Oxidation Property of Y2O3 Dispersed Fe-20 mass%Cr Alloys

The high temperature oxidation mechanism of Fe-20Cr alloys with various amounts of Y2O3 dispersion was investigated by means of optical reflectance measurement together with conventional methods. Mechanically alloyed samples were cyclically oxidized at 1100 K in O2 for up to 82 cycles. The surface reflectance of oxidized samples decreased with decreasing Y2O3 content. The variation in the reflectance was much more sensitive than the mass change. The reflectance method will be useful for the study of initial oxidation. Dispersed Y2O3 is considered to retard the diffusion of alloying elements into the oxide film. The inhomogeneous distribution of Y2O3 and its insufficient dispersion generated numerous oxide nodules.