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Abstract: A large Mg-4.50Zn-1.13Ca (wt%) alloy ingot 350mm in diameter and 1730mm long was successfully fabricated by semi-continuous casting. The microstructures and mechanical properties of the as-cast and as-extruded alloys were investigated. The as-cast alloy exhibits uniform chemical composition and microstructure from the centre to the surface of the ingot and mainly consists of α-Mg and Ca2Mg6Zn3. The coarse grains and network-like second phases that are distributed at the grain boundaries result in poor mechanical properties for the as-cast alloy. The mechanical properties of the as-extruded alloys are significantly enhanced. The high yield strengths of the as-extruded alloys mainly result from the fine DRXed grain and the stronger basal texture. [Copyright &y& Elsevier]

Abstract: Mg–8.2Gd–3.8Y–1.0Zn–0.4Zr alloy sheets containing long period stacking ordered (LPSO) phase were prepared by hot rolling at 400°C with total reduction of 96%. Microstructure evolution of the sheets during hot rolling was investigated, and its influence on mechanical properties was discussed. Twinning occurred during the early stage of hot rolling, and disappeared after total reduction higher than 89%. Average grain size was gradually refined, microstructure became much more homogeneous and volume fraction of LPSO phase decreased with increasing rolling reduction. Furthermore, the type of LPSO phases far from and near the block shaped phases were identified to be different. Basal texture was obtained during rolling process, but the intensity declined with the further rolling, which is mainly due to the dynamic recrystallization and the addition of RE elements. The as-rolled sheet with 96% reduction shows excellent mechanical properties: yield strength of 318MPa, ultimate tensile strength of 403MPa and elongation to failure of 13.7% at ambient temperature along the rolling direction. [Copyright &y& Elsevier]