Interplay between fracture and diffusion behaviors: Modeling and phase field computation

Theoretical model and phase-field method (PFM) were developed to investigate and obtain oxygen diffusion behavior at the crack tip. The results show because of the r - 1 2 stress singularity, oxygen concentration at the crack tip has much higher singularity, i.e. e r - 1 2 . Therefore, even if the environment oxygen concentration is low, oxygen concentration at the crack tip will be sufficiently high to cause local oxidation and degradation in actual applications. We used the oxide area to evaluate the oxygen enrichment degree at the crack tip. The relation between oxide area and environment parameters such as oxygen concentration and stress intensity factor was discussed. Our study indicates that the oxygen diffusion at the crack tip affects both stress intensity factor and the fracture toughness of materials. In most situations, whether oxidation will promote or prevent crack propagation depends on the interaction of these two mechanisms.