Electron channelling contrast imaging techniques were applied to the study of dislocation behavior in the region of crack tips in high-purity stoichiometric single crystals. The technique was based upon the dependence of the intensity of back-scattered electrons upon the incident beam orientation with respect to the crystal lattice and upon defects near to the specimen surface, and permitted near-surface defects to be imaged in bulk specimens. The technique avoided many of the constraints which were imposed by the use of thin foils. Dislocations which were associated with crack propagation were observed by examining 4-point bend bulk specimens which had been deformed in situ in a field emission scanning electron microscope. Dislocations were directly observed in the crack-tip region as well as along the crack paths.

Application of the Electron Channelling Contrast Imaging Technique to the Study of Dislocations Associated with Cracks in Bulk Specimens. B.C.Ng, B.A.Simkin, M.A.Crimp: Ultramicroscopy, 1998, 75[3], 137-45