Corrosion resistance of alloys F91 and Fe-12Cr-2Si in leadabismuth eutectic up to 715 degree C

The corrosion characteristics of alloys F91 and Fe-12Cra2Si in static leadabismuth eutectic (LBE) have been investigated at low (600-615 degree C) and high (700-715 degree C) temperatures, at oxidative and reductive oxygen potentials with respect to iron oxide formation. Very thin (100as of nm) interaction layers were observed for Fe-12Cr-2Si in both environments, while continued internal oxidation in oxidizing environments or selective liquid metal dissolution of chromium in reducing environments was observed in alloy F91. Fe-12Cr-2Si forms a protective system of Cr, Si, and Fe oxide layers upon exposure to LBE at both oxidizing and reducing oxygen potentials. The iron oxides are shown to disappear with increased exposure in LBE below the oxygen potential for Fe-oxide formation. Following this, a thin layer of more-protective silica forms beneath the chromia layer in both environments.