Mechanical properties of lightweight Mg-1RE-0.5Zn-0.5Zr-xLi alloys

The effects of Li content on the mechanical properties of lean Mg-1RE-0.5Zn-0.5Zr-xLi alloys in the as-cast condition were investigated, for which the improvement of mechanical properties due to the advantages of Li, RE (rare earth), Zn, and Zr addition were considered. Lithium up to 3 wt% resulted in the grain refinement of α-Mg matrix but effectively saturated thereafter. Moreover, a decrease in the crystallographic texture intensity was observed. Accordingly, the addition of 3 wt% Li improved the mechanical properties, as evaluated by the tension and compression tests. Moreover, the strength-ductility synergy improved, as investigated by the tensile toughness. However, Li concentrations higher than ~ 3 wt% led to the appearance of the deleterious intergranular α-Mg/β-Li eutectics, resulting in inferior as-cast mechanical behavior. Finally, Hall–Petch formulae of σ_T = 59.5 + 299.6/√D and σ_C = 47.5 + 294.6/√D were proposed for tensile and compressive yield stresses, respectively. Accordingly, this work revealed that the as-cast Mg-1RE-0.5Zn-0.5Zr-3Li alloy is a promising candidate for future lightweight applications.