Metal-Ceramic Interfaces Studied with High-Resolution Transmission Electron Microscopy

How the core structure of an interface dislocation network depends on both misfit and bond strength across the interface is investigated. It is shown that, in principle at least, it is possible to assess the bond strength by investigating the atomic structure of the dislocation cores. As examples, the misfit-dislocation structures at Ag/Mn3O4, Cu/MnO interfaces formed by parallel close-packed planes of Ag or Cu and O obtained by internal oxidation were studied using HRTEM and lattice static calculations. The lattice static calculations are instrumental in indicating the possible dislocation network and their results served as input for HRTEM image simulations which are then compared with experimental HRTEM images. In addition, the influence of dissolution of a segregating element (Sb) in these systems was also studied using HRTEM. The influence on Mn3O4 precipitates in Ag is distinct, namely: (i) the initial precipitates, sharply facetted by solely {111}, are changed into a globular shape with sometimes also short {220} and (002) facets, (ii) a partial reduction of Mn3O4 into MnO occurs for a part of the precipitates. Further Sb appeared to prevent Oswald ripening of the precipitates.