Super-ductile magnesium alloy at room temperature

Li, H.*; Gong, W.   ; Kawasaki, Takuro   ; Harjo, S.   ; Zheng, R.*; 6 of others*

The quest for lightweight and highly formable magnesium (Mg) alloys has drawn significant attention due to the growing demand for energy-efficient structural materials. Achieving high ductility in Mg at room temperature, which is critical for mass production of structural components, remains a formidable challenge despite decades of research. In this study, we demonstrate super-ductility in an ultrafine-grained (UFG) Mg alloy at room temperature. By microalloying with trace manganese (Mn) and reducing the grain size to sub-micron scale, Mg-0.3Mn binary alloy achieves an exceptional room temperature tensile elongation of 135% at a quasi-static strain rate. Detailed microstructural analysis reveals that grain boundary (GB) sliding, rather than intragranular dislocation slip, is the dominant deformation mechanism in the UFG Mg-0.3Mn alloy. Unlike conventional alloying strategies that lead to GB pinning, the segregation of Mn element along GBs in a manner of nano-clusters could reduce interfacial bonding strength, acting as a lubricant to facilitate GB sliding and thus dramatically boost the ductility. This innovative GB engineering approach unlocks unprecedentedly remarkable deformability of Mg-based alloys at room temperature, paving the way for next-generation lightweight structural applications.