The Oxidation of Fe-2 and 5 at.% Y Alloys at 600-800°C in Air

Abstract

The oxidation of Fe-Y alloys containing 2 and 5at.% Y and pure iron has been studied at 600-800°Cin air. The oxidation of pure iron follows the parabolicrate law at all temperatures. The oxidation of Fe-Y alloys at 600°C approximatelyfollows the parabolic rate law, but not at 700 and800°C, where the oxidation goes through severalstages with quite different rates. The oxide scales on Fe-2Y and Fe-5Y at 700 and 800°C arecomposed of external pure Fe oxides containingFe2O3,Fe3O4, and FeO, with FeO being themain oxide and an inner mixture of FeO andYFeO3. The scales on Fe-2Y and Fe-5Y at 600°C consist ofFe2O3,Fe3O4, andY2O3, with a minor amount of FeO.Significant internal oxidation in both Fe-Y alloysoccurred at all temperatures. The Y-containing oxidesfollow the distribution of the original intermetalliccompound phase in the alloys. The effects of Y on theoxidation of pure Fe are discussed.