Focussed ion beam sectioning for the 3D characterisation of cracking in oxide scales formed on commercial ZIRLO™ alloys during corrosion in high temperature pressurised water

Using FIB sectioning and reconstruction techniques we have performed a quantitative analysis on the microstructure of cracks and the topography of the metal-oxide interface in oxides formed on ZIRLO (TM) alloys in high-temperature water. The most significant observation is the continuous production of cracks both before and after the transition in kinetics, not a sudden burst of crack nucleation at transition as assumed in the literature. By concluding that cracks are not generated as a result of the transition and are not the primary cause, we suggest that a process by which cracks within the scale become connected to the oxidising environment through interconnected nanoporosity may be critical in controlling the overall rate of oxidation. (C) 2011 Elsevier Ltd. All rights reserved.