Enhancing yield strength by suppressing detwinning in a rolled Mg-3Al-1Zn alloy with {101¯2} twins

A remarkable improvement in the tensile yield strength of rolled Mg-3Al-1Zn alloy with pre-existing {101¯2} twins was achieved by inducing double twinning through compression deformation. The resulting formation of {101¯2}-{101¯2} double twins inside pre-existing {101¯2} twin bands effectively suppressed the detwinning of pre-existing twins during subsequent deformation. This in turn led to a change in the dominant deformation mode from detwinning to slip, significantly increasing the yield strength. The mechanisms behind this behavior are considered to be a combination of the redistribution of residual tensile stress within pre-existing twins, refinement of pre-existing twins by double twins, a change in texture due to double twinning and a loss of coherency at twin boundaries.