High Temperature Deformation and Dislocation Structure of -Al2O3 Single Crystals
Atsutomo NAKAMURA, Takahisa YAMAMOTO and Yuichi IKUHARA
Abstract:The structure and glide behavior of basal dislocations in a-Al2O3 single crystals have been studied by high temperature deformation tests and transmission electron microscopy (TEM). Basal slips were dominant in the deformation at 1400 and edge-type basal dislocations belonging to primary slip system were mainly introduced in the sample. On the other hand, rhombohedral twinning formation frequently took place at 1200. It was confirmed by high-resolution electron microscopy (HREM) that the basal dislocation dissociates into two half partial dislocations along the [0001] direction. The two partials were separated with a distance of 4.7nm along the [0001] direction and were located at the nearest neighbor positions along the <11Q20> slip direction. This indicates that the basal dislocation dissociates by self-climb perpendicularly to the basal slip plane, and the stacking fault is formed on the {11Q20} plane between the two partials. However, the two partials are considered to dissociate on the same basal slip plane during deformation because the basal dislocation with climb dissociation can not glide on the basal slip plane. Key Words:a-Al2O3 Sapphirej, Single crystal, High temperature deformation, Dislocation, Transmission electron microscopy