Nucleation of new solid phases from chemical interactions at an interface

Abstract

Starting from the classical theory of nucleation as applied to such transitions as liquid-solid or liquid-gas in the vicinity of an equilibrium temperature it is shown that the same theory applies to the chemical formation of a new solid phase at the interface between two interacting phases, one of which is a solid. Proceeding from the oxidation of metals, where at constant pressure there exists a finite temperature where the metal, its oxide, and oxygen are in equilibrium, one considers next eutectoid reactions which also occur in the vicinity of an equilibrium point. The common feature of these nucleation-controlled reactions is that the driving free energy change is small. It is then finally shown that this is the condition necessary for nucleation to be rate controlling, even in the absence of any equilibrium point. © 1989, American Vacuum Society. All rights reserved.