Mg-Li alloys have their own charact

Mg-Li alloys have their own characteristics such as better plasticity and easier age softening compared with traditional magnesium alloy due to Li content. However, the composition devise for Mg-Li alloy can learn from the tradition Mg alloy as both alloys’ main element is magnesium. In traditional Mg-Zn-RE alloy, rare earth element such as Y, Gd, Er and etc. can form M-Zn-RE phases [8–14]. And this Mg-Zn-RE alloy containing Mg-Zn and Mg-Zn-RE phases has excellent mechanical properties. Similarly, addition of Zn and RE into Mg-Li alloy may also improve the strength of Mg-Li alloys. Up to now, some studies about Mg-Li alloys strengthened by Mg-Zn-RE phase mainly focused on Mg-LiZn-Y and Mg-Li-Zn-Gd alloys. D.K. Xu et al. simultaneously added Y and Zn elements into Mg-Li alloy, and the study showed that the strength of Mg-6 wt%Li alloy was improved by introduced Zn and Y [15–17]. And Y. Zhang et al. reported that the enhanced strength of extruded Mg-LiZn-Gd alloys was attributed to the grain refinement and the existence of crack I-phase particles [18]. However, there are few literatures about Er addition into Mg-Li-Zn alloys. It's known that Er element can also form Mg-Zn-Er phase with Zn and Mg in Mg-Zn-Er alloys [8,19–21]. Therefore, present work aims to explore the microstructure evolution associated with different Er content in as-cast Mg-Li-Zn alloy. The Zn element is added also for improving the strength of the Mg-Li alloys.