Enabling manufacturing of multi-axial forging-induced ultrafine-grained strong and ductile magnesium alloys: a perspective of process-structure-property paradigm

Magnesium (Mg) alloys are difficult to cold/warm-process due to their hexagonal close-packed (HCP) lattice, which has restricted slip systems and makes plastic deformation at low temperatures a challenging task. Multi-axial forging (MAF) and annealing of as-cast alloys were combined to create a texture-free ultrafine-grained (UFG) structure with a high strength-high ductility combination to address this challenge. The study showed a clear and fundamental change from basal and pyramidal dislocation slip to twinning in the strong and ductile UFG Mg alloy compared to the low strength coarse-grained (CG) Mg alloy counterpart. This implied that the dislocation activity, grain orientation, and particular grain boundary states played an important role in controlling the deformation mechanisms. The potential impact of processing Mg alloys by MAF opens-up a new frontier of strong and ductile low-density materials for light and efficient solutions including energy absorption and formability and provides a perspective in terms of process-structure-property relationship.

Automated summary

Combining multi-axial forging and annealing, a texture-free ultrafine-grained structure was created in magnesium alloys, resulting in a high strength-high ductility combination. This overcame the challenge of plastic deformation in hexagonal close-packed lattice at low temperatures. The study revealed a shift from basal and pyramidal dislocation slip to twinning in the ultrafine-grained magnesium alloy, indicating the importance of dislocation activity, grain orientation, and grain boundary states in controlling deformation mechanisms. The potential of processing magnesium alloys by multi-axial forging opens up new possibilities for lightweight and efficient solutions, including energy absorption and formability, and provides insights into the process-structure-property relationship.