Chemo-elastic phase-field simulation of multi-bubble coarsening kinetics

Helium-bubble coarsening under residual stress is a critical degradation mechanism in Fe-based structural materials, yet its stress-dependent kinetics remain unquantified. Here, a chemo-elastic phase-field model coupling the Cahn–Hilliard equation with micro-elasticity is developed to investigate the Ostwald ripening of He bubbles in Fe. Residual equibiaxial compressive and tensile stresses are applied to study the kinetic evolution of bubble number density, average radius, coarsening rate, and stress-modified mobility. The results show that both higher temperature and tensile stress accelerate coarsening, producing fewer and larger bubbles, whereas compressive stress suppresses evolution kinetics by reducing the activation-volume contribution to the mobility. In the late stage, the bubble size increased with time, and the fitted coarsening-rate constant showed an Arrhenius-type temperature dependence. These findings provide a quantitative basis for predicting stress-biased He-bubble evolution and offer mechanistic guidance for the design of radiation-tolerant Fe-based alloys.