Semi-solid state extrusion casting aluminum alloy for new energy automobile and preparation method thereof

Abstract

The invention relates to a semi-solid state extrusion casting aluminum alloy for a new energy automobile and a preparation method thereof. The alloy comprises, by weight, 5%-8% of Si, 3.5%-4% of Cu, 0.40%-0.80% of Fe, 0.00%-0.5% of Mg, less than or equal to 0.05% of other impurities, and the balance Al. The alloy melt is subjected to 50Hz mechanical vibration treatment within the temperature interval of 650-680 DEG C, and semi-solid state slurry is obtained after 180-240 s. Compared with the prior art, the aluminum alloy provided by the invention has the solid-liquid phase interval of 510-630DEG C, thereby having the semi-solid state extrusion casting performance. The aluminum alloy melt starts to be subjected to 50Hz mechanical vibration treatment within the temperature interval of 650-680 DEG C, and the semi-solid state slurry can be obtained after 180-240 s. The slurry is subjected to extrusion casting, heat treatment at 450 DEG C for 2 h and artificial ageing at 170 DEG C for 10 h. Eutectic silicon particles are distributed densely. Al2Cu serves as a main precipitated phase in the material, and a small number of Al5Cu2Mg8Si6 and Al8Mg3FeSi2 are generated simultaneously. The aluminum alloy has the tensile strength greater than 420 MPa, the yield strength greater than 380 MPa and the heat conductivity coefficient greater than 160 W / m.K under the enhancement effect of the precipitated phase.

Description

technical field [0001] The invention relates to an aluminum alloy, in particular to an ultra-high-strength, high-thermal conductivity heat-treatable semi-solid squeeze-cast aluminum alloy suitable for new energy vehicles and a preparation method thereof. Background technique [0002] With the release and implementation of my country's automobile energy conservation and emission reduction policies, since 2011, my country's new energy vehicles have shown a rapid development trend. However, the unit specific energy of the power battery that can be used by new energy passenger vehicles currently has a huge gap with the unit specific energy of liquid fuels used by traditional vehicles, resulting in a short cruising range. Taking the Tesla Model S as an example, its total weight is 2108kg, and the weight of the battery alone exceeds 500kg. In addition, there is a drive motor to increase the weight of the vehicle; while the total weight of the engine of a traditional car is general...

AI Technical Summary

Problems solved by technology

Simply using A356 and A357 aluminum alloys can no longer meet the comprehensive performance requirements of new energy vehicles for component strength, complex geometric dimensions, and cost. Therefore, it is urgent to develop a semi-solid extrusion casting with ultra-high strength and high thermal conductivity suitable for new energy vehicles. aluminum alloy

[0007] By adding about 8% Si element to the aluminum alloy to improve the fluidity of the melt and increase the solid-liquid phase interval, thereby widening the operating window of the semi-solid squeeze casting process and reducing the requirement for melt temperature control, but this aluminum The strength of the alloy material is still low

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