Modification of the mechanism for stress-aided grain boundary oxidation ahead of cracks

Abstract: In this work, we consider the diffusion mechanisms for different metal elements during oxidation and extend the stress–diffusion coupled model for stress-aided grain boundary oxidation ahead of cracks (Evans et al. in Scr Mater 69:179–182, 2013) to a more general situation including both outward and inward diffusion at the crack tip during oxidation. The analyses show that the transformation stress generated due to oxide formation near the crack tip could in principle promote the growth of Cr2O3oxide at the crack tip in the intrusion direction but has no enhancement effect on NiO oxide in the extrusion direction with respect to the original position of the crack tip. Graphical abstract: [Figure not available: see fulltext.]. © 2017, Springer Science+Business Media, LLC