Effect of pre-existing twinning on strain localization during deformation of a magnesium alloy

A fine dispersion of nanoscale gold surface markers was achieved on the surface of a Mg-alloy sample using a styrene-assisted remodeling process. The markers were used for a high resolution digital image correlation strain-field analysis, to achieve a better understanding of the effect of pre-existing twinning on strain localization during in-situ tensile deformation. A complex pattern of heterogeneous strain localization was found. The results show that twins do not deform uniformly, and that relative differences in Schmid factor may influence the early occurrence of strain localization. Additionally, strain localization was seen to occur preferentially at grain boundaries and twin boundaries due to the lack of efficient plastic mechanisms for strain transfer across such interfaces. The results demonstrate the ability to measure strain localization on a fine scale in Mg-alloys, and highlight the complex interaction between deformation mechanisms during plastic deformation.