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Abstract: 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 0.8wt.% 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 0.8wt.% and 1.2wt.%, respectively. The mechanisms of improvement are related to grain refinement and compound strengthening effects. [Copyright &y& Elsevier]

Abstract: As-cast Mg–5Li–3Al–2Zn–xRE (x =0–2.5wt.%) alloys were prepared under the ambient of pure argon, and the effects of Ce-rich rare earths (RE) and heat treatment on the microstructure and mechanical properties of Mg–Li–Al–Zn-based alloy were investigated. The results show that the main phase compositions of Mg–5Li–3Al–2Zn (LAZ532) alloy consist of α-Mg and AlLi. With the addition of RE, Al-RE precipitate forms, and increases gradually, whereas AlLi phase decreases. The room temperature tensile test reveals that the addition of RE could clearly improves the mechanical properties of alloys which are further improved after heat treatment. In more detail, excellent tensile strength and ductility are obtained in 1.5wt.% RE containing alloy in as-cast state. After heat treatment, the 1.0wt.% RE containing alloy attains superior tensile strength. The differences in tensile strength are related to the morphology, distribution of second phases and solid–solution strengthening in different alloy systems. In addition, the fracture pattern of the alloy is predominantly brittle cleavage and tends to be quasi-cleavage with RE addition. [Copyright &y& Elsevier]