Aluminum alloy and preparation method thereof

Abstract

The invention provides an aluminum alloy and a preparation method thereof. The aluminum alloy comprises the following elements in percentage by mass: 0.4-0.6% of Mg element, 0.3-0.5% of Si element, 0.1-0.2% of Cu element, less than or equal to 0.15% of inevitable impurities and the balance of Al element, wherein the mass content of an Mg2Si phase in the aluminum alloy is 0.25 to 0.61 percent; the mass content of the Q phase in the aluminum alloy is 0.1-0.87%; the microhardness of the aluminum alloy ranges from 80 HV to 97 HV, and the conductivity of the aluminum alloy ranges from 58 IACS% to 60 IACS%. The aluminum alloy is simple in component, high strength and high conductivity can be considered, it is guaranteed that the conductivity is improved and the strength is not reduced after the aluminum alloy is subjected to aging treatment for a long time, and therefore the requirements of the new energy automobile light weight and the fast charging technology for the high-strength and high-conductivity aluminum material are met.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, and more specifically, to an aluminum alloy and its preparation method. Background Technology

[0002] Aluminum alloys, due to their light weight, low cost, and easy recyclability, are lightweight conductive materials used to replace copper and copper alloy conductive products in systems such as battery pack conductive systems for new energy vehicles, supercharging piles, and energy storage boxes. However, because aluminum's conductivity is lower than copper's, the cross-section needs to be increased to achieve the same conductivity as copper. Therefore, it is necessary to develop aluminum alloys with higher strength and higher conductivity to replace copper conductors in the conductive systems of new energy vehicles, thereby significantly reducing vehicle weight and manufacturing costs, improving vehicle energy efficiency and driving range, and meeting the rapid development requirements of lightweighting and fast charging technology in new energy vehicles.

[0003] However, common methods for strengthening aluminum alloys, such as alloying, strain strengthening, and precipitation strengthening, all reduce the material's electrical conductivity by increasing the number of solid-solution atoms of alloying elements, introducing crystal defects, and generating high-density precipitates, which enhance electron scattering. Therefore, it is difficult to achieve both high strength and high conductivity in conductive aluminum alloys strengthened by traditional methods.

[0004] Conductive aluminum alloys typically improve their electrical conductivity by controlling the precipitation of elements from the matrix through heat treatment. As the aging process progresses, conductivity gradually increases, and the precipitation of elements within the matrix also contributes to strengthening. However, excessively long aging heat treatment times can lead to the growth of precipitated phases, resulting in a decrease in the alloy's strength. Furthermore, the industrial heat treatment process for aluminum involves long heating, holding, and cooling cycles, requiring a wide aging time window to ensure that both strength and conductivity meet application requirements. Therefore, there is an urgent need to simultaneously improve the electrical conductivity and strength of aluminum alloys while balancing the aging time. Summary of the Invention

[0005] The main objective of this invention is to provide an aluminum alloy and its preparation method, so as to solve the problem that aluminum alloys are difficult to balance high electrical conductivity and strength after long-term aging treatment in the prior art.

[0006] To achieve the above objectives, according to one aspect of the present invention, an aluminum alloy is provided, comprising, by mass percentage, the following elements: 0.4-0.6% Mg, 0.3-0.5% Si, 0.1-0.2% Cu, with the total content of unavoidable impurities ≤0.15%, and the balance being Al; wherein the mass content of the Mg2Si phase in the aluminum alloy is 0.25-0.61%; the mass content of the Q phase in the aluminum alloy is 0.1-0.87%; the microhardness of the aluminum alloy is 80-97 HV, and the electrical conductivity of the aluminum alloy is 58 IACS%-60 IACS.

[0007] Furthermore, by mass percentage, the above aluminum alloy comprises the following elements: 0.42~0.58% Mg, 0.32~0.48% Si, 0.11~0.18% Cu, with the total content of unavoidable impurities ≤0.15%, and the balance being Al.

[0008] Furthermore, the ratio of the total mass of Mg and Si elements to the mass of Cu elements is 4.5 to 9:1.

[0009] Furthermore, the mass ratio of Mg to Si is 1~1.8:1; and / or, the average grain length of the aluminum alloy is 150~600μm, and the average grain width of the aluminum alloy is 10~30μm.

[0010] According to another aspect of the present invention, a method for preparing the above-mentioned aluminum alloy is provided, the method comprising: step S1, wherein the raw materials corresponding to the aluminum alloy are batched and then sequentially subjected to melting, casting, homogenization heat treatment, hot rolling and first cold rolling to obtain a cold-rolled sheet; step S2, wherein the cold-rolled sheet is sequentially subjected to solution heat treatment, first cooling, first aging heat treatment, second cooling, second cold rolling, second aging heat treatment and third cooling to obtain an aluminum alloy; wherein the processing rate of the second cold rolling is 60~70%, the temperature of the second aging heat treatment is 160~180℃, and the time of the second aging heat treatment is ≥1h.

[0011] Furthermore, the temperature of the first aging heat treatment is 180~200℃, and the time of the first aging heat treatment is 2~10h; and / or, the time of the second aging heat treatment is 1~22h.

[0012] Furthermore, the solution heat treatment temperature is 540~560℃, and the solution heat treatment time is 60~120s.

[0013] Furthermore, the melting temperature is 720~780℃, and the melting time is 3~8h.

[0014] Furthermore, the homogenization heat treatment temperature is 540~560℃, the homogenization heat treatment time is 6~12h, and the homogenization heat treatment heating rate is 30~60℃ / h.

[0015] Furthermore, the initial rolling temperature of the hot rolling is 520~560℃, the final rolling temperature of the hot rolling is 280~330℃; and / or, the processing rate of the first cold rolling is 50~60%.

[0016] Applying the technical solution of this invention, most aluminum alloys currently incorporate various trace elements, resulting in a large number of elements in minute quantities that are difficult to control. However, the aluminum alloy of this application has a simple composition, and the composition and content of the elements are controlled within the aforementioned range, enabling the improvement of electrical conductivity while maintaining high strength. Specifically, the addition of Mg and Si elements forms the Mg2Si phase, significantly increasing the strength of the aluminum alloy. The addition of Cu elements at the aforementioned levels forms the Q phase, strengthening the alloy while further consuming Mg and Si elements within the matrix, thereby increasing the electrical conductivity of the aluminum alloy. This simultaneously improves both the electrical conductivity and strength of the aluminum alloy, ensuring that the conductivity remains high and the strength does not decrease after prolonged aging treatment. Therefore, the aluminum alloy of this application can balance high strength and high conductivity, thus meeting the requirements of lightweight and fast-charging technologies for high-strength, high-conductivity aluminum materials in new energy vehicles. Attached Figure Description

[0017] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0018] Figure 1 The diagram shows a comparison of the changes in microhardness and electrical conductivity of aluminum alloys in Embodiment 1 and Comparative Examples 1 to 3 of this application as the second aging heat treatment time increases. Detailed Implementation

[0019] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0020] Aging heat treatment window: The shortest aging heat treatment time when the electrical conductivity meets the requirements, and the longest aging heat treatment time when the microhardness meets the requirements. The time period consisting of these two times is the wide aging heat treatment window.

[0021] As analyzed in the background section of this application, existing technologies have problems such as difficulty in achieving both high electrical conductivity and strength after aluminum alloys undergo long-term aging treatment. In order to solve the above problems, this application provides an aluminum alloy and its preparation method.

[0022] In a typical embodiment of this application, an aluminum alloy is provided, comprising, by mass percentage: 0.4-0.6% Mg; 0.3-0.5% Si; 0.1-0.2% Cu, with unavoidable impurities totaling ≤0.15%, and the balance being Al; wherein the mass content of the Mg2Si phase in the aluminum alloy is 0.25-0.61%; the mass content of the Q phase in the aluminum alloy is 0.1-0.87%; the microhardness of the aluminum alloy is 80-97 HV; and the electrical conductivity of the aluminum alloy is 58 IACS%-60 IACS.

[0023] Currently, most aluminum alloys contain various trace elements, which are numerous and present in minute quantities, making them difficult to control. However, the aluminum alloy of this application has a simple composition, and the element composition and content are controlled within the aforementioned range, enabling it to maintain high strength while improving electrical conductivity. Specifically, the addition of Mg and Si elements forms the Mg2Si phase, significantly increasing the strength of the aluminum alloy. The addition of Cu elements at the aforementioned amounts forms the Q phase, strengthening the alloy while further consuming Mg and Si elements within the matrix, thereby increasing the electrical conductivity of the aluminum alloy. This results in a simultaneous improvement in both electrical conductivity and strength, and ensures that the aluminum alloy maintains its strength despite increased conductivity after prolonged aging treatment. Therefore, the aluminum alloy of this application achieves a balance between high strength and high electrical conductivity, meeting the requirements of lightweight and fast-charging technologies for high-strength, high-conductivity aluminum materials in new energy vehicles.

[0024] To further improve the strength and electrical conductivity of the aluminum alloy, in one embodiment of this application, the aluminum alloy comprises the following elements by mass percentage: 0.42~0.58% Mg, 0.32~0.48% Si, 0.11~0.18% Cu, with the total content of unavoidable impurities ≤0.15%, and the balance being Al.

[0025] In one embodiment of this application, the ratio of the total mass of Mg and Si elements to the mass of Cu elements is 4.5 to 9:1.

[0026] The optimal ratio of the total mass of Mg and Si elements to the mass of Cu elements within the above range helps to promote the balanced precipitation of Mg2Si and Q phases inside the aluminum alloy, forming a Mg2Si phase with the above-mentioned content and uniform distribution, thereby achieving precipitation strengthening of the alloy and improving the strength of the aluminum alloy. At the same time, it promotes the formation of Q phase, strengthens the alloy, and further consumes Mg and Si elements inside the matrix, thereby further improving the electrical conductivity of the aluminum alloy.

[0027] In addition, the ratio of the total mass of Mg and Si elements to the mass of Cu elements can be 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7.0:1, 7.5:1, 8.0:1, 8.5:1, or 9:1.

[0028] In one embodiment of this application, the mass ratio of Mg to Si is 1~1.8:1; and / or, the average grain length of the aluminum alloy is 150~600μm, and the average grain width of the aluminum alloy is 10~30μm.

[0029] Preferably controlling the mass ratio of Mg to Si within the above-mentioned range helps promote the formation of the Mg2Si phase, thereby further improving the strength of the aluminum alloy. Preferably controlling the average grain length and average grain width of the aluminum alloy within the above-mentioned range not only helps to enhance the strength and electrical conductivity of the aluminum alloy, but also helps to broaden the heat treatment window.

[0030] In another typical embodiment of this application, a method for preparing the above-mentioned aluminum alloy is provided. The method includes: step S1, after batching the raw materials corresponding to the aluminum alloy, performing melting, casting, homogenization heat treatment, hot rolling and first cold rolling in sequence to obtain a cold-rolled sheet; step S2, performing solution heat treatment, first cooling, first aging heat treatment, second cooling, second cold rolling, second aging heat treatment and third cooling in sequence to obtain the aluminum alloy; wherein, the processing rate of the second cold rolling is 60~70%, the temperature of the second aging heat treatment is 160~180℃, and the time of the second aging heat treatment is ≥1h.

[0031] Current aluminum alloy preparation methods often require short aging heat treatment windows to balance strength and electrical conductivity. This necessitates strict control of aging heat treatment time during engineering preparation, leading to reduced production efficiency, poor operability, and consequently, a significantly lower yield rate and increased production costs. The method described in this application uses an Al-Mg-Si alloy as the base alloy system, adding trace amounts of Cu to promote the formation of the Q phase. This phase consumes elements within the matrix and forms a highly stable strengthening phase, improving both electrical conductivity and strength while ensuring that electrical conductivity remains high and strength is not reduced after long-term aging treatment. Based on the aforementioned aluminum alloy composition, this method synergistically controls the processing rate of the second cold rolling within the specified range, while simultaneously performing a short-duration low-temperature second aging heat treatment. This allows for achieving high microhardness and electrical conductivity in a shorter second aging heat treatment time, enabling the preparation of high-strength, high-conductivity aluminum alloys with a wide aging heat treatment window. This facilitates engineering preparation and meets the requirements for the industrial production of high-strength, high-conductivity aluminum materials. This application controls the processing rate of the second cold rolling within the aforementioned range, enabling the generation of dislocations through deformation, which are difficult to eliminate at low temperatures. The mechanical properties are further improved through changes in the phase precipitation rate and deformation strengthening. Furthermore, the dislocations formed by cold deformation serve as precipitation channels, facilitating the precipitation of the Q phase. Simultaneously, the low-temperature second heat aging treatment is highly effective, consuming solid solution elements within the matrix and thus improving the electrical conductivity of the aluminum alloy. Within a wide heat treatment window, even with extended aging times, the aluminum alloy of this application maintains high hardness and electrical conductivity, solving the problem of balancing strength and electrical conductivity in traditional processes. It also provides a wide aging heat treatment window, ensuring that even with extended aging times in engineering preparation, the aluminum alloy retains its high strength and high conductivity characteristics. This meets the demand for high-strength, high-conductivity aluminum materials for lightweight and fast-charging technologies in new energy vehicles, and helps reduce energy consumption, shorten production cycles, and lower production costs.

[0032] In one embodiment of this application, the temperature of the first aging heat treatment is 180~200℃, the time of the first aging heat treatment is 2~10h; and / or, the time of the second aging heat treatment is 1~22h.

[0033] The preferred temperature and time for the first aging heat treatment are within the above-mentioned range, which helps to promote the stable precipitation of the Q phase and Mg2Si phase, reduce the strength reduction caused by excessive growth, and improve the electrical conductivity of the aluminum alloy. The preferred methods for the second and third cooling are each independent air cooling.

[0034] In one embodiment of this application, the solution heat treatment temperature is 540~560℃ and the solution heat treatment time is 60~120s.

[0035] The preferred solution heat treatment is salt bath solution heat treatment. Rapid heating in a salt bath, with the temperature and time controlled within the aforementioned range, helps promote the formation of the Q phase, strengthening the alloy while further consuming Mg and Si elements within the matrix, thereby improving the electrical conductivity of the aluminum alloy. The preferred primary cooling method is water cooling.

[0036] In one embodiment of this application, the melting temperature is 720~780℃ and the melting time is 3~8h.

[0037] Preferably controlling the melting temperature and time within the above range helps the alloying elements to dissolve fully, thereby promoting the uniform distribution of precipitated phases during subsequent heat treatment and improving the overall performance of the aluminum alloy.

[0038] In one embodiment of this application, the homogenization heat treatment temperature is 540~560℃, the homogenization heat treatment time is 6~12h, and the heating rate of the homogenization heat treatment is 30~60℃ / h.

[0039] Preferably controlling the temperature and time of the homogenization heat treatment within the above range helps to optimize the microstructure and control grain growth, which in turn facilitates subsequent solution treatment and aging treatment.

[0040] In one embodiment of this application, the opening temperature of hot rolling is 520~560°C, the final rolling temperature of hot rolling is 280~330°C; and / or, the processing rate of the first cold rolling is 50~60%.

[0041] Preferably controlling the initial and final rolling temperatures within the aforementioned ranges helps improve the plasticity of the aluminum alloy, thereby promoting uniform deformation during hot rolling, reducing crack formation, and ultimately enhancing the overall performance and surface quality of the finished aluminum alloy product. Preferably controlling the first cold rolling processing rate within the aforementioned range also helps refine the grain size and adjust the thickness of the cold-rolled sheet.

[0042] The beneficial effects of this application will be further illustrated below with reference to the embodiments.

[0043] Example 1

[0044] By mass percentage, aluminum alloy raw materials were blended with 0.5% Mg, 0.4% Si, 0.1% Cu, and the balance Al. The mixture was then melted at 750℃ for 5 hours, followed by casting to obtain an ingot with dimensions of 50 mm × 50 mm × 200 mm. The ingot underwent homogenization heat treatment, with the temperature increased to 560℃ at a rate of 30℃ / h for 6 hours to obtain a homogenized ingot. The homogenized aluminum alloy was then hot-rolled at 520℃, reducing the thickness from 50 mm to 6 mm. The final rolling temperature was 300℃, yielding a hot-rolled sheet. The hot-rolled sheet underwent a first cold rolling to obtain a cold-rolled sheet with a thickness of 3 mm, representing a processing rate of 50%.

[0045] The cold-rolled sheet was subjected to salt bath solution heat treatment at 540℃ for 60 seconds, followed by first cooling with water, then first aging heat treatment at 180℃ for 2 hours in a drying oven, then second cooling with air cooling, and then second cold rolling to a thickness of 1 mm with a processing rate of 66.7%, followed by second aging heat treatment at 180℃ for 6 hours in a drying oven, and finally third cooling with air cooling to obtain the aluminum alloy.

[0046] Example 2

[0047] The difference from Example 1 is that, by mass percentage, the aluminum alloy raw material is prepared according to the composition of 0.4% Mg, 0.5% Si, 0.15% Cu, with the balance being Al, to finally obtain the aluminum alloy.

[0048] Example 3

[0049] The difference from Example 1 is that, by mass percentage, the aluminum alloy raw material is prepared according to the composition of 0.6% Mg, 0.3% Si, 0.2% Cu, with the balance being Al, to finally obtain the aluminum alloy.

[0050] Example 4

[0051] The difference from Example 1 is that the total mass of Mg, Si and Cu elements is 1%, and the ratio of the total mass of Mg and Si elements to the mass of Cu elements is 9:1, resulting in an aluminum alloy.

[0052] Example 5

[0053] The difference from Example 1 is that the total mass of Mg, Si and Cu elements is 1%, and the ratio of the total mass of Mg and Si elements to the mass of Cu elements is 4:1, resulting in an aluminum alloy.

[0054] Example 6

[0055] The difference from Example 1 is that the total mass of Mg and Si elements is 0.9%, and the mass ratio of Mg to Si elements is 1:1, resulting in an aluminum alloy.

[0056] Example 7

[0057] The difference from Example 1 is that the total mass of Mg and Si elements is 0.9%, and the mass ratio of Mg to Si elements is 1.8:1, resulting in an aluminum alloy.

[0058] Example 8

[0059] The difference from Example 1 is that the total mass of Mg and Si elements is 0.9%, and the mass ratio of Mg to Si elements is 0.8:1, resulting in an aluminum alloy.

[0060] Example 9

[0061] The difference from Example 1 is that the cold-rolled sheet is subjected to salt bath solution heat treatment at 540°C for 60 seconds, followed by first cooling with water, then first aging heat treatment at 200°C for 10 hours in a drying oven, then second cooling with air cooling, then second cold rolling to a thickness of 1 mm, then second aging heat treatment at 160°C for 22 hours in a drying oven, and finally third cooling with air cooling to obtain an aluminum alloy.

[0062] Comparative Example 1

[0063] By mass percentage, aluminum alloy raw materials were blended with 0.5% Mg, 0.4% Si, and the balance Al, and then melted at 750℃ for 5 hours. The resulting ingot was cast to obtain an ingot with dimensions of 50mm (thickness) × 50mm (width) × 200mm (length). The ingot underwent homogenization heat treatment, with the temperature increased to 560℃ at a rate of 30℃ / h for 6 hours to obtain a homogenized ingot. The homogenized aluminum alloy was then hot-rolled at 520℃ to reduce the thickness from 50mm to 6mm, with a final rolling temperature of 300℃, resulting in a hot-rolled sheet. The hot-rolled sheet underwent a first cold rolling to obtain a cold-rolled sheet with a thickness of 3mm, representing a processing rate of 50%.

[0064] The cold-rolled sheet was subjected to salt bath solution heat treatment at 540℃ for 60 seconds, followed by first cooling with water, then second cold rolling to a thickness of 1 mm, and then second aging heat treatment at 180℃ in a drying oven for 6 hours. After completion, it was subjected to third cooling with air to obtain an aluminum alloy.

[0065] Comparative Example 2

[0066] The difference from Comparative Example 1 is that, by mass percentage, the aluminum alloy raw materials are prepared according to the composition of 0.5% Mg, 0.4% Si, 0.1% Cu, with the balance being Al, to obtain the final aluminum alloy.

[0067] Comparative Example 3

[0068] The difference from Example 1 is that, by mass percentage, the aluminum alloy raw material is prepared with 0.5% Mg, 0.4% Si, and the balance being Al, to obtain the final aluminum alloy.

[0069] Comparative Example 4

[0070] The difference from Example 1 is that, by mass percentage, the aluminum alloy raw material is prepared according to the composition of 0.5% Mg, 0.4% Si, 0.3% Cu, with the balance being Al, to finally obtain the aluminum alloy.

[0071] Comparative Example 5

[0072] The aluminum alloy raw material, by mass percentage, is blended with 0.5% Mg, 0.4% Si, 0.3% Cu, and the balance Al. It is then melted at 750℃ for 5 hours, followed by casting to obtain an ingot with dimensions of 0mm (thickness) × 50mm (width) × 200mm (length). The ingot undergoes homogenization heat treatment, with a heating rate of 30℃ / h to 560℃ for 6 hours to obtain a homogenized ingot. The homogenized aluminum alloy is then hot-rolled at 520℃, reducing the thickness from 50mm to 6mm. The final rolling temperature is 300℃, yielding a hot-rolled sheet. The hot-rolled sheet undergoes a first cold rolling to obtain a cold-rolled sheet with a thickness of 3mm, representing a processing rate of 50%.

[0073] The cold-rolled sheet was subjected to salt bath solution heat treatment at 540℃ for 60 seconds, followed by first cooling with water, then first aging heat treatment at 180℃ for 2 hours in a drying oven, and finally second cooling with air cooling.

[0074] Test method:

[0075] The second heat aging treatment in Examples 1 and Comparative Examples 1 to 3 was set at 1h, 5h, 10h, 15h, and 22h respectively, and the changes in microhardness and electrical conductivity of aluminum alloys with heat aging treatment time were tested.

[0076] Microhardness test: The test was conducted according to GB / T 4340.1-2024 "Metallic materials Vickers hardness test - Part 1: Test method".

[0077] Electrical conductivity test: The test was conducted in accordance with GB / T 12966-2022 "Eddy current test method for electrical conductivity of aluminum and aluminum alloys".

[0078] Mass content test of Mg2Si phase and Q phase: calculated by phase diagram.

[0079] The test results are shown in Table 1.

[0080] Table 1

[0081]

[0082] in, Figure 1 This is a comparison chart showing the changes in microhardness and electrical conductivity of aluminum alloys in Examples 1 and Comparative Examples 1 to 3 as the second aging heat treatment time increases. Figure 1 a and Figure 1 As can be seen from b, in Comparative Example 1, when the microhardness of the aluminum alloy is ≥80HV, the second aging heat treatment time is <4h; when the electrical conductivity is ≥58IACS%, the second aging heat treatment time is >3h. That is, the aging heat treatment window of Comparative Example 1 is 3~4h, with a window period of only 1h. In Comparative Example 2, when the microhardness of the aluminum alloy is ≥80HV, the second aging heat treatment time is <9h; when the electrical conductivity is ≥58IACS%, the second aging heat treatment time is >6h. That is, the aging heat treatment window of Comparative Example 2 is 6~9h, with a window period of only 3h. In Comparative Example 3, when the microhardness of the aluminum alloy is ≥80HV, the second aging heat treatment time is <10h; when the electrical conductivity is ≥58IACS%, the second aging heat treatment time is >3h. Therefore, the aging heat treatment window for Comparative Example 1 is 3~10h, with a window period of 7h. In Example 1, when the microhardness of the aluminum alloy is ≥80HV, the second aging heat treatment time is met within 22h; when the electrical conductivity is ≥58IACS%, the aging heat treatment time is >1h. Therefore, the second aging heat treatment window for Example 1 is >1h, a relatively long window period. The short aging heat treatment windows in Comparative Examples 1 to 3 necessitate strict control of the aging heat treatment time during engineering preparation, leading to reduced production efficiency and poor operability, resulting in a significantly lower yield of aluminum alloys and consequently increased production costs. It is evident that the elemental ratios and preparation methods of this application can achieve a wide aging heat treatment window, while simultaneously improving strength and electrical conductivity. Furthermore, the wide aging heat treatment window enhances production efficiency and stability, and reduces production costs.

[0083] As can be seen from the above description, the embodiments of the present invention achieve the following technical effects:

[0084] Currently, most aluminum alloys contain various trace elements, which are numerous and present in minute quantities, making them difficult to control. However, the aluminum alloy of this application has a simple composition, and the element composition and content are controlled within the aforementioned range, enabling it to maintain high strength while improving electrical conductivity. Specifically, the addition of Mg and Si elements forms the Mg2Si phase, significantly increasing the strength of the aluminum alloy. The addition of Cu elements at the aforementioned amounts forms the Q phase, strengthening the alloy while further consuming Mg and Si elements within the matrix, thereby increasing the electrical conductivity of the aluminum alloy. This results in a simultaneous improvement in both electrical conductivity and strength, and ensures that the aluminum alloy maintains its strength despite increased conductivity after prolonged aging treatment. Therefore, the aluminum alloy of this application achieves a balance between high strength and high electrical conductivity, meeting the requirements of lightweight and fast-charging technologies for high-strength, high-conductivity aluminum materials in new energy vehicles.

[0085] The above are merely embodiments of the present invention and are not intended to limit the invention. Those skilled in the art will recognize that the present invention can have various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An aluminum alloy, characterized in that, The aluminum alloy comprises the following elements by weight percentage: 0.4~0.6% Mg element; 0.3~0.5% Si element; 0.1~0.2% Cu element, unavoidable total impurity content ≤0.15%, balance Al element; The aluminum alloy contains 0.25-0.61% Mg2Si phase by mass. The mass content of the Q phase in the aluminum alloy is 0.1~0.87%; The aluminum alloy has a microhardness of 80~97HV and an electrical conductivity of 58IACS%~60IACS.

2. The aluminum alloy according to claim 1, characterized in that, The aluminum alloy comprises the following elements by weight percentage: 0.42~0.58% of the Mg element; 0.32~0.48% of the Si element; The Cu element is 0.11-0.18%, the total content of unavoidable impurities is ≤0.15%, and the balance is Al element.

3. The aluminum alloy according to claim 1 or 2, characterized in that, The ratio of the total mass of Mg and Si elements to the mass of Cu element is 4.5 to 9:

1.

4. The aluminum alloy according to claim 1 or 2, characterized in that, The mass ratio of Mg to Si is 1~1.8:1; and / or the average grain length of the aluminum alloy is 150~600μm, and the average grain width of the aluminum alloy is 10~30μm.

5. A method for preparing the aluminum alloy according to any one of claims 1 to 4, characterized in that, The preparation method includes: Step S1: After the raw materials corresponding to the aluminum alloy are batched, they are sequentially smelted, cast, homogenized heat treatment, hot rolling and first cold rolling to obtain cold-rolled sheet; Step S2: The cold-rolled sheet is subjected to solution heat treatment, first cooling, first aging heat treatment, second cooling, second cold rolling, second aging heat treatment and third cooling in sequence to obtain the aluminum alloy; The processing rate of the second cold rolling is 60-70%, the temperature of the second aging heat treatment is 160-180℃, and the time of the second aging heat treatment is ≥1h.

6. The preparation method according to claim 5, characterized in that, The temperature of the first aging heat treatment is 180~200℃, and the time of the first aging heat treatment is 2~10h; and / or, the time of the second aging heat treatment is 1~22h.

7. The preparation method according to claim 6, characterized in that, The solution heat treatment temperature is 540~560℃, and the solution heat treatment time is 60~120s.

8. The preparation method according to any one of claims 5 to 7, characterized in that, The melting temperature is 720~780℃, and the melting time is 3~8h.

9. The preparation method according to any one of claims 5 to 7, characterized in that, The homogenization heat treatment temperature is 540~560℃, the homogenization heat treatment time is 6~12h, and the heating rate of the homogenization heat treatment is 30~60℃ / h.

10. The preparation method according to any one of claims 5 to 7, characterized in that, The hot rolling opening temperature is 520~560℃, the hot rolling final rolling temperature is 280~330℃; and / or, the processing rate of the first cold rolling is 50~60%.

Images