LAUSR

Abstract The present study investigated the effect of Gd on the microstructures and mechanical properties of permanent mould cast Mg-4Al-5RE (wt%) (where RE represents La-Ce mischmetal) alloy. Coarse grains and acicular Al11RE3 phases in Mg-4Al-5RE alloy are successfully refined by the addition of 0.66 wt% Gd. The average grain size is dramatically decreased from 493.9 μm to 205.8 μm, and the acicular Al11RE3 phase is modified to rod-like sharp with a pronouncedly decreased average length from 22.0 μm to 3.8 μm. The modified microstructures are attributed to the formation of Al2(Gd, RE) particles, which act as nucleation sites for both α-Mg and Al11RE3. Eventually, the modified alloy exhibits dramatically enhanced yield strength (YS), ultimate tensile strength (UTS) and elongation (EL) about 12%, 23% and 48%, respectively.