High-strength and high-toughness heat-treatment-free die-casting aluminum alloy, structural member and preparation method thereof

Abstract

This application belongs to the field of aluminum alloy die casting technology, and more specifically, relates to a high-strength and high-toughness heat-free die-cast aluminum alloy, structural components, and a preparation method. The high-strength and high-toughness heat-free die-cast aluminum alloy provided in this application overcomes the limitations of traditional heat-free die-cast aluminum alloys in terms of low tolerance to Fe and insufficient toughness of traditional high-Fe content aluminum alloys by designing its elemental composition system and employing multi-strategy synergistic regulation. By adopting a Ca-Sr composite modification strategy and a Cr-Mn synergistic regulation strategy, the Fe content tolerance is extended to 0.5wt%~1.6wt%, while the waste recycling rate of this die-cast aluminum alloy is high. Based on the synergistic strengthening effect of each element in the composition, the tensile strength and elongation of high-Fe content die-cast aluminum alloys can be synergistically improved without heat treatment, resulting in a heat-free die-cast aluminum alloy with both high tensile strength and high toughness, suitable for preparing complex structural components such as deep-cavity shells and multi-fin heat sinks.

Description

Technical Field

[0001] This application belongs to the field of aluminum alloy die casting technology, and more specifically, relates to a high-strength and high-toughness heat-free die-cast aluminum alloy, structural parts, and preparation method. Background Technology

[0002] In fields such as new energy vehicles, aerospace, and emerging manufacturing, lightweight material upgrades and structural integration innovations have become core directions for technological breakthroughs. Aluminum alloys, with their superior specific strength, excellent corrosion resistance, and outstanding formability, have become fundamental materials supporting the high-quality development of the die-casting industry. However, the mechanical properties of widely used traditional die-casting aluminum alloys (such as ADC12 and A356.2) rely on subsequent heat treatment processes such as solution treatment and aging. This process has significant drawbacks in the production of large die-cast parts: during heat treatment, castings are prone to deformation due to uneven thermal stress distribution, and surface defects such as blistering and oxidation are easily observed. These problems not only force companies to invest heavily in correction and repair but also directly lead to a surge in scrap rates, severely restricting the efficiency and quality improvement of high-end equipment manufacturing. Against this backdrop, the development of die-casting aluminum alloys that can achieve high strength and high toughness without heat treatment has become an urgent need for the industry.

[0003] Currently, the following technical bottlenecks still exist in the practical engineering applications of heat-free die-cast aluminum alloys:

[0004] First, the tolerance for Fe is low. In traditional die-cast aluminum alloys such as ADC12, the Fe content typically needs to be controlled below 0.5 wt%. Excessive Fe promotes the formation of coarse, needle-like Al-Si-Fe phases, severely disrupting the matrix and leading to a significant decrease in alloy toughness. Meanwhile, recycled aluminum typically has a high Fe content, further limiting its reuse rate in production and increasing production costs.

[0005] Secondly, existing alloy composition designs and modification strategies are not sufficiently adaptable to Fe content. While traditional modification treatments (such as Sr modification) can improve the morphology of the Si phase to some extent, their modification effect on Fe-rich phases is limited, making it difficult to effectively suppress their adverse effects on toughness. Furthermore, existing aluminum alloy composition systems lack a synergistic strengthening mechanism that can simultaneously improve tensile strength and elongation, resulting in high-Fe-content aluminum alloys having comprehensive mechanical properties that fail to meet the requirements of structural components.

[0006] Third, production stability is poor. Traditional die casting processes rely on offline compositional analysis of the die-cast aluminum alloy to control the melting effect, mold temperature, and injection speed. This results in feedback lag, low control precision, and large temperature fluctuations, easily leading to filling defects such as cold shuts and under-casting, and a narrow process window. Furthermore, in the temperature range of 580℃ to 650℃, Fe-rich phases readily precipitate rapidly and form needle-like structures. Existing alloy composition design strategies and current die casting processes are insufficient to effectively suppress their growth, severely impacting product quality consistency and making it difficult to meet the requirements of large-scale manufacturing. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this application is to provide a high-strength and high-toughness heat-free die-cast aluminum alloy, structural parts and preparation method, which aims to solve the problems of insufficient production stability, low tolerance of Fe element (Fe content usually needs to be controlled below 0.5wt%), tensile strength and toughness need to be further improved, and poor recyclability and low recycling rate of waste materials in existing heat-free die-cast aluminum alloys.

[0008] To achieve the above objectives, in a first aspect, this application provides a high-strength and high-toughness heat-free die-cast aluminum alloy, comprising the following components by weight percentage: 8wt%~10wt% Si, 0.5wt%~1.6wt% Fe, 0.1wt%~0.8wt% Mn, 0.1wt%~0.6wt% Cu, 0.1wt%~0.6wt% Zn, 0.1wt%~0.5wt% Mg, 0.1wt%~0.6wt% Cr, 0.1wt%~0.3wt% Ti, 0.05wt%~0.1wt% Ca, 0.01wt%~0.05wt% Sr, with the balance being Al;

[0009] Furthermore, the total weight percentage of Ca and Sr is less than 0.15%, and the weight ratio of Ca to Sr is not less than 1:1;

[0010] The total weight percentage of Cr and Mn is <1% and the weight ratio of Cr to Mn is not greater than 1:1;

[0011] The weight ratio of Ca to Cr is no greater than 1:1.

[0012] Preferably, in the above-mentioned heat-free die-cast aluminum alloy, the weight percentage of Mn is 0.3wt%~0.5wt%, the weight percentage of Cr is 0.2wt%~0.4wt%, the weight percentage of Ca is 0.05wt%~0.08wt%, and the weight percentage of Sr is 0.02wt%~0.04wt%.

[0013] Preferably, in the above-mentioned heat-free die-cast aluminum alloy, the weight percentage of Si is 9wt%~10wt%, the weight percentage of Fe is 0.8wt%~1.5wt%, the weight percentage of Cu is 0.2wt%~0.5wt%, the weight percentage of Zn is 0.2wt%~0.5wt%, the weight percentage of Mg is 0.2wt%~0.5wt%, and the weight percentage of Ti is 0.1wt%~0.2wt%.

[0014] Preferably, in the above-mentioned heat-free die-cast aluminum alloy, the weight ratio of Ca to Sr is (1~3):1.

[0015] Preferably, in the above-mentioned heat-free die-cast aluminum alloy, the weight ratio of Cr to Mn is 1:(1~2).

[0016] Preferably, in the above-mentioned heat-free die-cast aluminum alloy, the weight ratio of Ca to Cr is 1:(1~4).

[0017] Preferably, the above-mentioned heat-free die-cast aluminum alloy has a room temperature ultimate tensile strength ≥320MPa, a room temperature yield strength ≥210MPa, and a room temperature elongation ≥12%.

[0018] Secondly, this application provides a method for preparing the above-mentioned heat-free die-cast aluminum alloy, comprising the following steps:

[0019] S1. Prepare the raw materials according to the above-mentioned composition of heat-free die-cast aluminum alloy, and then melt, alloy, refine and remove slag, and modify the raw materials to obtain aluminum alloy melt.

[0020] S2. Use an online melt monitoring device to detect the viscosity and temperature of the above-mentioned aluminum alloy melt. When both viscosity and temperature are within the preset range, perform die casting to obtain the above-mentioned heat-free die-cast aluminum alloy.

[0021] Preferably, in step S2, the online melt monitoring device includes a viscosity sensor and a temperature sensor.

[0022] Preferably, the preset range of the above viscosity is 1.2 Pa·s to 1.5 Pa·s.

[0023] Preferably, the preset temperature range is 700℃~730℃.

[0024] Preferably, the pressure of the die casting is 40MPa to 60MPa.

[0025] Thirdly, this application provides a high-strength and high-toughness structural component, at least a portion of which is the above-mentioned heat-free die-cast aluminum alloy, or a heat-free die-cast aluminum alloy prepared by the above-mentioned preparation method.

[0026] Preferably, the above-mentioned structural component is a deep cavity shell type structural component or a multi-fin heat dissipation type structural component.

[0027] In summary, the technical solutions conceived in this application have the following main technical advantages compared with the prior art:

[0028] (1) The high-strength and high-toughness heat-free die-cast aluminum alloy provided in this application overcomes the limitations of low tolerance to Fe element and insufficient toughness of traditional heat-free die-cast aluminum alloys by designing a unique element composition system and multi-strategy synergistic regulation. This application significantly suppresses the harmful effects of Fe-rich phase by adopting a Ca-Sr composite modification strategy and a Cr-Mn synergistic regulation strategy, expanding the tolerance of Fe content to 0.5wt%~1.6wt%, while supporting multiple recycling of waste aluminum alloy materials and improving the utilization rate of recycled materials. Based on the synergistic strengthening effect of each element in the aluminum alloy composition system, the mechanical properties of aluminum alloy die castings can be regulated without heat treatment, synergistically improving the tensile strength and elongation of high Fe content aluminum alloys in the as-cast state, and finally obtaining a heat-free die-cast aluminum alloy with both high tensile strength and high toughness.

[0029] (2) By using Ca-Sr composite modification treatment and controlling the ratio of the two, the casting fluidity, solidification characteristics and defect control of die-cast aluminum alloys can be positively affected. The eutectic Si phase in the die-cast aluminum alloy structure is significantly refined and made complete, thereby reducing the viscosity of the melt during solidification, reducing flow blockage between dendrites, making the melt easier to fill the mold (especially complex thin-walled parts), reducing the risk of undercasting. At the same time, after the eutectic Si phase is refined, the solidification shrinkage of the aluminum alloy is more uniform, which can reduce the formation of shrinkage cavities and porosity during die casting. In addition, the Ca element in the composition has a low affinity for gases (such as hydrogen), making it less likely to form pores, which helps to improve the density of the casting.

[0030] (3) To address the issues of low tolerance for Fe content and poor recyclability of waste in traditional die-cast aluminum alloys, this application employs Cr-Mn synergistic treatment and controls their ratio to transform the Fe-rich phase into harmless Chinese character-shaped or fishbone-shaped phases, avoiding the brittle fracture of the traditional needle-like phase. Simultaneously, the Ca element in the composition preferentially combines with Fe and Si to form stable Al-Si-Ca-Fe compounds (such as Al2Si2CaFe), whose morphology changes from needle-like to blocky or granular, with a more diffuse distribution, allowing the tolerance for Fe content to reach 0.8wt%~1.5wt%, while significantly improving the utilization rate of recycled aluminum. Furthermore, the Cr element in the composition can form multi-component strengthening phases with Mg2Si, Al2Cu, etc., breaking through the toughness bottleneck of traditional high-Fe content aluminum alloys.

[0031] (4) This application optimizes the composition system and process of die-cast aluminum alloys. By using an online melt monitoring device, the viscosity and temperature of the aluminum alloy melt can be obtained in real time, effectively solving the feedback lag problem caused by traditional offline composition detection. Process parameters can be adjusted in real time to control the physical properties of the aluminum alloy melt, ensuring that the aluminum alloy melt is die-cast in the most suitable state. This effectively reduces casting defects caused by factors such as uneven composition and temperature fluctuations during production, thereby reducing the scrap rate and significantly improving the quality consistency and production stability of die-cast aluminum alloy products. At the same time, it can effectively shorten the production cycle, minimize the impact of aluminum alloy melt state fluctuations on mold filling, significantly reduce mold filling defects, and facilitate large-scale production.

[0032] (5) Compared with existing die-casting aluminum alloys, the die-casting aluminum alloy melt provided in this application has excellent spiral fluidity and good filling effect, making it suitable for preparing complex die-casting parts such as deep cavity shells and multi-fin heat dissipation parts. In addition, the die-casting aluminum alloy melt provided in this application can achieve efficient, continuous, and non-sticky production of deep cavity shell and multi-fin heat dissipation die-casting parts with a low amount of water-based release agent, significantly reducing the amount of release agent used, reducing mold repair costs, and effectively solving the production pain points such as large core-holding force, mold pulling, and film sticking when preparing complex die-casting parts with existing die-casting aluminum alloy melts, thereby improving the production efficiency of complex die-casting parts.

[0033] (6) The high-strength and high-toughness heat-free die-cast aluminum alloy prepared in this application has a room temperature ultimate tensile strength ≥320MPa, a room temperature yield strength ≥210MPa, and a room temperature elongation ≥12%, and can be used as structural components in the fields of automobiles, high-speed rail, ships, aerospace, mobile devices, home appliances, chemical industry, and construction. Attached Figure Description

[0034] Figure 1 This is a schematic flowchart of the preparation method of the high-strength and high-toughness heat-free die-cast aluminum alloy provided in this application;

[0035] Figure 2 This is the spiral flow mold used in this application to test the fluidity of aluminum alloy melt;

[0036] Figure 3 It is the spiral flow length of the aluminum alloy melt prepared in Example 1 of this application after it is poured into a spiral flow mold and cooled and solidified;

[0037] Figure 4 This describes the structure of the deep cavity shell-like aluminum alloy die-cast blank prepared according to the embodiments of this application;

[0038] Figure 5This application describes the demolding of aluminum alloy die castings obtained after spraying deep cavity shell die casting molds with water-based release agent diluents of different concentrations in Example 1 of this application; wherein the mass ratio of water-based release agent to water in the water-based release agent diluents used in contents (a), (b), and (c) are 1:100, 1:150, and 1:200, respectively.

[0039] Figure 6 This is the metallographic structure of the aluminum alloy die casting prepared in Example 1 of this application; wherein content (a) is the aluminum alloy die casting produced for the first time, and content (b) is the aluminum alloy die casting obtained after five rounds of recycling;

[0040] Figure 7 It is the spiral flow length of the aluminum alloy ADC12 melt prepared in Comparative Example 1 of this application after being poured into a spiral flow mold and cooled and solidified;

[0041] Figure 8 This is the demolding condition of the aluminum alloy ADC12 die casting obtained after spraying a water-based release agent diluent with a mass ratio of 1:100 (water-based release agent to water) onto a deep cavity shell type die casting mold in Comparative Example 1 of this application. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0043] In the description of this application, it should be understood that the term "and / or" describes a relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. The symbol " / " in this document indicates that the related objects are in an "or" relationship; for example, A / B means A or B.

[0044] In the specification of this application, the terms “first,” “second,” “third,” and “fourth,” etc., are used to distinguish different objects, rather than to describe a specific order of objects, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated.

[0045] In the description of the embodiments in this application, the words "exemplary" or "for example" are used to indicate that they are examples, illustrations, or descriptions. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design options. Specifically, the use of the words "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0046] In the description of the embodiments of this application, unless otherwise stated, "multiple" means two or more.

[0047] This application provides a high-strength and high-toughness heat-free die-cast aluminum alloy, comprising the following components by weight percentage: 8wt%~10wt% Si, 0.5wt%~1.6wt% Fe, 0.1wt%~0.8wt% Mn, 0.1wt%~0.6wt% Cu, 0.1wt%~0.6wt% Zn, 0.1wt%~0.5wt% Mg, 0.1wt%~0.6wt% Cr, 0.1wt%~0.3wt% Ti, 0.05wt%~0.1wt% Ca, 0.01wt%~0.05wt% Sr, with the balance being Al;

[0048] Furthermore, the total weight percentage of Ca and Sr is less than 0.15%, and the weight ratio of Ca to Sr is not less than 1:1;

[0049] The total weight percentage of Cr and Mn is <1% and the weight ratio of Cr to Mn is not greater than 1:1;

[0050] The weight ratio of Ca to Cr is no greater than 1:1.

[0051] In some embodiments, the above-mentioned heat-free die-cast aluminum alloy comprises, by weight percentage, the following components: 9wt%~10wt% Si, 0.8wt%~1.5wt% Fe, 0.3wt%~0.5wt% Mn, 0.2wt%~0.5wt% Cu, 0.2wt%~0.5wt% Zn, 0.2wt%~0.5wt% Mg, 0.2wt%~0.4wt% Cr, 0.1wt%~0.2wt% Ti, 0.05wt%~0.08wt% Ca, 0.02wt%~0.04wt% Sr, with the balance being Al.

[0052] In some embodiments, the weight percentage of Si in the above-mentioned heat-free die-cast aluminum alloy may be 9wt%, 9.1wt%, 9.2wt%, 9.3wt%, 9.4wt%, 9.5wt%, 9.6wt%, 9.7wt%, 9.8wt%, 9.9wt%, or 10wt%.

[0053] In some embodiments, the weight percentage of Fe in the above-mentioned heat-free die-cast aluminum alloy may be 0.8wt%, 0.9wt%, 1wt%, 1.1wt%, 1.2wt%, 1.3wt%, 1.4wt%, or 1.5wt%.

[0054] In some embodiments, the weight percentage of Mn in the above-mentioned heat-free die-cast aluminum alloy may be 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, or 0.5wt%.

[0055] In some embodiments, the weight percentage of Cu in the above-mentioned heat-free die-cast aluminum alloy may be 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, or 0.5wt%.

[0056] In some embodiments, the weight percentage of Zn in the above-mentioned heat-free die-cast aluminum alloy may be 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, or 0.5wt%.

[0057] In some embodiments, the weight percentage of Mg in the above-mentioned heat-free die-cast aluminum alloy may be 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, or 0.5wt%.

[0058] In some embodiments, the weight percentage of Cr in the above-mentioned heat-free die-cast aluminum alloy may be 0.2wt%, 0.25wt%, 0.3wt%, 0.35wt%, 0.4wt%, 0.45wt%, or 0.5wt%.

[0059] In some embodiments, the weight percentage of Ti in the above-mentioned heat-free die-cast aluminum alloy may be 0.1wt%, 0.11wt%, 0.12wt%, 0.13wt%, 0.14wt%, 0.15wt%, 0.16wt%, 0.17wt%, 0.18wt%, 0.19wt%, or 0.2wt%.

[0060] In some embodiments, the weight percentage of Ca in the above-mentioned heat-free die-cast aluminum alloy may be 0.05wt%, 0.055wt%, 0.06wt%, 0.065wt%, 0.07wt%, 0.075wt%, or 0.08wt%.

[0061] In some embodiments, the weight percentage of Sr in the above-mentioned heat-free die-cast aluminum alloy may be 0.02wt%, 0.022wt%, 0.025wt%, 0.028wt%, 0.03wt%, 0.032wt%, 0.035wt%, 0.038wt%, or 0.04wt%.

[0062] In some embodiments, in the above-mentioned heat-free die-cast aluminum alloy, the weight ratio of Ca to Sr is (1~3):1, specifically 1:1, 1.25:1, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, 2.8:1 or 3:1; the weight ratio of Cr to Mn is 1:(1~2), specifically 1:1, 1:1.25, 1:1.5, 1:1.8 or 1:2; the weight ratio of Ca to Cr is 1:(1~4), specifically 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5 or 1:4.

[0063] The high-strength, high-toughness, heat-free die-casting aluminum alloy provided in this application controls the mechanical properties of die-cast aluminum alloy parts by designing the types and contents of its elemental composition. Through Ca-Sr composite modification treatment and adjusting the ratio of the two elements, the casting fluidity, solidification characteristics, and defect control of the die-cast aluminum alloy are positively affected. The eutectic Si phase in the die-cast aluminum alloy microstructure is significantly refined, making it completely global. This reduces the viscosity of the melt during solidification, reduces flow blockage between dendrites, and makes the melt easier to fill the mold (especially for complex thin-walled parts), reducing the risk of undercasting. Simultaneously, after the eutectic Si phase is refined, the solidification shrinkage of the aluminum alloy is more uniform, reducing the formation of shrinkage cavities and porosity during die casting. Furthermore, the Ca element in the composition has a low affinity for gases (such as hydrogen), making it less prone to porosity and contributing to improved casting density. On the other hand, addressing the issues of low Fe content tolerance and poor recyclability of waste in traditional die-cast aluminum alloys, this application employs Cr-Mn synergistic treatment and controls their ratio to transform the Fe-rich phase into a harmless Chinese character-shaped structure, avoiding the brittle fracture of the traditional needle-like phase. Simultaneously, the Ca element in the composition preferentially combines with Fe and Si to form stable Al-Si-Ca-Fe compounds (such as Al2Si2CaFe), whose morphology changes from needle-like to blocky or granular, with a more dispersed distribution, allowing for a Fe content tolerance of 0.8%~1.5%, while significantly improving the utilization rate of recycled materials. Furthermore, the Cr element in the composition can form multi-component strengthening phases with Mg2Si, Al2Cu, etc., overcoming the toughness bottleneck of traditional high-Fe content alloys. Through the synergistic strengthening effect of each element in the composition, the tensile strength and elongation of the as-cast high-Fe content aluminum alloy are synergistically improved, resulting in a heat-free die-cast aluminum alloy with both high strength and high toughness.

[0064] In some embodiments, the heat-free die-cast aluminum alloy provided in this application has a room temperature ultimate tensile strength ≥320MPa (specifically, 320MPa, 329MPa, 330MPa, 335MPa, 340MPa, 350MPa, etc.), a room temperature yield strength ≥210MPa (specifically, 210MPa, 215MPa, 220MPa, 228MPa, 230MPa, 235MPa, 240MPa, 250MPa, etc.), and a room temperature elongation ≥12% (specifically, 12%, 12.3%, 12.8%, 13%, 13.4%, 14%, 15%, etc.), exhibiting excellent mechanical properties and being suitable for manufacturing various structural components.

[0065] On the other hand, this application also provides a method for preparing the above-mentioned heat-free die-cast aluminum alloy, such as... Figure 1 As shown, it includes the following steps:

[0066] S1. Prepare the raw materials according to the above-mentioned composition of heat-free die-cast aluminum alloy, and then melt, alloy, refine and remove slag, and modify the raw materials to obtain aluminum alloy melt.

[0067] S2. Use an online melt monitoring device to detect the viscosity and temperature of the above-mentioned aluminum alloy melt. When both viscosity and temperature are within the preset range, perform die casting to obtain the above-mentioned heat-free die-cast aluminum alloy.

[0068] In some embodiments, the raw materials prepared above include aluminum-containing raw materials, silicon-containing raw materials, manganese-containing raw materials, titanium-containing raw materials, chromium-containing raw materials, copper-containing raw materials, zinc-containing raw materials, iron-containing raw materials, strontium-containing raw materials, calcium-containing raw materials, and magnesium-containing raw materials. It is understood that this application does not limit the form of the above raw materials; they can be alloys or pure metals containing the above elements, as long as the composition of the die-cast aluminum alloy obtained after melting the added raw materials is within the range defined in this application. In some embodiments, the above raw materials may include pure Al or Al alloys, pure Si or Si alloys, pure Mn or Mn alloys, pure Ti or Ti alloys, pure Cr or Cr alloys, pure Cu or Cu alloys, pure Zn or Zn alloys, pure Fe or Fe alloys, pure Sr or Sr alloys, pure Ca or Ca alloys, and pure Mg or Mg alloys. In some specific embodiments of this application, the above raw materials include pure Al, pure Mg, aluminum-silicon alloys, aluminum-manganese alloys, aluminum-titanium alloys, aluminum-chromium alloys, aluminum-copper alloys, aluminum-zinc alloys, aluminum-iron alloys, aluminum-strontium alloys, and aluminum-calcium alloys.

[0069] In some embodiments, the order in which the above-mentioned raw materials are added can be selected according to actual needs. In some embodiments, the order in which the raw materials are added in step S1 is as follows: first, pure Al and aluminum-silicon alloy are heated to 800℃~820℃ (specifically, 800℃, 805℃, 810℃, 815℃, 820℃, etc.), and after the raw materials are completely melted, the temperature is lowered to 740℃~760℃ (specifically, 740℃, 745℃, 750℃, 755℃, 760℃, etc.), and aluminum-manganese alloy, aluminum-titanium alloy, and aluminum-chromium alloy master alloys are added for alloying treatment. After complete melting, the mixture is stirred evenly, and then the temperature is raised to 800℃. At ~820℃ (specifically 800℃, 805℃, 810℃, 815℃, 820℃, etc.), aluminum-copper alloy, aluminum-zinc alloy, and aluminum-iron alloy intermediate alloys are added for smelting. At the same time, a protective gas is applied for refining and degassing. Then, the temperature is lowered to 740℃~760℃ (specifically 740℃, 745℃, 750℃, 755℃, 760℃, etc.) and pure Mg is added for smelting. At the same time, aluminum-strontium alloy and aluminum-calcium alloy are added for smelting to carry out composite modification treatment. After complete melting, the surface slag is removed to obtain the aluminum alloy melt with the target composition.

[0070] In some embodiments, to ensure uniform mixing of the melt after each smelting and to facilitate refining and slag removal, electromagnetic stirring can be activated after the raw materials are completely melted. Those skilled in the art can select appropriate electromagnetic stirring parameters based on actual experimental conditions. In some embodiments, the stirring speed can be 300 r / min to 500 r / min, and the stirring time can be, but is not limited to, 5 min to 10 min. It is understood that adaptively adjusting the stirring speed and stirring time according to the type of electromagnetic stirring equipment and production scale is within the scope of protection of this application. In some embodiments, to improve the purity of the aluminum alloy melt, refining and slag removal can be performed after each smelting. In some embodiments, the protective gas applied during refining and slag removal is one or more of high-purity argon and high-purity nitrogen.

[0071] In some embodiments, the online melt monitoring device in step S2 includes a viscosity sensor and a temperature sensor. By using the online melt monitoring device, the viscosity and temperature of the aluminum alloy melt can be acquired in real time, effectively solving the feedback lag problem caused by traditional offline composition detection. Process parameters can be adjusted instantly to control the physical properties of the aluminum alloy melt, significantly improving the quality consistency and production stability of die-cast aluminum alloys. Simultaneously, it effectively shortens the production cycle, minimizes the impact of aluminum alloy melt state fluctuations on mold filling, significantly reduces filling defects (such as cold shuts and undercasting), and facilitates large-scale production.

[0072] In some embodiments, the preset viscosity range of the aluminum alloy melt is 1.2 Pa·s to 1.5 Pa·s, and the preset temperature range of the aluminum alloy melt is 700℃ to 730℃. When the online melt monitoring device detects that the viscosity of the aluminum alloy melt is lower than 1.2 Pa·s, the viscosity can be increased by lowering the holding temperature of the melt and / or extending the holding time of the melt, until the viscosity is within the preset range. When the online melt monitoring device detects that the viscosity of the aluminum alloy melt is higher than 1.5 Pa·s, the viscosity can be decreased by raising the holding temperature of the melt and / or by stirring, until the viscosity is within the preset range. In some embodiments, the cooling step can be 5℃ to 10℃, specifically 5℃, 6℃, 7℃, 8℃, 9℃, or 10℃. In some embodiments, the heating step can be 15℃ to 25℃, specifically 15℃, 18℃, 20℃, 22℃, or 25℃. In some embodiments, the holding time can be 10 min to 20 min, specifically 10 min, 12 min, 15 min, 18 min, or 20 min. In some embodiments, the stirring can be one or more of mechanical stirring and magnetic stirring, but not limited to these. In some embodiments, the stirring speed can be 50 r / min to 100 r / min. When the viscosity and temperature of the aluminum alloy melt are adjusted to within the above-mentioned preset range, die casting can be performed.

[0073] In some embodiments, the pressure of die casting in step S2 is 40MPa~60MPa.

[0074] In some embodiments, step S2, before die casting using a die casting mold, further includes preheating and vacuuming the mold. The preheating temperature of the mold can be 200℃~250℃, and the vacuum level can be 50mbar~100mbar. In some embodiments, when die casting is performed using an integrated die casting method in step S2, the conditions for the injection punch can be: a low-speed injection speed of 0.1m / s~0.3m / s and a high-speed injection speed of 4m / s~5m / s.

[0075] On the other hand, this application also provides a high-strength and high-toughness structural component, at least a portion of which is the aforementioned heat-free die-cast aluminum alloy, or a heat-free die-cast aluminum alloy prepared by the aforementioned method. This structural component possesses high tensile strength and superior elongation, and can be manufactured by die casting, making it suitable for manufacturing thin-walled structural components. It is understood that this structural component can be entirely manufactured from the aforementioned heat-free die-cast aluminum alloy; alternatively, it can be partially manufactured from the aforementioned heat-free die-cast aluminum alloy, with the remaining portion made from other materials (such as plastics, other metals, etc.), allowing for flexible selection based on actual application needs.

[0076] It is understood that this application does not impose any particular limitation on the specific types of the aforementioned structural components, and they can be any structural components suitable for aluminum alloy manufacturing. Furthermore, the structure and properties of this structural component can be referenced from conventional technologies, and will not be elaborated further here. This structural component can be applied in new energy vehicles as an automotive structural component, such as the entire vehicle body, rear wheel arch inner panel, rear longitudinal beam, floor connecting plate, rear floor plate, beam internal reinforcing plate, hood, mudguards, doors, rear cargo box, and roof, etc. This structural component can also be used in other fields, such as aerospace, high-speed rail, shipbuilding, mobile devices, home appliances, chemical industry, and construction.

[0077] In some embodiments, the aforementioned structural components may be, but are not limited to, structural components with complex structures such as deep-cavity shells and multi-fin heat sinks. Compared to existing die-cast aluminum alloys, the high-strength, high-toughness, heat-free die-cast aluminum alloy provided in this application exhibits excellent spiral flowability and good filling effect, making it suitable for preparing complex die-cast parts such as deep-cavity shells and multi-fin heat sinks. Furthermore, this application achieves efficient, continuous, and non-sticky production of deep-cavity shell and multi-fin heat sink die-cast parts with a relatively low amount of water-based release agent, significantly reducing the amount of release agent used, lowering mold repair costs, and effectively solving production pain points such as large core-holding force, mold pulling, and film sticking when preparing complex die-cast parts using existing die-cast aluminum alloys, thereby improving the production efficiency of complex die-cast parts.

[0078] It should be understood that materials of the same or similar type, model, quality, properties, or function as the reagents and instruments used in the following embodiments can be used to implement this application. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0079] The following are examples and comparative examples:

[0080] Example 1

[0081] The high-strength, high-toughness, heat-free die-cast aluminum alloy provided in this embodiment has the following composition and weight percentage: Si: 9.5wt%, Cu: 0.35wt%, Mn: 0.3wt%, Mg: 0.25wt%, Zn: 0.4wt%, Ti: 0.15wt%, Sr: 0.025wt%, Fe: 1.5wt%, Ca: 0.07wt%, Cr: 0.2wt%, with the balance being Al.

[0082] The preparation method of high-strength, high-toughness, heat-free die-cast aluminum alloy based on the above composition includes the following steps:

[0083] (1) Ingredients

[0084] Weigh the raw materials according to the above design, including Al-20Si, Al-10Cu, Al-10Mn, Al-10Zn, Al-10Ti, Al-10Sr, Al-10Fe, Al-10Ca, Al-10Cr master alloy, industrial pure Mg ingot, and industrial pure aluminum, and grind to remove the surface oxide layer.

[0085] (2) Smelting

[0086] Melting: Industrial pure aluminum and Al-20Si master alloy are added to a graphite crucible preheated to 400°C and melted in a melting furnace at 800°C to obtain the first melt;

[0087] Alloying treatment: After the first melt is cooled to 750℃, Al-10Mn, Al-10Ti, and Al-10Cr master alloys are added for smelting. After complete melting, electromagnetic stirring (magnetic field strength of 0.2mT and frequency of 20Hz) is turned on and stirred at 500r / min for 5min to make the melt uniform and the element distribution uniform, while inhibiting the growth of Fe-rich phase in the melt. The slag is removed to obtain the second melt.

[0088] Refining: The second melt is heated to 800℃, and Al-10Cu, Al-10Zn and Al-10Fe master alloys are added to continue smelting. After complete melting, the temperature is lowered to 750℃, and electromagnetic stirring (magnetic field strength of 0.2mT and frequency of 20Hz) is turned on and stirred at 500r / min for 5min. Then argon gas is introduced and rotated to remove gas for 10min to remove slag and obtain the third melt.

[0089] Composite modification treatment: Under argon protection, Al-10Sr, Al-10Ca and pure Mg are added to the third melt to prevent oxidation. After complete melting, electromagnetic stirring (magnetic field strength of 0.2mT and frequency of 20Hz) is turned on and stirred at 500r / min for 5min. Slag is removed to obtain the fourth melt, namely aluminum alloy melt, and then kept at the temperature.

[0090] The molten aluminum alloy is poured into a container such as Figure 2 In the spiral flow mold shown, the flowability of the aluminum alloy melt provided in this application was evaluated by measuring the spiral flow length of the aluminum alloy melt after cooling and solidification in the mold. The results are shown in Table 1. Figure 3 As shown.

[0091] (3) Online monitoring of melt parameters

[0092] The viscosity and temperature of the fourth melt are monitored by online sensors. Specifically, a viscosity detection device is used to detect the viscosity of the fourth melt, controlling it to be between 1.2 and 1.5 Pa·s. If the viscosity is below 1.2 Pa·s, the holding temperature of the fourth melt is reduced (in 10°C increments) and the holding time is extended (to 15 minutes) until the viscosity reaches the target. If the viscosity is above 1.5 Pa·s, the holding temperature of the fourth melt is increased (in 20°C increments) and electromagnetic stirring is started (at a speed of 50 r / min) until the viscosity reaches the target. Additionally, a thermocouple is used to control the temperature of the fourth melt between 700°C and 730°C when adjusting its viscosity. Once both the viscosity and temperature of the fourth melt reach the target, the next step is performed.

[0093] (4) Die casting

[0094] The deep-cavity die-casting mold was preheated to 200°C, and then sprayed with diluted water-based release agent solutions of different concentrations (mass ratios of release agent to water were 1:100, 1:150, and 1:200, respectively). After evacuating to a vacuum of 80 mbar, a fourth melt with suitable melt parameters (viscosity 1.4 Pa·s, temperature 710°C) was poured into the die-casting mold's barrel. The low-speed injection speed of the punch was 0.2 m / s, and the high-speed injection speed was 4.5 m / s. Die-casting production was carried out at a pressure of 60 MPa, resulting in a structure as shown in the image. Figure 4 The aluminum alloy die-cast blank shown is denoted as D. The demolding condition of the die-cast part, the metallographic structure of the die-cast part, and the room temperature mechanical properties of the first-produced die-cast part D were tested with reference to GB / T228.1-2021. The number of test specimens was 10, and the average value was taken. The results are shown in Table 2.

[0095] Depend on Figure 5 Content (a), Figure 5 Content (b) Figure 5 As can be seen from content (c), none of the deep-cavity shell die-castings produced using the different concentrations of release agent diluent exhibited film pulling or sticking. This demonstrates that the aluminum alloy melt provided in this application can achieve efficient, continuous, and film-free production of deep-cavity shell die-castings or multi-fin heat dissipation die-castings with a relatively low amount of water-based release agent. In actual production, it can effectively reduce the amount of release agent used, lower mold repair costs, and improve the production efficiency of complex die-castings, effectively solving the production pain points such as large core-holding force, film pulling, and film sticking that exist when preparing complex die-castings from existing die-cast aluminum alloy melts.

[0096] (5) Recyclability of high-strength, high-toughness, heat-free die-cast aluminum alloys

[0097] To evaluate the recycling performance of the die-cast aluminum alloy provided in this embodiment, the aluminum alloy die-casting parts and gating system prepared above were used as recycled aluminum materials and roasted at 480°C for 3 hours. After removing the organic coating, they were broken into blocks of 50~100mm. Then, they were mixed with new alloy raw materials (the weight ratio of recycled aluminum materials was 50%) and put into the furnace. The recycled aluminum materials were recycled and remelted through the above steps (1)~(4). The above recycling and regeneration steps were repeated five times to obtain the melt after five rounds of recycling and remelting.

[0098] Following the melt flowability test method described above, the flowability of the melt after five rounds of recycling and remelting was evaluated, and the results are shown in Table 1. The melt after five rounds of recycling and remelting was then die-cast to obtain a recycled aluminum alloy casting, denoted as D5. The metallographic structure of the recycled aluminum alloy casting was observed, and the room temperature mechanical properties of the die-casting D5 were tested according to GB / T228.1-2021. Ten samples were used for each sample, and the average value was taken. The results are shown in Table 3.

[0099] Figure 6 Content (a), Figure 6 Content (b) shows the metallographic structure of the first-produced high-strength, high-toughness, heat-free aluminum alloy die casting D and the aluminum alloy die casting D5 after five rounds of recycling. It can be seen that, compared with the first-produced aluminum alloy die casting D, the microstructure of the aluminum alloy die casting D5 after five rounds of recycling did not show obvious coarsening, indicating that the microstructure of the aluminum alloy die casting is stable after recycling.

[0100] Example 2

[0101] The high-strength, high-toughness, heat-free die-cast aluminum alloy provided in this embodiment has the following composition and weight percentage: Si: 9.5wt%, Cu: 0.35wt%, Mn: 0.5wt%, Mg: 0.3wt%, Zn: 0.3wt%, Ti: 0.1wt%, Sr: 0.04wt%, Fe: 1.3wt%, Ca: 0.08wt%, Cr: 0.3wt%, with the balance being Al.

[0102] The preparation method of high-strength, high-toughness, heat-free die-cast aluminum alloy based on the above composition includes the following steps:

[0103] S1, Ingredients

[0104] Weigh the raw materials according to the above design, including Al-20Si, Al-10Cu, Al-10Mn, Al-10Zn, Al-10Ti, Al-10Sr, Al-10Fe, Al-10Ca, Al-10Cr master alloy, industrial pure Mg ingot, and industrial pure aluminum, and grind to remove the surface oxide layer.

[0105] S2, Smelting

[0106] Melting: Industrial pure aluminum and Al-20Si master alloy are added to a graphite crucible preheated to 400°C and melted in a melting furnace at 820°C to obtain the first melt;

[0107] Alloying treatment: After the first melt is cooled to 750℃, Al-10Mn, Al-10Ti and Al-10Cr master alloys are added for smelting. After complete melting, electromagnetic stirring (magnetic field strength of 0.2mT and frequency of 20Hz) is turned on and stirred at 300r / min for 10min. Slag is removed to obtain the second melt.

[0108] Refining: The second melt is heated to 800℃, and Al-10Cu, Al-10Zn and Al-10Fe master alloys are added to continue smelting. After complete melting, the temperature is lowered to 750℃, and electromagnetic stirring (magnetic field strength of 0.2mT and frequency of 20Hz) is turned on and stirred at 300r / min for 10min. Then argon gas is introduced to degas the mixture for 10min and the slag is removed to obtain the third melt.

[0109] Composite modification: Under argon protection, Al-10Sr, Al-10Ca and pure Mg are added to the third melt to prevent oxidation. After complete melting, electromagnetic stirring (magnetic field strength of 0.2mT and frequency of 20Hz) is turned on and stirred at 300r / min for 10min. Slag is removed to obtain the fourth melt, namely aluminum alloy melt, and the temperature is maintained.

[0110] S3. Online monitoring of melt parameters

[0111] The viscosity and temperature of the fourth melt are monitored by online sensors. Specifically, a viscosity detection device is used to detect the viscosity of the fourth melt, controlling it to be between 1.2 and 1.5 Pa·s. If the viscosity is below 1.2 Pa·s, the holding temperature of the fourth melt is reduced (in 5°C increments) and the holding time is extended (to 15 minutes) until the viscosity reaches the target. If the viscosity is above 1.5 Pa·s, the holding temperature of the fourth melt is increased (in 15°C increments) and electromagnetic stirring is started (at 100 rpm) until the viscosity reaches the target. Additionally, a thermocouple is used to control the temperature of the fourth melt between 700°C and 730°C when adjusting its viscosity. Once both the viscosity and temperature of the fourth melt reach the target, the next step is performed.

[0112] S4, die casting

[0113] The die-casting mold is subjected to hot molding, spraying, and vacuuming treatment. It is preheated to 250°C and the vacuum degree is 80mbar. Then, a fourth melt with suitable melt parameters (viscosity of 1.3Pa·s and temperature of 720°C) is poured into the barrel of the die-casting mold. The low-speed injection speed of the punch is 0.2m / s and the high-speed injection speed is 4.5m / s. Die-casting production is carried out at a pressure of 50MPa to obtain an aluminum alloy die-casting part, denoted as D.

[0114] The high-strength, high-toughness, heat-free aluminum alloy die-casting D produced in the first batch was recycled and remelted according to the method provided in Example 1, resulting in a melt that underwent five rounds of recycling and remelting. Then, referring to the melt flowability test method described above, the flowability of the first batch of aluminum alloy melt and the melt that underwent five rounds of recycling and remelting were tested, and the results are shown in Table 1.

[0115] The high-strength, high-toughness, heat-free aluminum alloy die casting D produced in the first batch was recycled and regenerated according to the method provided in Example 1. Then, it was die-cast to obtain an aluminum alloy die casting that had undergone five rounds of recycling, denoted as D5. The mechanical properties of the first batch of die casting D and the die casting D5 that had undergone five rounds of recycling were then tested. Ten samples were used for each sample, and the average value was taken. The results are shown in Tables 2 and 3.

[0116] Comparative Example 1

[0117] The die-cast aluminum alloy used in this comparative example is ADC12. The alloy was prepared according to its composition, and an ADC12 melt was obtained. Its fluidity was tested using the melt fluidity test method provided in Example 1, and the results are shown in Table 1. Figure 7 As shown.

[0118] Following the method provided in Example 1, the melt parameters of aluminum alloy ADC12 were adjusted. Then, the deep-cavity die-casting mold was preheated and sprayed with a diluted water-based release agent (the mass ratio of water-based release agent to water was 1:100). After vacuuming, the aluminum alloy ADC12 melt with suitable melt parameters was die-cast to obtain die-cast aluminum alloy ADC12. The demolding of the die-cast parts was observed, and the results are as follows: Figure 8 As shown in Table 2, its room temperature mechanical properties were tested according to the test method provided in Example 1.

[0119] To evaluate the recycling performance of die-cast aluminum alloy ADC12, the die-cast aluminum alloy ADC12 was recycled and remelted to obtain a melt that had undergone five rounds of recycling and remelting. The flowability of the melt after five rounds of recycling and remelting was tested using the melt flowability test method provided in Example 1. Then, die casting was performed to obtain aluminum alloy die castings that had undergone five rounds of recycling. The room temperature mechanical properties of the aluminum alloy castings that had undergone five rounds of recycling and remelting were then tested according to the test method provided in Example 1. The results are shown in Table 3.

[0120] Comparative Example 2

[0121] The die-cast aluminum alloy used in this comparative example is A356. The alloy was prepared according to its composition, and an A356 melt was obtained. Its fluidity was tested using the melt fluidity test method provided in Example 1, and the results are shown in Table 1.

[0122] Following the method provided in Example 1, the melt parameters of aluminum alloy A356 were adjusted. Then, the deep-cavity die-casting mold was preheated and sprayed with a diluted water-based release agent (the mass ratio of water-based release agent to water was 1:100). After vacuuming, the aluminum alloy A356 melt with suitable melt parameters was die-cast to obtain die-cast aluminum alloy A356. Its room temperature mechanical properties were then tested according to the test method provided in Example 1, and the results are shown in Table 2.

[0123] To evaluate the recycling performance of die-cast aluminum alloy A356, the alloy was recycled and remelted to obtain a melt that had undergone five rounds of recycling and remelting. The melt flowability of the melt after five rounds of recycling and remelting was tested using the melt flowability test method provided in Example 1. The melt was then die-cast to obtain aluminum alloy die castings that had undergone five rounds of recycling. The room temperature mechanical properties of the recycled aluminum alloy castings were then tested according to the test method provided in Example 1, and the results are shown in Table 3.

[0124] Comparative Example 3

[0125] The die-cast aluminum alloy used in this comparative example is AlSi10MnMg. The alloy was prepared according to its composition, and an AlSi10MnMg melt was obtained. Its fluidity was tested using the melt fluidity test method provided in Example 1, and the results are shown in Table 1.

[0126] The melt parameters of the aluminum alloy AlSi10MnMg were adjusted according to the method provided in Example 1. Then, the deep-cavity die-casting mold was preheated and sprayed with a diluted water-based release agent (the mass ratio of water-based release agent to water was 1:100). After vacuuming, the AlSi10MnMg melt with suitable melt parameters was die-cast to obtain the die-cast aluminum alloy AlSi10MnMg. Its room temperature mechanical properties were then tested according to the test method provided in Example 1, and the results are shown in Table 2.

[0127] To evaluate the recycling performance of the die-cast aluminum alloy AlSi10MnMg, the alloy was recycled and remelted to obtain a melt that had undergone five rounds of recycling and remelting. The melt flowability of the melt after five rounds of recycling and remelting was tested using the melt flowability test method provided in Example 1. The melt was then die-cast to obtain aluminum alloy die castings that had undergone five rounds of recycling. The room temperature mechanical properties of the recycled aluminum alloy castings were then tested according to the test method provided in Example 1, and the results are shown in Table 3.

[0128] Comparative Example 4

[0129] The composition and weight percentage of the die-cast aluminum alloy provided in this comparative example are as follows: Si: 9.5 wt%, Cu: 0.35 wt%, Mn: 0.5 wt%, Mg: 0.3 wt%, Zn: 0.3 wt%, Ti: 0.1 wt%, Sr: 0.02 wt%, Fe: 1.3 wt%, Ca: 0.075 wt%, Cr: 0.4 wt%, with the balance being Al (Ca / Sr weight ratio is 4:1). Its preparation method and recycling / remelting process are the same as in Example 1. Following the melt flowability testing method provided in Example 1, the flowability of the initially prepared aluminum alloy melt and the melt after five rounds of recycling / remelting were tested, and the results are shown in Table 1.

[0130] The aluminum alloy melt prepared initially and the melt recycled through five rounds of recycling were die-cast to obtain die-cast part D obtained in the first production and die-cast part D5 obtained through five rounds of recycling. The mechanical properties of die-cast part D obtained in the first production and die-cast part D5 obtained through five rounds of recycling were tested according to the test method provided in Example 1. Ten samples were used for each sample, and the average value was taken. The results are shown in Tables 2 and 3.

[0131] Comparative Example 5

[0132] The composition and weight percentage of the die-cast aluminum alloy provided in this comparative example are as follows: Si: 9.5 wt%, Cu: 0.35 wt%, Mn: 0.3 wt%, Mg: 0.3 wt%, Zn: 0.3 wt%, Ti: 0.1 wt%, Sr: 0.02 wt%, Fe: 1.3 wt%, Ca: 0.08 wt%, Cr: 0.6 wt%, with the balance being Al (Cr / Mn weight ratio is 2:1). Its preparation method and recycling / remelting process are the same as in Example 1. Following the melt flowability testing method provided in Example 1, the flowability of the initially prepared aluminum alloy melt and the melt after five rounds of recycling / remelting were tested, and the results are shown in Table 1.

[0133] The aluminum alloy melt prepared in the first production and the melt recycled through five rounds were die-cast to obtain die-cast part D obtained in the first production and die-cast part D5 obtained through five rounds of recycling. The mechanical properties of die-cast part D obtained in the first production and die-cast part D5 obtained through five rounds of recycling were tested according to the test method provided in Example 1. Ten samples were used for each sample, and the average value was taken. The results are shown in Tables 2 and 3.

[0134]

[0135]

[0136]

[0137] From Table 1, Figure 3 , Figure 7As can be seen, compared with commonly used die-cast aluminum alloys, the aluminum alloy melt prepared in this embodiment has excellent spiral flowability and good filling effect, making it suitable for preparing die-cast parts such as deep cavity shells and multi-fin heat sinks. Furthermore, when using the aluminum alloy melt for die casting to prepare die-cast parts such as deep cavity shells and multi-fin heat sinks, compared with commonly used die-cast aluminum alloys (… Figure 5 , Figure 8 The aluminum alloy melt provided in this application can achieve efficient, continuous, and non-sticky production of deep cavity shell or multi-fin heat dissipation die castings with a lower amount of water-based release agent. This reduces the amount of release agent used, lowers mold repair costs, and improves the production efficiency of complex die castings. It effectively solves the production pain points of existing die casting aluminum alloy melts in the preparation of complex die castings, such as large core-holding force, mold pulling, and film sticking.

[0138] The mechanical property test results (Tables 2 and 3) show that, compared to Comparative Examples 1-3, the die-cast aluminum alloy provided in this application, by designing its elemental composition and content, has developed a die-cast aluminum alloy that can achieve high strength and high toughness in the as-cast state without heat treatment, and can tolerate high Fe content (Fe weight percentage of 0.5wt%~1.6wt%). Specifically, the room temperature ultimate tensile strength of the first-produced heat-free aluminum alloy die castings is greater than 320MPa, the room temperature yield strength is greater than 210MPa, exhibiting excellent tensile strength, and the room temperature elongation is greater than 10%, exhibiting excellent toughness. Furthermore, the aluminum alloy die castings obtained by remelting the first-produced aluminum alloy die castings in the examples after five rounds of recycling still exhibit superior tensile strength and toughness, indicating that the high-strength, high-toughness die-cast aluminum alloy provided in this application has good recyclability and strong material performance retention. This also demonstrates the high stability and reliability of the production process provided in this application. In practical applications, this characteristic gives aluminum alloy die castings significant advantages in sustainable development and industrial production. Through multiple recycling, it can reduce resource waste and environmental pollution, as well as reduce production costs and improve the economic efficiency of materials, resulting in significant economic and environmental benefits.

[0139] By comparing Example 1 and Comparative Examples 4-5, it can be seen that the strength and toughness of the aluminum alloy die castings produced for the first time in Comparative Examples 4 and 5, as well as the aluminum alloy die castings that underwent five rounds of recycling and remelting, both decreased significantly. The reason for this may be that when the Ca / Sr weight ratio is too high (the Ca / Sr weight ratio in Comparative Example 4 is 4:1), coarse AlCa intermetallic compounds precipitate in the microstructure. This phase has low hardness, is easily corroded, and is easily detached. As an intergranular brittle phase, it causes matrix fracture, resulting in a severe decrease in the strength of the aluminum alloy die casting. When the Cr / Mn weight ratio is too high (the Cr / Mn weight ratio in Comparative Example 5 is 2:1), Cr and Mn compete for the positions of Fe atoms in the AlSiFe phase crystal structure, hindering the transformation of the Chinese character-shaped AlSi(Mn,Cr)Fe phase, which seriously harms the mechanical properties of the aluminum alloy die casting and leads to a decrease in toughness. The high-Fe-content, heat-free die-casting aluminum alloy provided in this application, through Ca-Sr composite modification treatment and control of their ratio, can positively impact the casting fluidity, solidification characteristics, and defect control of the die-casting aluminum alloy. It significantly refines the eutectic Si phase in the die-casting aluminum alloy microstructure, making it completely global, thereby reducing the viscosity of the melt during solidification, reducing flow blockage between dendrites, and making the melt easier to fill the mold (especially for complex thin-walled parts), reducing the risk of undercasting. Simultaneously, after the eutectic Si phase is refined, the solidification shrinkage of the aluminum alloy is more uniform, reducing the formation of shrinkage cavities and porosity during die casting. Furthermore, Ca has a low affinity for gases (such as hydrogen), making it less prone to porosity formation, which helps improve the density of the casting. On the other hand, addressing the problems of low Fe content tolerance and poor scrap recyclability in traditional die-casting aluminum alloys, this application uses Cr-Mn synergistic treatment and controls their ratio to transform the Fe-rich phase into a harmless Chinese character-shaped structure, avoiding the brittle fracture of the traditional needle-like phase. Simultaneously, Ca in the composition preferentially combines with Fe and Si to form stable Al-Si-Ca-Fe compounds (such as Al2Si2CaFe), whose morphology changes from needle-like to blocky or granular, and whose distribution becomes more diffuse. This allows for a tolerance of Fe content of 0.5wt%~1.6wt%, while significantly improving the utilization rate of recycled materials. Furthermore, Cr in the composition can form multi-component strengthening phases with Mg2Si, Al2Cu, etc., breaking through the toughness bottleneck of traditional high-Fe content alloys. Through the synergistic strengthening effect of various elements in the composition, the tensile strength and elongation of the as-cast aluminum alloy are synergistically improved.

[0140] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-strength, high-toughness, heat-treasure-free die-cast aluminum alloy, characterized in that, The composition, by weight percentage, comprises the following components: 8 wt% to 10 wt% Si, 0.5 wt% to 1.6 wt% Fe, 0.1 wt% to 0.8 wt% Mn, 0.1 wt% to 0.6 wt% Cu, 0.1 wt% to 0.6 wt% Zn, 0.1 wt% to 0.5 wt% Mg, 0.1 wt% to 0.6 wt% Cr, 0.1 wt% to 0.3 wt% Ti, 0.05 wt% to 0.1 wt% Ca, 0.01 wt% to 0.05 wt% Sr, with the balance being Al; Furthermore, the total weight percentage of Ca and Sr is <0.15% and the weight ratio of Ca to Sr is (1~3):1; The total weight percentage of Cr and Mn is <1% and the weight ratio of Cr to Mn is not greater than 1:1; The weight ratio of Ca to Cr is no greater than 1:

1.

2. The heat-free die-cast aluminum alloy according to claim 1, characterized in that, In the heat-free die-cast aluminum alloy, the weight percentage of Mn is 0.3wt%~0.5wt%, the weight percentage of Cr is 0.2wt%~0.4wt%, the weight percentage of Ca is 0.05wt%~0.08wt%, and the weight percentage of Sr is 0.02wt%~0.04wt%.

3. The heat-free die-cast aluminum alloy according to claim 2, characterized in that, In the heat-free die-cast aluminum alloy, the weight percentage of Si is 9wt%~10wt%, the weight percentage of Fe is 0.8wt%~1.5wt%, the weight percentage of Cu is 0.2wt%~0.5wt%, the weight percentage of Zn is 0.2wt%~0.5wt%, the weight percentage of Mg is 0.2wt%~0.5wt%, and the weight percentage of Ti is 0.1wt%~0.2wt%.

4. The heat-free die-cast aluminum alloy according to claim 2, characterized in that, In the heat-free die-cast aluminum alloy, the weight ratio of Cr to Mn is 1:(1~2).

5. The heat-free die-cast aluminum alloy according to claim 4, characterized in that, In the heat-free die-cast aluminum alloy, the weight ratio of Ca to Cr is 1:(1~4).

6. The heat-free die-cast aluminum alloy according to claim 5, characterized in that, The heat-free die-cast aluminum alloy has a room temperature ultimate tensile strength ≥300MPa, a room temperature yield strength ≥200MPa, and a room temperature elongation ≥12%.

7. A method for preparing a heat-free die-cast aluminum alloy as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Prepare the raw materials according to the composition of the heat-free die-cast aluminum alloy, and then melt, alloy, refine and remove slag and modify the raw materials to obtain aluminum alloy melt; S2. Use an online melt monitoring device to detect the viscosity and temperature of the aluminum alloy melt. When both viscosity and temperature are within the preset range, perform die casting to obtain the heat-free die-cast aluminum alloy.

8. The preparation method according to claim 7, characterized in that, In step S2, the online melt monitoring device includes a viscosity sensor and a temperature sensor; and / or, The preset viscosity range is 1.2 Pa·s to 1.5 Pa·s; and / or, The preset temperature range is 700℃~730℃; and / or, The pressure of the die casting is 40MPa~60MPa.

9. A high-strength and high-toughness structural component, characterized in that, At least a portion of the structural component is a heat-free die-cast aluminum alloy as described in any one of claims 1 to 6, or a heat-free die-cast aluminum alloy prepared by the preparation method described in claim 7 or 8.

10. The structural component according to claim 9, characterized in that, The structural component is either a deep cavity shell type or a multi-fin heat dissipation type.

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