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Abstract 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. Highlights • 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. [ABSTRACT FROM AUTHOR]

High-performance as-extruded and peak-aged Mg-9.2Gd-3.3Y-1.2Zn-0.9Mn (wt%) alloys have been fabricated by semi-continuous casting, heat-treating, extruding and ageing processes. The effects of different heat treatments on the microstructure and mechanical properties have been investigated. Lamellar and bulk-shaped 14H-type long-period stacking ordered (LPSO) phase and few RE-rich (RE: rare earth element) particles form by different heat treatments. After hot extrusion, the heat-treated alloy with bulk-shaped LPSO phase exhibits an equal-axial microstructure, while the heat-treated alloy with lamellar LPSO phase across the grains shows bimodal grain microstructure consisting of fine equal-axial grains and coarse deformed grains. The more profuse lamellar LPSO phase in heat-treated alloy generates higher volume fraction of deformed grains and finer equal-axial grains, hence leads to higher strength but lower ductility. After ageing, the alloy with profuse LPSO and β′ phases achieves the superior mechanical properties with ultimate tensile strength (UTS) of 525 MPa, tensile yield strength (TYS) of 420 MPa and elongation to failure (EL) of 6.3%. The alloy strengthening is mainly attributed to the bimodal grain microstructure, LPSO phase, Mg 5 Gd (β) phase and β′ phase. [ABSTRACT FROM AUTHOR]