Coupling mechanism of hydrogen corrosion and oxide film fracture: A multiphase multiphysics simulation

The fracture of oxide film during hydrogen corrosion substantially undermines the integrity of metal surface, and significantly accelerates the degradation of metal. However, the mechanism and interactions underlying this phenomenon have not been comprehensively elucidated. Here, we develop a thermodynamically consistent multiphase multiphysics model that tightly integrates the descriptions of corrosion and damage, implementing a simultaneous exploration of hydrogen corrosion and its induced oxide film failure on the surface of uranium. The results indicate that the growth of hydride induces tensile stresses at the hydride-oxide interface, consequently leading to the development of a damage layer within the oxide film directly above the interface and exacerbating cracking along the oxide grain boundaries. These damages and cracks, in turn, create fast tracks for ambient hydrogen attack, significantly accelerating corrosion along the metal-oxide interface. Furthermore, the fracture stress of the oxide film positively correlates with its uplift rate resulting from the underlying hydrogen corrosion. Our model also allows to explore the effects of ambient hydrogen pressure, grain boundary equilibrium segregation and complex texture on hydrogen corrosion. The simulated corrosion morphology and multi-site fracture behavior of the oxide film are qualitatively consistent with the experimental results. The estimated corrosion front velocity aligns within the experimental range. Especially, the model approximately captures the experimentally observed 0.5-order dependence of hydrogen corrosion kinetics on pressure. The model proposed in this paper is generally applicable to the study of hydrogen corrosion coupling with oxide film fracture in any binary metal-hydrogen system.