A high-toughness, corrosion-resistant die-cast aluminum alloy suitable for shells, preparation method and application thereof

Abstract

The present invention relates to a high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a shell, a preparation method thereof, and an application thereof. The alloy comprises: Si: 7.5-10.5wt%; Fe: 0.10-0.45wt%; Mn: 0.20-0.75wt%; Cr: 0.01-0.3wt%; Mg: 0.05-0.60wt%; Zr: 0.01-0.20wt%; Re: 0.005-0.25wt%; Ti: 0.01-0.25w%; and Sr: 0.001-0.03wt%. Cu and Zn are controlled as impurities, Cu+Zn: ≤0.10wt%, the sum of the weight percentages of other impurities is controlled to be below 0.5wt%, and the balance is Al. Re is one or both of Ce and La, and the total weight of Ce and La is ≤0.25wt%. The Cr / Re mass ratio is 1:1-6:1. Compared with the prior art, the die-cast aluminum alloy of the present invention has good die-casting properties, high toughness and excellent corrosion resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of die-cast aluminum alloys, and in particular to a high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a shell and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of the security surveillance industry, camera housings, as a core component, have become increasingly demanding. Currently, die-cast aluminum alloy ADC12 is widely used in the manufacture of security camera housings due to its excellent formability, lightweight design, and cost advantages. However, as an Al-Si-Cu alloy, ADC12's high content of Cu, Zn, and Fe creates a significant potential difference with the aluminum matrix, easily forming a micro-battery effect in corrosive media. This significantly reduces the material's corrosion resistance in humid, salt-spray, or acidic environments, making it susceptible to pitting and intergranular corrosion, which directly impacts product reliability and service life. High salinity can accelerate surface corrosion, leading to blistering, discoloration, and even perforation on the housing surface, threatening the sealing and functional integrity of internal electronic components. Furthermore, due to its complex composition, ADC12 has poor toughness and is prone to cracking. This makes die-cast ADC12 security brackets prone to fracture, threatening the functional integrity of security products.

[0003] To improve the corrosion resistance of ADC12, the industry generally adopts a dual protection approach combining passivation with anodizing or organic coating. For example, anodizing creates an aluminum oxide layer on the surface of aluminum alloys to enhance corrosion resistance, which is then supplemented with an organic coating (such as powder coating) to further isolate it from environmental corrosion. However, this approach has significant limitations. First, the anodizing and passivation processes involve treatment with strong acids, strong bases, and heavy metals (such as chromate passivation). The production process easily generates wastewater and waste residue containing heavy metals, polluting the ecological environment and posing high costs for subsequent wastewater treatment. Second, the process is complex, requiring multiple pretreatment, oxidation, sealing, and coating steps. This not only consumes a lot of energy and requires a long cycle, but also increases manufacturing costs. Furthermore, even with multiple protection measures, the coating can easily develop microcracks due to differences in thermal expansion coefficients or mechanical damage in environments with high salt fog, high temperature, and high humidity. Corrosive media can still penetrate the protective layer and corrode the substrate, rendering the protective effect unsustainable.

[0004] Patent CN 118547189A discloses a high-strength, corrosion-resistant die-cast aluminum alloy. The alloy comprises the following raw materials by weight: 7.5-10.5% Si, 0.8-1.7% Mg, 0-0.35% Fe, 0.15-0.40% Cr, 0.1-0.25% Ti, 0.01-0.04% Sr, and the balance aluminum. This alloy improves strength through the Mg2Si formed by Mg and Si, modifies the Fe phase morphology through Cr, and enhances demoldability through the Fe-to-Cr mass ratio. However, the high Mg content in this patent increases the material's brittleness. As is well known, the addition of high Mg content significantly increases the material's shrinkage and hot cracking susceptibility, making it prone to cracking when die-casting thin-walled, deep-cavity products, making them difficult to produce. Furthermore, since the Fe in the material is modified solely through Cr, the modification effect is limited. Furthermore, Cr is a transition element that easily precipitates and accumulates slag, making it difficult to ensure a satisfactory modification effect in actual production.

[0005] The shortcomings of existing technologies have given rise to the industry's urgent demand for new materials or green and efficient protection technologies. There is an urgent need for a solution that takes into account environmental protection, economy and long-term corrosion resistance. The development of a new shell material that does not require complex surface treatment, is environmentally friendly and has excellent corrosion resistance, die-casting and toughness has become a key direction to break through industry bottlenecks. Summary of the Invention

[0006] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a high-toughness, corrosion-resistant die-cast aluminum alloy suitable for shells and a preparation method thereof.

[0007] The object of the present invention can be achieved by the following technical solutions: A high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a shell, the alloy comprising: Si: 7.5-10.5wt%; Fe: 0.10-0.45wt%; Mn: 0.20-0.75wt%; Cr: 0.01-0.3wt%; Mg: 0.05-0.60wt%; Zr: 0.01-0.20wt%; Re: 0.005-0.25wt%; Ti: 0.01-0.25w%; Sr: 0.001-0.03wt%; wherein Cu and Zn are controlled as impurities, Cu+Zn: ≤0.10wt%, the sum of the weight percentages of the remaining impurities is controlled to be below 0.5wt%, and the balance is Al;

[0008] Wherein: Re is one or both of Ce and La, and the total mass of Ce and La is ≤0.25wt%; and the mass ratio of Cr / Re is 1:1~6:1.

[0009] Furthermore, the alloy comprises: Si: 7.5-10.5wt%; Fe: 0.10-0.35wt%; Mn: 0.20-0.50wt%; Cr: 0.05-0.2wt%; Mg: 0.2-0.6wt%; Zr: 0.01-0.1wt%; La: 0.001-0.05wt%; Ce: 0.05-0.12wt%; Ti: 0.1-0.2w%; Sr: 0.01-0.03wt%; the sum of the weight percentages of the remaining impurities is controlled below 0.5wt%, with the balance being Al;

[0010] The total mass of Cu and Zn is ≤0.08 wt%; the total mass of Ce and La is ≤0.20 wt%; and the mass ratio of Cr / Re is 1:1 to 3:1.

[0011] Furthermore, the aluminum alloy structure includes α-Al, eutectic structure and precipitation phase;

[0012] The eutectic structure is mainly a eutectic structure formed by Al and Si; the precipitated phase mainly includes: Al 11 Ce3 phase, Al 11 La3 phase, Mg2Si phase, Al3Zr phase and multi-component AlMSi phase, wherein M is one or more of Fe, Mn, Cr or Re.

[0013] The present invention also provides a method for preparing the high-toughness, corrosion-resistant die-cast aluminum alloy suitable for the housing, comprising the following steps:

[0014] Step S1: weighing pure Al raw material, Al-Si alloy, Mg ingot, Al-Fe alloy, Al-Cr alloy, Al-Zr alloy, Al-Mn alloy, Al-La alloy, Al-Ce alloy, Al-Ti alloy and Al-Sr alloy according to mass ratio;

[0015] Step S2: Place pure Al raw material into a heating furnace and heat to 680°C. After the aluminum metal is completely melted into molten aluminum liquid, let it stand and keep warm for 20-30 minutes;

[0016] Step S3: heating to 780°C, adding Al-Si alloy, Al-Fe alloy, Al-Cr alloy, Al-Mn alloy, and Al-Zr alloy in proportion, and waiting for them to be completely dissolved;

[0017] Step S4: Cooling to 750°C, adding Al-Ce alloy, Al-La alloy, and Al-Ti alloy, and keeping the temperature for 20-30 minutes;

[0018] Step S5: Cooling to 720°C, adding Mg ingots and Al-Sr alloy, keeping the temperature for 15-20 minutes, and then performing degassing and refining;

[0019] Step S6: Cast a sample for component analysis. If the sample is qualified, the melt is sent to a molding device to be molded to obtain a rare earth-transition group synergistically modified high-toughness and corrosion-resistant die-cast aluminum alloy ingot.

[0020] Furthermore, the aluminum alloy ingot obtained in step S6 is melted again at 700-720° C. and kept warm. A protective gas is introduced during the heat preservation to isolate it from the air. The ingot is then injected into a die-casting mold for die-casting to obtain a high-toughness, corrosion-resistant aluminum alloy product.

[0021] Further, the molten material is injected into the barrel of the die-casting mold for pre-filling, and the pre-filling speed is controlled at 0.4~0.5m / s;

[0022] The material in the barrel is injected into the mold by injection, and the injection adopts a filling method of first low speed and then high speed. The low speed is controlled at 0.10~0.25m / s and the high speed is controlled at 3.5-5.5m / s.

[0023] The injection pressure is 120~180bar, the injection flow rate is 70~90%, the return hammer pressure is 140~200bar, the injection time is 3~5s, and the holding time is 3~5s.

[0024] The die casting mold is temperature controlled by an oil temperature controller, which is set at 220~260℃.

[0025] The present invention also provides an application of the high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing, wherein the high-toughness, corrosion-resistant die-cast aluminum alloy is used as a housing for security monitoring equipment.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention aims to solve the problems of insufficient corrosion resistance, poor toughness, complicated process and high coating defect rate of ADC12 used in existing security housings, and provides a high-toughness corrosion-resistant die-cast aluminum alloy. This new alloy achieves corrosion resistance comparable to that of ADC12 after passivation and anodic coating without the need for passivation and anodic coating. At the same time, its strength and toughness are better than ADC12, which improves the reliability of product structure. It has a significant promoting effect on enterprise cost reduction, efficiency improvement, after-sales market customer complaints and environmental friendliness.

[0028] 2. This invention primarily utilizes an Al-Si system. Si releases latent heat of crystallization during solidification, and the Al-Si eutectic structure exhibits excellent shrinkage-feeding properties, thereby ensuring material fluidity. Since security housings are deep-cavity products, the addition of Fe is necessary to enhance the material's release ability and prevent mold sticking and die-drawing defects. However, Fe tends to form needle-like Al3Fe phases during solidification. These long needle-like phases easily split the matrix, causing cracks. Furthermore, Fe is a strong cathodic phase relative to the aluminum matrix, reducing the material's corrosion resistance and necessitating modification of the Fe phase. The present invention refines the Fe phase structure and promotes uniform phase distribution. Simultaneously, the addition of Cr forms an Al(FeMnCr)Si multinary compound. This multinary compound exhibits a lower potential difference with the aluminum matrix than the Fe phase, further mitigating the adverse effects of Fe on the alloy's corrosion resistance. Furthermore, the more dispersed and uniformly distributed Fe phase reduces its matrix-splitting effects, contributing to improved material toughness. Cu and its corresponding Al2Cu phase are strongly cathodic to the Al matrix, significantly degrading corrosion resistance. Zn, due to its low potential and significant difference from the Al matrix, also reduces the material's corrosion resistance, necessitating strict control of the Cu+Zn ratio. Zr addition forms a nanoscale Al3Zr dispersion, enhancing performance. Sr addition refines the Si phase, preventing the formation of coarse, plate-like Si phases. Coarse Si phases not only reduce mechanical properties but also tend to form microcracks or stress concentration points on the surface, accelerating corrosion.

[0029] 3. The present invention reduces impurities and purifies aluminum liquid by adding rare earth Ce and La. At the same time, Ce and La can be enriched on the surface of the Fe phase during solidification, hindering the growth of the Fe phase and further refining the Fe phase morphology. At the same time, the corresponding aluminum rare earth precipitation phase can serve as a heterogeneous nucleation point to promote the further refinement of α-Al, thereby improving the strength and toughness of the material. At the same time, the present invention has verified that the synergistic addition of Re and Cr can improve the surface state of aluminum alloys, wherein the Cr / Re ratio is more suitable to be controlled at 1:1~6:1. The endogenous Al-Cr-Re-O composite passivation layer formed at this ratio has a better effect on Cl compared to the traditional porous Al2O3 passivation layer. - It has a more significant barrier effect on the penetration of corrosive media, delaying the entry and spread of corrosive media and improving the corrosion resistance of the material. At the same time, it has been verified that the total amount of rare earth added must be controlled below 0.25wt.%. Adding too much rare earth easily forms coarse phases and deteriorates performance. At the same time, due to the large difference in potential between the rare earth itself and the Al matrix, adding too much rare earth will also deteriorate the corrosion resistance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the microstructure (500 times) of the die-cast aluminum alloy ingot of Example 2 of the present invention.

[0031] Figure 2This is the microstructure (500 times) of the die-cast aluminum alloy sheet of Example 2 of the present invention.

[0032] Figure 3 This is the microstructure of the commercially available ADC12 die-cast aluminum alloy ingot (500x).

[0033] Figure 4 This is a microscopic metallographic image (500x) of a commercially available ADC12 die-cast aluminum alloy sheet. DETAILED DESCRIPTION

[0034] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process. However, the protection scope of the present invention is not limited to the following embodiment.

[0036] The object of the present invention can be achieved by the following technical solution: A high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing, the alloy comprising:

[0037] Si: 7.5-10.5wt%; Fe: 0.10-0.40wt%; Mn: 0.20-0.50wt%; Cr: 0.01-0.3wt%; Mg: 0.05-0.6wt%; Zr: 0.01-0.2wt%; La: 0.001-0.05wt%; Ce: 0.05-0.12wt%; Ti: 0.01-0.25w%; Sr: 0.001-0.03wt%; wherein Cu and Zn are controlled as impurities, Cu+Zn: ≤0.10wt%, the sum of the weight percentages of impurities is controlled below 0.5wt%, and the balance is Al, wherein: Re is one or both of Ce and La, and the total mass of Ce and La is ≤0.25wt%; and the Cr / Re mass ratio is 1:1~6:1.

[0038] The compositions of Examples 1-5, Comparative Examples 1-5 and commercially available ADC12 alloy are shown in Table 1 below:

[0039] Table 1 is the aluminum alloy content of the examples and comparative examples

[0040]

[0041] The alloys of the above embodiments and comparative examples were prepared by the following method:

[0042] Step S1: first weigh commercially available pure Al raw material, Al-20Si alloy, Mg ingot, Al-20Fe alloy, Al-5Zr alloy, Al-10Cr alloy, Al-15Mn alloy, Al-20La alloy, Al-20Ce alloy, Al-75Ti alloy, and Al-10Sr alloy according to mass ratio;

[0043] Step S2: First, pure Al element is placed in a heating furnace and heated to 680°C. After the aluminum metal is completely melted into molten aluminum liquid, it is kept at this temperature for 20-30 minutes.

[0044] Step S3: heating to 780°C, adding Al-20Si alloy, Al-20Fe alloy, Al-10Cr alloy, Al-15Mn alloy, and Al-5Zr alloy in proportion, and waiting for them to be completely dissolved;

[0045] Step S4: cooling to 750°C, adding Al-20Ce alloy, Al-20La alloy, and Al-75Ti master alloy, and keeping the temperature for 20-30 minutes;

[0046] Step S5: Cooling to 720°C, adding Mg ingots and Al-10Sr, keeping the temperature for 15-20 minutes, and then performing degassing and refining;

[0047] Step S6: Cast a sample for component analysis. If qualified, the melt is sent to a molding device to be molded into a high-toughness, corrosion-resistant die-cast aluminum alloy ingot.

[0048] Step S7: The aluminum alloy ingot obtained in step S6 is melted again at 720°C and kept warm. During the insulation, a protective gas (N2 is used in this embodiment) is introduced to isolate it from the air, and then injected into the barrel of the die-casting mold for pre-filling. The pre-filling speed is controlled at 0.4m / s. The material in the barrel is injected into the mold by injection. The injection adopts a filling method of first low speed and then high speed. The low speed is controlled at 0.15m / s and the high speed is controlled at 4m / s. The injection pressure is 140bar, the injection flow rate is 70%, the back hammer pressure is 160bar, the injection time is 4s, and the holding time is 4s. The die-casting mold is temperature-controlled by an oil temperature machine, where the oil temperature machine is set at 230°C. High-pressure die-casting is performed to obtain a high-toughness and corrosion-resistant aluminum alloy product.

[0049] The obtained alloy was subjected to performance testing, and the results are shown in Table 2 below:

[0050] In the examples in Table 2, the material state refers to the state of the alloy after high-pressure die casting without any heat treatment;

[0051] The mechanical properties, tensile strength, yield strength and elongation of the present invention are tested in accordance with the national standard GB / T 228.1-2010;

[0052] Electrochemical corrosion detection in the present invention: Examples 1 to 5 / Comparative Examples 1 to 5 / commercially available ADC12 as the working electrode; the reference electrode is a saturated calomel electrode (SCE); the corrosive medium is a 3.5 wt% NaCl solution; the corrosion potential (V SCE ) and corrosion current (A / cm²) were obtained according to the Tafel extrapolation method;

[0053] Table 2 Performance of Examples 1-5 / Comparative Examples 1-5 / Performance of Commercially Available ADC12

[0054]

[0055] Analyze the specific results from Table 2 above:

[0056] The elongation of Examples 1 to 5 of the present application is higher than 10%, which is significantly improved compared with the elongation of 3.4% of commercially available ADC12. The tensile strength and yield strength are also higher than those of commercially available ADC12. The equilibrium corrosion current of commercially available ADC12 is 1.74×10 -5 A / cm², the corrosion current of Examples 1 to 5 is one order lower than that of ADC12, and the comprehensive corrosion resistance is significantly improved, and it can replace ADC12 in the manufacture of camera housing products.

[0057] Comparative Example 1 adds Cu to Example 2. It can be found that the addition of Cu improves the tensile strength of the material and shifts the equilibrium corrosion potential positively, but significantly increases the equilibrium corrosion current and decreases corrosion resistance. This is because Cu itself has a high potential, and the corresponding compound is a strong cathodic phase relative to the Al matrix, causing micro-area corrosion and reducing corrosion resistance. Therefore, the amount of Cu is strictly limited.

[0058] Comparative Example 2 adds Zn to Example 2. It can be seen that the addition of Zn slightly improves mechanical properties, shifts the equilibrium corrosion potential negatively, increases the equilibrium corrosion current, and decreases corrosion resistance. This is because Zn itself has a relatively negative potential, which lowers the material's equilibrium potential, increases the corrosion tendency, and reduces corrosion resistance. Therefore, the Zn content is strictly limited.

[0059] Comparative Example 3 adds a larger amount of rare earth elements to Example 2. Excessive addition of rare earth elements can easily lead to the formation of rare earth particulate phases, reducing the material's elongation. It also increases corrosion current and reduces corrosion resistance. This is because rare earths have low solid solubility. Excessive rare earth addition forms coarse rare earth precipitates. These hard and brittle intermetallic compounds can fracture the matrix, leading to a decrease in elongation. Furthermore, the significant potential difference between excessive coarse rare earth compounds and the matrix can lead to a decrease in corrosion resistance. Therefore, the total amount of rare earth added is controlled.

[0060] Comparative Example 4 is based on Example 2, but no rare earth element is added. It can be found that the equilibrium corrosion current of the sample without rare earth addition is increased compared to Example 2 with rare earth addition, and the corrosion resistance is lower than that of Example 2.

[0061] Comparative Example 5, based on Example 2, does not add the additional modifiers Mn / Cr and rare earth elements. It can be seen that the equilibrium corrosion current of Comparative Example 5 increases significantly compared to Example 2, and the corrosion resistance decreases. This is because Fe and its corresponding phases are strong cathode phases, with a large potential difference from the Al matrix, which easily leads to micro-region galvanic cells, resulting in a decrease in corrosion resistance. In contrast, in Example 2, which adds modifiers and rare earth elements, the Fe phase morphology is more dispersed and simultaneously transforms into the Al(Fe, Mn, Cr, Re)Si multi-element phase, reducing the potential difference with the matrix, resulting in a reduced corrosion rate and improved corrosion resistance.

[0062] Figure 1 This is the microstructure of the die-cast aluminum alloy ingot of Example 2 (500 times). It can be seen from the figure that: the Fe phase and Si phase are evenly metamorphosed, the particle morphology is round, no abnormal precipitates such as coarse phase and needle phase are found, the grain distribution is uniform, and the addition of elements with large potential differences is controlled and restricted to ensure the overall potential distribution of the precipitate phase and the matrix, thereby obtaining good mechanical properties and excellent corrosion resistance.

[0063] Figure 2 This is the microstructure of the die-cast aluminum alloy sheet of Example 2 (500 times). It can be seen from the figure that after the ingot is die-cast into a test piece, the overall Si phase and Fe phase are dispersed, the particles are regular, and no abnormal precipitates such as coarse phase and needle-like phase are found. The grains and precipitates are evenly distributed, and good mechanical properties and excellent corrosion resistance can be obtained.

[0064] Figure 3 This is a microstructure of the commercially available ADC12 die-cast aluminum alloy ingot (500 times). It can be seen from the figure that there are more coarse phases and long needle-like phases in the aluminum ingot structure. This coarse needle phase can easily split the matrix, resulting in a decline in mechanical properties. At the same time, due to the high content of alloying elements such as Fe and Cu and their uneven distribution, there is a large difference in potential with the matrix, which can easily lead to obvious electrochemical corrosion and a decrease in corrosion resistance.

[0065] Figure 4 This is a microscopic metallographic image of a commercially available ADC12 die-cast aluminum alloy sheet (500x). It can be seen from the figure that after the aluminum ingot is die-cast into a test piece, a large number of long needle-like phases are still present in the structure. This coarse needle phase can easily cut the matrix, causing a decline in mechanical properties. At the same time, due to the high content of alloying elements such as Fe and Cu and their uneven distribution, the potential difference with the matrix is large, which can easily lead to obvious electrochemical corrosion and cause a decrease in corrosion resistance.

[0066] The above are preferred implementation modes and descriptions of the present invention, but the protection scope of the present invention is not limited to the above implementations. All technical solutions under the concept of the present invention fall within the protection scope of the present invention.

Claims

1. A high-toughness, corrosion-resistant die-cast aluminum alloy suitable for housings, characterized in that: The alloy Including: Si: 7.5-10.5wt%; Fe: 0.10-0.45wt%; Mn: 0.20-0.75wt%; Cr: 0.01-0.3wt%; Mg : 0.05-0.60wt%; Zr: 0.01-0.20wt%; Re: 0.005-0.25wt%; Ti: 0.01-0.25w%; Sr: 0.001-0.03wt%; Cu and Zn are controlled as impurities, Cu+Zn: ≤0.10wt%, the sum of the weight percentages of other impurities is controlled below 0.5wt%, and the balance is Al; wherein: Re is one or both of Ce and La, and the total mass of Ce and La is ≤0.25wt%; the mass ratio of Cr / Re is 1:1 to 6:1, at which an endogenous Al-Cr-Re-O composite passivation layer is formed; the high-toughness, corrosion-resistant die-cast aluminum alloy is used as a housing for security monitoring equipment; The alloy is prepared by the following method: Step S1: weighing pure Al raw material, Al-Si alloy, Mg ingot, Al-Fe alloy, Al-Cr alloy, Al-Zr alloy, Al-Mn alloy, Al-La alloy, Al-Ce alloy, Al-Ti alloy and Al-Sr alloy according to mass ratio; Step S2: Place pure Al raw material into a heating furnace and heat to 680°C. After the aluminum metal is completely melted into molten aluminum liquid, let it stand and keep warm for 20-30 minutes; Step S3: heating to 780°C, adding Al-Si alloy, Al-Fe alloy, Al-Cr alloy, Al-Mn alloy, and Al-Zr alloy in proportion, and waiting for them to be completely dissolved; Step S4: Cooling to 750°C, adding Al-Ce alloy, Al-La alloy, and Al-Ti alloy, and keeping the temperature for 20-30 minutes; Step S5: Cooling to 720°C, adding Mg ingots and Al-Sr alloy, keeping the temperature for 15-20 minutes, and then performing degassing and refining; Step S6: Casting a sample for component analysis, and if qualified, sending the melt into a molding device to form a rare earth-transition group synergistically modified high-toughness and corrosion-resistant die-cast aluminum alloy ingot; The aluminum alloy ingot obtained in step S6 is melted again at 700-720° C. and kept warm, while introducing a protective gas to isolate it from the air, and then injected into a die-casting mold for die-casting to obtain a high-toughness, corrosion-resistant die-cast aluminum alloy product; During the die-casting process, the material in the barrel is injected into the mold by injection. The injection adopts a filling method of first low speed and then high speed. The low speed is controlled at 0.10~0.25m / s and the high speed is controlled at 3.5-4.5m / s. The injection pressure is 120~180bar, the injection flow rate is 70~90%, the return hammer pressure is 140~200bar, the injection time is 3~5s, and the holding time is 3~5s.

2. The high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing according to claim 1, characterized in that: The alloy Including: Si: 7.5-10.5wt%; Fe: 0.10-0.35wt%; Mn: 0.20-0.50wt%; Cr: 0.05-0.2wt%; Mg: 0.2-0.6wt%; Zr: 0.01-0.1wt%; La: 0.001-0.05wt%; Ce: 0.05-0.12wt%; Ti: 0.1-0.2w%; Sr: 0.01-0.03wt%; The sum of the weight percentages of impurities is controlled below 0.5wt%, with the remainder being Al; The total mass of Cu and Zn is ≤0.08 wt%; the total mass of Ce and La is ≤0.20 wt%; and the mass ratio of Cr / Re is 1:1 to 3:

1.

3. The high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing according to claim 1, characterized in that: Aluminum alloy structure includes α-Al, eutectic structure and precipitation phase; Wherein, the eutectic structure is mainly a eutectic structure formed by Al and Si; The precipitated phase mainly includes: Al 11 Ce3 phase, Al 11 La3 phase, Mg2Si phase, Al3Zr phase and multi-component AlMSi phase, wherein M is one or more of Fe, Mn, Cr or Re.

4. A method for preparing a high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing as claimed in any one of claims 1 to 3, characterized in that: The steps include: Step S1: weighing pure Al raw material, Al-Si alloy, Mg ingot, Al-Fe alloy, Al-Cr alloy, Al-Zr alloy, Al-Mn alloy, Al-La alloy, Al-Ce alloy, Al-Ti alloy and Al-Sr alloy according to mass ratio; Step S2: Place pure Al raw material into a heating furnace and heat to 680°C. After the aluminum metal is completely melted into molten aluminum liquid, let it stand and keep warm for 20-30 minutes; Step S3: heating to 780°C, adding Al-Si alloy, Al-Fe alloy, Al-Cr alloy, Al-Mn alloy, and Al-Zr alloy in proportion, and waiting for them to be completely dissolved; Step S4: Cooling to 750°C, adding Al-Ce alloy, Al-La alloy, and Al-Ti alloy, and keeping the temperature for 20-30 minutes; Step S5: Cooling to 720°C, adding Mg ingots and Al-Sr alloy, keeping the temperature for 15-20 minutes, and then performing degassing and refining; Step S6: Cast a sample for component analysis. If the sample is qualified, the melt is sent to a molding device to be molded to obtain a rare earth-transition group synergistically modified high-toughness and corrosion-resistant die-cast aluminum alloy ingot.

5. The method for preparing a high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing according to claim 4, characterized in that: The aluminum alloy ingot obtained in step S6 is melted again at 700-720° C. and kept warm. During the keeping warm period, a protective gas is introduced to isolate the ingot from the air. The ingot is then injected into a die-casting mold for die-casting to obtain a high-toughness, corrosion-resistant die-cast aluminum alloy product.

6. The method for preparing a high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing according to claim 5, characterized in that: The molten material is injected into the barrel of the die-casting mold for pre-filling, and the pre-filling speed is controlled at 0.4~0.5m / s.

7. The method for preparing a high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing according to claim 6, characterized in that: The material in the barrel is injected into the mold by injection, which adopts a filling method of first low speed and then high speed. The low speed is controlled at 0.10~0.25m / s and the high speed is controlled at 3.5-4.5m / s. The injection pressure is 120~180bar, the injection flow rate is 70~90%, the return hammer pressure is 140~200bar, the injection time is 3~5s, and the holding time is 3~5s.

8. The method for preparing a high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing according to claim 7, characterized in that: The die casting mold is temperature controlled by an oil temperature controller, which is set at 220~260℃.

9. An application of the high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing as claimed in any one of claims 1 to 3, characterized in that: The high-toughness and corrosion-resistant die-cast aluminum alloy is used as the shell of security monitoring equipment.

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