W.-Z. Zhang
Tsinghua University School of Materials Science and Engineering, China
Title: Identification of Singular interfaces with ï€ ï„g vectors
Biography
Biography: W.-Z. Zhang
Abstract
Microstructures generated from solid state phase transformations often display a self-resemble morphology characterized with faceted interfaces of unique crystallographic orientations. Being stable in the transformation condition, the reproducible facets are likely singular interfaces, associated with singularity in the interfacial energy. This singularity is believed to be also associated with singularity in the interfacial structures. The structure of a singular interface must consist of certain kind of low energy building blocks in major area, but existence of limited defects is possible. One may identify a singular interface based on elimination of interfacial defects, either ledges or dislocations. Based on elimination of ledges, a typical singular interface is atomic flat, which is usually normal to a low index reciprocal vector, g. Based on elimination of dislocations, an ideal singular interface is free of any dislocations, but these interfaces are rare. A singular interface can be identified according to elimination of at least one type of dislocations which must exist in any vicinal interface. Such a singular interface must be normal to one or more reciprocal vectors, ï„g, connected to gï¡ and gï¢, of the two phases (ï„g = gï¡ ï€ gï¢). It is simple to elucidate the puzzling high index orientation of a facet with ï„g, since ï„g may not be parallel to any low index gï¡ or gï¢. The reason behind the ï„g approach is mainly based on the O-lattice theory. This will be explained in presentation together with examples from various materials to demonstrate the applications of this approach.