The formation of networks of misfit dislocations at the (00•1)sapphire||(111)Nb interface was investigated by using an approach which used a very simple pair-potential to describe interactions between metal and substrate. This model contained the strength of interfacial adhesion as a parameter. The calculations demonstrated that the strength of bonding between the 2 materials decided the form of the network and the atomic structure of the cores of the dislocations. It also revealed that diffusion was essential for the formation of an observed triangular network of ½<111> dislocations. The calculated structures were used to investigate related high-resolution electron microscopic images by using a multi-slice technique. In these simulations, translational symmetry along the electron beam was not assumed but different sub-structures were used for each slice of material along the beam. This permitted the detailed investigation of the effect of dislocation intersections upon the images of dislocation cores. Their effect was appreciable if an intersection was in the region which produced the image but, if not, the images of the cores of misfit dislocations were only slightly affected.

Structure of Misfit Dislocations in Niobium-Sapphire Interfaces and Strength of Interfacial Bonding - an Atomistic Study. A.Levay, G.Möbus, V.Vitek, M.Rühle, G.Tichy: Acta Materialia, 1999, 47[15], 4143-52