It was noted that the polarization of deformation twinning (propagation in a certain sense but not in the opposite one) was taken for granted. However, the same phenomenon could also occur during super-dislocation glide, as demonstrated here. The consequences for the plastic deformation of polysynthetically twinned TiAl crystals, having lamellar interfaces parallel to the loading direction, were considered. It was concluded that it was not the interface itself which was an obstacle to the propagation of deformation, but also the fact that a deformation mode involving the parallel Burgers vector could not be activated in neighboring lamella; due to the directionality of super-dislocation motion which led to an additional stress increase.

Polarization of Plastic Deformation Modes in Polysynthetically Twinned TiAl Crystals. V.Paidar, K.Kishida, M.Yamaguchi: Journal of Materials Research, 2003, 18[3], 702-8