Effect of alloying and extrusion temperature on the microstructure and mechanical properties of Mg–Zn and Mg–Zn–RE alloys

Extruded Mg–Zn–RE alloys have been shown to exhibit excellent combinations of yield strength and ductility, but it is not completely clear how adding rare earth metals to Mg–Zn alters the microstructure and affects the mechanical properties. Microstructural changes and the resulting mechanical properties from changes in composition and extrusion temperature have been investigated for Mg-x Zn-y RE (x=2.5 and 5 wt.%, y=0 and 1 wt. %, and RE=Gd and Y) alloys. Adding RE to Mg–Zn increased the strength and reduced the ductility, while increasing the zinc concentration in the Mg–Zn–RE alloys had the reverse effect.