Abstract
High temperature deformation tests of α-Al2O3 single crystals oriented for basal slip were conducted in order to clarify the effect of preliminary deformation. Basal slip was dominant deformation mode at single 1400°C, while rhombohedral twinning was dominant at single 1200°C. In contrast, it was found that after the preliminary deformation at 1400°C, rhombohedral twinning in the additional deformation of 1200°C was considerably restrained and basal slip became dominant. Moreover, dislocation density introduced by this two step deformation was over 1.0×109/cm2. These indicate that glide dislocations introduced by preliminary deformation enhance slip deformation and restrain the formation of twinning.
