Reaction–Diffusion–Stress Coupling Effect in Inelastic Oxide Scale During Oxidation

Abstract

Stress is induced in a thermally grown oxide scale during high-temperature oxidation. Under certain conditions, the oxidation causes plastic deformation. An inhomogeneous growth strain formulation is proposed based on evolution equations. Using the inhomogeneous growth strain, a reaction–diffusion–stress coupling elastic–plastic model, which accounts for factors, such as the chemical reaction, kinetics of the oxide scale and diffusion of reactant species, is developed for the analysis of stress and effects of stress on these factors in the oxide scale during high-temperature oxidation. Numerical results reveal large compressive stresses and a significant stress gradient in the oxide scale with the largest compressive stress at the oxide/substrate interface and the lowest compressive stress at the oxygen/oxide interface, which is consistent with experimental observations. The stress developed in the oxide scale has an influence on the oxidation reaction rate and distribution of the reactant species concentration, which in return affects the stress distribution.