Corrosion of cast Stellite-3 analogue in simulated PWR conditions

Wear resistant alloys are required for deployment in pressurised water reactor primary circuits and in this context, the corrosion behaviour of a cast cobalt-based alloy following exposure for 30 days in lithiated water at 300 degrees C was investigated. Corrosion of the surface was observed, resulting in the formation of a similar to 100 nm thick chromium- and silicon-rich oxide. Preferential corrosion of the matrix at its interface with just one of the carbide types was observed to a depth of similar to 1 mu m; for the first time this was shown to be not due to any inhomogeneity in the matrix but instead to be an electrochemical effect.