Effect of ageing treatment on the precipitation behaviour of Mg-Gd-Y-Zn-Zr alloy

► Solution treated Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr alloy was aged at 200 °C and 225 °C, respectively. ► The precipitation sequence is supersaturated solid solution (SSSS) → β′′ (D019) → β′ (bco). ► SF and 14H LPSO phase formed in the alloy over-aged at 200 °C and 225 °C, respectively. ► Equilibrium β phase and precipitate free zone (PFZ) formed at the grain boundaries.