Influence of yttrium on microstructure and mechanical properties of as-cast Mg–5Li–3Al–2Zn alloy

The influence of Y on microstructure and mechanical properties of as-cast Mg–5Li–3Al–2Zn alloy was investigated. The results show that the phase compositions of Mg–5Li–3Al–2Zn consist of α-Mg and AlLi phases. Adding Y to the alloy results in the formation of Al2Y compound and facilitates grain refinement. The addition of 0.8 wt.% Y produces the smallest grain size. The tensile tests performed at room temperature show that the additions of Y can improve the mechanical properties of the alloy; the tensile strength and ductility reach peak values when the Y additions are 0.8 wt.% and 1.2 wt.%, respectively. The mechanisms of improvement are related to grain refinement and compound strengthening effects.

► The effects of Y additions (0–2.0 wt.%) on the microstructure and mechanical properties of Mg–5Li–3Al–2Zn alloy have been studied.
► The new phase generated after Y addition has been identified, the change of grain size due to Y addition has also been discussed.
► The mechanisms of the improvement of the mechanical properties due to Y addition have been investigated.