Physical Properties of Grain-Boundary Materials: Comparison of EAM (Embedded-Atom-Method) and Central-Force Potentials

摘要

Three types of grain-boundary phenomena expected to be particularly sensitive functions of a local-volume dependence in the interatomic interaction potentials employed are investigated by means of many-body (embedded-atom and Finnis-Sinclair) and pair potentials. These phenomena are the zero-temperature volume expansion localized at the grain boundaries, the local elastic constants of grain-boundary materials, and their high-temperature stability. The same qualitative behavior is found in all these phenomena for both types of potentials, from which it is concluded that the local-volume dependence, incorporated in the many-body potentials only, does not have a strong effect on the predicted properties of grain-boundary materials. The reasons for these similarities are thought to arise from the fact that most grain-boundary properties are governed, as are those of liquids, by atoms in very close contact; i.e., by the short-range part of the interatomic potential which is of a central-force type in both sets of potentials. However, many-body potentials are expected to represent a given material better than pair-potentials since (1) they usually permit a larger number of adjustable parameters to be fitted to real-material properties, and (2) in contrast to equilibrium pair-potentials they do not satisfy the Cauchy relation. 34 refs., 16 figs. (ERA citation 14:019881)