A die-cast aluminum alloy and a method for producing the same

Abstract

In order to overcome the problem that the casting performance, mechanical property and heat conduction property of the existing die-casting aluminum alloy cannot be considered simultaneously, the present application provides a die-casting aluminum alloy, which comprises the following components by mass percentage: the content of Si is 9-12%, the content of Mg is 1.2-1.7%, the content of Fe is 0.5-1.0%, the content of Zn is 0.15-1.0%, the content of Mn is 0.05-0.25%, the content of Cu is 0.05-0.5%, the content of Sr is 0.02-0.05%, the content of Ti is 0.05-0.1%, the content of Cr is 0-0.01%, and the content of Al is 83.24-88.98%. Meanwhile, the present application also discloses a preparation method of the die-casting aluminum alloy. The die-casting aluminum alloy provided by the present application realizes the improvement of the mechanical properties such as the yield strength, tensile strength and elongation at break of the aluminum alloy under the premise of meeting the die-casting fluidity, and makes the aluminum alloy have good heat conductivity, so that the aluminum alloy has good comprehensive performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of alloy materials, and particularly relates to a die-casting aluminum alloy and a preparation method thereof. BACKGROUND

[0002] Aluminum alloys have the characteristics of light weight, good strength and toughness, corrosion resistance, and unique metal luster, and are widely used in electronic appliances, communication equipment, lighting devices, automobile parts, such as the shells of smart phones, notebook computers, and tablet computers, the heat sinks and lampshades of LED lamps, the heat sinks and cabinets of 3G and 4G wireless communication base stations, the heating plates of electric rice cookers, induction cookers, and water heaters, and the controller cabinets and drive motor shells of new energy vehicles. In order to meet the needs of thin-walled, lightweight, high-strength, and casting production of parts, the casting fluidity and mechanical properties of aluminum alloys are required to be higher and higher. The most commonly used casting aluminum alloy is an Al-Si series casting aluminum alloy, and typical grades include ADC12. The Al-Si series casting aluminum alloy generally contains more than 6.5% of Si elements, and thus has good casting fluidity, meeting the process requirements of casting. However, the mechanical properties of the product body of the Al-Si series casting aluminum alloy after die casting are generally that the tensile strength is 250-300 MPa, and the yield strength is 170-190 MPa, which cannot meet the requirements of aluminum alloy die castings with high comprehensive performance of mechanics and heat conduction. SUMMARY

[0003] In view of the problem that the casting performance, mechanical properties, and heat conduction performance of the existing die-casting aluminum alloy cannot be considered, the application provides a die-casting aluminum alloy and a preparation method thereof.

[0004] The technical scheme adopted by the application to solve the above technical problems is as follows:

[0005] In one aspect, the application provides a die-casting aluminum alloy, which comprises the following components in mass percentage:

[0006] The content of Si is 9-12%, the content of Mg is 1.2-1.7%, the content of Fe is 0.5-1.0%, the content of Zn is 0.15-1.0%, the content of Mn is 0.05-0.25%, the content of Cu is 0.05-0.5%, the content of Sr is 0.02-0.05%, the content of Ti is 0.05-0.1%, the content of Cr is 0-0.01%, and the content of Al is 83.24-88.98%.

[0007] Optionally, the die-casting aluminum alloy further comprises RE, and the content of RE is 0.1-0.15% in mass percentage, RE includes La and Ce, and the weight ratio of La to Ce is 50-65:35-50.

[0008] Optionally, in the die-casting aluminum alloy, the mass ratio of Ti and Sr satisfies the condition (2-4):1.

[0009] Optionally, in the die-casting aluminum alloy, the mass ratio of Si and Zn satisfies the condition (16-80):1.

[0010] Optionally, in the die-casting aluminum alloy, the mass percentage of Fe, Si and Mn satisfies 0.06Si+0.5Mn-Fe≥0.

[0011] Optionally, in the die-casting aluminum alloy, the content of other elements is less than 0.1%, and the other elements include V, Zr, Na, Pb and Sn.

[0012] Optionally, the yield strength of the die-casting aluminum alloy is greater than 230MPa, the tensile strength is greater than 350MPa, the fracture elongation is greater than 3%, the thermal conductivity is greater than 140W / m.K, and the fluidity is greater than 1400mm.

[0013] In another aspect, the present application provides a preparation method of the die-casting aluminum alloy as described above, comprising the following steps:

[0014] The Al agent, Ca agent, Si agent, Fe agent, Mn agent, Cu agent and Cr agent in the required proportion are weighed according to the element proportion in the aluminum alloy, and are added into a smelting furnace for smelting to obtain a melt;

[0015] The melt is refined by using a refining agent, the Ca agent is removed, inert gas is introduced, and dross is removed;

[0016] The Mg agent and Zn agent in the required proportion are weighed and added into the smelting furnace;

[0017] The Sr agent and Ti agent in the required proportion are respectively weighed for modification treatment;

[0018] The aluminum alloy ingot is die-casting formed.

[0019] Optionally, the added Ca element in the Ca agent in the smelting process is 0.01-0.05% based on 100% of the mass of the melt.

[0020] Optionally, the RE agent including La and Ce is also added.

[0021] Optionally, the die-casting formed aluminum alloy ingot is subjected to natural aging treatment at room temperature for 7 days.

[0022] The die-cast aluminum alloy provided by the present invention, through the restriction of the proportion of each element, enables the die-cast aluminum alloy to maintain good die-casting fluidity, allowing it to be well formed under different die-casting conditions, avoiding internal and surface cracks, reducing the requirements for controlling die-casting condition parameters, and enabling the die-casting formation of some thin-walled or fine structures. At the same time, while satisfying the die-casting fluidity, it improves the mechanical properties of the aluminum alloy, such as yield strength, tensile strength, and elongation at break, and gives the aluminum alloy good thermal conductivity, resulting in good comprehensive performance and meeting the application requirements of high-strength and high-heat-dissipation fields such as mobile phone structural parts and automotive parts. Detailed Implementation

[0023] To make the technical problems solved, the technical solutions, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] One embodiment of the present invention provides a die-cast aluminum alloy comprising the following components by mass percentage:

[0025] The content of Si is 9-12%, the content of Mg is 1.2-1.7%, the content of Fe is 0.5-1.0%, the content of Zn is 0.15-1.0%, the content of Mn is 0.05-0.25%, the content of Cu is 0.05-0.5%, the content of Sr is 0.02-0.05%, the content of Ti is 0.05-0.1%, the content of Cr is 0-0.01%, and the content of Al is 83.24-88.98%.

[0026] By limiting the proportions of each element, the die-cast aluminum alloy can maintain good die-casting fluidity, enabling it to be well formed under different die-casting conditions, avoiding internal and surface cracks, reducing the requirements for controlling die-casting parameters, and enabling the die-casting of thin-walled or fine structures. At the same time, while satisfying the die-casting fluidity requirement, the mechanical properties of the aluminum alloy, such as yield strength, tensile strength, and elongation at break, are improved, and the aluminum alloy also has good thermal conductivity, resulting in good comprehensive performance and meeting the application requirements of high-strength and high-heat-dissipation fields such as mobile phone structural components and automotive parts.

[0027] In the materials involved in this invention, Si is used as the main additive element. An appropriate amount of silicon can effectively improve the material's molding fluidity, increase its hardness, enhance the alloy's strength and corrosion resistance, while reducing shrinkage, lowering the tendency for hot cracking, and ensuring the molding effect after die casting.

[0028] Mg: Mg can significantly improve the yield strength and tensile strength of the die-cast aluminum alloy, and adding an appropriate amount of Mg can ensure the toughness of the die-cast aluminum alloy.

[0029] Fe: Adding Fe elements within the above range to die-cast aluminum alloys can reduce the difficulty of demolding aluminum alloys and reduce the erosion effect of aluminum alloys on molds.

[0030] Zn: Zn can improve the fluidity of aluminum alloys during die casting. Existing aluminum alloys have poor machinability. Zn has a low melting point and is distributed in the matrix of aluminum alloys in a free state. By adding Zn within the above-mentioned content range to the aluminum alloy, the softening and melting of Zn during cutting deformation is conducive to the formation of fine chips at the workpiece and tool interface, reducing the friction between the tool and the aluminum alloy. This can effectively improve the machinability of die-cast aluminum alloys and give them a richer forming structure.

[0031] Mn: The addition of Mn helps to prevent the recrystallization process of aluminum alloys, increase the recrystallization temperature, and significantly refine the recrystallized grains. At the same time, the addition of Mn also helps to dissolve iron and form the (Fe,Mn)Al6 reinforcing phase. However, excessive addition of Mn will lead to a decrease in the thermal conductivity of aluminum alloys.

[0032] Cu: Cu can form the Al2Cu phase with the Al matrix, increasing the copper content in aluminum alloys. This is beneficial for improving the fluidity, tensile strength, and hardness of aluminum alloys. However, the content of Cu should not be too high, as excessive Cu addition will lead to an increase in the tendency of aluminum alloys to hot crack.

[0033] Sr: Sr is a surface-active element that can transform long needle-like eutectic silicon into granular form, improving its thermal conductivity. At the same time, strontium can change the behavior of intermetallic compound phases in crystallography. Using strontium for modification has the characteristics of long effective time, good effect and reproducibility, which can improve the mechanical properties and plasticity of materials.

[0034] Ti: Since this die-cast aluminum alloy contains a small amount of Fe, adding an appropriate amount of Ti is beneficial for forming the Al3Ti reinforcing phase. It also significantly refines the Fe-rich phase morphology in the aluminum alloy, which is beneficial for improving the elongation at break and fluidity of the die-cast aluminum alloy. Excessive Ti, however, is detrimental to improving the thermal conductivity of the aluminum alloy.

[0035] Cr: In AlSiMg alloys with high Mg content, even trace amounts of Cr can lead to a significant decrease in material toughness. Furthermore, Cr has a significant impact on thermal conductivity; even trace amounts of Cr can cause a substantial reduction in thermal conductivity.

[0036] In a preferred embodiment, the die-cast aluminum alloy comprises the following components by mass percentage:

[0037] The content of Si is 10-12%, the content of Mg is 1.2-1.7%, the content of Fe is 0.5-1.0%, the content of Zn is 0.15-1.0%, the content of Mn is 0.05-0.25%, the content of Cu is 0.05-0.5%, the content of Sr is 0.02-0.05%, the content of Ti is 0.05-0.1%, the content of Cr is 0-0.01%, and the content of Al is 83.24-87.98%.

[0038] In other specific embodiments, the Si content may be selected from 9.0%, 9.2%, 9.5%, 9.9%, 10.2%, 10.5%, 10.7%, 11.0%, 11.2%, 11.5%, 11.7%, or 12.0%; the Mg content may be selected from 1.2%, 1.25%, 1.3%, 1.35%, 1.4%, 1.45%, 1.5%, 1.55%, 1.6%, or 1%. The Fe content can be selected from 0.5%, 0.53%, 0.6%, 0.65%, 0.72%, 0.76%, 0.79%, 0.83%, 0.88%, 0.9%, or 1.0%; the Zn content can be selected from 0.15%, 0.25%, 0.3%, 0.4%, 0.5%, 0.53%, 0.6%, 0.65%, 0.72%, 0.76%, or 0. The content of Mn can be selected from 0.05%, 0.10%, 0.11%, 0.13%, 0.15%, 0.18%, 0.2%, 0.24%, or 0.25%; the content of Cu can be selected from 0.05%, 0.15%, 0.2%, 0.24%, 0.3%, 0.36%, 0.4%, 0.45%, or 0.5%. The Sr content can be selected from 0.02%, 0.025%, 0.03%, 0.035%, 0.04%, 0.045%, or 0.05%; the Ti content can be selected from 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, or 0.1%; and the Cr content can be selected from 0%, 0.0015%, 0.005%, 0.006%, 0.008%, or 0.010%.

[0039] In some embodiments, the die-cast aluminum alloy further includes RE, with the RE content being 0.1-0.15% by mass percentage. The RE includes La and Ce, and the weight ratio of La to Ce is 50-65:35-50.

[0040] Specifically, the content of RE can be selected from 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15%.

[0041] RE: Rare earth elements composed of La and Ce have the effect of reducing the hydrogen, oxygen and sulfur content in aluminum alloys. In addition, RE forms binary compounds such as RES, REAs and REPb with low-melting-point harmful impurities. These compounds have the characteristics of high melting point, low density and stable chemical properties. They can float to the surface as slag and be removed, thereby purifying the aluminum liquid. The form in which rare earth elements exist in aluminum and aluminum alloys is closely related to their amount. Generally, when the RE content is within the above range, the role of RE is mainly to strengthen grains and solid solution.

[0042] In some embodiments, the mass ratio of Ti to Sr in the die-cast aluminum alloy satisfies condition (2-4):1.

[0043] Since the die-cast aluminum alloy contains eutectic silicon and primary silicon, as well as impurities such as Fe, the presence of multiple elements will have a certain impact on the formation of the Al3Ti phase. Sr also has a modifying effect, which can reduce the influence of eutectic silicon, primary silicon, Fe, etc. on Ti. When Sr and Ti meet the above ratio conditions, the modification effect is better, and the improvement effect on mechanical properties and thermal conductivity is better.

[0044] In some embodiments, the mass ratio of Si to Zn in the die-cast aluminum alloy satisfies the condition (16-80):1.

[0045] In the die-cast aluminum alloy, Mg combines with Si to form the Mg2Si reinforcing phase, thereby improving the strength of the aluminum alloy material. However, excessive addition of Zn can easily lead to Zn combining with Mg, which in turn reduces the Mg2Si reinforcing phase and reduces the strength. When Si and Zn are added within the above-mentioned mass ratio range, it can be ensured that most of the Mg and Si form the Mg2Si reinforcing phase, thus ensuring that the die-cast aluminum alloy has good mechanical strength.

[0046] In some embodiments, the mass percentage content of Fe, Si and Mn in the die-cast aluminum alloy satisfies 0.06Si+0.5Mn-Fe≥0.

[0047] The higher the Fe content in aluminum alloys, the easier it is to form β-acicular Fe. β-acicular Fe can cleave the matrix and severely reduce the toughness of the alloy. Increasing the Si and Mn content can interact with Fe to reduce the formation of β-acicular Fe. When the Fe, Si, and Mn contents meet the above relationship, it can be ensured that no or very small amounts of acicular Fe will appear, resulting in better toughness of the alloy.

[0048] In some embodiments, the content of other elements in the die-cast aluminum alloy is less than 0.1%, and the other elements include V, Zr, Na, Pb and Sn.

[0049] The other elements are impurity elements that dissolve into the alloy and form impurity phases with the elements in the aluminum alloy, reducing the thermal conductivity or mechanical properties of the alloy. In the aluminum alloy, these impurities should be avoided as much as possible. In a preferred embodiment, the aluminum alloy does not include the aforementioned other elements.

[0050] In some embodiments, the die-cast aluminum alloy has a yield strength greater than 230 MPa, a tensile strength greater than 350 MPa, a fracture elongation greater than 3%, a thermal conductivity greater than 140 W / mK, and a flowability greater than 1400 mm.

[0051] It should be noted that the flowability test used a single-spiral flowability sample mold with a cross-sectional area of ​​5.5 × 3 mm, and the soup volume used was 45 cm³. 3 The injection speed was fixed, and the casting temperature was 700℃. A spiral-shaped sample was formed by die casting, and the length was recorded according to the scale at the end of the sample to obtain the flowability parameters.

[0052] Another embodiment of the present invention provides a method for preparing the die-cast aluminum alloy as described above, comprising the following steps:

[0053] Weigh out the required proportions of Al, Ca, Si, Fe, Mn, Cu, Cr, and RE agents according to the element ratio in the aluminum alloy, add them to the melting furnace for melting, and obtain the melt;

[0054] The melt is refined using a refining agent to remove the Ca agent, inert gas is introduced, and scum is skimmed off.

[0055] Weigh out the required proportions of Mg and Zn agents and add them to the smelting furnace;

[0056] Weigh out the required proportions of Sr agent and Ti agent separately for deterioration treatment;

[0057] The aluminum alloy ingot is die-cast into shape.

[0058] In this invention, Al agent, Ca agent, Si agent, Fe agent, Mn agent, Cu agent, Cr agent, Mg agent, Zn agent, Sr agent, Ti agent, and RE agent are materials that can provide the various elements required to prepare the die-cast aluminum alloy of this invention. They can be intermediate alloys, metal compounds, or pure metals containing the above elements, as long as the composition of the aluminum alloy obtained after melting the aluminum alloy raw materials is within the above range.

[0059] In some embodiments, the mass of Ca added in the Ca agent added during the smelting process is 0.01-0.05%, based on the mass of the melt as 100%.

[0060] In the preparation method provided by this invention, an excess of Ca agent is first added during the smelting process, followed by the addition of a refining agent to refine and remove the Ca agent, then the addition of Mg agent and Zn agent, and finally the addition of Sr agent, Ti agent and RE agent for modification treatment, and then casting and die casting to obtain the aluminum alloy provided by this invention. By introducing an excess of Ca agent, the smelting speed of elements with high melting points such as Cu, Mn and Ti can be effectively increased, energy consumption can be shortened and efficiency can be improved. At the same time, the excess Ca agent can be removed by the refining agent without introducing excess impurities.

[0061] In some embodiments, the method for removing Ca agents includes:

[0062] Add AlF3 as a Ca removal agent;

[0063] Alternatively, chlorine or carbon tetrachloride can be introduced using the inert gas as a carrier to remove the Ca agent.

[0064] By introducing AlF3, chlorine, or carbon tetrachloride to react with the Ca agent to generate CaF2, the Ca agent can be effectively removed without introducing new impurities.

[0065] In some embodiments, the refining agent includes one or both of hexafluoroethane and aluminum refining agent ZS-AJ01C, and the inert gas includes nitrogen and / or argon.

[0066] In some embodiments, the die-casting molten metal temperature is 700–750°C, the mold temperature is 200–300°C, and the barrel temperature is 100–200°C.

[0067] In some embodiments, the die-cast aluminum alloy ingot is subjected to natural aging treatment at room temperature for 7 days.

[0068] The present invention will be further illustrated by the following examples.

[0069] Table 1 shows the mass percentage (%) of the aluminum alloy components in each embodiment and comparative example of the present invention. The total mass of the aluminum alloy is 100%. In addition to the components listed in Table 1, the mass percentage of the remaining components is Al.

[0070] Table 1

[0071]

[0072]

[0073] Example 1

[0074] This embodiment illustrates the die-cast aluminum alloy and its preparation method disclosed in this invention, including the following steps:

[0075] Step 1: Weigh and prepare the raw materials according to the aluminum alloy composition shown in Table 1;

[0076] Step 2: During the smelting process, 80% pure aluminum is first put into the smelting furnace. When the temperature reaches about 700℃, Al-Si master alloy and Ca agent are added.

[0077] Step 3: After the temperature rises to above 800℃, add Fe agent, Mn agent, Cu agent, Cr agent and RE agent. Stir every 10 minutes for 3 minutes each time, and let stand for 7 minutes after stirring.

[0078] Step 4: Add the remaining pure aluminum and adjust the melting temperature to 760℃;

[0079] Step 5: Refine the melt using a refining agent. The refining agent is injected into the melt along with an inert gas to remove excess Ca elements. The temperature is 730-750℃. After refining, remove the surface scum.

[0080] Step 6: After the alloy has completely melted, lower the temperature to 760℃ and add Mg and Zn agents;

[0081] Step 7: Reduce the temperature to 720℃, add Sr agent and Ti agent for deterioration treatment, and then perform degassing casting;

[0082] Step 8: Perform die casting on the aluminum alloy ingot, setting the die casting pouring temperature to 700-750℃, the mold temperature to 200-300℃, and the barrel temperature to 100-200℃.

[0083] Step 9: Place the die-cast samples at room temperature for 7 days for natural aging treatment.

[0084] Examples 2-29

[0085] Examples 2-29 illustrate the aluminum alloy and its preparation method disclosed in this invention, including most of the operational steps in Example 1, with the following differences:

[0086] The aluminum alloy compositions shown in Examples 2-29 of Table 1 were used, and the other operating steps were the same as in Example 1.

[0087] Comparative Examples 1-17

[0088] Comparative Examples 1-17 are used to compare and illustrate the aluminum alloy and its preparation method disclosed in this invention, including most of the operational steps in Example 1, the difference being:

[0089] The aluminum alloy compositions shown in Comparative Examples 1 to 17 in Table 1 were used, and the other operating steps were the same as in Example 1.

[0090] Performance testing

[0091] The aluminum alloys prepared in Examples 1-29 and Comparative Examples 1-17 were subjected to the following performance tests: tensile test

[0092] Referring to standard GBT 228.1-2010, tensile properties (yield strength, tensile strength, and elongation) were tested using an electronic universal testing machine of model CMT5105. The gauge length was 50 mm, the loading rate was 2 mm / min, and three tensile specimens were measured, with the average value taken as the tensile test result.

[0093] Thermal conductivity test

[0094] The thermal conductivity test adopts the flash method of GBT 22588-2008 to measure the thermal diffusivity or thermal conductivity. The sample size is Φ12.6~12.7×(2~4)mm. The test equipment model is Netzsch LFA 467. The sample surface must be smooth and flat.

[0095] Liquidity test

[0096] The flowability test used a single-spiral flowability sample mold with a cross-sectional area of ​​5.5 × 3 mm and a soup volume of 45 cm³. 3 The injection speed was fixed, and the casting temperature was 700℃. A spiral-shaped sample was die-cast, and its length was recorded according to the graduations at the tail end. The test results are recorded in Table 2.

[0097] Table 2

[0098]

[0099]

[0100]

[0101] As can be seen from the test results in Table 2, the die-cast aluminum alloy provided by the present invention has excellent yield strength, tensile strength and thermal conductivity. While ensuring strength and thermal conductivity, it also has good elongation and fluidity, which can meet different die-casting conditions.

[0102] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A die-cast aluminum alloy, characterized in that, The components include the following mass percentages: The content of Si is 9-12%, the content of Mg is 1.2-1.7%, the content of Fe is 0.5-1.0%, the content of Zn is 0.15-1.0%, the content of Mn is 0.05-0.25%, the content of Cu is 0.05-0.5%, the content of Sr is 0.02-0.05%, the content of Ti is 0.05-0.1%, the content of Cr is 0-0.01%, and the balance is aluminum and unavoidable impurities; In the die-cast aluminum alloy, the mass ratio of Ti to Sr satisfies condition (2~4):

1.

2. The die-cast aluminum alloy according to claim 1, characterized in that, In the die-cast aluminum alloy, the mass ratio of Si to Zn satisfies the condition (16~80):

1.

3. The die-cast aluminum alloy according to claim 1, characterized in that, In the die-cast aluminum alloy, the mass percentage content of Fe, Si and Mn satisfies 0.06Si+0.5Mn-Fe≥0.

4. The die-cast aluminum alloy according to claim 1, characterized in that, The impurity content in the die-cast aluminum alloy is less than 0.1%, and the impurities include V, Zr, Na, Pb and Sn.

5. The die-cast aluminum alloy according to claim 1, characterized in that, The die-cast aluminum alloy has a yield strength greater than 230 MPa, a tensile strength greater than 350 MPa, a fracture elongation greater than 3%, a thermal conductivity greater than 140 W / m·K, and a fluidity greater than 1400 mm.

6. The method for preparing die-cast aluminum alloy according to any one of claims 1 to 5, characterized in that, The following steps are included: Weigh out the required proportions of Al, Ca, Si, Fe, Mn, Cu, and Cr agents according to the element ratio in the aluminum alloy, add them to the melting furnace for melting, and obtain a melt. Based on the mass of the melt as 100%, the mass of Ca added in the Ca agent during the melting process is 0.01~0.05%. The melt is refined using a refining agent to remove the Ca agent, inert gas is introduced, and scum is skimmed off. Weigh out the required proportions of Mg and Zn agents and add them to the smelting furnace; Weigh out the required proportions of Sr agent and Ti agent separately for deterioration treatment; Die casting.

7. The method for preparing die-cast aluminum alloy according to claim 6, characterized in that, The die-cast aluminum alloy ingots were placed at room temperature for 7 days of natural aging treatment.

8. The die-cast aluminum alloy according to claim 1, characterized in that, The die-cast aluminum alloy also includes RE, with a content of 0.1-0.15% by mass percentage. RE includes La and Ce, and the weight ratio of La to Ce is 50-65:35-50.

9. The method for preparing die-cast aluminum alloy as described in claim 8, characterized in that, The following steps are included: Weigh out the required proportions of Al, Ca, Si, Fe, Mn, Cu, and Cr agents according to the element ratio in the aluminum alloy, add them to the melting furnace for melting to obtain a melt. RE agents, including La and Ce, are also added. Based on the melt mass of 100%, the mass of Ca added in the Ca agent during the melting process is 0.01~0.05%. The melt is refined using a refining agent to remove the Ca agent, inert gas is introduced, and scum is skimmed off. Weigh out the required proportions of Mg and Zn agents and add them to the smelting furnace; Weigh out the required proportions of Sr agent and Ti agent separately for deterioration treatment; Die casting.

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