High resolution analysis of oxidation in Ni-Fe-Cr alloys after exposure to 315°C deaerated water with added hydrogen

Alloy 600 (Ni-16Cr-9Fe) and Alloy 800 (Fe-35Ni-23Cr) were exposed to simulated primary water at 315°C. Oxidation phenomena were studied using high resolution electron microscopy. Extensive intergranular oxidation was observed in Alloy 600. In Alloy 800, only shallow intergranular oxygen penetration was detected. The mechanism of intergranular embrittlement in Alloy 600 is likely analogous to internal oxidation. Internal oxidation may not apply …