Twinning and mechanical behavior of an extruded Mg-6Al-3Sn alloy with a dual basal texture

Uniaxial compression tests were performed on an extruded Mg-6Al-3Sn (AT63) alloy with a dual basal texture, along the extrusion direction (ED), transverse direction (TD) and normal direction (ND). Unlike the single basal texture commonly seen in rolled Mg alloys, for which either extension or contraction twinning is favored in one compression, the dual basal texture appreciates both extension and contraction twinning. Nevertheless extension and contraction twinning display different activities among the three compressions. The results suggest that extension twinning propagates largely for ED compression while it displays limited propagations for TD and ND compressions, although it nucleates at the onset of plasticity for all the three compressions. In contrast, contraction twinning nucleates early and widely for TD and ND compressions while it is largely suppressed for ED compression. It is the wider propagations of extension twinning and belated contraction twinning that result in a larger drop and a higher peak in the strain hardening curve for ED compression. Our results shed some light on deformation mechanisms of the Mg alloys consisting of multiple texture components.