High-toughness corrosion-resistant die-casting aluminum alloy suitable for shell and preparation method and application of high-toughness corrosion-resistant die-casting aluminum alloy

Abstract

The invention relates to a high-toughness corrosion-resistant die-casting aluminum alloy suitable for a shell and a preparation method and application of the high-toughness corrosion-resistant die-casting aluminum alloy. The high-toughness corrosion-resistant die-casting aluminum alloy comprises 7.5-10.5 wt% of Si; 0.10 wt% to 0.45 wt% of Fe; 0.20 to 0.75 wt% of Mn; 0.01 to 0.3 wt% of Cr; mg: 0.05 to 0.60 wt%; zr: 0.01 to 0.20 wt%; re: 0.005 to 0.25 wt%; ti: 0.01 to 0.25 wt%; 0.001 wt% to 0.03 wt% of Sr; wherein Cu and Zn are controlled as impurities, the content of Cu and Zn is less than or equal to 0.10 wt%, the sum of the weight percentages of the other impurities is controlled to be less than 0.5 wt%, and the balance is Al; wherein Re is one or two of Ce and La, and the total mass of Ce and La is less than or equal to 0.25 wt%; the mass ratio of Cr to Re is (1: 1)-(6: 1). Compared with the prior art, the die-casting aluminum alloy has good die-casting performance, obdurability and excellent corrosion resistance.

Description

Technical Field

[0001] The 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 monitoring industry, the performance requirements of the camera shell material have become increasingly stringent as one of the core equipment. At present, die-cast aluminum alloy ADC12 is widely used in the manufacture of security camera shells due to its excellent formability, lightweight and cost advantages. However, as an Al-Si-Cu alloy, ADC12 has a significant potential difference with the aluminum matrix due to its high content of Cu, Zn and Fe phases, and is prone to form a micro-battery effect in the corrosive medium, resulting in a significant decrease in the corrosion resistance of the material in a humid, salt spray or acidic environment, and is prone to pitting and intergranular corrosion, which directly affects the reliability and service life of the product. High-salinity environment will accelerate the corrosion of the material surface, causing blistering, discoloration and even perforation on the shell surface, threatening the sealing and functional integrity of the internal electronic components. At the same time, due to the complex composition, poor toughness and easy cracking of ADC12, the die-cast security bracket of ADC12 is prone to the risk of fracture, threatening the functional integrity of the security product.

[0003] In order to improve the corrosion resistance of ADC12, the industry generally adopts a dual protection solution of passivation treatment combined with anodized coating or organic coating. For example, an aluminum oxide layer is generated on the surface of aluminum alloy through an anodizing process to improve corrosion resistance, and then an organic coating (such as powder coating) is used to further isolate environmental erosion. However, this method has significant limitations: first, the anodizing and passivation processes involve strong acid, strong alkali and heavy metal treatment (such as chromate passivation), and heavy metal-containing wastewater and waste residue are easily generated during the production process, which pollutes the ecological environment, and the subsequent wastewater treatment costs are high; secondly, the process flow is cumbersome and requires multiple pretreatment, oxidation, sealing and coating processes, which not only consumes a lot of energy and has a long cycle, but also increases the manufacturing cost. In addition, even after multiple protections, in an environment with high salt fog, high temperature and high humidity, the coating is prone to microcracks due to differences in thermal expansion coefficients or mechanical damage, and the corrosive medium may still penetrate the protective layer and corrode the substrate, resulting in unsustainable protection effects.

[0004] Patent CN 118547189A discloses a high-strength and corrosion-resistant die-cast aluminum alloy, which includes the following raw materials in weight percentage: 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 is aluminum. The alloy improves the strength of the alloy through Mg2Si formed by Mg and Si, changes the Fe phase morphology through Cr, and improves the demoulding property through the mass ratio of Fe to Cr. However, due to the high Mg content in this patent, the brittleness of the material increases. As we all know, the addition of high Mg content will seriously increase the shrinkage and hot cracking of the material, and it is easy to crack when die-casting thin-walled deep-cavity products, making it difficult to produce. At the same time, since the deterioration of Fe in the material is only carried out through the Cr element, the deterioration effect is single, and Cr is a transition element that is easy to accumulate slag and is easy to precipitate, it is difficult to ensure a good deterioration effect in the actual production process.

[0005] The shortcomings of existing technologies have given rise to the industry's urgent need for new materials or green and efficient protection technologies. A solution that takes into account environmental protection, economy and long-term corrosion resistance is urgently needed. 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 and corrosion-resistant die-cast aluminum alloy suitable for shells and a preparation method thereof.

[0007] The purpose 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; 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.

[0008] 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%, and the balance is Al; Wherein: the total mass of Cu and Zn is ≤0.08wt%; the total mass of Ce and La is ≤0.20wt%; and the mass ratio of Cr / Re is 1:1~3:1.

[0009] Further, the aluminum alloy structure includes α-Al, eutectic structure and precipitation phase; 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.

[0010] The present invention also provides a method for preparing the high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing, comprising the following steps: 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: Put the pure Al raw material into a heating furnace, heat it to 680°C, and after the aluminum metal is completely melted into molten aluminum liquid, let it stand and keep warm for 20-30 minutes; Step S3: raising the temperature 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 ingot and Al-Sr alloy, keeping the temperature for 15-20 minutes and then performing degassing and refining; Step S6: The casting sample is subjected to component analysis. If the sample is qualified, the melt is sent to a molding device to obtain a rare earth-transition group synergistically modified high-toughness, corrosion-resistant die-casting aluminum alloy ingot.

[0011] Furthermore, 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 it from the air. Then, it is injected into a die-casting mold for die-casting to obtain a high-toughness and corrosion-resistant aluminum alloy product.

[0012] 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 0.4-0.5 m / s; 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.

[0013] 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.

[0014] The die casting mold is temperature controlled by an oil temperature controller, where the oil temperature controller is set at 220~260℃.

[0015] The present invention also provides an application of the high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a shell, and the high-toughness, corrosion-resistant die-cast aluminum alloy is used as a shell of a security monitoring device.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention aims to provide a high-toughness, corrosion-resistant die-cast aluminum alloy to address the problems of insufficient corrosion resistance, poor toughness, complicated process, and high coating defect rate of ADC12 used in existing security housings. The 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, the toughness is better than ADC12, which improves the reliability of product structure and has a significant role in reducing corporate costs, improving efficiency, reducing customer complaints in the after-sales market, and being environmentally friendly.

[0017] 2. The present invention is mainly based on the Al-Si system. Si releases latent heat of crystallization during the solidification process. At the same time, the Al-Si eutectic structure has good shrinkage compensation, thereby ensuring the fluidity of the material. Since the security shell is a deep-cavity product, it is necessary to add Fe to improve the demoulding ability of the material to avoid sticking and drawing defects. However, Fe is easy to generate a needle-like Al3Fe phase during the solidification process. This long needle-like phase is easy to split the matrix and produce cracks. At the same time, Fe is a strong cathode phase relative to the aluminum matrix, which will reduce the corrosion resistance of the material and require the Fe phase to be modified. The present invention refines the Fe phase structure and promotes the uniform distribution of the phase by adding Mn. At the same time, the Cr element is added to form an Al (Fe Mn Cr) Si multi-compound. The potential difference between this multi-compound and the aluminum matrix is ​​lower than that of the Fe phase, which further reduces the adverse effect of Fe on the corrosion resistance of the alloy. At the same time, due to the dispersion and uniform distribution of the Fe phase, the splitting effect on the matrix can be reduced, which is conducive to the improvement of the strength and toughness of the material. Cu phase and corresponding Al2Cu are strong cathode phases for Al matrix, which will seriously deteriorate the corrosion resistance. Zn will also reduce the corrosion resistance of the material due to its low potential and large difference with Al matrix, so the Cu+Zn ratio needs to be strictly controlled. The addition of Zr is used to form nano-scale Al3Zr dispersion phase to improve performance. The addition of Sr is used to refine the Si phase to avoid the appearance of coarse plate-like Si phase. In addition to reducing mechanical properties, the coarse Si phase is easy to form microcracks or stress concentration points on the surface, accelerating corrosion.

[0018] 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 Fe phase during solidification, hindering the growth of Fe phase and further refining the Fe phase morphology. At the same time, the corresponding aluminum rare earth precipitation phase can be used as a heterogeneous nucleation point to promote the further refinement of α-Al, thereby improving the toughness of the material. At the same time, the present invention verifies that the synergistic addition of Re and Cr can improve the surface state of aluminum alloy, 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 under this ratio has a better effect on Cl compared with the traditional porous Al2O3 passivation layer. - It has a more obvious barrier effect on the penetration of corrosive media, delaying the entry and spread of corrosive media and improving the corrosion resistance of materials. At the same time, it has been verified that the total amount of rare earth added needs to be controlled below 0.25wt.%. Too much addition will easily form a coarse phase and deteriorate the performance. At the same time, due to the large difference in the potential of the rare earth itself and the Al matrix, the addition of too much rare earth will also deteriorate the corrosion resistance of the material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the microstructure (500 times) of the die-cast aluminum alloy ingot of Example 2 of the present invention.

[0020] Figure 2This is the microstructure (500 times) of the die-cast aluminum alloy sheet of Example 2 of the present invention.

[0021] Figure 3 This is the microstructure of the commercially available ADC12 die-cast aluminum alloy ingot (500 times).

[0022] Figure 4 This is the microstructure of the commercially available ADC12 die-cast aluminum alloy sheet (500 times). DETAILED DESCRIPTION

[0023] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0024] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0025] 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: 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 or La, and the total mass of Ce and La is ≤0.25wt%; the Cr / Re mass ratio is 1:1~6:1.

[0026] The compositions of Examples 1-5, Comparative Examples 1-5 and commercially available ADC12 alloy are shown in Table 1 below: Table 1 is the aluminum alloy content of the embodiment and the comparative example

[0027] The alloys of the above embodiments and comparative examples were prepared by the following method: 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; Step S2: firstly, pure Al element is put into a heating furnace and heated to 680°C. After the aluminum metal is completely melted into molten aluminum liquid, it is kept at the temperature for 20-30 minutes; 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; Step S4: cooling to 750° C., adding Al-20Ce alloy, Al-20La alloy, and Al-75Ti master alloy, and keeping the temperature for 20 to 30 minutes; 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; Step S6: The casting sample is subjected to component analysis. If the sample is qualified, the melt is sent to a molding device to be molded into a high-toughness, corrosion-resistant die-cast aluminum alloy ingot.

[0028] Step S7: The aluminum alloy ingot obtained in step S6 is melted again at 720°C and kept warm. During the heat preservation, 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 return 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, wherein the oil temperature machine is set at 230°C, and high-pressure die-casting is performed to obtain a high-toughness and corrosion-resistant aluminum alloy product.

[0029] The obtained alloy was tested for performance, and the results are shown in Table 2 below: In the example of Table 2, the material state refers to the state of the alloy after high pressure die casting without any heat treatment; The testing of mechanical properties, tensile strength, yield strength and elongation in the present invention is carried out in accordance with the national standard GB / T 228.1-2010; Electrochemical corrosion detection in the present invention: Examples 1 to 5 / Comparative Examples 1 to 5 / Commercially available ADC12 is used 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; Table 2 Performance of Examples 1-5 / Comparative Examples 1-5 / Performance of Commercially Available ADC12

[0030] From the specific results analysis of Table 2 above: The elongation of Examples 1 to 5 of the present application is higher than 10%, which is significantly higher than the elongation of 3.4% of commercially available ADC12, and the toughness is significantly improved, and the tensile strength and yield strength are also higher than commercially available ADC12. Among them, 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 for the manufacture of camera housing products.

[0031] Comparative Example 1 is based on Example 2, and Cu element is added. It can be found that the addition of Cu element can improve the tensile strength of the material, and the equilibrium corrosion potential is positively shifted, but the equilibrium corrosion current is significantly increased, and the corrosion resistance is reduced. This is because the Cu element itself has a high potential, and the corresponding compound is a strong cathode phase relative to the Al matrix, which constitutes micro-area corrosion, resulting in a decrease in corrosion resistance, so the Cu element is strictly limited.

[0032] Comparative Example 2 is based on Example 2, and Zn element is added. It can be found that the addition of Zn element can slightly improve the mechanical properties, negatively shift the equilibrium corrosion potential, increase the equilibrium corrosion current, and reduce the corrosion resistance. This is because the potential of the Zn element itself is relatively negative, which reduces the equilibrium potential of the material, increases the corrosion trend, and reduces the corrosion resistance, so the Zn element is strictly limited.

[0033] Comparative Example 3 is based on Example 2, but a relatively large amount of rare earth elements is added. It can be found that excessive addition of rare earth elements easily results in rare earth particle phase, which reduces the elongation of the material, and it can be found that the corrosion current increases and the corrosion resistance decreases. This is because the rare earth has a low solid solubility, and excessive rare earth addition forms a coarse rare earth precipitation phase. This intermetallic compound is hard and brittle, which cuts the matrix and causes the elongation to decrease. At the same time, there is also a significant potential difference between the excessive coarse rare earth compound and the matrix, which will lead to a decrease in corrosion resistance, so the total amount of rare earth added is controlled.

[0034] 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 comparative example 4 increases compared with Example 2 with rare earth added, and the corrosion resistance is lower than that of Example 2.

[0035] Comparative Example 5 is based on Example 2, without adding additional metamorphic elements Mn / Cr and rare earth elements. It can be found that the equilibrium corrosion current of Comparative Example 5 increases significantly compared with Example 2, and the corrosion resistance decreases. This is because Fe and the corresponding phase are strong cathode phases, and the potential difference with the Al matrix is ​​large, which easily leads to micro-region galvanic cells, resulting in a decrease in corrosion resistance. In Example 2, which adds metamorphic elements and rare earth elements, the Fe phase morphology is more dispersed and is transformed into Al (Fe, Mn, Cr, Re) Si multi-phase, which reduces the potential difference with the matrix, reduces the corrosion rate, and improves the corrosion resistance.

[0036] 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 precipitation phases 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 to ensure the overall potential distribution of the precipitated phase and the matrix, thereby obtaining good mechanical properties and excellent corrosion resistance.

[0037] 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, no abnormal precipitation phases such as coarse phase and needle phase are found, the grains and precipitation phases are evenly distributed, and good mechanical properties and excellent corrosion resistance can be obtained.

[0038] Figure 3 This is the 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 cut 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 cause a decrease in corrosion resistance.

[0039] Figure 4 This is the microstructure of the commercially available ADC12 die-cast aluminum alloy sheet (500 times). It can be seen from the figure that after the aluminum ingot is die-cast into a test piece, there are still many long needle-like phases in the organization. This coarse needle phase can easily cut 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 cause a decrease in corrosion resistance.

[0040] 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 belong to the protection scope of the present invention.

Claims

1. A high-toughness, corrosion-resistant die-cast aluminum alloy suitable for a housing, 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%; and the mass ratio of Cr / Re is 1:1~6:

1.

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; Wherein: the total mass of Cu and Zn is ≤0.08wt%; the total mass of Ce and La is ≤0.20wt%; and the mass ratio of Cr / Re is 1:1~3:

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: Put the pure Al raw material into a heating furnace, heat it to 680°C, and after the aluminum metal is completely melted into molten aluminum liquid, let it stand and keep warm for 20-30 minutes; Step S3: raising the temperature 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 ingot and Al-Sr alloy, keeping the temperature for 15-20 minutes and then performing degassing and refining; Step S6: The casting sample is subjected to component analysis. If the sample is qualified, the melt is sent to a molding device to obtain a rare earth-transition group synergistically modified high-toughness, corrosion-resistant die-casting 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 it from the air. Then, the ingot is injected into a die-casting mold for die-casting to obtain a high-toughness and corrosion-resistant 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, 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 3.5-4.5m / 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, where the oil temperature controller 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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