~720°C.

10. An aluminum alloy die casting made from the aluminum alloy according to any one of claims 1 to 6.

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