Oxidation kinetics and mechanisms of Ni-base alloys in pressurised water reactor primary conditions: Influence of subsurface defects

International audienceOxidation of Alloy 690 in PWR primary water conditions has been investigated, considering particularly the role played by subsurface structural defects. To simulate a defective surface state, Xe implantation has been set up on samples. Corrosion experiments were thereafter performed in a corrosion loop simulating the PWR medium with durations between 24 h and 1000 h. Microstructural observations and NRA measurements underlined the role played by defects on the crystallinity of the continuous oxide spinel layer, on the nucleation of Cr2O3 nodules and on the oxidation rate. The higher defects concentration seemed to modify the oxygen diffusion in the oxide scale