LAUSR

Abstract We investigate the deformation dynamics in pre-twinned Mg–3Al–1Zn alloy under uniaxial compression based on in situ synchrotron X-ray diagnostics. Stress–strain curves, strain field mapping and X-ray diffraction are achieved simultaneously. The same measurements are conducted on the as-received Mg alloy for comparison. Massive { 10 1 ¯ 2 } – { 10 1 ¯ 2 } double twinning is observed in preexisting twins of the pre-twinned specimen, and abundant { 10 1 ¯ 2 } extension twins are activated in the as-received specimen. The { 10 1 ¯ 2 } extension twinning in the as-received specimen can rapidly boost strain hardening rate by slowing down the process of strain localization. The { 10 1 ¯ 2 } – { 10 1 ¯ 2 } double twinning does not lead to significant reduction in the rate of strain localization, and thus the corresponding increase in strain hardening rate is modest.