Strong and formable Mg-Zn-Ca alloy sheet with layered heterogeneous microstructure

We fabricated a lean Mg-1.52mass%Zn-0.09mass%Ca alloy sheet having a unique layered heterogeneous microstructure, which consisted of a recrystallized surface-layer and an internal-layer with non-recrystallized grains. An excellent 0.2 % proof stress (PS) and limiting dome height (LDH) were simultaneously achieved. The PS along the rolling direction and LDH reached 263 MPa and 7.4 mm, respectively. The key factor was a degree of recrystallization, and the good LDH was obtained with the PS when the depth of the recrystallized region was ∼100 μm, establishing a new design guidance for the development of strong and formable Mg alloy sheets for automotive sheet applications.