An experimental and theoretical study was made, of misfit dislocations in metal/ceramic interfaces, with the aim of revealing the atomic structures of the cores of misfit dislocations. Two interfaces in the Nb/sapphire system were investigated. These corresponded to differing interface planes between the Nb and Al2O3 crystals: (01•0)sapphire||(112)Nb or (00•1)sapphire||(111)Nb. It was found that misfit dislocations were present in Nb, with no stand-off from the interface, and their cores were investigated by using high-resolution electron microscopy. Atomistic studies of these misfit dislocations were carried out by using very simple models for both the ceramic crystal and for the atomic interactions across the interface. Good agreement between the calculated and observed core structures was found for certain values of the cohesive strength across the interface. The results were analyzed with the aim of establishing a relationship between the atomic structure of the misfit dislocations and the cohesion of the interface.

V.Vitek, G.Gutekunst, J.Mayer, M.Rühle: Philosophical Magazine A, 1995, 71[6], 1219-39