Achieving strength-ductility synergy of Mg–Al–Ca–Zn alloy with a lamellar heterogeneous structure
Yang Zhou, Hansong Xue, Jinyu Zhang, Shanyi Lan, Jingfeng Wang, Jia She, Dingfei Zhang, Fusheng Pan
Abstract
The development of heterogeneous metal material is the key issue in improving the absolute strength of low-alloyed magnesium (Mg) alloys. In the present work, a novel lamellar heterogeneous low-alloyed Mg-1.2Al-0.6Ca-0.4Zn alloy with strength-ductility synergy was developed by the traditional extrusion process. The results demonstrate that regulating the proportion of soft-zone and hard-zone grains via various Zn additions plays a key role in constructing the lamellar heterogeneous structure. The Mg-1.2Al-0.6Ca-0.4Zn alloy exhibits a lamellar heterogeneous characteristic with the proportion of soft/hard zone grains of 7: 3, which provides a remarkable synergistic improvement of strength and ductility compared with the uniform structure Zn-free Mg-1.2Al-0.6Ca alloy. During the deformation process, numerous dislocations arise from the soft/hard interface, and the dislocations bypassed by nanoscale rod-like Al 2 Ca precipitates predominantly formed at deformed grain induce geometrically necessary dislocations (GNDs) to accommodate the strain, which offers hetero-deformation induced (HDI) hardening to enhance the strength of AX-0.4Zn alloys.