A quantitative demonstration of the grain boundary diffusion mechanism for the oxidation of metals
A. Atkinson, R. I. Taylor, A.E. Hughés
Philosophical magazine. A/Philosophical magazine. A. Physics of condensed matter. Structure, defects and mechanical properties
Abstract
Abstract Below 1000°C the oxidation of nickel cannot be controlled by the diffusion of ions through the bulk crystal lattice of the pure oxide, because the measured oxidation rates are several orders of magnitude faster than would be predicted on this basis. Short-circuit diffusion through oxide grain boundaries or dislocations has usually been held responsible, but there has hitherto been no proper quantitative confirmation of this mechanism. We report measurements of the oxide scale thickness and oxide grain size as a function of time during the oxidation of high-purity nickel in the temperature range 500–800°C. All the oxidation experiments were carried out in pure oxygen at a pressure of one atmosphere. The measured parabolic oxidation rate constants have been compared with those calcu