Micromechanical deformation of single-crystal alumina surfaces

In the present study, the micromechanical properties of single-crystal Al2O3 have been tested using a micromechanical depth-sensing testing device. A series of microscratches are produced on the annealed {0001}, {112̄0} sapphire specimens of special geometry. The scratches were positioned in pre-selected crystallographic directions, determined with the back-reflection Laue method X-ray diffraction method. The microscratch tracks were examined with transmission electron microscopy (TEM). The main emphasis in the analysis of deformation structure of sapphire has been placed on the correlation of irregularities observed on load-displacement curves to the extent of elastically deformed regions, nucleation of the dislocations on the surface, unique nature of the crack-dislocation networks associated the sapphire anisotropic deformation behavior.