Detwinning and twinning dynamics in pre-twinned Mg–3Al–1Zn alloy under uniaxial tension: a synchrotron-based multiscale study

The effects of pre-twinning on deformation of a textured Mg–3Al–1Zn (AZ31) magnesium alloy are investigated with real-time, in situ synchrotron-based, multiscale diagnostics. Samples are pre-compressed along the rolling direction (RD, perpendicular to the c-axis) to introduce \(\{10\bar{1}2\}\) twins, and then subjected to uniaxial tension along RD or the normal direction (ND, parallel to the c-axis). Bulk stress–strain curves (macroscale), strain fields (mesoscale) and X-ray diffraction patterns (microscale) are obtained simultaneously. The yield strength is enhanced by pre-twinning. For tension along RD, plastic deformation is primarily driven by detwinning, followed by prismatic slip. Conversely, for tension along the ND, plastic deformation is initially dominated by basal slip and subsequently by twinning. Additionally, stress relaxation occurs within the matrix upon twinning, and within the pre-compression-induced twins upon detwinning.