Atomic structure of heterophase interfaces

Abstract

High-resolution electron microscopy (HREM) has been used to study internal interfaces between dissimilar materials, notably ceramic-metal interfaces. Structures observed for systems with small and large misfits are compared in metal-metal, metal-ceramic, and ceramic-ceramic boundaries. The interfaces were prepared by a variety of techniques, including internal reduduction, internal oxidation, and epitaxial growth by MOCVD and special thin-film techniques. While interfaces produced by internal oxidation and reduction in f.c.c. systems typically form boundaries on (111) planes, non-equilibrium boundaries have also been generated using special thin film techniques. All boundaries can be characterized by their tendency to form coherent structures. While it appears that the amount of misfit and the bond strength primarily determine the degree of coherency, kinetic factors and substrate defects also seem to play an important role in determining the local defect structure at the boundary and the type of misfit localization.