Comment: On the nature of unconventional twins in magnesium

Unconventional twins were reported by Cayron and Loge' [1] to form in plastically deformed magnesium. They were used to show the occurrence of a new twinning mode which was used to argue for reconsidering the theory of deformation twinning that is based on simple shear [1], and to support a concept of axial weak twins [2]. Our paper demonstrates the incorrect interpretation of their electron back-scatter diffraction map in [1], and that the so-called unconventional twins are just conventional extension twins that have impinged with each other. Therefore, the so-called habit plane of the unconventional twins is a boundary resulting from impingement of these two different variants of the extension twin, and is therefore not expected to be invariant.

Automated summary

This paper reveals that the so-called unconventional twins reported by Cayron and Loge' are actually conventional extension twins that have impinged with each other, leading to the formation of an invariant boundary.