Effect of Sn alloying and cold rolling on microstructure and mechanical properties of Mg14Li alloy

Highlights: • It provides a new idea for the design of as cast bcc structure Mg-14Li alloys. Mg-14Li-(0, 2, 4, 6)Sn alloys were prepared. Effect of Sn alloying and cold rolling on microstructure and mechanical properties of Mg14Li alloy have been studied. It is found that the introduction of Sn into Mg14Li alloy effectively promotes the grain refinement and columnar-to-equiaxed grain transition (CET). The alloys contain three kinds of compounds, Mg₂Sn, MgLi₂Sn and Li₁₃Sn₅. Mg₂Sn is mainly distributed at the grain boundaries, MgLi₂Sn is mainly distributed on the stacking faults inside Mg₂Sn, and Li₁₃Sn₅ is distributed inside the grains. With the increase of Sn content from 2 wt% to 6 wt%, the grain size gradually decreases. Both the strength and ductility increase. However, when the Sn content reaches 6 wt%, the ductility decreases. After 50% cold rolling, due to the work hardening effect, the strength of Mg-14Li-(0, 2, 4) Sn alloys increases and their ductility decreases. As for Mg-14Li-6Sn alloy, due to the dynamic recrystallization, both the strength and ductility after 50% cold rolling are improved.