Aluminum alloy and preparation method therefor, die casting, welding assembly, and electronic device

Abstract

Provided are an aluminum alloy and a preparation method therefor, a die casting, a welding assembly, and an electronic device. Based on the total weight of the aluminum alloy, the aluminum alloy comprises the following elements in percentages by weight: 0.01-15% of La; 0.01-15% of Ce; 0.3-3% of Fe; 0.3-3.0% of Mn; and 0.01%-0.5% of Zr. La and Ce content together total 3%-15%, and the balance is Al and inevitable impurities, the content of any individual impurity element among the inevitable impurities being less than or equal to 0.2%.

Description

Aluminum alloy and preparation method thereof, die casting and welding assembly, and electronic equipment

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office of China on November 30, 2023, with application number 202311626856.5 and application name “Aluminum alloy and its preparation method, die casting and welded assembly and electronic equipment”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the field of aluminum alloys, and in particular to an aluminum alloy and a preparation method thereof, die-castings and welded assemblies, and electronic equipment. Background Art

[0004] Brazing is a welding method in which the filler metal, which is lower than the melting point of the workpieces, and the workpieces are heated simultaneously to the melting point of the filler metal. Liquid filler metal then fills the gap between the solid workpieces, creating a metal connection. Die-cast aluminum alloys are widely used due to their high production efficiency, low cost, and ability to form complex structures in one go. However, current die-cast aluminum alloys often contain the element Si. Al-Si alloys have relatively low melting points. For example, the commonly used Al-Si alloy grades ADC12 and ADC10 have a melting point of 516°C and 538°C, respectively. High-temperature brazing temperatures are typically around 600°C, which causes the aluminum alloy to melt during the brazing process. While Al-1.6Mn can be brazed at high temperatures, the material softens significantly during the process, resulting in very low post-brazing strength. Therefore, there is currently a lack of die-cast aluminum alloys that can maintain high strength even after high-temperature brazing. Summary of the Invention

[0005] The present application provides an aluminum alloy and a preparation method thereof, a die-casting and a welding assembly, and an electronic device, so as to increase the melting point of the aluminum alloy and the strength of the aluminum alloy after brazing.

[0006] In a first aspect, the present application provides an aluminum alloy, which includes the following elemental composition in weight percentage, based on the total weight of the aluminum alloy: La 0.01% to 15%, Ce 0.01% to 15%, Fe 0.3% to 3%, Mn 0.3% to 3.0%, and Zr 0.01% to 0.5%, wherein the sum of the La and Ce contents is 3% to 15%, and the balance includes Al and unavoidable impurities, and the content of any impurity element among the unavoidable impurities is less than 0.2%.

[0007] In the aluminum alloy of the present application, the addition of 0.01% to 15% by mass of La and 0.01% to 15% by mass of Ce can form a high eutectic aluminum-lanthanum-cerium rare earth alloy with Al, resulting in an aluminum alloy with a higher melting point, such as a melting point above 640°C. The addition of Fe can form an elongated second phase with Al, which is used to increase the yield strength of the aluminum alloy. The added iron can reduce the adhesion of the aluminum alloy to the steel mold during die-casting, reduce mold sticking, and improve the release efficiency of the aluminum alloy, thereby ensuring the die-casting effect. The addition of Mn can, on the one hand, synergize with Fe to further improve the release efficiency, and on the other hand, increase the spheroidization of the Fe-containing second phase, thereby enhancing the strengthening effect of the aluminum alloy second phase. The addition of Zr can form a precipitate phase with Al, such as Al3Zr, which has a precipitation strengthening effect. The combined action of these elements can achieve a high melting point for the resulting aluminum alloy, preventing melting of the aluminum alloy due to the high temperature of brazing; at the same time, the aluminum alloy can also have a high strength after high-temperature brazing.

[0008] In an optional implementation, the aluminum alloy may contain La in an amount of 2% to 10% by weight, such as 2% to 7% or 2.4% to 4.0% by weight. In an optional implementation, the aluminum alloy may contain Ce in an amount of 2% to 10% by weight, such as 5% to 8% or 5.2% to 7.2% by weight. In an optional implementation, the sum of the La and Ce contents is 8% to 11% or 9% to 10.5% by weight.

[0009] In an optional implementation, the weight fraction of Fe in the aluminum alloy may be 0.5% to 2.5%, such as 1% to 1.5%, or even 1.1% to 1.3%, calculated as a percentage by weight.

[0010] In an optional implementation, when the aluminum alloy does not contain Cr, the weight fraction of Mn may be 0.5% to 2%, such as 0.6% to 1.5%, such as 0.6% to 1%, and such as 0.85% to 1%.

[0011] In an optional implementation, the weight fraction of Zr in the aluminum alloy may be 0.1% to 0.5%, such as 0.15% to 0.40%, such as 0.20% to 0.35%, and such as 0.20% to 0.30%.

[0012] In one alternative embodiment, the aluminum alloy comprises, by weight, the following elements: La: 2% to 7%, Ce: 5% to 8%, Fe: 1.0% to 1.5%, Mn: 0.6% to 1%, and Zr: 0.2% to 0.5%. In another alternative embodiment, the aluminum alloy comprises, by weight, the following elements: La: 2% to 5%, Ce: 5% to 7.5%, Fe: 1.1% to 1.3%, Mn: 0.8% to 1%, and Zr: 0.2% to 0.3%. Aluminum alloys of this composition can have a higher melting point and higher yield strength after high-temperature brazing.

[0013] In an optional implementation, the aluminum alloy further comprises 0.01% to 0.5% Cr, for example, 0.15% to 0.5%, for example, 0.15% to 0.4%, or even 0.15% to 0.25% by weight. The addition of Cr forms a reinforcing Cr-containing second phase and refines the grains, thereby increasing the strength of the aluminum alloy. In an optional implementation, when the aluminum alloy contains Cr, the weight fraction of Mn, for example, 0.5% to 1.2% by weight, for example, 0.5% to 0.9%, or even 0.5% to 0.6%, can be used.

[0014] In one alternative embodiment, the aluminum alloy comprises the following elements: La 2% to 7%, Ce 5% to 8%, Fe 1.0% to 1.5%, Mn 0.45% to 0.60%, Zr 0.2% to 0.5%, and Cr 0.1% to 0.4%. In another alternative embodiment, the aluminum alloy comprises the following elements: La 2% to 5%, Ce 5% to 7.5%, Fe 1.1% to 1.3%, Mn 0.5% to 0.6%, Zr 0.2% to 0.35%, and Cr 0.2% to 0.3%. This aluminum alloy may have a higher melting point and a higher yield strength after high-temperature brazing.

[0015] In an optional implementation, the aluminum alloy further comprises, by weight, at least one of the following elements: Sc 0.01% to 0.5%, V 0.01% to 0.5%, Mo 0.01% to 0.5%, Ti 0.01% to 0.5%, and Mg 0.01% to 0.5%. The addition of these elements can help improve the thermal conductivity, hardness, and other properties of the aluminum alloy.

[0016] In an optional implementation, the melting point of the aluminum alloy is ≥620° C. In an optional implementation, the thermal conductivity of the aluminum alloy is ≥120 W / m·K. In an optional implementation, the yield strength of the aluminum alloy after brazing at 590-630° C. is ≥80 MPa.

[0017] In a second aspect, the present application provides a method for preparing an aluminum alloy, which comprises: melting the intermediate alloys of the elements according to the components of the aluminum alloy of the present application to obtain an alloy melt, and then refining, degassing, and deslagging the alloy melt and then die-casting to obtain the aluminum alloy.

[0018] In a third aspect, the present application provides a die-casting part, which is prepared using the aluminum alloy of the present application.

[0019] In a fourth aspect, the present application provides a welding assembly, comprising a metal substrate and the die-casting of the present application, wherein the die-casting is connected to the metal substrate by brazing.

[0020] In a fifth aspect, the present application provides an electronic device, comprising a processing unit and a packaging component for packaging the processing unit, wherein at least some structural parts of the packaging component are the die-cast parts of the present application.

[0021] The technical effects that can be achieved in the above-mentioned second to fifth aspects can be described with reference to the corresponding effects in the above-mentioned first aspect, and will not be repeated here.

[0022] Among them, the data in the above-mentioned possible implementation methods of the present application, such as the weight percentages of La, Ce, Fe, Mn and Zr, etc., when measured, the values ​​within the engineering measurement error range should be understood to be within the range specified in the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic structural diagram of a heat dissipation plate;

[0024] FIG2 is a microstructure diagram of an aluminum alloy according to an embodiment;

[0025] FIG3 is an ultrasonic inspection diagram of the welding surface of the die casting after brazing;

[0026] FIG4 is a DSC test curve diagram of the aluminum alloy of Example 1;

[0027] FIG5 is a stress and strain curve of the aluminum alloy after brazing in Example 1;

[0028] FIG6 is a schematic diagram of the weld after brazing the aluminum alloy of Example 1 with other components;

[0029] FIG7 is a stress and strain curve at the weld of the aluminum alloy of Example 1;

[0030] FIG8 is a photo of a die-cast structural part and a plate subjected to pressure explosion after brazing in one embodiment. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of this application clearer, this application will be further described in detail below with reference to the accompanying drawings.

[0032] The terms used in the following examples are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification of this application and the appended claims, the singular expressions "a", "an", "above", "the" and "this" are intended to also include expressions such as "one or more", unless the context clearly indicates otherwise. References to "one embodiment" or "some embodiments" described in this specification mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized. In this application, unless otherwise specified, percentages (%) or parts refer to weight percentages or weight parts relative to the composition. In this application, unless otherwise specified, the components involved or their preferred components can be combined with each other to form new technical solutions. In this application, unless otherwise specified, the numerical range "a to b" represents an abbreviation for any real number combination between a and b, where a and b are both real numbers.

[0033] Aluminum alloys are widely used in communications equipment, automobiles, and consumer electronics due to their high production efficiency, low cost, and ability to form complex structures. For example, aluminum alloys are widely used in the housings of various electronic devices, such as, but not limited to, communications equipment, including large-scale multiple-receiver multiple-transmitter systems, remote radio frequency units, and active antenna processing units. Of course, electronic equipment beyond communications equipment also includes computers, numerical control equipment, programmable control equipment, in-vehicle thermal circulation enclosures, and cooling enclosures for vehicle computers, among other devices, which are not listed here.

[0034] Exemplarily, the electronic device may include: a housing and a processing unit located in the housing. The processing unit may be any unit with processing functions in the electronic device, such as a processor, a processing circuit, etc. The components of the housing may include a heat sink, and the processing unit may be arranged on the heat sink, and the heat sink is used to cool the processing unit. Figure 1 is a schematic structural diagram of a heat sink. The heat sink can be used as a part of the housing of the electronic device. As shown in Figure 1, the heat sink may include a base and a cover. The structure of the cover is shown in Figure (a) of Figure 1, and the structure of the base is shown in Figure (b) of Figure 1. The structure after the base and the cover are sealed is shown in Figure (c) of Figure 1. A coolant flow channel is provided in the base to enable the flow of coolant. The cover is sealed to the base to achieve sealing of the coolant flow channel. The sealed connection between the base and the cover can be brazing. The base 10 includes a frame a1, a base plate a2, and an island structure a3 disposed on the base plate a2. Part of the island structure a3 is connected to the frame a1, and the island structure a3 is disposed within the space enclosed by the frame a1 and the base plate a2. The base can be formed by die-casting aluminum alloy through a die-casting process to save materials and reduce machining processes. The cover plate 20 is a brazing composite plate (as shown in FIG. (a)). The cover plate 20 is a flat plate structure having a certain thickness. When the base and the cover plate are welded, brazing material can be placed on the surface of the cover plate 20 so that a side surface of the cover plate 20 having the brazing material contacts the base 10, thereby causing the brazing material on the surface of the cover plate 20 to contact the frame a1 of the base 10 and the island structure a3. After high-temperature brazing, the cover plate 20 and the base 20 can be welded together through the island structure a3 and the frame a1. The area between the cover plate 20 and the base 20, excluding the island structure a3, forms a cavity, which serves as a coolant flow channel. When the heat sink is used to dissipate heat, refrigerant can be injected into the two coolant channels through the injection pipe 30 provided on the cover plate 20, so that the refrigerant can evaporate, cool, and circulate in the cavity, thereby removing heat and achieving the heat dissipation function. Of course, the cover plate 20 is not limited to a flat plate structure, but can also be other structures that can be sealed and connected to the base and form a space between the two. It should be understood that the structure of the die-casting of the present application is not limited to that shown in Figure 1, and can also be other shapes set according to factors such as actual application scenarios and usage purposes, which are not limited here.

[0035] Among them, when welding aluminum alloy die-castings, high-temperature brazing can be used for welding. This requires ensuring that the melting point of the aluminum alloy die-casting is higher than the temperature used during high-temperature brazing. If the melting point of the aluminum alloy casting is lower than the temperature used during high-temperature brazing, the aluminum alloy die-casting will melt during high-temperature brazing and the desired structure cannot be obtained. Usually, the temperature used for high-temperature brazing is about 600°C, and the commonly used aluminum alloy die-castings are generally Al-Si alloys. The melting point of Al-Si alloys is relatively low, about 577°C. Obviously, the melting point of Al-Si alloys is lower than the temperature used during high-temperature brazing, so aluminum alloy castings made of Al-Si alloys cannot be used in the field of high-temperature brazing.

[0036] In view of this, an embodiment of the present application provides an aluminum alloy. The aluminum alloy can be used in a die-casting process to form various complex die-castings. The aluminum alloy may have a high melting point, such as a melting point of 640°C and above. The die-casting formed using the aluminum alloy of the embodiment of the present application can withstand the high temperature of brazing without melting, and can also have a higher yield strength after high-temperature brazing, for example, a yield strength of 120 MPa or more, to meet the requirements of high structural strength and high reliability. At the same time, the aluminum alloy of the embodiment of the present application will not react with the brazing material, affecting the appearance and mechanical properties of the aluminum alloy.

[0037] The aluminum alloy of the embodiment of the present application includes Al, alloying elements and inevitable impurities. Wherein, based on the total weight of the aluminum alloy, the alloying elements may include the following elemental composition in weight percentage: La 0.01% to 15%, Ce 0.01% to 15%, Fe 0.3% to 3%, Mn 0.3% to 3.0%, Zr 0.01% to 0.5%, and the sum of the contents of La and Ce is 3% to 15%. When Si exists in the form of inevitable impurities, the content is less than or equal to 0.2%, preferably ≤0.1%. In addition, in the aluminum alloy of the embodiment of the present application, the content of any impurity element in the inevitable impurities is less than 0.2%. Wherein, the total amount of inevitable impurities is ≤0.4%.

[0038] Lanthanum La and Cerium Ce

[0039] Regarding the addition of lanthanum and cerium: by adding 0.01% to 15% by mass of lanthanum, an aluminum-lanthanum alloy with a eutectic temperature above 640°C can be formed. By adding 0.01% to 15% by mass of cerium, an aluminum-cerium alloy with a eutectic temperature above 640°C can be formed. As a result, the aluminum alloy with the addition of lanthanum and cerium has a higher melting point, and the melting point of this aluminum alloy can reach above 630°C. When the high-temperature brazing temperature is around 600°C, the melting point of this aluminum alloy is higher than the high-temperature brazing temperature, so this aluminum alloy will not melt during high-temperature brazing, making it suitable for high-temperature brazing. Moreover, the standard electrode potential of lanthanum is about -2.379V, the standard electrode potential of cerium is about -2.336V, and the standard electrode potential of aluminum is about -1.66V. Obviously, the ability of lanthanum and cerium to lose electrons is higher than that of aluminum. Therefore, when corrosion occurs, lanthanum and cerium are corroded first, while aluminum is less likely to be corroded. Therefore, the introduction of lanthanum and cerium protects aluminum and improves the corrosion resistance of aluminum alloy. In addition, during the solidification and cooling stage of the die-casting melt, the introduced lanthanum and cerium can form intermetallic compound second phase particles with aluminum, such as Al 11 (La,Ce)3, this intermetallic compound second phase particle can be called authigenic second phase particles, and these intermetallic compound second phase particles can increase the number of crystal nuclei in the aluminum alloy as heterogeneous crystal nuclei. During the crystal nucleus growth process, various crystal nuclei collide with each other and inhibit grain growth, thereby refining the grains. Since the intermetallic compound second phase particles are only produced during the melt solidification and cooling stage of die casting, before the melt solidification and cooling stage of die casting, these intermetallic compound second phase particles are absent and cannot play the role of heterogeneous crystal nuclei in refining the grains. Therefore, the addition of lanthanum and cerium can improve the mechanical properties of aluminum alloys after die casting to a certain extent, but the degree of improvement is limited.

[0040] In the embodiments of the present application, the La content is controlled to be 0.01% to 15%, further 2% to 10%, for example, 2% to 7%, and further for example 2.4% to 4.0%, and the effect of increasing the melting point of the aluminum alloy is more obvious. In terms of weight percentage, the amount of La added to the aluminum alloy can be, for example, 0.01%, 0.5%, 1%, 1.5%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.5%, 9%, 10%, 11%, 12%, 13%, 15%, or any value in between. The values ​​listed above are all examples. The lower limit of the amount of La added can be any of the above values ​​or a value between the above two values; the lower limit of the amount of La added can be any of the above values ​​or a value between the above two values.

[0041] In the embodiments of the present application, when the La content is controlled at 0.01% to 15%, further at 2% to 10%, for example, at 5% to 8%, and further at 5.2% to 8%, the effect of increasing the melting point of the aluminum alloy is more obvious. In terms of weight percentage, the Ce addition amount in the aluminum alloy can be, for example, 0.5%, 1%, 1.5%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.2%, 4.5%, 4.8%, 5%, 5.2%, 5.5%, 5.8%, 6%, 6.2%, 6.5%, 6.8%, 7%, 7.2%, 7.5%, 7.8%, 8%, 8.5%, 9%, 10%, 11%, 12%, 13%, 15%, or any value in between. The values ​​listed above are all examples. The lower limit of the amount of Ce added can be any of the above values ​​or a value between the above two values; the lower limit of the amount of Ce added can be any of the above values ​​or a value between the above two values.

[0042] Wherein, by weight percentage, the total addition amount of La and Ce in the aluminum alloy can be 3% to 15%, such as 8% to 11%, and further such as 9% to 10.5%. For example, for example, 8%, 8.2%, 8.5%, 8.7%, 9%, 9.2%, 9.5%, 9.7%, 10%, 10.2%, 10.5%, 10.7%, 11%, 12%, 13%, or 15% or any value between the above two values. The above values ​​are for illustration only. The lower limit of the addition amount of La and Ce can be any of the above values ​​or a value between the above two values; the lower limit of the addition amount of La and Ce can be any of the above values ​​or a value between the above two values.

[0043] Iron Fe:

[0044] For Fe: By adding 0.3% to 3% by mass of iron, during the solidification and cooling stage of the molten metal during die casting, iron can also form intermetallic compound second phase particles in the aluminum liquid, such as (La, Ce)Fe2Al 10 These intermetallic compound second-phase particles, also known as autogenous second-phase particles, act as heterogeneous nuclei during the die-casting process of aluminum alloys, refining the grain size. Since these intermetallic compound second-phase particles are generated during the solidification and cooling phase of the die-casting melt, they can also improve the mechanical properties of the aluminum alloy to a certain extent, but the degree of improvement is limited. Furthermore, the added iron can reduce the adhesion of the aluminum alloy to the steel mold during the die-casting process, reducing mold sticking and improving the release of the aluminum alloy, thereby enhancing the die-casting effect.

[0045] When the content of Fe is 0.3% to 3%, further 0.5% to 2.5%, for example 1% to 1.5%, and for example 1.1% to 1.3%, the effect of increasing the yield strength of the aluminum alloy is more obvious. In terms of weight percentage, the addition amount of Fe in the aluminum alloy can be, for example, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, or 3% or any value between the above two values. The numerical values ​​listed above are all examples. The lower limit of the amount of Fe added can be any of the above numerical values ​​or a value between the above two numerical values; the lower limit of the amount of Fe added can be any of the above numerical values ​​or a value between the above two numerical values.

[0046] Manganese Mn:

[0047] Regarding added manganese: Adding 0.3% to 3% manganese by mass provides solid solution strengthening. Furthermore, manganese can transform flaky, iron-containing intermetallic compound second-phase particles into fine, spherical intermetallic compound second-phase particles, thereby improving the strengthening effect of the iron-containing intermetallic compound second-phase particles. Consequently, under the action of manganese, the iron-enhancing effect on the mechanical properties of the aluminum alloy can be increased. Furthermore, because the eutectic temperature of aluminum and manganese is approximately 658°C, while the solidification point of aluminum is approximately 660°C, the addition of manganese has little effect on the melting point of the aluminum alloy. Furthermore, the combination of manganese and iron further reduces the tendency of castings to stick to steel molds, thereby improving the die-casting process.

[0048] The content of Mn can be 0.3% to 1.2%. When the aluminum alloy does not contain Cr, the effect of increasing the yield strength of the aluminum alloy is more obvious when the Mn content is in the range of 0.7% to 1.1%, for example, 0.7% to 1%, or even 0.85% to 1%. In terms of weight percentage, the amount of Mn added to the aluminum alloy can be, for example, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, 0.8%, 0.85%, 0.9%, 0.95%, 1.0%, 1.05%, 1.1%, 1.15%, or 1.2%, or any value in between. The above-listed values ​​are for illustration only. The lower limit of the amount of Mn added may be any of the above values ​​or a value between the above two values. The lower limit of the amount of Mn added may be any of the above values ​​or a value between the above two values.

[0049] Zirconium Zr:

[0050] Regarding added zirconium: By adding 0.01% to 0.5% by mass, zirconium acts as a heterogeneous nucleus to promote the formation of a large number of nano-precipitated phases, such as Al3Zr. This refines the grain size during the die-casting process of the aluminum alloy, further improving the mechanical properties of the aluminum alloy after die-casting and high-temperature brazing. Too low a Zr content will not effectively refine the grain size and improve the strength of the aluminum alloy. Too high a Zr content will not significantly improve strength and will significantly increase costs.

[0051] Among them, when the content of Zr is 0.01% to 0.5%, such as 0.1% to 0.5%, further 0.15% to 0.5%, such as 0.2% to 0.4%, and further such as 0.2% to 0.35%, the effect of increasing the yield strength of the aluminum alloy is more obvious. In terms of weight percentage, the addition amount of Zr in the aluminum alloy can be, for example, 0.01%, 0.02%, 0.03%, 0.05%, 0.07%, 0.08%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.33%, 0.35%, 0.38%, 0.4%, 0.42%, 0.45%, or 0.5%, or any value in between. The values ​​listed above are all examples. The lower limit of the amount of Zr added can be any of the above values ​​or a value between the above two values; the lower limit of the amount of Zr added can be any of the above values ​​or a value between the above two values.

[0052] In summary, by adding specific amounts of lanthanum, cerium, iron, manganese and zirconium to aluminum, they can work together to increase the melting point and mechanically strengthen the aluminum alloy, so that the resulting aluminum alloy has a higher melting point and can be used for high-temperature brazing. It also has good mechanical properties, corrosion resistance, and die-casting molding effects.

[0053] In some embodiments, the aluminum alloy comprises the following elemental composition by weight, based on the total mass of the aluminum alloy: La 2% to 7%, Ce 5% to 8%, Fe 1.0% to 1.5%, Mn 0.7% to 1%, and Zr 0.2% to 0.5%. The sum of the La and Ce contents is 5% to 15%, such as 8% to 11%. The aluminum alloy does not contain Si or Si is present as an unavoidable impurity, with the remainder comprising Al and unavoidable impurities. The content of any impurity element among the unavoidable impurities is less than 0.2%, and the content of Si, when present as an unavoidable impurity, is less than 0.2%, such as ≤0.1%.

[0054] Chromium Cr:

[0055] In some embodiments of the aluminum alloy, the alloy composition may also include Cr. In terms of weight percentage, the Cr content may be, for example, 0.01% to 0.5%. The addition of Cr can form an AlCeCrMn phase with Al, Ce, and Mn, transforming the intermetallic compound into a dense second-phase particle with higher sphericity, thereby refining the grain size, reducing internal defects, improving the strengthening effect, and further increasing the strength of the aluminum alloy. Specifically, when the Cr content is 0.15% to 0.5%, further 0.15% to 0.4%, and for example 0.2% to 0.4%, the effect of increasing the yield strength of the aluminum alloy is more significant. In terms of weight percentage, the amount of Cr added to the aluminum alloy may be, for example, 0.01%, 0.02%, 0.05%, 0.07%, 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.22%, 0.25%, 0.28%, 0.3%, 0.32%, 0.35%, 0.37%, 0.4%, 0.42%, 0.45%, 0.48%, or 0.5%, or any value between the above two values. The above values ​​are for illustration only, and the lower limit of the amount of Cr added may be any of the above values ​​or a value between the above two values; the lower limit of the amount of Cr added may be any of the above values ​​or a value between the above two values.

[0056] Among them, when the aluminum alloy contains Cr, the addition amount of Mn in the aluminum alloy can be 0.3% to 0.7%, such as 0.4% to 0.7%, such as 0.45% to 0.7%, and such as 0.45% to 0.60%, thereby further increasing the yield strength of the aluminum alloy.

[0057] In some embodiments, the aluminum alloy comprises the following elemental composition by weight, based on the total mass of the aluminum alloy: La 2% to 7%, Ce 5% to 8%, Fe 1.0% to 1.5%, Mn 0.45% to 0.6%, Zr 0.2% to 0.5%, and Cr 0.1% to 0.4%. The sum of the La and Ce contents is 5% to 15%, such as 8% to 11%. The aluminum alloy does not include Si or Si is present as an unavoidable impurity, with the remainder comprising Al and unavoidable impurities. The content of any impurity element among the unavoidable impurities is less than 0.2%, and the content of Mg, when present as an unavoidable impurity, is ≤ 0.2%.

[0058] Figure 2 is a microstructure diagram of an aluminum alloy according to an embodiment. As shown in Figure 2, the microstructure of the aluminum alloy according to the embodiment of the present application shows that the various phases are evenly distributed and relatively small in size, and the grain morphology approaches a spherical equiaxed structure. This indicates that the aluminum alloy according to the present application has a relatively large number of second phases uniformly embedded in the aluminum matrix. After high-temperature brazing, the large amount of second phases effectively inhibits grain growth and strengthens the aluminum alloy.

[0059] In the crystal structure shown in FIG2 , the grain morphology of different phases and the composition of the phase components are listed in Table 1 .

[0060] Table 1

[0061] Combined with Figure 2 and Table 1, it can be seen that the elements interact with each other to form phase structures with different morphologies. Among them, Al3(La, Ce) is evenly distributed in a dotted manner, and Al3(La, Ce)+α-Al is distributed in a network structure between the grains of the spherical α-Al matrix. The second phases Al(La, Ce)FeMn and AlCeCrMn are evenly dispersed in blocks to help improve the strength of the aluminum alloy. At the same time, Zr exists in the form of Al3Zr precipitation phase, with a nano-spherical structure, which can refine the grains of each phase and improve the material strength by hindering dislocation movement through the precipitation phase. The above elements form different second phases / precipitations to refine the grains and hinder grain growth, and work together to ensure that the brazed material maintains a higher strength.

[0062] Among them, the melting point of the aluminum alloy containing the above components may be ≥600°C, such as greater than or equal to 630°C. In addition, the thermal conductivity of the aluminum alloy containing the above components may be ≥120W / m·K. At the same time, the yield strength of the aluminum alloy of the embodiment of the present application after brazing at 590-630°C is ≥100MPa, such as ≥120MPa. The aluminum alloy of the embodiment of the present application can pass the neutral salt spray 720h test. The bubbling height of the die casting surface after brazing is ≤0.5mm, such as ≤0.2mm, or no bubbling. The brazing rate is ≥60%, such as ≥70%, or ≥90%. As a result, during the brazing process, the phenomenon of cold welding and empty welding is reduced.

[0063] In addition to the aforementioned elemental components, the aluminum alloys of the embodiments of the present application may further include, by weight, at least one of the following elements: V 0.01% to 0.5%, Mo 0.01% to 0.5%, Ti 0.01% to 0.5%, Sc 0.01% to 0.5%, and Mg 0.01% to 0.5%. For example, in some embodiments, the aluminum alloy may include 0.01% to 0.5% by weight of V. In some embodiments, the aluminum alloy may include 0.01% to 0.5% by weight of Mo. In some embodiments, the aluminum alloy may include 0.01% to 0.5% by weight of Ti. In some embodiments, the aluminum alloy may include 0.01% to 0.5% by weight of Sc. In some embodiments, the aluminum alloy may include 0.01% to 0.5% by weight of Mg. V, Mo, Ti, and Mg may have similar effects to Cr and Zr in the aluminum alloy. Sc may further strengthen the aluminum alloy, thereby further improving the mechanical properties and corrosion resistance of the aluminum alloy. Therefore, the addition of the above elements can help to further improve the melting point, yield strength, thermal conductivity, hardness and other properties of aluminum alloy.

[0064] The amount of V added can be, for example, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, or any value between the above two values. The above values ​​are for illustration only. The lower limit of the amount of V added can be any of the above values ​​or a value between the above two values; the lower limit of the amount of V added can be any of the above values ​​or a value between the above two values. The amount of Mo added can be, for example, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, or any value between the above two values. The above-listed values ​​are all examples. The lower limit of the amount of Mo added can be any of the above values ​​or a value between the above two values; the lower limit of the amount of Mo added can be any of the above values ​​or a value between the above two values. The amount of Ti added can be, for example, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, or any value between the above two values. The above-listed values ​​are all examples. The lower limit of the amount of Ti added can be any of the above values ​​or a value between the above two values; the lower limit of the amount of Ti added can be any of the above values ​​or a value between the above two values. The amount of Sc added can be, for example, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, or any value between the above two values. The values ​​listed above are all examples. The lower limit of the amount of Sc added can be any of the above values ​​or a value between the above two values; the lower limit of the amount of Sc added can be any of the above values ​​or a value between the above two values. The amount of Mg added can be, for example, 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%, or any value between the above two values. The values ​​listed above are all examples. The lower limit of the amount of Mg added can be any of the above values ​​or a value between the above two values; the lower limit of the amount of Mg added can be any of the above values ​​or a value between the above two values.

[0065] It should be noted that the aluminum alloy of the embodiment of the present application is mainly composed of aluminum, and the sum of the mass percentages of each component is 100%. The inevitable impurities in the embodiment of the present application may be introduced by the raw materials of each component, or introduced by production equipment or tooling during the processing and preparation process. For example, the inevitable impurities may include Si, Cu, Ni, Zn, Ti, Pb, Sn and other impurities. Among them, the content of each inevitable impurity may be less than or equal to 0.20%. For example, by weight percentage, the Si content is ≤0.2%, such as ≤0.12%, the Cu content is 0.2%, such as ≤0.15%, the Mg content is 0.2%, such as ≤0.05%, the Ni content is 0.2%, such as ≤0.05%, the Zn content is 0.2%, such as ≤0.10%, the Ti content is 0.2%, such as ≤0.15%, the Pb content is 0.2%, such as ≤0.02%, the Sn content is 0.2%, such as ≤0.02%, and the total amount of other impurities is 0.4%, such as ≤0.3%. In order not to affect the final performance of the aluminum alloy, the content of inevitable impurities can be controlled below 0.4%, and further can be controlled below 0.3%. For example, the content of impurities finally introduced can be controlled by controlling the purity of the raw materials and the cleanliness of the equipment during the preparation process.

[0066] The above has explained the composition of the aluminum alloy. The following will further explain the preparation method of the aluminum alloy.

[0067] The method for preparing the aluminum alloy of the embodiment of the present application may include the following steps: melting aluminum and a master alloy containing various elements according to the composition of the aluminum alloy of the present application to obtain a molten alloy; refining, degassing, and deslagging the molten alloy, and then die-casting the molten alloy to obtain the aluminum alloy. In this way, an aluminum alloy casting having a specific composition can be produced. The produced aluminum alloy casting has a high melting point, can be used for high-temperature brazing, and also has good mechanical properties, corrosion resistance, and excellent die-casting performance.

[0068] The molten aluminum can be obtained by heating and melting pure aluminum ingots. The pure aluminum ingots can be recycled aluminum raw materials. Other elements can be added in the form of master alloys to reduce production costs. For example, the master alloy of La and Ce can be, for example, an Al-(La, Ce) mixed rare earth master alloy. In the Al-(La, Ce) mixed rare earth master alloy, the mass ratio of La to Ce can be, for example, 30:70 to 50:50, such as 30:70, 35:65, 40:60, or 50:50. The master alloy of Fe can be an Al-Fe master alloy. The master alloy of Mn can be an Al-Mn master alloy. The master alloy of Zr can be an Al-Zr master alloy. The master alloy of Cr can be an Al-Cr master alloy.

[0069] For example, the molten alloy is prepared as follows: After cleaning the surface of the recycled aluminum ingot, place the ingot in a crucible and heat it to melt it. The temperature of the molten aluminum is controlled between 710 and 730°C. Once the molten aluminum reaches 710-730°C, the temperature is raised to 780-800°C. The dried master alloys of each element are added to the molten aluminum and held at this temperature for 10-20 minutes to ensure that all the added master alloys are evenly dissolved.

[0070] It is understandable that, in addition to smelting pure aluminum ingots first and then melting other components, pure aluminum ingots and various components can also be added together and heated to obtain an alloy melt. As long as the raw materials weighed according to the components of the aluminum alloy can be mixed and melted, the order of adding the raw materials is not limited here.

[0071] The refining, degassing, and slag removal process is as follows: When the temperature of the molten alloy drops to 730-750°C, a sodium-free aluminum alloy refining agent is pressed into the molten aluminum using a rotary degasser for refining. Refining is performed for a predetermined time, such as 10-30 minutes. The slag is then removed and the molten aluminum is allowed to stand for 0.5-1.5 hours. After this standing time, the gas content is measured using a hydrogen meter. When the hydrogen content reaches 0.3 ml / 100 g or less, for example, ≤0.2 ml / 100 g, die casting is performed.

[0072] For example, in the refining, degassing and deslagging process, a refining agent is first added to the alloy melt, and a rotary degasser is used to refine and degas the alloy melt with the refining agent. After the refining and degassing is preset for a time, deslagging is performed, and the alloy melt is allowed to stand for a period of time. After that, a hydrogen meter is used to detect the hydrogen content in the alloy melt after standing, and it is determined whether the hydrogen content is greater than a threshold value. If it is greater than, it means that the hydrogen content in the alloy melt is still high and further deslagging and degassing treatment is required, so the above-mentioned deslagging and degassing process is continued; if it is not greater than, it means that the hydrogen content in the alloy melt has met the requirements. At this time, it can be determined that the deslagging and degassing is completed and the die casting process can be performed. Among them, the threshold value can be designed based on factors such as the influence of hydrogen content on aluminum alloy castings and the performance requirements of aluminum alloy castings. It is not limited here. For example, but not limited to, the threshold value is set to no more than 0.3ml / 100g. Further, the threshold value can be optimized to 0.2ml / 100g, at which time the hydrogen content in the alloy melt is less than or equal to 0.2ml / 100g. And the type of refining agent can be selected according to actual conditions, such as but not limited to the selection of sodium-free refining agent, which is not limited here. It should be understood that when making alloy melt, the solubility of hydrogen in the alloy melt is high under high temperature conditions, making hydrogen very soluble in liquid aluminum. During the die-casting process, as the temperature of the alloy melt decreases, the solubility of hydrogen decreases, causing hydrogen to gradually precipitate. If degassing is not performed before die-casting, defects such as pores and pinholes will be generated in the aluminum alloy casting. These defects will cause the surface of the aluminum alloy casting to bubble during high-temperature brazing. Therefore, after slag removal and degassing treatment, the bubbling phenomenon of the aluminum alloy casting after high-temperature brazing can be reduced, so that the bubbling height after high-temperature brazing does not exceed 0.5mm. By further optimizing the threshold, the bubbling height after high-temperature brazing can be further reduced to within 0.2mm or there is no bubbling phenomenon.

[0073] Die Casting: Degassed molten aluminum is placed in a mold cavity for vacuum die casting. The cavity vacuum is maintained at ≤100 mbar, for example, ≤50 mbar, or even 30 mbar. Optimizing the vacuum level can improve the die-casting effect during vacuum die-casting, reduce the amount of gas contained in the aluminum alloy casting, and further enhance the mechanical properties of the aluminum alloy casting. Furthermore, optimizing the vacuum level can further reduce bubbling in the die-cast aluminum alloy casting after high-temperature brazing, as well as reduce the fluidity of the molten alloy.

[0074] In the preparation methods of the present invention, after degassing the alloy melt and high-vacuum die-casting, the die-cast parts have low gas content. High-temperature brazing can reduce blistering and even eliminate blistering. Testing has shown that the surface blister height of die-cast parts after brazing is ≤0.5mm, and some die-cast parts have a blister height of ≤0.2mm. Some die-cast parts even have no blistering at all.

[0075] Based on the same invention purpose, the embodiment of the present application further provides a die casting, which can be made from the aluminum alloy of the embodiment of the present application. The die casting of the embodiment of the present application can be used for heat dissipation.

[0076] For example, the die-castings of the embodiments of this application can be used primarily in wireless communications applications, such as in massive input and output (MIMO) units and RRUs, and in liquid-cooled heat sink enclosures. They can also be used in automotive heat dissipation components, such as those in modular drivetrain (MDC) devices. The aluminum alloys of this application can be used to manufacture components such as heat sinks and radiators for these devices.

[0077] Based on the same inventive purpose, embodiments of the present application also provide a welded assembly comprising a metal substrate and a die-casting according to embodiments of the present application. The die-casting can be welded to the metal substrate, such as by tunnel furnace atmosphere brazing or vacuum furnace brazing. The metal substrate can be formed from the aluminum alloy according to embodiments of the present application, or from other weldable aluminum alloys.

[0078] Based on the same invention purpose, an embodiment of the present application further provides an electronic device, which may include a processing unit and a packaging component, wherein at least some structural parts of the packaging component may be obtained by die-casting the aluminum alloy of the embodiment of the present application.

[0079] The aluminum alloy of the present application will be further described in detail below with reference to the embodiments.

[0080] Example 1

[0081] This embodiment is a die-casting. The aluminum alloy composition is: Al-3.17La-5.86Ce-1.3Fe-0.54Mn-0.23Zr-0.22Cr. La accounts for 3.17% of the total mass of the aluminum alloy. Ce accounts for 5.86% of the total mass of the aluminum alloy. Fe accounts for 1.3% of the total mass of the aluminum alloy. Mn accounts for 0.54% of the total mass of the aluminum alloy. Cr accounts for 0.12% of the total mass of the aluminum alloy. Zr accounts for 0.17% of the total mass of the aluminum alloy. Except for Al, the other elements are unavoidable impurities. The contents of unavoidable impurities are listed in Table 2.

[0082] Example 2

[0083] The composition of the aluminum alloy of this embodiment is: Al-2.96La-5.88Ce-1.2Fe-0.85Mn-0.25Zr-0.03Cr.

[0084] Example 3

[0085] The composition of the aluminum alloy of this embodiment is: Al-3.15La-5.85Ce-0.7Fe-0.54Mn-0.23Zr-0.23Cr.

[0086] Example 4

[0087] The composition of the aluminum alloy of this embodiment is: Al-3.14La-5.83Ce-1.3Fe-0.3Mn-0.23Zr-0.22Cr.

[0088] Example 5

[0089] The composition of the aluminum alloy of this embodiment is: Al-3.18La-5.82Ce-1.3Fe-0.56Mn-0.1Zr-0.22Cr.

[0090] Example 6

[0091] The composition of the aluminum alloy of this embodiment is: Al-3.16La-5.85Ce-1.3Fe-0.57Mn-0.23Zr-0.6Cr.

[0092] The compositions of the aluminum alloys of Examples 1-6 are listed in Table 1.

[0093] Comparative Examples 1-3

[0094] Comparative Examples 1-3 are each an aluminum alloy, and the compositions of the aluminum alloys are listed in Table 3.

[0095] Table 2

[0096] Table 3

[0097] Note: “-” in Table 3 indicates that the element does not exist or exists as an unavoidable impurity element.

[0098] The aluminum alloys of each embodiment and comparative example were tested for melting point, yield strength after brazing, tensile strength after brazing, and thermal conductivity. The test results are listed in Table 4. The high-temperature brazing process conditions were: tunnel furnace atmosphere brazing, a welding temperature of 600°C (optionally 590°C, 600°C, 610°C, 620°C, or 630°C), and a brazing filler metal of 4343 (optionally 4045 or 4047).

[0099] The specific testing process of each parameter is as follows:

[0100] Melting point test: Differential scanning calorimetry (DSC) was performed on the aluminum alloy casting samples to obtain the melting point.

[0101] Mechanical properties test: According to the requirements of GB / T 228, standard tensile mechanical test pieces were cut from the aluminum alloys of each embodiment and comparative example, and the mechanical properties were tested on a tensile testing machine.

[0102] Thermal conductivity: Tested using the laser flash method (ASTM E 1561-01) with a sample size of Φ12.7 mm × 3 mm. Specific heat is determined in accordance with ISO 11357 and ASTM E1269. Density is determined in accordance with ISO 1183-1:2004.

[0103] Table 4

[0104] It can be seen from the relevant data in Table 4 that the aluminum alloys of Examples 1-6, since the melting points of the aluminum alloys of the embodiments of the present application are all higher than 620°C, the aluminum alloys of the embodiments of the present application do not melt the base material during the brazing process. The aluminum alloy of Comparative Example 1 has a relatively low melting point and cannot be brazed. Melting occurs after brazing. The aluminum alloys of Comparative Example 2 and Comparative Example 3 have relatively high melting points, but after brazing, the yield strength is too low, less than 60 MPa, and slippage is likely to occur during the installation process, for example, when performing threaded connections.

[0105] Among them, the comparative data of Example 1 and Example 3 show that when the Fe content is in the range of 1.1%-1.3%, it can help the aluminum alloy die casting obtain a higher yield strength. The comparative data of Example 1, Example 4 and Example 6 show that when the aluminum alloy contains Cr, and the Cr content is in the range of 0.1%-0.25% and the Mn content is in the range of 0.5%-0.60%, it can help improve the mechanical properties of the aluminum alloy die casting. The comparative data of Example 1 and Example 5 show that when the Zr content of the aluminum alloy is in the range of 0.2%-0.35%, it can help improve the mechanical properties of the aluminum alloy die casting.

[0106] After high-temperature brazing, the aluminum alloy die-castings in Example 1 were tested for the brazing rate of the welded parts. Figure 3 is a surface ultrasonic inspection diagram of the die-casting after brazing. As shown in Figure 3, the gray area is the area covered by the brazing filler metal. The brazing rate of the brazing filler metal can reach more than 90%, which can better weld the two aluminum alloy die-castings together and improve the strength of the welding. Therefore, the aluminum alloy die-castings provided in the embodiment of the present application are not only suitable for high-temperature brazing, but also have good welding strength after high-temperature brazing, thereby improving the strength of the structure after welding. In addition, the aluminum alloy die-castings in the embodiment of the present application do not have bubbles on the casting surface after brazing.

[0107] Figure 4 is a DSC test curve of the aluminum alloy of Example 1. As shown in Figure 4, the endothermic peak of the aluminum alloy of Example 1 is around 640°C. This indicates that the melting point of the aluminum alloy of the present application example is significantly higher than the brazing temperature.

[0108] Figure 5 is a stress and strain curve of the aluminum alloy after brazing of Example 1. As shown in Figure 5, the yield strength of the aluminum alloy of Example 1 of the present application after brazing can reach more than 120 MPa.

[0109] Figure 6 is a schematic diagram of the weld after brazing the aluminum alloy and other metal components in Example 1. As shown in Figure 6, the upper component is aluminum alloy and the lower component is other metal substrate. After brazing, no weld holes appear at the weld.

[0110] Figure 7 shows the stress and strain curves at the weld of the aluminum alloy of Example 1. Two aluminum alloys from Example 1 were welded to form a symmetrical tensile test bar with a width of 10 mm. The weld was located midway between the two aluminum alloys. As shown in Figure 7, the tensile strength of the weld can reach over 100 MPa.

[0111] FIG8 is a schematic diagram of the blasting structure of a die-cast structural part and a plate after brazing in one embodiment. As shown in FIG8 , the die-cast structural part in (a) is formed by die-casting using the aluminum alloy of the present application. Its structure is complex and can be die-cast in one step. The plate in (b) the figure can be a 3003 plate. The die-cast structural part and the plate are blasted and separated after welding, and the blasting pressure is 11 MPa. As shown in FIG8 , the high blasting pressure can also reflect that a high-strength sealed connection structure can be formed between the die-cast structural part and the plate of the present application, which can meet the requirements of high-pressure brazing sealing.

[0112] The above are only specific embodiments of the present application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. An aluminum alloy, characterized in that: Based on the total weight of the aluminum alloy, the aluminum alloy includes the following elemental compositions in weight percentage: La 0.01% to 15%, Ce 0.01% to 15%, Fe 0.3% to 3%, Mn 0.3% to 3%, Zr 0.01% to 0.5%, the sum of the contents of La and Ce is 3% to 15%, and the remainder includes Al and unavoidable impurities, wherein the content of any impurity element among the unavoidable impurities is less than 0.2%.

2. The aluminum alloy according to claim 1, characterized in that: In terms of weight percentage, the contents of La, Ce, Fe, Mn and Zr in the aluminum alloy are as follows: La 2% to 7%, Ce 5% to 8%, Fe 1.0% to 1.5%, Mn 0.6% to 1% and Zr 0.2% to 0.5%.

3. The aluminum alloy according to claim 1, characterized in that: Calculated by weight percentage, the aluminum alloy further includes 0.01% to 0.5% Cr.

4. The aluminum alloy according to claim 3, characterized in that: In terms of weight percentage, the contents of La, Ce, Fe, Mn, Zr and Cr in the aluminum alloy are as follows: La 2% to 7%, Ce 5% to 8%, Fe 1.0% to 1.5%, Mn 0.45% to 0.6%, Zr 0.2% to 0.5% and Cr 0.1% to 0.4%.

5. The aluminum alloy according to any one of claims 1 to 4, characterized in that: The aluminum alloy further includes at least one of the following elements by weight: Sc 0.01% to 0.5%, V 0.01% to 0.5%, Mo 0.01% to 0.5%, Mg 0.01% to 0.5%, and Ti 0.01% to 0.5%.

6. The aluminum alloy according to any one of claims 1 to 5, characterized in that: The melting point of the aluminum alloy is ≥620°C.

7. The aluminum alloy according to any one of claims 1 to 6, characterized in that: The thermal conductivity of the aluminum alloy is ≥120 W / m·K.

8. The aluminum alloy according to any one of claims 1 to 7, characterized in that: The yield strength of the aluminum alloy after brazing at 590-630° C. is ≥80 MPa.

9. A method for preparing an aluminum alloy, characterized in that: include: According to the composition of the aluminum alloy as described in any one of claims 1 to 8, the intermediate alloys of the elements are melted to obtain a molten alloy, and the molten alloy is refined, degassed and deslaged and then die-casted to obtain the aluminum alloy.

10. A die casting, characterized in that: The aluminum alloy is prepared by using the aluminum alloy as described in any one of claims 1 to 8.

11. A welding assembly, characterized in that: The invention comprises a metal substrate and the die casting according to claim 10, wherein the die casting is connected to the metal substrate by brazing.

12. An electronic device, characterized in that: The invention comprises a processing unit and a packaging component for packaging the processing unit, wherein at least part of the structural parts of the packaging component are formed by die-casting of the aluminum alloy according to any one of claims 1 to 8.

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