| Summary: | Oxidation resistance of the ferritic Fe-Cr-W-Zr alloy with dispersed Fe<sub>2</sub>Zr phase were investigated in stagnant air and in static oxygen-saturated liquid Pb-Bi eutectic separately considering the service environment in the advanced generation IV nuclear reactors. A duplex structure including an outer Fe<sub>2</sub>O<sub>3</sub> layer and an inner (Fe,Cr,Zr)<sub>2</sub>O<sub>3</sub> layer is developed after oxidation in air, while a three-layered structure consisting of outer magnetite layer, inner Fe-Cr spinel layer, and internal oxidation zone is formed after oxidation in liquid Pb-Bi eutectic. The dispersed Fe<sub>2</sub>Zr phase shows delayed oxidation with respect to the α-Fe in air and in liquid Pb-Bi eutectic, which significantly affects the oxidation behaviors of the alloy. After oxidation in air at 923 K, the incorporated Fe<sub>2</sub>Zr phase in the scale would obstruct the diffusion of metal/oxygen across the scale, resulting in the nonuniform oxidation behavior. After oxidation in static oxygen-saturated liquid Pb-Bi eutectic at 823 K, a reduction in the Fe supply to the magnetite/Fe-Cr spinel interface is present adjacent to the Fe<sub>2</sub>Zr phase, which might lead to the creation of cavities in the outer magnetite layer with prolonged oxidation time.
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