On Recrystallization Twinning in Al-l%wt.Mn Single Crystals of Two Stable Orientations

The intensity of recrystallization twinning has been characterized in {110} and {110} oriented single crystals of Al-l%wt.Mn deformed to a strain of 0.5 and then lightly annealed. SEM/EBSD measurements indicate that the quantity of recrystallization twins depends on the sample depth. In partly recrystallized sample of {110} orientation the highest fraction of twinned grains was observed in the Vi sample section, but on the surface in the case of {110} crystals. Most of the grains that fulfil the Brandon criterion for twin-related areas are in fact incoherent twins since the boundary plane does not coincide with a {111} plane. A new algorithm to identify coherent and incoherent twin boundaries was applied. In the case of coherent twins, most of the twinning plane normals lie among the rotation axes of the misorientation relations between the recrystallized grains and their as-deformed neighbourhood. The incoherent twins always appear between the growing grains.