Mg alloys generally suffer from their poor formability at low temperatures due to their strong basal texture and a lack of adequate
deformation systems. In the present study, a small amount of Sn was added instead of Zn to Mg-3Al alloy to modify its
deformation behavior and improve the stretch formability. Microstructural examinations of the deformed Mg-3Al-1Sn (AT31) alloy by electron backscatter diffraction and transmission electron microscopy show that prismatic <a> slip is quite
active during
deformation, resulting in much lower r-values and planar anisotropy than the counterpart Mg-3Al-1Zn (AZ31) alloy. Polycrystal plasticity simulation based on visco-plasticity self-consistent (VPSC) model also shows that prismatic <a> slip is the dominant
deformation mode in AT31 alloy besides basal <a> slip. As a consequence, AT31 alloy shows a much higher stretch formability than AZ31 alloy. On the other hand, AZ31 alloy shows the development of intense shear bands during stretch forming, and these shear bands act as crack propagating paths, limiting the stretch formability of AZ31 alloy.
