Elasto-plastic phase field modelling of oxidation of zirconium alloys

A phase field model is proposed to study the oxidation behaviour of zirconium alloys at high temperatures. The oxidation diffusion process is described by the time-dependent Cahn-Hilliard equation, and the elasto-plastic deformation is predicted using an elastic-perfectly plastic model and the Norton power law creep equation. The corresponding finite element formulations are derived using the Galerkin approach and the Newton-Raphson iteration scheme. The phase field modelling results are validated using a one-dimensional oxidation case, and the results are in good agreement with published experimental results. Some numerical examples are carried out, and the influences of an initial rough surface and microvoids on the mechanical behaviour of the oxide layer are analysed and discussed in detail. The mechanical failure mechanisms of the protective oxide layer are discussed and compared with related experimental observations.