The effect of different ageing processes on microstructure and mechanical properties of cast A/-3Li-2Cu-0.2Zr alloy was cinvestigated using transmission electron microscopy and tensile tests.The results showed that the mean size of δ'-A/3Li particles and the number density of Cu-rich precipitates both increased with increasing ageing temperature from 150 to 190 ℃ for 24 h,resulting in increasingly high strength.In contrast,the ductility deteriorated with the increase in ageing temperature as a result of the intensified planar slip.The duplex low-to-high ageing treatment (120 ℃ for 6 h followed by 160 ℃ for 24 h) was shown to be beneficial to the ductility compared with the corresponding single-stage ageing treatment (160 ℃ for 24 h).The reduced slip length induced by the precipitation of θ'-Al2Cu phases was found to be mainly responsible for this ductility improvement.