Corrosion Behavior of FeCrAl Alloys in Static Lead-Bismuth Eutectic (Lbe) at 500 °C Under Saturated/Poor Oxygen Concentrations

The corrosion behavior of FeCr13Alx alloys (x = 3, 4, 5, 6, 7) in oxygen-poor and oxygen-saturated lead-bismuth eutectic (LBE) environments at 500 °C was investigated. A comprehensive analysis was conducted on the surface morphology, elemental composition, fibrous structure, and crystal structure of the corrosion layers at different Al concentrations. The effect of increasing Al content on the corrosion resistance of the alloy varies under saturated oxygen and controlled oxygen environments. In an oxygen-saturated environment, as the Al content increases, a thinner and denser oxide layer (mainly composed of Al2O3) forms on the corroded surface, significantly enhancing the corrosion resistance. In contrast, under oxygen-deficient conditions, an increase in Al content leads to more pronounced selective dissolution corrosion and detachment of the oxide layer on the alloy surface, resulting in higher rates of both dissolution and oxidative corrosion. In some alloys, a multi-layered oxide structure forms on the surface, composed primarily of Fe3O4, Fe(Cr, Al)2O4, and a small amount of Al2O3 particles.