A Chemomechanical Model for Stress Evolution and Distribution in the Viscoplastic Oxide Scale during Oxidation

Using the location-dependent growth strain, a chemomechanical model is developed for the analysis of the stress evolution and distribution in the viscoplastic oxide scale during higherature oxidation. The problem of oxidizing a semi-infinite substrate is formulated and solved. The numerical results reveal high compressive stress and significant stress gradient. The maximum stress is at the oxide/substrate interface and the minimum stress at the oxygen/oxide interface in short oxidation time, while the maximum stress is no longer at the oxide/substrate interface in long oxidation time. The stress evolutions at different locations are also presented. The predicted results agree well with the experimental data.