Deformation dynamics in pre-strained Mg-3Al-1Zn alloy: An in situ synchrotron X-ray study

The effects of preexisting dislocations generated via pre-strain on deformation twinning in a textured magnesium alloy are investigated via real-time, in situ, synchrotron X-ray imaging and diffraction. One sample is stretched along the rolling direction (RD, perpendicular to the c-axis) to introduce dislocations, and then compressed along RD. For comparison, an as-received sample is directly compressed along RD. Bulk stress- strain curves (macroscale), strain fields (mesoscale) and X-ray diffraction patterns (microscale) are obtained simultaneously. Postmortem electron backscatter diffraction characterizations are performed as a complement. The {1012} extension twinning in both samples can boost strain hardening rate by slowing down the strain localization process. However, the dislocations generated with pre-strain interact with the twin boundaries, and obstruct twin motion and growth. Therefore, strain localization mitigation due to twinning in the pre-strained sample is reduced compressed to its counterpart.

Automated summary

The effects of pre-strain induced preexisting dislocations on deformation twinning in a textured magnesium alloy are investigated using real-time synchrotron X-ray imaging and diffraction. Comparisons are made between samples with and without pre-strain. The study finds that while twinning can enhance strain hardening rate, the dislocations generated with pre-strain impede the motion and growth of twinning, resulting in reduced strain localization mitigation in the pre-strained sample compared to the as-received sample.