Oxidation and dissolution of iron in flowing lead–bismuth eutectic at 450 °C

Technically pure iron (Fe) was exposed to flowing oxygen-containing lead–bismuth eutectic (LBE) at 450 °C in the CORRIDA loop for up to 8000 h. The flow velocity and concentration of dissolved oxygen were 2 m/s and 1.1 × 10−6 mass%, respectively. The corrosion phenomena observed range from formation of a bi-layer magnetite (Fe3O4) scale, adhering well to the Fe surface, to intergranular dissolution of Fe where the adherent scale was not maintained. The characteristics of oxidation and dissolution such as oxide scale thickness and loss of cross-section of the Fe specimens were quantified using metallographic methods. The evaluation of the experimental results with respect to mechanistic and kinetic aspects shows the significance of processes at the Fe/Fe3O4 interface for the overall corrosion behaviour.

► Oxidation and dissolution of iron in lead–bismuth eutectic was assessed quantitatively.
► Formation of an adherent magnetite scale gradually changes into intergranular dissolution.
► Integrity of the oxide scale is determined by processes at the metal/oxide interface rather than magnetite dissolution or erosion.