Abstract
Abstract The standard theory of cation diffusion-controlled oxidation in the scaling region (oxide film thicknesses > 10−4 cm) is extended to take account of metal lattice vacancies generated at the oxide–metal interface. The general rate law for oxide layer growth has three limiting forms. Linear kinetics obtain if there is a large energy barrier for cation transfer from metal to oxide; X∝t, where X is the film thickness and t is the oxidation time. If vacancy diffusion in the metal is slower than cation transport in the oxide, vacancy diffusion from the interface to sinks is rate-limiting and X 3∝t 2. Otherwise the oxide growth kinetics are parabolic, X 2∝t, but the rate constant is reduced for metal substrates which can support a vacancy supersaturation.
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