Abstract: Effect of copper content and aging process on microstructure, mechanical properties and corrosion resistance of the Al-Cu-Mg-Si alloy was investigated. The results show that, with the increase of Cu content, both the quantity and size of Al₂Cu phase in as-cast aluminum alloy increase, and the morphology changes from point to coarse network. The strength of the as-cast aluminum alloy also increases, but the corrosion resistance decreases. Within the aging range of 180 ℃×(4-28) h, the overall hardness of the alloy increases first and then decreases, with 0.5%Cu and 1.5%Cu alloys reaching the peak value under 8 h and 2.5%Cu alloy reaching the peak value under 12 h. The Al₂Cu phase precipitates from the aluminum alloy after solution treatment at 530 ℃ and aging at 180 ℃ for 8 h, with the increase of Cu content, the content of Al₂Cu phase increases, and the hardness shows a significant increase. After solution treatment at 530 ℃ and aging at 180 ℃ for 8 h, the tensile strength of the alloy with 2.5%Cu reaches the peak of 325.0 MPa, the yield strength reaches 258.8 MPa and the elongation is 4.5%, the strength is equivalent to that of traditional cast iron for electric power fittings.

Key words: aluminum alloy, Cu content, T6 treatment, microstructure and properties