In this work, we successfully fabricate an ultra-high strength Mg-11Gd-3Y-0.5Zr alloy with ultimate tensile strength of 523 MPa and enhanced ductility via cost-effective bi-directional forging (BDF) and subsequent annealing heat treatments. To elucidate the role of BDF and gain a fundamental understanding of the remarkable simultaneous increase of strength and ductility, systematic microstructure characterization and analysis are performed. It is revealed that the double-peak basal texture, with basal poles located at the center of two mutually perpendicular forging directions, serves as an essential factor for the strength–ductility synergy of the Mg-11Gd-3Y-0.5Zr alloy processed with BDF. Roles of the double-peak basal texture in overcoming the strength–ductility trade-off include promoting non-basal slip, increasing ductility, and enlarging the Hall–Petch effect along the sample elongation direction while reducing the extent of anisotropy in critical resolved shear stresses of different slip systems. This study demonstrates that texture engineering is a powerful strategy to control magnesium alloy performance and BDF is a promising processing technique for enhancing mechanical properties of magnesium alloys.

Effects of rare-earth (RE) and precipitates on twin evolution in cast Mg-10Gd-3Y-0.5Zr (wt.%) (GW103) alloys of solid solution (T4) and aged (T6) states are investigated performing quasi-static room temperature compression tests and microstructural characterization. It is found that both {10–12} and {11–21} extension twins (ET1 and ET2) can appear in the T4 and T6 states but with different emergence sequences. As the aging heat treatment leads to consumption of RE solutes which could inhibit atomic shuffling required for nucleation of ET1 but not ET2, ET2 occurs prior to ET1 in the T4 state, and ET1 emerges before ET2 in the T6 state. The extension twins here mainly coordinate the plastic deformation through the non-Schmid effect. Our results shed light on the influence of RE elements on twin evolution in magnesium alloys and have implications in developing high-performance Mg-RE alloys.