Effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y alloy

This study was conducted to discuss the effect of rolling strain on microstructure and tensile properties of dual-phase Mg-8Li-3Al-2Zn-0.5Y (wt%) alloy, which was prepared by casting, and then homogenized and rolled at 200 °C. The rolling process was conducted with 10% reduction per pass and five different accumulated strains, varying from 10% to 70%. The results indicate that the as-cast and as-rolled Mg-8Li-3Al-2Zn-0.5Y alloys are composed of α-Mg, β-Li, AlLi and Al2Y phases. After rolling process, anisotropic microstructure was observed. α-Mg phase got elongated in both rolling direction and transverse direction with the addition of rolling strain. Consequently, the strength of the alloy in both directions was notably improved whereas the elongation declined, mainly caused by strain hardening and dispersion strengthening. The tensile properties of the as-rolled alloys in the RD, no matter the YS, UTS or the elongation, are higher than those of the TD due to their larger deformation strain and significant anisotropy in the hcp α-Mg phase. In addition, the fracture and strengthening mechanism of the tested alloys were also investigated systematically.