Achieving good ductility in high-strength Mg-19Gd binary alloy by stacking faults induced 〈c+a〉 slip

A Mg-19Gd binary alloy with exceptionally good synergy of strength and ductility has been fabricated by conventional hot extrusion and aging. The aged alloy with a specific bimodal-grained structure achieves a yield strength of 482 MPa and an ultimate tensile strength of 535 MPa with a good elongation of 5%. The high strength arises from the high number density of β′ precipitates and a strong texture, while the good ductility is related to the excellent deformation ability of fine dynamic recrystallized grains and the compatible ability of slips within elongated grains, activated by the high density of I₁ stacking faults inside. This work presents a novel approach to overcome the low ductility of ultrahigh-strength Mg-Gd alloys by promoting the nucleation of non-basal slip from I1 stacking faults within elongated grains.