WO2020224468A1 - Die-cast aluminum alloy, preparation method therefor, and structural member for communication product - Google Patents

Abstract

Disclosed are a die-cast aluminum alloy, a method for preparing the die-cast aluminum alloy, and a structural member for a communication product prepared by the die-cast aluminum alloy. The die-cast aluminum alloy comprises the following components in mass percentages: 0.1-7% of magnesium, 7-35% of zinc, 0.2-0.8% of manganese, 0.1-0.7% of iron, 0.07-0.2% of titanium and/or zirconium, with the inevitable impurities being ≤0.3%, and the balance being aluminum. The die-cast aluminum alloy combines a high strength, a high toughness and an excellent fluidity, and is suitable for molding complex thin-walled products.

Description

Die-casting aluminum alloy and its preparation method and communication product structure

This application claims the priority of a Chinese patent application filed with the State Intellectual Property Office of China with application number 201910372923.2 on May 6, 2019, and a Chinese patent application with the title of “die-cast aluminum alloy and its preparation method and communication product structure” The priority of, the entire content of which is incorporated in this application by reference.

Technical field

The invention relates to the technical field of aluminum alloy materials, in particular to a die-cast aluminum alloy, a preparation method thereof, and a communication product structure.

Background technique

While maintaining the advantages of traditional aluminum alloys such as high strength, high heat dissipation and high corrosion resistance, die-casting aluminum alloy has the characteristics of high fluidity, which meets the industrialized die-casting production process, and is widely used in household appliances, automobiles, electronic products and other fields. However, with the development of multi-functional, light and thin products, the structural space is further compressed, especially the fast-paced electronics industry, which puts forward higher requirements for the strength and toughness of die-casting materials.

Compared with commonly used aluminum-silicon die-cast aluminum alloys, aluminum-magnesium die-cast aluminum alloys have higher strength and excellent flexural toughness, but their fluidity is poor and die-casting friendliness is insufficient. The use of product die-casting parts (such as mobile phone midplanes) and other scenarios is limited. Therefore, it is necessary to develop a die-cast aluminum alloy with high strength, high toughness and excellent fluidity.

Summary of the invention

In view of this, the embodiments of the present invention provide a die-cast aluminum alloy and a preparation method thereof. The die-cast aluminum alloy has high strength, high toughness and excellent fluidity, so as to solve the flow of the existing aluminum-magnesium die-cast aluminum alloy to a certain extent. Poor performance, leading to the problem of limited use in the scene of thin-walled electronic product die castings.

Specifically, the first aspect of the embodiments of the present invention provides a die-cast aluminum alloy, which includes the following components by mass percentage:

Magnesium: 0.1%-7%,

Zinc: 7%-35%,

Manganese: 0.2%-0.8%,

Iron: 0.1%-0.7%,

Titanium and/or zirconium: 0.07%-0.2%,

Inevitable impurities ≤ 0.3%, and aluminum.

The die-cast aluminum alloy of the embodiment of the present invention improves the fluidity of the alloy by increasing the content of zinc, while comprehensively controlling the content of elements such as magnesium, iron, and manganese, so that the aluminum alloy can have high strength and high strength while obtaining better fluidity. Good comprehensive mechanical properties such as toughness.

In the embodiment of the present invention, the mass percentage of the zinc is 12%-33%.

In the embodiment of the present invention, the mass percentage of the zinc is 17%-23%.

In the embodiment of the present invention, the mass percentage of the magnesium is 2%-6%.

In the embodiment of the present invention, the mass percentage of the magnesium is 3.3%-5.1%.

In the embodiment of the present invention, the mass percentage of the iron is 0.12%-0.35%.

In the embodiment of the present invention, the mass percentage of the iron is 0.2%-0.3%.

In the embodiment of the present invention, the mass percentage of the manganese is 0.25-0.7%.

In the embodiment of the present invention, the mass percentage of the manganese is 0.35%-0.6%.

In the embodiment of the present invention, the mass percentage of the titanium and/or zirconium is 0.08%-0.12%.

In the embodiment of the present invention, the component of the die-cast aluminum alloy further includes silicon, and the mass percentage of the silicon is greater than 0 and less than or equal to 2.3%.

In the embodiment of the present invention, the mass percentage of the silicon is 0.5%-1.9%.

In the embodiment of the present invention, the mass percentage of the silicon is 0.7%-1.6%.

In the embodiment of the present invention, the component of the die-cast aluminum alloy further includes copper, and the mass percentage of the copper is greater than 0 and less than or equal to 2.6%.

In the embodiment of the present invention, the mass percentage of the copper is 0.3%-2.3%.

In the embodiment of the present invention, the mass percentage of the copper is 0.7%-1.6%.

In the embodiment of the present invention, the phases inside the structure of the die-cast aluminum alloy include an α-Al phase and an intermetallic compound, and the intermetallic compound is distributed at the grain boundary position or precipitated in the α-Al phase. Intermetallic compounds include MgZn ₂ phase and iron-rich phase.

In the embodiment of the present invention, under the same conditions, the fluidity of the die-cast aluminum alloy is 91% or more of that of the ADC12 die-cast aluminum alloy.

In the embodiment of the present invention, the yield strength of the die-cast aluminum alloy is ≥240MPa, and the elongation is ≥3%.

The die-cast aluminum alloy provided by the first aspect of the embodiment of the present invention has both high strength, high toughness and excellent fluidity, and can greatly improve the existing aluminum-magnesium die-cast aluminum alloy with low fluidity, poor fillability, easy drawing molds, and molds. Easy erosion and other issues can meet the molding of complex structure communication products, especially suitable for the molding of thin-walled products such as mobile phone midplanes that require high fluidity.

In the second aspect, the embodiment of the present invention also provides a method for preparing the die-cast aluminum alloy, including the following steps:

According to the composition ratio of the die-cast aluminum alloy, the pure aluminum ingot is first added to the smelting furnace. After the aluminum ingot is melted, the metal element source that can provide other element components other than aluminum is added for smelting, and then after refining and degassing treatment, The die-cast aluminum alloy is obtained by casting, and the die-cast aluminum alloy includes the following mass percentages of components: magnesium: 0.1%-7%, zinc: 7%-35%, manganese: 0.2%-0.8%, iron: 0.1 %-0.7%, titanium and/or zirconium: 0.07%-0.2%, unavoidable impurities ≤ 0.3%, and aluminum.

In the embodiment of the present invention, after adding a pure aluminum ingot into the melting furnace, it is heated to 730°C-760°C to melt the aluminum ingot. After the aluminum ingot is completely melted, the aluminum manganese alloy, pure zinc ingot, iron powder, aluminum titanium After cooling the alloy and/or aluminum-zirconium alloy to 700°C-720°C, add pure magnesium ingot, stir and keep for 15-25 minutes.

In the embodiment of the present invention, during the casting molding process, the casting temperature is 650°C-720°C.

The preparation method provided by the second aspect of the present invention has simple process, high yield rate and low production cost, can be applied to complex thin-walled parts and similar scenarios, and has broad application prospects.

The third aspect of the embodiments of the present invention provides a communication product structural component, which is cast by using the die-cast aluminum alloy provided in the first aspect of the embodiment of the present invention. The communication product structure includes a mobile phone midplane.

The communication product structural part provided by the third aspect of the embodiment of the present invention has both high strength, high toughness and excellent forming performance, and can meet the design requirements of complex thin-walled structural parts.

Detailed ways

The embodiments of the present invention will be described below in conjunction with some specific implementation manners of the present invention.

Existing aluminum-magnesium die-casting aluminum alloy, although it has the characteristics of high strength and high toughness, but its fluidity is poor. In the forming process of thin-walled electronic product structural parts (such as mobile phone midplane), it faces poor die-casting molding, many cracks, and Die erosion and other issues have seriously affected production results and delivery capabilities. In order to effectively solve this problem, the embodiment of the present invention provides a die-cast aluminum alloy with high strength, high toughness and excellent fluidity.

Specifically, the embodiment of the present invention provides a die-cast aluminum alloy composed of the following components by mass percentage:

Magnesium: 0.1%-7%,

Zinc: 7%-35%,

Manganese: 0.2%-0.8%,

Iron: 0.1%-0.7%,

Titanium and/or zirconium: 0.07%-0.2%,

Inevitable impurities ≤ 0.3%, and aluminum.

The composition of the die-cast aluminum alloy of the embodiment of the present invention is determined by comprehensively considering the contribution of each chemical element to the comprehensive performance indicators of the alloy (including fluidity, strength, toughness, hardness, etc.), and through the combined effect of the above-mentioned specific content of each element, Various properties are balanced, a stable crystal structure is formed, and a die-cast aluminum alloy with excellent comprehensive properties is obtained.

The phases inside the structure of the die-cast aluminum alloy of the embodiment of the present invention include an α-Al phase and an intermetallic compound, and the intermetallic compound is distributed at the grain boundary position or precipitated in the α-Al phase. Wherein, the phase refers to a uniform and continuous component with the same chemical composition, the same atomic aggregation state and properties, and there is an interface separation between different phases. The intermetallic compound refers to a compound formed by a metal and a metal, and a metal and a metalloid. Specifically, in the crystal structure of the die-cast aluminum alloy of the present invention, the intermetallic compound includes MgZn ₂ phase and iron-rich phase. When the composition of the die-cast aluminum alloy also includes copper (Cu), the intermetallic compound also Including Al ₂ Cu, and when silicon (Si) is included in the composition of the die-cast aluminum alloy, the intermetallic compound also includes Mg ₂ Si. The zinc, magnesium, iron, copper, manganese, titanium, and zirconium are partially solid-dissolved in the α-Al phase in the form of atoms.

In some embodiments of the present invention, the composition of the die-cast aluminum alloy may also include silicon (Si) element, and the content of silicon (Si) element is controlled at a lower level greater than 0 and less than or equal to 2.3%. Due to the high brittleness of silicon, the lower content The silicon is beneficial to improve the toughness of aluminum alloy; and the addition of a small amount of silicon can reduce the tendency of hot cracking and improve the dimensional stability. At the same time, Si can combine with Mg to form Mg2Si to ensure a certain strength of aluminum alloy. In some embodiments, the mass percentage of silicon may be 0.5%-1.9%. In other embodiments, the mass percentage of silicon may also be 0.7%-1.6%. In some embodiments, the mass percentage of silicon may specifically be 0.8%, 1.2%, 1.5%, or 1.7%.

In the embodiment of the present invention, magnesium (Mg) combines with Zn and Si elements to form the strengthening phases MgZn ₂ and Mg ₂ Si, which significantly improves alloy strengthening. At the same time, the increase of magnesium content can improve alloy fluidity to a certain extent. However, magnesium is easy to burn and has a serious tendency to inclusion. Excessive Mg content will greatly affect the normal die-casting production and reduce the toughness of the alloy. In the embodiment of the present invention, the content of magnesium is controlled within the range of 0.1%-7%. In some embodiments, the mass percentage of magnesium may be 2%-6%; in other embodiments, the mass percentage of magnesium is also It can be 3.3%-5.1%. In some embodiments, the mass percentage of magnesium may specifically be 1%, 3%, 4%, 5%, 6%.

In the embodiment of the present invention, an increase in the content of zinc (Zn) can reduce the liquidus temperature and improve the fluidity of the alloy. When the Zn element content is ≥20%, it has the effect of significantly improving the fluidity of the alloy. At the same time, Zn element can be dissolved in α-Al to achieve a solid solution strengthening effect, but the strength improvement is limited. When the strength requirement is high, by adding other elements, such as Mg element, combined with Zn to form a second phase (such as MgZn ₂ phase), the strength of the alloy can be significantly improved. Too high Zn element content will lead to problems such as reduced corrosion resistance, poor thermal stability and high thermal cracking tendency. At the same time, it will increase the alloy density and cause a rapid increase in product weight. Therefore, under the condition that the fluidity meets the requirements, the Zn content is controlled and other strengthening elements are appropriately added to achieve the effect of high strength and toughness. At the same time, it has great benefits for product weight reduction and raw material cost, especially for 3C products. In some embodiments, the mass percentage of zinc can also be 12%-33%. In other embodiments, the mass percentage of the zinc can also be 17%-23%. In some other embodiments, the mass percentage of zinc can also be 7%-12%. In some embodiments, the mass percentage of zinc may specifically be 17%, 18%, 19%, 20%, 22%.

In the embodiment of the present invention, the addition of iron (Fe) element can reduce the tendency of mucous film in the aluminum alloy die casting process, and ensure the smooth progress of die casting. However, when Fe is too much, a thick needle-like iron-rich phase is formed, which impairs the toughness of the alloy. Therefore, in order to ensure higher toughness, in the embodiment of the present invention, the mass percentage of iron is controlled at 0.1-0.7%. In some embodiments, the mass percentage of iron can also be 0.12%-0.35%, and in other embodiments, the mass percentage of iron can also be 0.2%-0.3%. In the embodiment of the present invention, the content of Fe element is controlled at the middle and lower limit (0.12%-0.35%), which can make the aluminum alloy have higher toughness.

In the embodiment of the present invention, the addition of an appropriate amount of manganese (Mn) element can transform the coarse and large needle-like iron-rich phase to form a fine iron-rich phase, reducing the adverse effect of Fe on the mechanical properties, and the addition of manganese can reduce the aluminum alloy The tendency of the mucosa. In the embodiment of the present invention, the mass content of manganese is controlled within the range of 0.2%-0.8%. In some embodiments, the mass percentage of manganese may be 0.25%-0.7%. In other embodiments, the mass percentage of manganese may also be 0.35%-0.6%. In some embodiments, the mass percentage of manganese may specifically be 0.3%, 0.4%, 0.5%, 0.55%, 0.65%.

In some embodiments of the present invention, the composition of the die-cast aluminum alloy may further include copper (Cu) element, which has obvious solid solution strengthening effect and can form an intermetallic compound Al ₂ Cu with Al to further enhance the strength of the alloy. In the embodiment of the present invention, the mass percentage of the copper is ≤2.6%. In some embodiments, the mass percentage of copper may be 0.3-2.3%. In other embodiments, the mass percentage of copper may also be 0.7%-1.6%. In some embodiments, the mass percentage of copper may specifically be 0.5%, 0.8%, 1.2%, 1.4%, 1.5%, 2.0%.

In the embodiment of the present invention, titanium (Ti) element and zirconium (Zr) element can be used as heterogeneous nucleation points to refine crystal grains and improve the strength and toughness of aluminum alloy. In the embodiment of the present invention, titanium element may be added separately, zirconium element may be added separately, or titanium element and zirconium element may be added at the same time. In some embodiments, the mass percentage of titanium and/or zirconium can be 0.07%-0.12%, and in other embodiments, the mass percentage of titanium and/or zirconium can also be 0.08%-0.1%.

In the embodiments of the present invention, in order to obtain better overall performance, in some embodiments, the sum of the mass percentages of the four elements of magnesium, copper, manganese, and titanium can be controlled to be greater than or equal to 4%. In other embodiments, the sum of the mass percentages of the four elements of magnesium, copper, manganese, and titanium can be controlled to be greater than or equal to 6%.

In an embodiment of the present invention, the die-cast aluminum alloy is composed of the following components by mass percentage: silicon: 0.7-1.6%, zinc: 17%-23%, magnesium: 3.3%-5.1%, copper: 0.7%-1.6 %, iron: 0.12%-0.35%, manganese: 0.35-0.6%, titanium and/or zirconium: 0.07%-0.12%. In the die-cast aluminum alloy of the embodiment of the present invention, by comprehensively considering the effects of various elements on the properties of the alloy, under the condition that the fluidity meets the requirements, the content of Zn is controlled to 17%-23%, and strengthening elements such as Mg and Cu are appropriately added. To achieve better high-strength and high-toughness effects, while controlling the alloy weight, raw material cost, thermal stability, corrosion resistance, etc., are all at a better level, so as to better meet the application requirements of 3C products.

In the embodiment of the present invention, since the increase of impurity elements will reduce the performance of the material, the embodiment of the present invention controls the content of the inevitable impurity elements to ≤0.3%.

In the embodiment of the present invention, under the combined effect of the specific content of the specific element, the fluidity of the die-cast aluminum alloy is more than 91% of the ADC12 under the same conditions. In the embodiment of the present invention, the yield strength of the die-cast aluminum alloy is ≥240MPa, and the elongation is ≥3%. The yield strength is the yield limit when the metal material yields, that is, the stress that resists minor plastic deformation. For metal materials with no obvious yield phenomenon, the stress value that produces 0.2% residual deformation is specified as its yield limit, which is called conditional yield limit or yield strength. The elongation refers to the index describing the plastic properties of the material, and is the percentage of the ratio of the total deformation ΔL of the gauge length section after the sample tensile fracture to the original gauge length L.

The above-mentioned die-cast aluminum alloy provided by the embodiments of the present invention has both high strength, high toughness and excellent fluidity, and can greatly improve the existing aluminum-magnesium die-cast aluminum alloy, which has low fluidity, poor fillability, easy drawing molds, and easy punching. Corrosion and other issues can meet the forming of complex structure communication products, especially suitable for thin-walled parts with high fluidity requirements. Specifically, it can be applied to mobile phones, notebook computers, communication equipment industries, automobiles, civil hardware and other fields. Specifically, an embodiment of the present invention provides a communication product structural component, which is cast by using the die-cast aluminum alloy provided in the embodiment of the present invention. The communication product structure includes a mobile phone midplane. Of course, in communication products, other structural parts that can be made of aluminum alloy can also be cast by the die-cast aluminum alloy of the embodiment of the present invention, such as a housing, a bracket, and the like. The wall thickness of the communication product structure of the embodiment of the present invention is not particularly limited. It can be as thick as possible, or as thin as possible, for example, it can be 0.25mm-2mm, and further 0.4mm-1mm. Thickness may refer to the local wall thickness of the structural component, for example, a wall thickness of more than 50% of the area, or a wall thickness of more than 70% of the area.

Correspondingly, the embodiment of the present invention also provides a method for preparing the die-cast aluminum alloy, including the following steps:

S10. According to the composition ratio of the die-cast aluminum alloy, first add a pure aluminum ingot into the smelting furnace, and after the aluminum ingot is melted, add a metal element source that can provide elements other than aluminum for smelting;

S20. After refining and degassing treatment, casting to obtain the die-cast aluminum alloy, the die-cast aluminum alloy includes the following mass percentages of components: magnesium: 0.1%-7%, zinc: 7%-35%, and manganese: 0.2%-0.8%, iron: 0.1%-0.7%, titanium and/or zirconium: 0.07%-0.2%, inevitable impurities ≤ 0.3%, and aluminum.

In some embodiments, the composition of the die-cast aluminum alloy may further include copper. In some embodiments, the composition of the die-cast aluminum alloy may further include silicon.

In the embodiment of the present invention, the metal element source that can provide other elemental components other than aluminum may be pure metal ingots, master alloys, metal powders, etc., specifically including pure zinc ingots, pure magnesium ingots, aluminum-silicon alloys, Iron powder, aluminum-manganese alloy, aluminum-copper alloy, aluminum-titanium alloy, aluminum-zirconium alloy, etc. In the embodiment of the present invention, various pure metal ingots and intermediate alloys can be cleaned and dried to remove the surface oxide layer and dirt.

In the embodiment of the present invention, in step S10, after adding pure aluminum ingots into the melting furnace, heating to 730°C-760°C to melt the aluminum ingots. After all the aluminum ingots are melted, the aluminum-manganese alloy, pure zinc ingot, and iron are added first. After cooling powder, aluminum titanium alloy and/or aluminum zirconium alloy to 700°C-720°C, add pure magnesium ingot, stir and keep for 15 minutes to 25 minutes. More specifically, after adding a pure aluminum ingot into the smelting furnace, it is heated to 730°C-760°C and held for 30 minutes to melt the aluminum ingot. After the aluminum ingot is completely melted, the aluminum-manganese alloy, pure zinc ingot, iron powder, The aluminum-titanium alloy and/or aluminum-zirconium alloy is added with a refining agent and slagging, followed by standing for 15 minutes to 25 minutes; then adding pure magnesium ingot, stirring and maintaining for 15 minutes to 25 minutes.

In the embodiment of the present invention, during the casting process, the material temperature, that is, the casting temperature, is 650°C to 720°C.

In the embodiment of the present invention, during the refining process, a special refining agent for aluminum alloy is added, argon gas is passed in for rotating degassing, and then it is left standing for 15-20 minutes to fully separate impurities. Before the casting and forming, online hydrogen removal and two-stage filtration are performed. In the embodiment of the present invention, the refining agent is a commercially available conventional special refining agent for aluminum alloy, and the on-line hydrogen removal and two-stage filtration are conventional operations in the field, and the present invention is not specifically limited.

In the embodiment of the present invention, the mass percentage of the silicon may be ≤2.3%. In some embodiments, the mass percentage of silicon may be 0.5%-1.9%. In other embodiments, the mass percentage of silicon may also be 0.7%-1.6%. In some embodiments, the mass percentage of silicon may specifically be 0.8%, 1.2%, 1.5%, or 1.7%.

In some embodiments, the mass percentage of magnesium can be 2%-6%; in other embodiments, the mass percentage of magnesium can also be 3.3%-5.1%. In some embodiments, the mass percentage of magnesium may specifically be 1%, 3%, 4%, 5%, 6%.

In some embodiments, the mass percentage of zinc can also be 12%-33%. In other embodiments, the mass percentage of the zinc can also be 17%-23%. In some other embodiments, the mass percentage of zinc can also be 7%-12%.

In some embodiments, the mass percentage of iron can also be 0.12%-0.35%, and in other embodiments, the mass percentage of iron can also be 0.2%-0.3%.

In some embodiments, the mass percentage of manganese may be 0.25%-0.7%. In other embodiments, the mass percentage of manganese may also be 0.35%-0.6%.

In the embodiment of the present invention, the mass percentage of the copper may be ≤2.6%. In some embodiments, the mass percentage of copper may be 0.3-2.3%. In other embodiments, the mass percentage of copper may also be 0.7%-1.6%.

In the embodiment of the present invention, titanium element may be added separately, zirconium element may be added separately, or titanium element and zirconium element may be added at the same time. In some embodiments, the mass percentage of titanium and/or zirconium can be 0.07%-0.12%, and in other embodiments, the mass percentage of titanium and/or zirconium can also be 0.08%-0.1%.

In the embodiments of the present invention, in order to obtain better overall performance, in some embodiments, the sum of the mass percentages of the four elements of magnesium, copper, manganese, and titanium can be controlled to be greater than or equal to 4%. In other embodiments, the sum of the mass percentages of the four elements of magnesium, copper, manganese, and titanium can be controlled to be greater than or equal to 6%.

In the embodiment of the present invention, since the increase of impurity elements will reduce the performance of the material, the embodiment of the present invention controls the content of the inevitable impurity elements to ≤0.3%.

The present invention can further combine existing casting processes (such as liquid die casting, gravity casting, etc.) to prepare various aluminum alloy molded parts, including the communication product structural parts described in the embodiments of the present invention.

The preparation method provided by the embodiment of the present invention has the advantages of simple process flow, high yield, low production cost, etc. The prepared die-cast aluminum alloy has high strength, high toughness and excellent fluidity, and is suitable for complex thin-walled parts And similar scenarios, the application prospect is broad.

The following further describes the embodiments of the present invention through a number of examples.

Example 1

A die-cast aluminum alloy composed of the following mass percentage components: silicon: 1.69%, magnesium: 5.62%, zinc: 8.52%, copper: 2.38%, manganese: 0.538%, iron: 0.121%, titanium: 0.104%, Zirconium is 0.0015%, the inevitable impurity content is ≤0.3%, and the rest is aluminum.

The preparation method of die-cast aluminum alloy in this example includes the following steps:

According to the composition ratio of the die-cast aluminum alloy, first add pure aluminum ingots into the melting furnace, heat to 730℃-760℃, keep for 30 minutes to melt the aluminum ingots. After all the aluminum ingots are melted, add pure zinc ingots and aluminum silicon. Alloy, iron powder, aluminum-manganese alloy, aluminum-copper alloy, aluminum-titanium alloy and aluminum-nickel alloy, then add refining agent and slag, then stand for 15 minutes-25 minutes; then cool to 700℃-720℃, add Pure magnesium ingot, stir evenly and keep it for 15-25 minutes; then add special refining agent for aluminum alloy, blow in argon gas for rotating degassing, and then stand for 20 minutes to fully separate impurities, then slag and ash removal; On-line hydrogen removal and two-stage filtration, and then casting to form a die-cast aluminum alloy ingot, the casting temperature is 650-720℃.

Example 2-3

The specific formula of its die-cast aluminum alloy is shown in Table 1.

The die-cast aluminum alloy of Examples 1-3 of the present invention, the traditional Al-Mg-Si series aluminum alloy and the aluminum alloy with the brand ADC12 were tested for mechanical properties and fluidity.

Mechanical performance test: the die-cast aluminum alloy ingot obtained by casting in Example 1-3 of the present invention is re-melted, heated to 700°C, and in accordance with the provisions of the national standard GB/T228.1-2010, a 250T die-casting machine is used to prepare a stretch of 6mm in diameter The sample was tested for its yield strength and elongation, and the tensile rate was 1.5 mm/min. The same method was used to test the mechanical properties of traditional Al-Mg-Si series aluminum alloy and aluminum alloy grade ADC12. The test results are shown in Table 1.

Fluidity test: Use the metal spiral method to test its fluidity. Under the same conditions, test the fluidity of traditional Al-Mg-Si aluminum alloys and aluminum alloys with the grade ADC12. The test results are shown in Table 1.

Table 1

It can be seen from the results in Table 1 that the fluidity of the die-cast aluminum alloy in the examples of the present invention is better than that of the traditional Al-Mg-Si die-cast aluminum alloy, which is better than that of the conventional ADC12 (Al-Si-Cu series) die-cast aluminum alloy. 91% or more. It can be learned from Examples 2 and 3 that while maintaining high toughness, the strength of the aluminum alloy of the multi-element (Zn, Mg, Cu) synergistic strengthening solution of Example 2 is better than that of the ultra-high Zn content solution of Example 3. Although higher Zn element content is conducive to the improvement of fluidity, it will cause the product weight to be too high, and the thermal stability and corrosion resistance will decrease. Therefore, under the conditions of meeting fluidity and toughness, the Zn element should be controlled within a moderate content range ( Such as 17%-23%), and through the synergistic strengthening of other elements such as magnesium, copper, etc., it is beneficial to obtain a die-cast aluminum alloy with better comprehensive performance to better meet the needs of 3C products.

Claims (24)

1. A die-cast aluminum alloy, which is characterized in that it includes the following components in mass percentage:

   Magnesium: 0.1%-7%,

   Zinc: 7%-35%,

   Manganese: 0.2%-0.8%,

   Iron: 0.1%-0.7%,

   Titanium and/or zirconium: 0.07%-0.2%,

   Inevitable impurities ≤ 0.3%, and aluminum.
2. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the zinc is 12%-33%.
3. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the zinc is 17%-23%.
4. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the magnesium is 2%-6%.
5. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the magnesium is 3.3%-5.1%.
6. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the iron is 0.12%-0.35%.
7. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the iron is 0.2%-0.3%.
8. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the manganese is 0.25%-0.7%.
9. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the manganese is 0.35%-0.6%.
10. The die-cast aluminum alloy according to claim 1, wherein the mass percentage of the titanium and/or zirconium is 0.08%-0.12%.
11. The die-cast aluminum alloy according to claim 1, wherein the composition of the die-cast aluminum alloy further includes silicon, and the mass percentage of the silicon is greater than 0 and less than or equal to 2.3%.
12. The die-cast aluminum alloy according to claim 11, wherein the mass percentage of the silicon is 0.5%-1.9%.
13. The die-cast aluminum alloy according to claim 12, wherein the mass percentage of the silicon is 0.7%-1.6%.
14. The die-cast aluminum alloy according to claim 1, wherein the composition of the die-cast aluminum alloy further includes copper, and the mass percentage of the copper is greater than 0 and less than or equal to 2.6%.
15. The die-cast aluminum alloy according to claim 14, wherein the mass percentage of the copper is 0.3%-2.3%.
16. The die-cast aluminum alloy according to claim 15, wherein the mass percentage of the copper is 0.7%-1.6%.
17. The die-cast aluminum alloy according to claim 1, wherein the internal phases of the structure of the die-cast aluminum alloy include α-Al phase and intermetallic compounds, and the intermetallic compounds are distributed at grain boundary positions or precipitated in the grain boundaries. In the α-Al phase, the intermetallic compound includes a MgZn ₂ phase and an iron-rich phase.
18. The die-cast aluminum alloy according to any one of claims 1-17, wherein, under the same conditions, the fluidity of the die-cast aluminum alloy is more than 91% of the ADC12 die-cast aluminum alloy.
19. The die-cast aluminum alloy according to any one of claims 1-18, wherein the yield strength of the die-cast aluminum alloy is ≥240 MPa, and the elongation is ≥3%.
20. A method for preparing die-cast aluminum alloy is characterized in that it comprises the following steps:

    According to the composition ratio of the die-cast aluminum alloy, the pure aluminum ingot is first added to the smelting furnace. After the aluminum ingot is melted, the metal element source that can provide other element components other than aluminum is added for smelting, and then after refining and degassing treatment, The die-cast aluminum alloy is obtained by casting, and the die-cast aluminum alloy includes the following mass percentages of components: magnesium: 0.1%-7%, zinc: 7%-35%, manganese: 0.2%-0.8%, iron: 0.1 %-0.7%, titanium and/or zirconium: 0.07%-0.2%, unavoidable impurities ≤ 0.3%, and aluminum.
21. The preparation method according to claim 20, characterized in that, after adding pure aluminum ingots in the melting furnace, heating to 730°C-760°C to melt the pure aluminum ingots, the aluminum ingots are completely melted and then the aluminum-manganese alloy, Pure zinc ingot, iron powder, aluminum-titanium alloy and/or aluminum-zirconium alloy, after cooling to 700°C-720°C, add pure magnesium ingot, stir and keep for 15-25 minutes.
22. The preparation method according to claim 20, wherein the temperature of the material is 650°C-720°C during the casting process.
23. A structural part of a communication product, characterized in that the structural part of a communication product is cast by the die-cast aluminum alloy according to any one of claims 1-19.
24. 22. The communication product structure of claim 23, wherein the communication product structure includes a mobile phone midplane.