|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Magnesium Technology 2017
||Contraction Twinning Dominated Tensile Deformation and Subsequent Fracture in Extruded Mg-1Mn (wt%) at Ambient Temperature
||Ajith Chakkedath, Philip Eisenlohr, Tias Maiti, Carl Boehlert, Jan Bohlen, Sangborg Yi, Dietmar Letzig
|On-Site Speaker (Planned)
To improve the cold formability of Mg alloys it is critical to understand the mechanisms that limit the elongation-to-failure. In this study, a contraction twinning based mechanism was responsible for failure at low tensile strains in extruded Mg-1Mn (wt%). Contraction twinning dominated the tensile deformation at 50°C. The contractions twins evolved into double twins which accounted for the formation of shear bands in the twinned volume. The shear band formation was expected to be due to the enhanced activity of basal <a> slip in the twinned region. Cracks developed along the shear bands and led to shear failure. The contraction twinning activity decreased with increased temperature, and at 250°C, no contraction twinning was observed. This was expected to be due to the lower CRSS for pyramidal <c+a> slip compared to contraction twinning at elevated temperatures. The improved elongation-to-failure at elevated temperatures was attributed to the limited activity of contraction twinning.