Aluminum alloy material for light weight die casting and method for manufacturing the same

Abstract

This application relates to the technical field of aluminum alloy materials, specifically disclosing a lightweight die-casting aluminum alloy material and its preparation method. The lightweight die-casting aluminum alloy material is prepared from the following raw materials in the indicated mass percentages: Si: 6.0%~8.0%, Mg: 0.6%~0.9%, Mn: 0.6%~1.2%, V: 0.05%~0.15%, Zr: 0.05%~0.1%, nanocomposite modifier: 0.05%~0.2%, Fe≤0.6%, unavoidable impurities: total ≤0.2%, balance being Al; the nanocomposite modifier has a core-shell structure, with TiC as the core and rare earth oxide REO as the outer layer. x Where RE is Y or Ce. The lightweight die-casting aluminum alloy material obtained in this application has good strength and plasticity in the die-cast state without heat treatment.

Description

Technical Field

[0001] This application relates to the technical field of aluminum alloy materials, and more specifically, to a lightweight die-casting aluminum alloy material and its preparation method. Background Technology

[0002] Driven by global industrial trends toward lightweighting, integration, and high performance, aluminum alloy die-casting products are entering a period of rapid development. On the one hand, the fields of automotive electrification, miniaturization of electronic devices, and 5G new infrastructure have an urgent need for "weight reduction, strength, and precision forming"; on the other hand, aluminum alloys, with their low density, high specific strength, and good die-casting fluidity, have become an ideal material to replace traditional metals (steel, copper alloys).

[0003] Currently, integrated die-casting technology has been widely applied in products such as battery boxes and vehicle body structural components. These components generally use heat-free Al-Si-Mg alloys, with the addition of elements such as Ti and B to refine the grains, and Sr to modify the eutectic silicon phase. However, TiB2 mainly refines α-Al grains and has no effect on modifying the eutectic silicon phase; while Sr can effectively improve the morphology of eutectic silicon, its modification effect is affected by various factors in the melt. When phosphorus is present in the melt, Sr preferentially forms stable Sr-P compounds with P, leading to a decrease in effective Sr content and a decline in modification effect; at the same time, the modification effect of Sr decreases significantly with the extension of melt settling time. The lack of this synergistic mechanism results in poor uniformity of alloy microstructure and difficulty in ensuring performance stability. In addition, to achieve high strength requirements, traditional processes usually use high magnesium content (>3%), but this exacerbates the melt oxidation tendency and hot cracking sensitivity, deteriorating the die-casting process performance.

[0004] Patent application CN112522557A discloses a high-strength and high-toughness die-cast aluminum alloy material, which, in addition to aluminum, comprises, by weight percentage: Mg: 4%~7%; Si: 1.6%~2.8%; Mn: 0.4%~0.9%; Ti: 0.1%~0.3%; Be: 0.002%~0.010%; aluminum-titanium-carbon-boron seed material: 0.3%~2%; Fe: ≤0.2%, wherein the ratio of Mg to Si should satisfy: Mg / Si≥2.5; the high-strength and high-toughness die-cast aluminum alloy material is refined using a sodium-free refining agent during the preparation process, and the order of adding Mg, Be and the sodium-free refining agent during the preparation process is: first add Mg, then add Be, and then add the sodium-free refining agent.

[0005] This scheme, while employing a high magnesium content of 4%–7% and combining it with highly toxic beryllium to improve performance, and claiming that beryllium inhibits magnesium oxidation by forming a dense beryllium oxide film, still suffers from the inherently oxidizable nature of high-magnesium melts, resulting in numerous microscopic oxide inclusions. These inclusions become stress concentration points and crack initiations during solidification, directly cleaving the metal matrix. This not only significantly reduces the material's impact toughness and elongation but also leads to fluctuations in strength properties and a decrease in fatigue life. Furthermore, the oxide slag generated during smelting easily causes internal defects in the castings, further compromising the material's density and performance consistency, fundamentally limiting the alloy's balance between strength and toughness. Summary of the Invention

[0006] To address the technical problem of the trade-off between strength and toughness in traditional aluminum alloys, this application provides a lightweight die-casting aluminum alloy material and its preparation method.

[0007] In a first aspect, this application provides a lightweight aluminum alloy material for die casting and a method for preparing the same, employing the following technical solution: A lightweight die-casting aluminum alloy material is prepared from the following raw materials in the indicated weight percentages: Si: 6.0%~8.0%, Mg: 0.6%~0.9%, Mn: 0.6%~1.2%, V: 0.05%~0.15%, Zr: 0.05%~0.1%, nanocomposite modifier: 0.05%~0.2%, Fe≤0.6%, unavoidable impurities: total ≤0.2%, balance Al; The nanocomposite modifier has a core-shell structure, with TiC as the core and rare earth oxide REO as the outer layer. x , where RE is Y or Ce.

[0008] In this scheme, on the one hand, relying on the combination of silicon and magnesium and the grain refinement effect of nano-modifiers, a balance between strength and toughness is achieved in a heat-free state, breaking the limitation of mutual restriction between the two; on the other hand, manganese and vanadium are used to synergistically regulate iron, transforming its harmful form into a stable and harmless microstructure; at the same time, the low magnesium content design reduces the risk of melt oxidation and hot cracking, and combined with the fluidity advantage of silicon and the grain refinement effect of zirconium and nano-modifiers, the die-casting process adaptability of the material is greatly improved, which can meet the integrated molding requirements of complex thin-walled parts; in addition, the protection of the nano-core and the melt purification effect of the rare earth oxide shell, combined with the microalloying effect of vanadium and zirconium, further ensures the long-term microstructure stability and corrosion resistance of the material.

[0009] Preferably, the preparation method of the nanocomposite modifier includes the following steps: TiC was dispersed in water, rare earth nitrates were added and mixed evenly, the pH was adjusted to 9-10, the temperature was raised to 120-160℃, and the hydrothermal reaction was carried out for 4-6 hours. After cooling, solid-liquid separation was performed, followed by washing, drying, calcination at 550-600℃ for 1-2 hours, and cooling to obtain the nanocomposite modifier.

[0010] Preferably, the mass ratio of TiC to rare earth nitrate (calculated as Y(NO3)3·6H2O or Ce(NO3)3·6H2O) is (2~4):1.

[0011] In this scheme, by precisely controlling the pH value, temperature and subsequent calcination process of the hydrothermal reaction, it is ensured that rare earth oxides can coat the surface of TiC nanoparticles with a uniform and dense shell structure, effectively avoiding the agglomeration of nanoparticles, significantly improving the dispersibility and stability of the modifier in the aluminum melt, so that it can give full play to the synergistic modification effect, thereby greatly improving the microstructure uniformity and mechanical property stability of the alloy.

[0012] Preferably, in the lightweight die-casting aluminum alloy material, 1.5 ≤ Mn / Fe ≤ 2.0.

[0013] In this scheme, by precisely controlling the Mn / Fe ratio within the range of 1.5 to 2.0, the Mn and Fe elements are encouraged to form stable multi-component compounds, which effectively inhibits the precipitation of the harmful acicular β-Fe phase. This not only significantly reduces the cutting effect of the iron-rich phase on the matrix, but also improves the toughness and elongation of the material.

[0014] Preferably, in the lightweight die-casting aluminum alloy material, 0.1 ≤ V / Fe ≤ 0.3.

[0015] In this scheme, the V / Fe ratio is precisely controlled within the range of 0.1 to 0.3, promoting the formation of a stable multi-component composite phase with elements such as V, Fe, and Mn. This composite phase not only further inhibits the precipitation of the harmful needle-like β-Fe phase, but also produces a significant precipitation enhancement effect through its fine and dispersed distribution.

[0016] Preferably, in the lightweight die-casting aluminum alloy material, 0.08 ≤ Mg / Si ≤ 0.12.

[0017] In this scheme, the low Mg / Si ratio design ensures the formation of sufficient Mg2Si reinforcing phase to improve strength, while fundamentally reducing the oxidation tendency and hot cracking sensitivity of the melt, and significantly improving the die casting process performance of the alloy.

[0018] Preferably, the lightweight die-casting aluminum alloy material further includes 0.2% to 0.8% composite seed crystals, wherein the composite seed crystals include aluminum-titanium-boron seed crystals and aluminum-zirconium seed crystals.

[0019] In this scheme, aluminum-titanium-boron seed crystals provide instantaneous nucleation sites, while aluminum-zirconium seed crystals provide a long-lasting grain refinement effect. The combination of the two significantly refines the grain size and improves the uniformity of the microstructure. This composite grain refinement mechanism not only enhances the strength and toughness of the material but also effectively reduces the tendency for hot cracking during die casting.

[0020] Preferably, the amount of aluminum zirconium seed crystals used is 20% to 40% of the total mass of the composite seed crystals.

[0021] Preferably, the lightweight die-casting aluminum alloy material further includes 0.05% to 0.25% Eu.

[0022] In this scheme, Eu can effectively refine the eutectic silicon phase and improve its morphology in the melt, while enhancing the oxidation resistance of the melt.

[0023] Preferably, the lightweight die-casting aluminum alloy material further includes 0.03% to 0.15% Dy.

[0024] In this scheme, the addition of Dy can form highly stable intermetallic compounds with elements such as Al and Si, which helps to suppress grain boundary movement and recrystallization processes and improve the high-temperature stability of the material.

[0025] Secondly, this application provides a method for preparing a lightweight die-casting aluminum alloy material, comprising the following steps: Under an inert atmosphere, the raw materials are put into a melting furnace and heated to 730~750℃. After complete melting, 0.3%~0.5% of sodium-free refining agent is added according to the total mass of the raw materials, and inert gas is introduced. The materials are refined for 15~25 minutes, allowed to stand for 15~25 minutes, and after slag removal, they are cast into shape at 680~710℃ and cooled to obtain lightweight die-casting aluminum alloy material.

[0026] In this scheme, the inert atmosphere protection throughout the process can effectively inhibit melt oxidation. Combined with sodium-free refining agent and inert gas refining, it can deeply remove gases and inclusions in the melt and improve melt purity. The static slag removal process further reduces impurity interference, laying a high-quality melt foundation for subsequent molding.

[0027] Preferably, the composite seed crystal is added simultaneously with the raw materials.

[0028] Preferably, the raw materials, except for magnesium and nanocomposite modifier, are first put into the smelting furnace and completely melted. Then, magnesium and nanocomposite modifier are added in sequence.

[0029] Preferably, raw materials other than magnesium, nanocomposite modifier and Eu are first put into the smelting furnace and completely melted, and then magnesium, nanocomposite modifier and Eu are added in sequence.

[0030] Preferably, raw materials other than magnesium, nanocomposite modifier, Eu and Dy are first put into the smelting furnace and completely melted, and then magnesium, nanocomposite modifier, Eu and Dy are added in sequence.

[0031] Preferably, the sodium-free refining agent is a commercially available granular sodium-free refining agent, whose main components are sodium-free salts such as KCl and MgCl2, and whose operating temperature range is 700℃~780℃.

[0032] In summary, this application has the following beneficial effects: The elemental ratio and core-shell structure nanocomposite modifiers used in this application are designed in synergy. By combining silicon and magnesium, the phase regulation is strengthened, manganese and vanadium are used to transform iron toxic forms, and low magnesium content controls oxidation risk. At the same time, the mechanical properties of the material are optimized by relying on the melt purification and grain refinement effect of rare earth oxides. Detailed Implementation

[0033] The present application will be further described in detail below with reference to the embodiments.

[0034] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application are all commercially available.

[0035] The lightweight aluminum alloy material prepared in this application is particularly suitable for thin-walled die-cast structural parts that require high strength and toughness.

[0036] The raw materials used in the following embodiments, Aluminum blocks: purity ≥99.7%, aluminum powder: purity ≥99.7%, silicon blocks: purity ≥99.0%; Al-20Mn master alloy; Al-10V master alloy; Al-10Zr master alloy; Al-20Fe master alloy; magnesium blocks: purity ≥99.8%, Al-3Eu master alloy; Al-10Dy master alloy; The aluminum-titanium-boron seed crystals were commercially available and had a composition of approximately Al-5Ti-1B; the aluminum-zirconium seed crystals were commercially available and had a composition of approximately Al-10Zr. The sodium-free refining agent is a commercially available granular sodium-free refining agent with a KCl to MgCl2 mass ratio of 1:1.

[0037] Preparation Examples 1-3: Nanocomposite Modifiers Preparation Example 1 The preparation method of the nanocomposite modifier in this preparation example includes the following steps: 5g of TiC nanoparticles with an average particle size of 50nm were added to 50mL of deionized water and transferred to an ultrasonic device. The mixture was ultrasonically treated for 30min at a power of 300W and a frequency of 40KHz. 2.5g of Y(NO3)3·6H2O was added and stirred at 300r / min for 10min. The pH was adjusted to 10 using 10% ammonia water. The mixture was then transferred to a hydrothermal reactor and heated to 160℃. The reactor was kept at this temperature for 4h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and centrifuged. The mixture was washed twice each with deionized water and anhydrous ethanol. The mixture was dried at 80℃ to constant weight and then transferred to a muffle furnace. The temperature was increased to 600℃ at a rate of 3℃ / min and calcined for 2h. The mixture was then cooled to room temperature with the furnace and lightly ground to disperse the nanocomposite modifier.

[0038] Preparation Example 2 The preparation method of the nanocomposite modifier in this preparation example includes the following steps: 5g of TiC nanoparticles with an average particle size of 50nm were added to 50mL of deionized water and transferred to an ultrasonic device. The mixture was ultrasonically treated for 30min at a power of 300W and a frequency of 40KHz. 1.25g of Y(NO3)3·6H2O was added and stirred at 300r / min for 10min. The pH was adjusted to 9 with 10% ammonia water. The mixture was then transferred to a hydrothermal reactor and heated to 120℃. The reactor was kept at this temperature for 6h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and centrifuged. The mixture was washed twice each with deionized water and anhydrous ethanol. The mixture was dried at 80℃ to constant weight and then transferred to a muffle furnace. The temperature was increased to 550℃ at a rate of 3℃ / min and calcined for 1h. The mixture was then cooled to room temperature with the furnace and lightly ground to disperse the nanocomposite modifier.

[0039] Preparation Example 3 The preparation method of the nanocomposite modifier in this preparation example includes the following steps: 5g of TiC nanoparticles with an average particle size of 50nm were added to 50mL of deionized water and transferred to an ultrasonic device. The mixture was ultrasonically treated for 30min at a power of 300W and a frequency of 40kHz. 1.25g of Y(NO3)3·6H2O and 0.75g of Ce(NO3)3·6H2O were added and stirred at 300r / min for 10min. The pH was adjusted to 9.5 with 10% ammonia water. The mixture was then transferred to a hydrothermal reactor, heated to 140℃, and held at that temperature for 5h. After the reaction was completed, the mixture was allowed to cool naturally to room temperature and centrifuged. The mixture was washed twice each with deionized water and anhydrous ethanol, and dried at 80℃ to constant weight. The mixture was then transferred to a muffle furnace and heated to 550℃ at a rate of 3℃ / min. The mixture was calcined for 1.5h and cooled to room temperature with the furnace. The mixture was then lightly ground and dispersed to obtain the nanocomposite modifier.

[0040] Example 1 The lightweight die-casting aluminum alloy material of this embodiment is prepared from the following raw materials by weight percentage: Si: 6.0%, Mg: 0.6%, Mn: 0.6%, V: 0.05%, Zr: 0.05%, nanocomposite modifier: 0.05%, Fe: 0.4%, unavoidable impurities ≤0.2%, balance Al; total raw material mass: 500g.

[0041] The nanocomposite modifier was derived from Preparation Example 1.

[0042] The method for preparing lightweight die-casting aluminum alloy material in this embodiment includes the following steps: According to the mass percentage of each component, take the corresponding mass of raw materials, and under the protection of argon atmosphere, put aluminum blocks, silicon blocks, Al-20Mn, Al-10V, Al-10Zr, and Al-20Fe into a melting furnace, heat to 730℃ to completely melt them, use a graphite bell jar to press magnesium blocks into the middle and below the melt, stir the melt to make its composition uniform, add nano-composite modifier, stir thoroughly again, add sodium-free refining agent accounting for 0.3% of the total mass of raw materials, purge with argon for 25 minutes, let stand for 25 minutes, thoroughly remove slag, reduce the temperature of the melt to 685℃±5℃, pour into a mold preheated to 200℃, cool to room temperature, and obtain lightweight die-casting aluminum alloy material.

[0043] Example 2 The lightweight die-casting aluminum alloy material of this embodiment is prepared from the following raw materials by weight percentage: Si: 8.0%, Mg: 0.8%, Mn: 1.2%, V: 0.15%, Zr: 0.1%, nanocomposite modifier: 0.2%, Fe: 0.6%, unavoidable impurities ≤0.2%, balance Al; total raw material mass: 500g.

[0044] The nanocomposite modifier was derived from Preparation Example 2.

[0045] The method for preparing lightweight die-casting aluminum alloy material in this embodiment includes the following steps: According to the mass percentage of each component, take the corresponding mass of raw materials, and under the protection of argon atmosphere, put aluminum blocks, silicon blocks, Al-20Mn, Al-10V, Al-10Zr, and Al-20Fe into a melting furnace, heat to 750℃ to completely melt them, use a graphite bell jar to press magnesium blocks into the middle and below the melt, stir the melt to make its composition uniform, add nano-composite modifier, stir thoroughly again, add sodium-free refining agent accounting for 0.5% of the total mass of raw materials, purge with argon for 18 minutes, let stand for 18 minutes, thoroughly remove slag, reduce the temperature of the melt to 705℃±5℃, pour into a mold preheated to 200℃, cool to room temperature, and obtain lightweight die-casting aluminum alloy material.

[0046] Example 3 The lightweight die-casting aluminum alloy material of this embodiment is prepared from the following raw materials by weight percentage: Si: 7.0%, Mg: 0.7%, Mn: 1%, V: 0.1%, Zr: 0.08%, nanocomposite modifier: 0.15%, Fe: 0.5%, unavoidable impurities ≤0.2%, balance Al; total raw material mass: 500g.

[0047] The nanocomposite modifier was derived from Preparation Example 3.

[0048] The method for preparing lightweight die-casting aluminum alloy material in this embodiment includes the following steps: According to the mass percentage of each component, take the corresponding mass of raw materials, and under the protection of argon atmosphere, put aluminum blocks, silicon blocks, Al-20Mn, Al-10V, Al-10Zr, and Al-20Fe into a melting furnace, heat to 740℃ to completely melt them, use a graphite bell jar to press magnesium blocks into the middle and below the melt, stir the melt to make its composition uniform, add nano-composite modifier, stir thoroughly again, add sodium-free refining agent accounting for 0.4% of the total mass of raw materials, purge with argon for 20 minutes, let stand for 20 minutes, thoroughly remove slag, reduce the temperature of the melt to 695℃±5℃, pour into a mold preheated to 200℃, cool to room temperature, and obtain lightweight die-casting aluminum alloy material.

[0049] Example 4 The lightweight die-casting aluminum alloy material of this embodiment is prepared from the following raw materials by weight percentage: Si: 7.0%, Mg: 0.7%, Mn: 1%, V: 0.1%, Zr: 0.08%, nano-composite modifier: 0.15%, composite seed crystal: 0.2%, Fe: 0.5%, unavoidable impurities ≤0.2%, balance Al; total mass of raw materials: 500g.

[0050] The nanocomposite modifier was derived from Preparation Example 3; the composite seed crystals included aluminum-titanium-boron seed crystals and aluminum-zirconium seed crystals, with the amount of aluminum-zirconium seed crystals being 20% ​​of the total mass of the composite seed crystals.

[0051] The method for preparing lightweight die-casting aluminum alloy material in this embodiment includes the following steps: According to the mass percentage of each component, take the corresponding mass of raw materials, and under the protection of argon atmosphere, put aluminum blocks, silicon blocks, Al-20Mn, Al-10V, Al-10Zr, Al-20Fe, and composite seed crystals into a melting furnace, heat to 740℃ to completely melt them, use a graphite bell jar to press magnesium blocks into the middle and below the melt, stir the melt to make its composition uniform, add nano-composite modifier, stir thoroughly again, add sodium-free refining agent accounting for 0.4% of the total mass of raw materials, purge with argon for 20 minutes, let stand for 20 minutes, thoroughly remove slag, reduce the temperature of the melt to 695℃±5℃, pour into a mold preheated to 200℃, cool to room temperature, and obtain lightweight die-casting aluminum alloy material.

[0052] Example 5 The difference between this embodiment and embodiment 4 is that: The amount of composite seed crystals used is 0.8%, and the composite seed crystals include aluminum titanium boron seed crystals and aluminum zirconium seed crystals. The amount of aluminum zirconium seed crystals used is 40% of the total mass of composite seed crystals.

[0053] The rest is the same as in Example 4.

[0054] Example 6 The lightweight die-casting aluminum alloy material of this embodiment is prepared from the following raw materials by weight percentage: Si: 7.0%, Mg: 0.81%, Mn: 1%, V: 0.1%, Zr: 0.08%, nano-composite modifier: 0.15%, composite seed crystal: 0.6%, Eu: 0.05%, Fe: 0.5%, unavoidable impurities ≤ 0.2%, balance Al; total mass of raw materials: 500g.

[0055] The nanocomposite modifier was derived from Preparation Example 3; the composite seed crystals included aluminum-titanium-boron seed crystals and aluminum-zirconium seed crystals, with the amount of aluminum-zirconium seed crystals being 30% of the total mass of the composite seed crystals.

[0056] The method for preparing lightweight die-casting aluminum alloy material in this embodiment includes the following steps: According to the mass percentage of each component, take the corresponding mass of raw materials, and under the protection of argon atmosphere, put aluminum blocks, silicon blocks, Al-20Mn, Al-10V, Al-10Zr, Al-20Fe, and composite seed crystals into a melting furnace, heat to 740℃ to completely melt them, use a graphite bell jar to press magnesium blocks into the middle and below the melt, stir the melt to make its composition uniform, add nano-composite modifier and Al-3Eu, stir thoroughly again, add sodium-free refining agent accounting for 0.4% of the total mass of raw materials, purge with argon for 20 minutes, let stand for 20 minutes, thoroughly remove slag, reduce the temperature of the melt to 695℃±5℃, pour into a mold preheated to 200℃, cool to room temperature, and obtain lightweight die-casting aluminum alloy material.

[0057] Example 7 The lightweight die-casting aluminum alloy material of this embodiment is prepared from the following raw materials by weight percentage: Si: 7.0%, Mg: 0.82%, Mn: 1%, V: 0.1%, Zr: 0.08%, nano-composite modifier: 0.15%, composite seed crystal: 0.6%, Eu: 0.05%, Dy: 0.03%, Fe: 0.5%, unavoidable impurities ≤ 0.2%, balance Al; total mass of raw materials: 500g.

[0058] The nanocomposite modifier was derived from Preparation Example 3; the composite seed crystals included aluminum-titanium-boron seed crystals and aluminum-zirconium seed crystals, with the amount of aluminum-zirconium seed crystals being 30% of the total mass of the composite seed crystals.

[0059] The method for preparing lightweight die-casting aluminum alloy material in this embodiment includes the following steps: According to the mass percentage of each component, take the corresponding mass of raw materials, and under the protection of argon atmosphere, put aluminum blocks, silicon blocks, Al-20Mn, Al-10V, Al-10Zr, Al-20Fe, and composite seed crystals into the melting furnace, heat to 740℃ to completely melt them, use a graphite bell jar to press magnesium blocks into the middle and below the melt, stir the melt to make its composition uniform, add nano-composite modifier, Al-3Eu, Al-10Dy, stir thoroughly again, add sodium-free refining agent accounting for 0.4% of the total mass of raw materials, purge with argon for 25 minutes, let stand for 25 minutes, thoroughly remove slag, reduce the temperature of the melt to 695℃±5℃, pour into a mold preheated to 200℃, cool to room temperature, and obtain lightweight die-casting aluminum alloy material.

[0060] Example 8 The lightweight die-casting aluminum alloy material of this embodiment is prepared from the following raw materials by weight percentage: Si: 7.0%, Mg: 0.87%, Mn: 1%, V: 0.1%, Zr: 0.08%, nano-composite modifier: 0.15%, composite seed crystal: 0.6%, Eu: 0.25%, Dy: 0.15%, Fe: 0.5%, unavoidable impurities ≤ 0.2%, balance Al; total mass of raw materials: 500g.

[0061] The nanocomposite modifier was derived from Preparation Example 3; the composite seed crystals included aluminum-titanium-boron seed crystals and aluminum-zirconium seed crystals, with the amount of aluminum-zirconium seed crystals being 30% of the total mass of the composite seed crystals.

[0062] The method for preparing lightweight die-casting aluminum alloy material in this embodiment includes the following steps: According to the mass percentage of each component, take the corresponding mass of raw materials, and under the protection of argon atmosphere, put aluminum blocks, silicon blocks, Al-20Mn, Al-10V, Al-10Zr, Al-20Fe, and composite seed crystals into the melting furnace, heat to 740℃ to completely melt them, use a graphite bell jar to press magnesium blocks into the middle and below the melt, stir the melt to make its composition uniform, add nano-composite modifier, Al-3Eu, Al-10Dy, stir thoroughly again, add sodium-free refining agent accounting for 0.4% of the total mass of raw materials, purge with argon for 25 minutes, let stand for 25 minutes, thoroughly remove slag, reduce the temperature of the melt to 695℃±5℃, pour into a mold preheated to 200℃, cool to room temperature, and obtain lightweight die-casting aluminum alloy material.

[0063] Example 9 The lightweight die-casting aluminum alloy material of this embodiment is prepared from the following raw materials by weight percentage: Si: 7.0%, Mg: 0.84%, Mn: 1%, V: 0.1%, Zr: 0.08%, nano-composite modifier: 0.15%, composite seed crystal: 0.6%, Eu: 0.15%, Dy: 0.1%, Fe: 0.5%, unavoidable impurities ≤ 0.2%, balance Al; total mass of raw materials: 500g.

[0064] The nanocomposite modifier was derived from Preparation Example 3; the composite seed crystals included aluminum-titanium-boron seed crystals and aluminum-zirconium seed crystals, with the amount of aluminum-zirconium seed crystals being 30% of the total mass of the composite seed crystals.

[0065] The method for preparing lightweight die-casting aluminum alloy material in this embodiment includes the following steps: According to the mass percentage of each component, take the corresponding mass of raw materials, and under the protection of argon atmosphere, put aluminum blocks, silicon blocks, Al-20Mn, Al-10V, Al-10Zr, Al-20Fe, and composite seed crystals into the melting furnace, heat to 740℃ to completely melt them, use a graphite bell jar to press magnesium blocks into the middle and below the melt, stir the melt to make its composition uniform, add nano-composite modifier, Al-3Eu, Al-10Dy, stir thoroughly again, add sodium-free refining agent accounting for 0.4% of the total mass of raw materials, purge with argon for 25 minutes, let stand for 25 minutes, thoroughly remove slag, reduce the temperature of the melt to 695℃±5℃, pour into a mold preheated to 200℃, cool to room temperature, and obtain lightweight die-casting aluminum alloy material.

[0066] Comparative Example 1 The difference between this comparative example and Example 1 is as follows: The nanocomposite modifier was replaced with an equal mass of TiC.

[0067] Everything else is the same as in Example 1.

[0068] Performance testing The lightweight die-casting aluminum alloy materials obtained in Examples 1-9 and Comparative Example 1 were respectively made into samples with a wall thickness of 4 mm, and then the tensile strength, yield strength and elongation were measured in sequence. The test results are shown in Table 1.

[0069] Table 1. Performance tests of lightweight die-casting aluminum alloy materials obtained in Examples 1-9 and Comparative Example 1

[0070] As can be seen from Examples 1-3 and Comparative Example 1, by using a high-silicon, low-magnesium aluminum alloy system and introducing components such as nanocomposite modifiers, compared with Comparative Example 1 which only uses TiC, Examples 1-3 achieve higher strength (tensile strength > 300 MPa) while ensuring elongation is stable at over 12%, achieving a basic balance between high strength and good plasticity. This indicates that the synergistic effect of the high-silicon, low-magnesium system and the nanocomposite modifier is the key to obtaining basic high performance of the material.

[0071] Based on Example 3, Examples 4 and 5, by introducing and adjusting the amount of composite seed crystals, showed a trend of simultaneous enhancement of strength and plasticity. This indicates that the introduction of composite seed crystals can effectively refine grains and optimize microstructure, thereby achieving a synergistic improvement in strength and plasticity in terms of basic properties.

[0072] As can be seen from Examples 5-9, by optimizing and adjusting the amount of rare earth elements Eu and Dy, the strength and plasticity can be effectively balanced. When the amount of rare earth is excessive, the performance fluctuates slightly but still remains at a high level.

[0073] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An aluminum alloy material for light weight die casting, characterized by comprising, in mass %, It is made from the following raw materials in the following weight percentages: Si: 6.0%~8.0%, Mg: 0.6%~0.9%, Mn: 0.6%~1.2%, V: 0.05%~0.15%, Zr: 0.05%~0.1%, nanocomposite modifier: 0.05%~0.2%, Fe≤0.6%, unavoidable impurities: total ≤0.2%, balance Al; wherein, 0.08≤Mg / Si≤0.12; The nanocomposite modifier has a core-shell structure, with TiC as the core and rare earth oxide REOx as the outer layer, wherein RE is Y or Ce; The preparation method of the nanocomposite modifier includes the following steps: TiC was dispersed in water, rare earth nitrates were added and mixed evenly, the pH was adjusted to 9-10, the temperature was raised to 120-160℃, the hydrothermal reaction was carried out for 4-6 hours, the mixture was cooled, the solid and liquid were separated, washed, dried, calcined at 550-600℃ for 1-2 hours, and cooled to obtain the nanocomposite modifier. The mass ratio of TiC to rare earth nitrate is (2~4):1, and the rare earth nitrate is Y(NO3)3·6H2O and / or Ce(NO3)3·6H2O; The lightweight die-casting aluminum alloy material also includes 0.05% to 0.25% Eu.

2. The lightweight die-casting aluminum alloy material according to claim 1, characterized in that, The lightweight die-casting aluminum alloy material also includes 0.2% to 0.8% composite seed crystals, which include aluminum-titanium-boron seed crystals and aluminum-zirconium seed crystals.

3. The lightweight die-casting aluminum alloy material according to claim 2, characterized in that, The amount of aluminum zirconium seed crystals used is 20% to 40% of the total mass of the composite seed crystals.

4. A method for preparing a lightweight die-casting aluminum alloy material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: Under an inert atmosphere, the raw materials are put into a melting furnace and heated to 730~750℃. After complete melting, 0.3%~0.5% of sodium-free refining agent is added according to the total mass of the raw materials, and inert gas is introduced. The materials are refined for 15~25 minutes, allowed to stand for 15~25 minutes, and after slag removal, they are cast into shape at 680~710℃ and cooled to obtain lightweight die-casting aluminum alloy material.

5. The method for preparing lightweight die-casting aluminum alloy material according to claim 4, characterized in that, First, put all raw materials except magnesium, nano-composite modifier and Eu into the smelting furnace. After they are completely melted, add magnesium, nano-composite modifier and Eu in sequence.

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