Effect of trace Sn addition on mechanical property and microstructure of Al-2.5Cu-1.5Mg alloy

The effects of trace Sn additions on the ageing behavior and microstructure evolution of Al-2.5Cu-1.5Mg alloy were investigated by the microhardness test, tensile test, SEM and TEM. The results indicate that the trace Sn addition can increase the hardening and strengthening of the second stage of ageing. Adding trace Sn can significantly improve the ductility of Al-2.5Cu-1.5Mg alloy, the elongation of Sn-containing alloy at peak aged is 20.5%, and the alloy elongation is still 10.5% after aged at 150°C for 1 000 h. The trace Sn addition can promote S phase precipitate and inhibit the S phase coarsen at over-aged.