Theory of oxygen tracer diffusion along grain boundaries and in the bulk in two-stage oxidation experiments. Part II: analysis of type B regime

(Received 14 September 1992, accepted 4 February 1993)

Abstract
In part I of this work a model of ¹⁸O transport in a growing oxide film with parallel grain boundaries has been proposed, and analysis of type A and type C regimes has been carried out. In this paper the analysis is extended to the intermediate, type B regime. We derive an analytical solution of the model, which describes both B and C type regimes as particular cases, and calculate tracer penetration profiles along grain boundaries depending on the drift velocity and time. The results of penetration profile analysis are presented as kinetic diagrams allowing to predict kinetic regimes of ¹⁸O transport under various conditions. We also discuss methods of profile processing for diffusion parameters determination. The analytical solutions obtained and the kinetic diagrams constructed can be used for the treatment of experimental profiles measured in two-stage oxidation experiments.