Microstructure and mechanical properties of Mg-Gd-Y-Zn-Mn alloy sheets processed by large-strain high-efficiency rolling

The high-performance Mg-8.8Gd-3.4Y-1Zn-0.8Mn (wt%) alloy sheets were prepared by large-strain high-efficiency rolling process. The large strains with ~ 87% and ~ 91% total reduction were introduced in the hard-to-deform Mg alloy by hard-plate rolling process at 400 °C for merely 3 and 2 rolling passes. The microstructural morphology and texture were examined, and the tensile tests were performed along rolling direction (RD) and transverse direction (TD). The large-strain rolling process brings in refined grains, homogeneous dispersive LPSO phase and β phase and weakened basal texture. The anisotropy of the strength and elongation is improved after rolling. The as-rolled sample with ~ 91% total reduction exhibits excellent mechanical properties with ultimate tensile strength (UTS) of 434 MPa, tensile yield strength (TYS) of 318 MPa and elongation to failure (EL) of 10.7% parallel to the TD. By quantitating the relation between grain orientations and the deformation modes, it is confirmed that the basal slip and prismatic slip are the dominant deformation modes at the initial stage of plastic deformation, meanwhile the pyramidal slip and extension twinning are the complementary deformation modes. •The hard-to-deform Mg alloy has been rolled with a large reduction per pass (~ 70%) and a large total reduction (~ 91%).•The as-rolled Mg alloy exhibits an improved anisotropy with high strength and appreciable ductility.•The quantitative relation between grain orientations and the deformation modes has been uncovered.