Hard soldering of die cast aluminium alloys and method of manufacture and use thereof

Abstract

The application discloses a kind of hard brazing die-casting aluminum alloy and its preparation method and application, according to mass percentage calculation, the hard brazing die-casting aluminum alloy includes following components: Si is 0.1~0.4%, Mg is 0.1~0.3%, Mn≤0.1%, Fe is 0.7~1.0%, Ti is 0.1~0.25%, Sr is 0.003-0.008%, RE is 1.5-2.0%;Wherein, RE is La and Ce;All remaining elements are impurity elements, and the content of single impurity element is less than 0.03%, the total amount of the impurity element is less than 0.15%, and the rest is aluminum.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, specifically to a brazed die-cast aluminum alloy, its preparation method, and its application. Background Technology

[0002] Because automotive power batteries generate a large amount of heat, and the battery pack is in a relatively enclosed environment, the battery temperature tends to rise. The battery module cooling system is a device used for heat dissipation in new energy vehicles. By cooling or heating the power battery, it maintains the battery at an optimal operating temperature, thereby improving its operating efficiency and extending its lifespan. Aluminum alloys, due to their low density, excellent electrical and thermal conductivity, high specific strength, and good machinability, are widely used in the new energy vehicle industry to achieve the goals of low cost and lightweight design in new energy vehicles.

[0003] Among them, the battery heat dissipation module of new energy is one of the key components of the battery system, which plays a role in cooling the power battery. In the existing technology, the aluminum components of the traditional heat dissipation module are formed by CNC machining of sheet metal or forging parts, welded by brazing, and machined into individual heat dissipation modules for use. This process of machining individual heat dissipation modules not only has high material loss, but also a long production cycle and excessively high overall production cost. Furthermore, the melting temperature of traditional die-casting materials ADC12 and A380 is generally below 610℃, which means that traditional die-casting materials do not meet the temperature requirements for hard brazing. At the same time, the electrical conductivity of their die-cast aluminum alloy materials is below 40% IACS, resulting in poor heat dissipation performance. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the existing technology, the purpose of this invention is to provide a brazed die-cast aluminum alloy, its preparation method and application, so as to solve the problems of large material loss, long production cycle, high production cost and the fact that traditional die-casting materials do not meet the temperature requirements of brazing and have poor electrical conductivity in the production process of aluminum components of battery heat dissipation modules.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A brazed die-cast aluminum alloy, calculated by mass percentage, comprises the following components: Si 0.1–0.4%, Mg 0.1–0.3%, Mn ≤0.1%, Fe 0.7–1.0%, Ti 0.1–0.25%, Sr 0.003–0.008%, and RE 1.5–2.0%; wherein RE is La and Ce; the remaining elements are impurity elements, and the content of a single impurity element is less than 0.03%, and the total amount of the impurity elements is less than 0.15%; the remainder is aluminum.

[0007] Preferably, in the aluminum alloy, the mass ratio of La to Ce is (1-3):(7-9).

[0008] Preferably, the aluminum alloy has a melting point of 630–640°C.

[0009] Preferably, the electrical conductivity of the aluminum alloy is greater than 45% IACS.

[0010] Preferably, the aluminum alloy has a tensile strength greater than 180 MPa, a yield strength greater than 130 MPa, and an elongation greater than 10%.

[0011] This invention also provides a method for preparing a brazed die-cast aluminum alloy, comprising the following steps:

[0012] Step 1: Weigh the raw materials according to the composition of the brazed die-cast aluminum alloy. The raw materials include aluminum ingots, magnesium ingots, iron additives, aluminum-manganese alloy, aluminum-titanium alloy, industrial silicon, aluminum-strontium alloy, and aluminum-rare earth alloy.

[0013] Step 2: Place the aluminum ingots into a melting furnace and heat them to melt to obtain molten aluminum. The temperature of the molten aluminum is controlled at 800-850℃. Then, add industrial silicon and iron additives. After it is completely melted, cool it down to 730-750℃ and add refining agents to refine the molten aluminum.

[0014] Step 3: Add magnesium ingots and aluminum rare earth alloy to the aluminum liquid obtained in Step 2. After it is completely melted, control the temperature at 720-740℃. Add aluminum titanium alloy and aluminum strontium alloy. After it is completely melted, test its composition. After the test is qualified, degas the aluminum liquid and keep the temperature of the aluminum liquid at 690-710℃.

[0015] Step 4: The aluminum obtained in Step 3 is pressed into a mold for die casting. After aging treatment, the brazed die-cast aluminum alloy is obtained.

[0016] Preferably, in step 3, if the composition of the tested material does not meet the requirements of the brazed die-cast aluminum alloy, the raw materials are adjusted to meet the requirements of the brazed die-cast aluminum alloy before degassing treatment.

[0017] This invention also provides an application of a brazed die-cast aluminum alloy, wherein the brazed die-cast aluminum alloy prepared by the above method is used in heat spreaders and liquid water cooling medium radiators.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. This invention adjusts the raw material composition of aluminum alloy, with Fe as the most important element, to ensure the formation of a certain amount of Al3Fe alloy phase structure in the aluminum melt, reducing the erosion reaction of the aluminum melt on the mold and thus forming an Al-Fe-Si intermediate phase, thereby reducing the adhesion of the aluminum melt to the mold, ultimately reducing the occurrence of die casting sticking, so as to facilitate casting, improve formability and production efficiency, and reduce production costs.

[0020] 2. This invention incorporates high levels of La and Ce. The addition of La and Ce effectively refines α-Al grains and reduces the length of Al3Fe phase flakes and needles. The Ce-rich mixed rare earth addition minimizes the average α-Al grain size and the length of Al3Fe flakes, thereby maximizing the tensile strength and elongation of the alloy and increasing the material's electrical conductivity. Simultaneously, Al-Fe-Ce can generate a new alloy phase, Al6CeFe alloy phase, which in turn enhances the new Al phase generated from Al-Fe-La. 12 The LaFe alloy phase transforms from a harmful phase into a reinforcing phase, reducing the die-casting sticking properties of the aluminum alloy and altering its high-temperature oxidation resistance through microalloying.

[0021] 3. The aluminum alloy described in this invention is rich in rare earth alloys. In the molten state of the aluminum alloy, Ce is a strong deoxidizer. After Ce completes the deoxidation reaction, the generated oxides will float to the surface of the alloy liquid in a solid phase and enter the slag liquid to be removed, thereby achieving the purpose of removing oxygen. At the same time, rare earth Ce easily reacts with hydrogen to generate stable gaseous compounds of CeH2 and CeH3 type. These low-density hydrides easily float to the surface of the alloy liquid and are re-decomposed at high temperature, or oxidized and enter the slag liquid to be removed. This improves the conductivity and strength of the die-casting material. Rich in Ce, it can serve as a long-lasting deoxidizer and dehydrogenation element for the material, extending the durability of the low hydrogen content in the die-casting alloy composition.

[0022] 4. The aluminum alloy described in this invention also contains trace amounts of Sr. Sr adsorbs on the growth steps of the eutectic silicon in the aluminum-silicon alloy, hindering the growth of silicon crystals into sheets via a step-growth mechanism. Simultaneously, Sr induces the formation of numerous {1111} crystal twins in the silicon crystal, causing it to grow via a twin valley mechanism, thereby increasing the chemical sites of α(Al) and promoting the growth of α(Al) crystals. Meanwhile, due to the restriction of α(Al), the eutectic silicon grows into fibers via a twin valley mechanism. Sr eliminates heterogeneous nucleation nuclei in silicon; reduces the spontaneous nucleation ability of silicon, and improves the material's electrical conductivity, thermal conductivity, and age-hardening properties. Detailed Implementation

[0023] This invention will describe the technical solutions of the embodiments of the invention clearly and completely. Obviously, the described embodiments are only some embodiments of the invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on this invention are within the scope of protection of this invention.

[0024] Unless otherwise specified in the specific circumstances, the numerical ranges listed in this invention include upper and lower limits, as well as all integers and fractions within that range, but are not limited to the specific values ​​listed when the range is defined.

[0025] I. A type of brazed die-cast aluminum alloy

[0026] The brazed die-cast aluminum alloy of the present invention comprises the following components by mass percentage: Si 0.1-0.4%, Mg 0.1-0.3%, Mn≤0.1%, Fe 0.7-1.0%, Ti 0.1-0.25%, Sr 0.003-0.008%, and RE 1.5-2.0%; wherein RE is La and Ce; the remaining elements are impurity elements, and the content of a single impurity element is less than 0.03%, the total amount of the impurity elements is less than 0.15%, and the remainder is aluminum.

[0027] In some embodiments, Fe is the most important additive element, with its dosage controlled between 0.7% and 1.0%. This is to ensure the formation of a certain amount of Al3Fe alloy phase in the molten aluminum. This alloy phase can reduce the formation of the Al-Fe-Si intermediate phase, which can cause the molten aluminum to stick to the mold, leading to mold sticking during die casting and hindering the forming of the die-cast parts. However, too much or too little Fe will affect the amount of Al3Fe alloy phase formed, thus affecting the beneficial effect of this alloy phase. Therefore, the dosage of Fe can be 0.7%, 0.73%, 0.8%, 0.83%, 0.9%, 0.95%, 0.96%, 0.98%, 1.0%, etc., as well as all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0028] In some embodiments, Si can improve the fluidity of die-cast aluminum alloys. Excessive Si content can lower the melting point of the alloy; however, insufficient Si content is detrimental to silicon crystal formation, preventing trace amounts of Sr from exerting their beneficial effects and instead amplifying the adverse effects of Si. Therefore, the amount of Si used in this invention is controlled between 0.1% and 0.4%. This can be 0.1%, 0.2%, 0.21%, 0.25%, 0.3%, 0.37%, 0.4%, etc., as well as all ranges and sub-ranges between these values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0029] In some embodiments, Mg can improve the corrosion resistance of aluminum alloy materials. Excessive Mg content will reduce the welding quality of brazing; conversely, insufficient Mg content will make the aluminum alloy material more susceptible to corrosion, which will also negatively impact the welding quality of brazing. In this invention, the amount of Mg is controlled between 0.1% and 0.3%. To improve the corrosion resistance of the aluminum alloy material, it can be 0.1%, 0.11%, 0.15%, 0.2%, 0.21%, 0.25%, 0.28%, 0.3%, etc., as well as all ranges and sub-ranges between these values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0030] In some embodiments, Mn can inhibit the recrystallization process of aluminum alloys, increase the recrystallization temperature, and significantly refine the recrystallized grains. The refinement of recrystallized grains is mainly achieved by the dispersed particles of Al6Mn compounds hindering grain growth. If the content exceeds a certain limit, it easily forms multi-component compounds, leading to hard spots and reduced electrical and thermal conductivity; if the content is insufficient, it will fail to effectively organize the recrystallization of the aluminum alloy. The dosage in this invention is controlled to be less than or equal to 0.1%, and can be 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.1%, etc., as well as all ranges and sub-ranges between these values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0031] In some embodiments, the amount of Ti element is controlled between 0.1% and 0.25%, and can be 0.1%, 0.12%, 0.15%, 0.18%, 0.2%, 0.25%, etc., as well as all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0032] In some embodiments, the amount of Sr element is controlled between 0.003% and 0.008%, and can be 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, etc., as well as all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0033] In some embodiments, the rare earth elements RE are La and Ce, and the amount of RE rare earth elements is controlled between 1.5% and 2.0%, which can be 1.5%, 1.55%, 1.6%, 1.65%, 1.7%, 1.8%, 1.9%, 1.98%, 2.0%, etc., and all ranges and subranges between the above values. Simultaneously, the mass ratio of La to Ce is controlled between (1-3):(7-9), which can be 1:7, 1:8, 1:9, 2:7, 2:8, 2:9, 3:7, 3:8, 3:9, etc., and all ranges and subranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0034] In this invention, strict control of impurity elements is required. All elements other than those included in the components of this invention are considered impurity elements, with the content of each individual impurity element less than 0.03%, and the total content of all impurity elements less than 0.15%. Particular attention must be paid to controlling Zr, Cr, and V, as these three elements will primarily form corresponding alloy phases with Al (Al3Zr alloy phase, Al7Cr alloy phase, and Al...). 21 V2 alloy phase), these alloy phases mainly exist in the form of solid solution, which will have an adverse effect on the electrical and thermal conductivity of aluminum alloys. Therefore, it is necessary to strictly control the content of these three elements, and the content of each of these three elements should be controlled below 0.01%.

[0035] In some embodiments, the melting point of the aluminum alloy can reach 630–640°C, and can be 630°C, 631°C, 635°C, 638°C, 640°C, etc., as well as all ranges and sub-ranges between the above values. It should be understood that, in embodiments, any of the above ranges can be combined with any other range.

[0036] II. A method for preparing a hard-brazed die-cast aluminum alloy

[0037] Step 1: Weigh the raw materials according to the composition of the brazed die-cast aluminum alloy. The raw materials include aluminum ingots, magnesium ingots, iron additives, aluminum-manganese alloy, aluminum-titanium alloy, industrial silicon, aluminum-strontium alloy, and aluminum-rare earth alloy.

[0038] Step 2: Place the aluminum ingots into a melting furnace and heat them until they melt to obtain molten aluminum. The temperature of the molten aluminum is controlled at 800-850℃. Then, add industrial silicon and iron additives. After it is completely melted, cool it down to 730-750℃ and add refining agents to refine the molten aluminum.

[0039] Step 3: Add magnesium ingots and aluminum rare earth alloy to the aluminum liquid obtained in Step 2. After complete melting, control the temperature at 720-740℃, then add aluminum-titanium alloy and aluminum-strontium alloy. After complete melting, test the composition. If the test is qualified, perform degassing treatment and maintain the aluminum liquid temperature at 690-710℃. If the composition does not meet the requirements of the brazed die-cast aluminum alloy, adjust the raw materials to meet the composition requirements of the brazed die-cast aluminum alloy before performing degassing treatment.

[0040] Step 4: The aluminum obtained in Step 3 is injected into the mold for die casting. After aging treatment, the resulting casting is obtained as the brazed die-cast aluminum alloy. The die-casting mold temperature controller maintains the temperature at 220-300℃. Simultaneously, the die-casting mold is equipped with an insulated barrel. During die casting, the barrel temperature is maintained at 280-380℃. The molten aluminum is cast under a pressure of 65-75MPa. The vacuum degree of the die-casting machine's mold cavity is below 5Kpa. The injection speed is 3-4m / s, and the aluminum rapidly enters the die-casting mold, cooling and solidifying to obtain the die-cast aluminum alloy casting. The aging treatment process for the casting product is as follows: aging temperature 200-250℃, holding time 3-6 hours.

[0041] In the preparation method described in this invention, the steps of the preparation method need to be strictly controlled:

[0042] (1) The final temperature of the aluminum liquid before die casting needs to be strictly controlled. If the temperature is too high, the Sr element is easily burned off, and the gas absorption rate of the aluminum liquid increases, which will reduce the strength and conductivity of the alloy material. If the temperature is too low, it will easily affect the fluidity of the die casting alloy.

[0043] (2) The aging temperature needs to be strictly controlled. If the temperature is too high, thin-walled parts are prone to high-temperature deformation; if the temperature is too low, the aging precipitation and aging strengthening are insufficient, affecting the electrical conductivity and mechanical properties, and failing to improve the electrical conductivity and mechanical properties.

[0044] III. Examples and Comparative Examples

[0045] Table 1 (Unit: wt%)

[0046]

[0047]

[0048] Example 1:

[0049] Step 1: Weigh the raw materials according to the proportions of each element in Table 1. The raw materials include A00 aluminum ingots, magnesium ingots, iron additives, aluminum-manganese alloy, aluminum-titanium alloy, industrial silicon, aluminum-strontium alloy, and aluminum-rare earth alloy.

[0050] Step 2: Place some A00 aluminum ingots into the melting furnace and heat them to melt. Control the temperature of the aluminum liquid at 800-850℃. Add industrial silicon while stirring thoroughly, then add iron additives. After all the aluminum is melted, stir it evenly, then cool it down to 730-750℃ and add refining agents to refine the aluminum liquid.

[0051] Step 3: Add magnesium ingots and aluminum rare earth master alloys to the melting furnace and melt them at a temperature controlled at 720-740℃. While stirring thoroughly, add aluminum-titanium alloy and aluminum-strontium master alloys. After melting, maintain the mixture for 20 minutes, stirring until homogeneous, and then degas with dry, high-purity argon gas. Take a sample and test its composition. If the composition is unqualified, supplement and adjust the raw materials to achieve the required alloy composition. Let it stand for 20 minutes. The temperature of the molten aluminum should then drop to 690-710℃.

[0052] Step 4: Obtain the heat-insulated aluminum alloy solution, and then use a robotic arm to press the aluminum alloy into the die-casting mold cavity to obtain the die-cast aluminum alloy casting.

[0053] Step 5: The die-casting mold temperature controller maintains the temperature at 220-300℃, and the die-casting mold is equipped with an insulated barrel. During die casting, the barrel temperature is maintained at 280-380℃, the molten aluminum is cast under a pressure of 65-75MPa, the vacuum degree of the die-casting machine mold cavity is below 5Kpa, and the injection speed is 3-4m / s to quickly enter the die-casting mold, cool and solidify to obtain the die-cast aluminum alloy casting.

[0054] Step 6: Aging treatment: The die casting with the riser removed is subjected to artificial aging treatment to obtain tensile test specimens of the die casting part body.

[0055] Step 7: Perform CNC machining on the die-cast aluminum parts after aging heat treatment to remove the oxide scale on the surface of the weld and ensure the dimensional accuracy of the weld. Then remove oil and oxides from the surface of the machined workpiece.

[0056] Step 8: After coating the inter-fiber welded surfaces of the die-cast shell and cover plate with fiber material, clamp and assemble the workpiece to fix it.

[0057] Step 9: Place in a vacuum brazing furnace at a brazing temperature of 610-625℃ to braze the die casting.

[0058] Step 10: After cooling, test to obtain the die-cast new energy aluminum alloy radiator assembly with hard brazed weld.

[0059] IV. Performance Comparison

[0060] Other examples and comparative examples were prepared using the preparation method of Example 1. The mechanical properties of the die-cast parts prepared in step 6 were tested at room temperature: tests were conducted according to GB / T 228.1-2021 Metallic materials, tensile testing—Part 1: Room temperature testing method; electrical conductivity was tested according to GB / T 12966-2022 Aluminum and aluminum alloys, eddy current testing method for electrical conductivity. The test results are shown in Table 2. Simultaneously, the conversion between electrical conductivity and thermal conductivity can be performed using the T / CNIA 0169-2022 standard (Group Standard for High Thermal Conductivity Aluminum Alloy Die-cast Parts for Heating Radiators).

[0061] Table 2

[0062] Test parameters Tensile strength (MPa) Yield strength (MPa) Elongation (%) Electrical conductivity (%IACS) Example 1 181 134 13.8 50.1 Example 2 185 138 13.0 51.3 Example 3 189 141 12.3 53.2 Example 4 191 146 11.8 53.4 Example 5 185 149 11.2 52.5 Example 6 186 143 10.8 52.1 Example 7 190 151 10.1 49.5 Comparative Example 1 188 162 5.1 40.1 Comparative Example 2 165 125 9.2 50.1 Comparative Example 3 195 152 8.5 37.3 Comparative Example 4 201 162 4.5 35.2

[0063] Combining Table 1 and Table 2, we can see that:

[0064] (1) The results show that the hard-brazed die-cast aluminum alloys prepared using the element content and composition of the present invention have excellent mechanical and electrical properties. Examples 1 to 7 all meet the required range of tensile strength and yield strength, with a tensile strength ≥180MPa, a yield strength ≥130MPa, and an elongation ≥10%. The electrical conductivity meets the requirement of ≥45% IACS, and the thermal conductivity is good. The brazing temperature is 610-625℃, and the hard-brazed die-cast parts have good welding performance.

[0065] (2) Compared with Example 3, the Fe element in Comparative Example 1 exceeded the set range of elements, and the amount of Fe element was increased, resulting in a relatively increased Al3Fe in the alloy. The alloy phase of the prepared alloy material contained a large number of long needle-like and a small number of plate-like Al3Fe phases, which caused a significant decrease in the elongation of the alloy material. At the same time, the increase in the number of such alloy phases also had an adverse effect on the conductivity, resulting in a significant decrease in conductivity.

[0066] (3) Compared with Example 3, the total content of rare earth elements in Comparative Example 2 is lower than the range value described in this invention. This makes the amount of La and Ce elements lower than the range value. The effect of La and Ce elements in refining α-Al grains is significantly weakened. From the microscopic observation results, Al3Fe in the alloy material obtained in Comparative Example 2 basically maintains the needle-like morphology and grows into a needle-like structure of a certain length. Similarly, Ce element failed to minimize the average grain size of α-Al and the length of Al3Fe sheets. The average grain size of α-Al and the length of Al3Fe sheets in the obtained alloy material are significantly higher than those in all examples. This results in a very significant decrease in the tensile strength, yield strength and elongation of the material. In particular, the tensile strength decreases much more than that of other comparative examples.

[0067] (4) Compared with Example 3, the Cr element impurity in Comparative Example 3 exceeded the range specified in this invention and was significantly higher than the range specified. Observation of the alloy material obtained in Comparative Example 3 revealed that the amount of Al7Cr alloy phase formed by the reaction of the excessive Cr impurity with the aluminum matrix was much greater than in other comparative examples and embodiments. This resulted in severe distortion of the alloy lattice, a significant increase in the resistivity of the material, and a decrease in both electrical and thermal conductivity. Although this lattice distortion improved the mechanical properties of the alloy material, it significantly reduced the elongation of the alloy material, making it more brittle and prone to fracture during brazing.

[0068] (5) In Comparative Example 4, the amount of Mn element is much higher than the range value described in this invention. Although Mn element can play a phase refinement role for Al3Fe, Mn element has high solid solubility in aluminum. The alloy material obtained in this comparative example has already formed Al6Mn phase, and this alloy phase is dissolved in the aluminum matrix. At the same time, the resistivity of Mn element is relatively large. These effects ultimately increase the resistivity of the aluminum alloy obtained in Comparative Example 4, significantly reduce the electrical conductivity of the aluminum alloy, and consequently reduce the thermal conductivity of the aluminum alloy.

[0069] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit the technical solutions. Those skilled in the art should understand that any modifications or equivalent substitutions to the technical solutions of the present invention without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A brazed die-cast aluminum alloy, characterized in that, The brazed die-cast aluminum alloy comprises the following components by mass percentage: Si 0.1~0.4%, Mg 0.1~0.3%, Mn≤0.1%, Fe 0.7~1.0%, Ti 0.1~0.25%, Sr 0.003~0.008%, and RE 1.5~2.0%; wherein RE is La and Ce, and the mass ratio of La to Ce is (1:7)~(3:8); the remaining elements are impurity elements, and the content of a single impurity element is less than 0.03%, the total amount of the impurity elements is less than 0.15%, and the content of the three impurity elements Zr, Cr and V is less than 0.01%; the remainder is aluminum.

2. The brazed die-cast aluminum alloy according to claim 1, characterized in that, The melting point of the aluminum alloy is 630~640℃.

3. The brazed die-cast aluminum alloy according to claim 2, characterized in that, The electrical conductivity of the aluminum alloy is greater than 45% IACS.

4. A method for preparing a hard-brazed die-cast aluminum alloy, characterized in that, The preparation of the brazed die-cast aluminum alloy according to any one of claims 1 to 3 comprises the following steps: Step 1: Weigh the raw materials according to the composition of the brazed die-cast aluminum alloy. The raw materials include aluminum ingots, magnesium ingots, iron additives, aluminum-manganese alloy, aluminum-titanium alloy, industrial silicon, aluminum-strontium alloy, and aluminum-rare earth alloy. Step 2: Place the aluminum ingots into a melting furnace and heat them to melt to obtain molten aluminum. The temperature of the molten aluminum is controlled at 800~850℃. Then, add industrial silicon and iron additives. After it is completely melted, cool it down to 730~750℃ and add refining agents to refine the molten aluminum. Step 3: Add magnesium ingots and aluminum rare earth alloy to the aluminum liquid obtained in Step 2. After it is completely melted, control the temperature at 720~740℃. Add aluminum titanium alloy and aluminum strontium alloy. After it is completely melted, test its composition. After the test is qualified, degas the aluminum liquid and keep the temperature of the aluminum liquid at 690~710℃. Step 4: The aluminum obtained in Step 3 is pressed into the mold for die casting. After aging treatment, the brazed die-cast aluminum alloy casting product is obtained.

5. The method for preparing the brazed die-cast aluminum alloy according to claim 4, characterized in that, In step 3, if the composition of the tested material does not meet the requirements of the brazed die-cast aluminum alloy, the raw materials are adjusted to meet the requirements of the brazed die-cast aluminum alloy before degassing treatment.

6. An application of a brazed die-cast aluminum alloy, characterized in that, The brazed die-cast aluminum alloy according to any one of claims 1 to 3 or the brazed die-cast aluminum alloy prepared by the preparation method according to any one of claims 4 to 5 is used in heat spreaders and liquid water cooling medium radiators.

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