Achieving strength-ductility synergy of Mg–Al–Ca–Zn alloy with a lamellar heterogeneous structure

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.