Effects of Li addition on the microstructure and mechanical properties of Mg–3Zn–1Sn–0.4Mn based alloys

• Mg–xLi–3Zn–1Sn–0.4Mn alloys were melted and extruded at 200 °C.
• Li addition resulted in the formation of MgLi2Sn intermetallic compound.
• Li addition resulted in the development of the random texture.
• By Li addition, the ductility was significantly increased.
• Sn addition resulted in the improvement of strength.

In this work, Mg–3 wt%Zn–1 wt%Sn–0.4 wt%Mn alloys with different Li addition (5, 8 and 11 wt%) were melted and extruded at 200 °C. Effects of Li addition on microstructure and mechanical properties of as-cast and as-extruded Mg–xLi–3Zn–1Sn–0.4Mn alloys were investigated. Li addition to Mg–3Zn–1Sn–0.4Mn based alloy resulted in the formation of MgLi2Sn intermetallic compound. By Li addition from 5 wt% to 8 and 11 wt%, the ductility was significantly increased from 18.1% to 30.9% and 49.3% at room temperature due to transformation from HCP to BCC crystal structure and formation of a weaker basal texture of the α-Mg phase region. The ultimate tensile strength (UTS) was decreased from 252.0, 201.1 and 148.7 MPa as Li content increased from 5 to 8 and 11 wt%. On the other hand, the tensile strength of Sn containing alloys was remarkably increased compared to the alloys without Sn addition due to the presence of the fine MgLi2Sn intermetallic compounds.