Tailoring the microstructure and texture of a dual-phase Mg–8Li alloy by varying the rolling path

Dual-phase Mg–Li alloys exhibit better formability than conventional Mg alloys. However, conventional processing methods, such as rolling and extrusion, usually result in a lamellar structure, which will generate a strong planar anisotropy. In the present study, an as-extruded dual-phase Mg-8Li plate was rolled along two different directions, extrusion direction (ED-rolling) and transverse direction (TD-rolling), with the aim to investigate the effect of rolling path on the microstructure, texture and in-plane mechanical anisotropy. The results show that the lamellar α+β structures in the initial plate well remained after 20% or 50% ED-rolling and subsequent annealing at 250 °C for 4 h. In contrast, this lamellar structure completely disappears after TD-rolling and subsequent annealing. The basal poles of grains close to the TD in α phase in the initial plate slightly rotate from TD towards the normal direction (ND) during ED-rolling, while are largely parallel to the ND after TD-rolling. The variation of rolling path hardly alters the texture of β phase. For both α and β phases, annealing does not change the type of texture, only reduce the maximum intensity of texture. The mechanisms for texture evolution during rolling were studied using visco-plastic self-consistent (VPSC) simulations. It is shown that the main texture features of rolled plates are determined by the activated deformation modes in each phase, while α/β phase boundaries will retard the texture evolution. After ED-rolling, there is an obvious anisotropy in work hardening behavior and elongation for tension along the TD and RD, while this mechanical anisotropy disappears after TD-rolling. The corresponding mechanism were discussed.