Surface Structure in Corundum: II, Dislocation Structure and Fracture of Deformed Single Crystals

Abstract

The dislocation structure in plastically deformed single crystals of corundum (α‐A1 2 O 3 ) was studied by etching and optical techniques. A special method of deformation was used which encouraged the participation of both the basal (0001), (1120) and the prismatic (1210), (1010) slip systems concurrently. This deformation resulted in highly stressed crystals which fractured spontaneously once the outside surface was scratched. Incoherent surface like imperfections, accompanied by distinctive dislocation arrays, were found embedded in the deformed crystals. These “surfaces” appeared as discontinuities, on each side of which dislocations etched differently. A possible origin of observed failure making use of the dislocation reaction ± [1010] = 3=1/3[2110] ± 1/3[1120] is suggested. A mechanism for the observed strain hardening in prismatic bending is presented.