Improving mechanical properties of Mg-Sn alloys by co-addition of Li and Al

In this work, a novel low-alloyed Mg-Sn-Li-Al alloy with high-strength has been developed. The addition of ∼1 ​wt% Li into the Mg-2Sn wt.% binary alloy can change the type of strengthening phases in Mg-2Sn-1Li sample (TL21), involving the formation of both Li2MgSn and Mg2Sn phases. The co-addition of ∼1 ​wt% Al and ∼1 ​wt% Li can further induce the higher density of both micron-sized phases and nano-precipitations in the Mg-2Sn-1Li-1Al sample (TLA211). The nano-precipitations can inhibit the grain growth, which thus lead to the fine grain size of ∼1.38 ​μm in TLA211 sample, and ∼1.59 ​μm in the TL21 sample. Besides, the profuse nano-phases would improve the yield strength via Orowan hardening effect. Consequently, the TL21 sample can exhibit the high yield strength of ∼204 ​MPa, and elongation of ∼6.6%. The TLA211 sample exhibits the much higher yield strength of ∼250 ​MPa, ultimate tensile strength of ∼291 ​MPa, and also high elongation of ∼9.0%. The high strength-ductility synergy, together with the low-Sn content, make the present Mg-Sn based alloy to be potential for the wider industrial applications.