Achieving superior strength and ductility synergy of WE54 alloy via combined dislocation introduction and twinning

Aging precipitation can effectively enhance the strength of Mg–RE alloys, but it is usually accompanied by a significant decrease in ductility, thus the strength–ductility trade-off is a longstanding challenge. In this study, we report a new strategy that coupled pre-deformation (pre-tension along the extrusion direction (ED) followed by pre-compression along transverse direction (TD)) with artificial aging to achieve an exceptional strength–ductility synergy in the WE54 alloy at RT. We analyzed the microstructure, deformation modes and mechanical properties of four samples: T6 (artificial aging), PT-T6 (pre-tension + artificial aging), PC-T6 (pre-compression + artificial aging), and PTC-T6 (coupled pre-deformation + artificial aging). The PTC-T6 sample exhibited the superior strength–plasticity synergy, showing a strength increase of 111.9 MPa over the T6 sample and only a slight decrease in elongation to fracture. The PTC-T6 sample features finer and denser precipitates, along with a higher dislocation density, particularly a significant presence of <c+a> dislocations. This microstructural configuration enhances strength and facilitates the activation of pyramidal slip, which is the primary factor underlying its superior strength–ductility synergy.