Oxidation mechanism of a Fe–9Cr–1Mo steel by liquid Pb–Bi eutectic alloy (Part I)

This paper is the first part of a global study on the oxidation process of a Fe–9Cr–1Mo martensitic steel (T91) in static liquid Pb–Bi. It focuses on the oxygen transport mode across the oxide scale. The oxide layer has a duplex structure composed of an internal Fe–Cr spinel layer and an external magnetite layer. Oxygen 18 tracer experiments are performed: they show that the magnetite layer grows at the Pb–Bi/ oxide interface whereas the Fe–Cr spinel layer grows at the metal/oxide interface. Oxygen seems to diffuse across the oxide scale dissolved inside nanometric lead penetrations called nano-channels. Specific experiments are performed to characterize the nano-channels.