Three-Dimensional analysis of oxide-oxide directionally solidified eutectic interfaces by high-resolution Microscopy and Electron Energy Loss Spectroscopy

Abstract

It is well appreciated that the strength of heterophase interfaces in ceramic composites plays an extremely influential role in the macroscopic mechanical behavior of the bulk material. It is therefore useful to understand the structure of such interfaces in order to make structure/ property relationships between interface structure and mechanical behavior. High Resolution Electron Microscopy (HREM) is an extremely useful technique for elucidating the atomic structure of heterophase interfaces in ceramic materials, but HREM has typically been used to image lattice planes along only one zone axis. Often, however, it is useful to obtain three-dimensional information about the interface in order to fully appreciate and understand the complete relaxation and structure of the interface. Directionally solidified eutectics (DSEs) offer a unique opportunity to study heterophase interfaces in three dimensions, because they contain numerous, identical interfaces with consistent crystallographic orientation relationships between the two phases. Of particular interest are those eutectics that have lamellar morphologies, because the planar interfaces may be viewed along two orthogonal directions (Fig.l).