Strain compatibility effect on the variant selection of connected twins in magnesium

•Connected twins are prevalent in compression of Mg alloy.•Connected twins have both high SF and high m′.•m′ is the determinant for variant selection in some cases.

Profuse extension twinning was activated in compression of a rolled Mg alloy along the transverse direction. The variant selection in twin pairs, twin chains and multiple twins inside one grain was studied by geometric compatibility factor (m′) and Schmid factor (SF). The results show that most connected twins have both high SF and high m′. In some cases (∼23%), m′ rank is more important than SF rank for variant selection in the connected twins. Due to the importance of local strain compatibility, synergetic nucleation of twins, twin transfer across neighboring grains and coexistence of ortho-position variants inside one grain are prevalent in the compressed sample. Such characteristics of variant selection affect microstructural evolution and plasticity of materials and should be considered into the development of physics-based simulation models for Mg alloys.

Graphical abstractConnected extension twins and variant selection.Figure optionsDownload full-size imageDownload as PowerPoint slide