Influence of crystallography on aspects of solid-solid nucleation theory
Abstract
Expressions for the major variables in the general rate equation for solid-solid nucleation were developed on the basis of various models of the critical nucleus shape during homogeneous and heterogeneous nucleation. These models are based upon spheres, but in some a facet was incorporated at one boundary orientation to represent the presence of a partially or fully coherent structure. Gibbs' relationship for the critical radius is applicable to all of the models. The other variables in the nucleation rate equation are affected by the model and by faceting. Reduction of AG* by faceting is concluded to be the primary cause for the presence of reproducible lattice orientation relationships and for the existence of transition phases during precipitation from solid solutions.