Oxidation Behavior of As-Forged Fe-25wt%Cr Alloys at 1100°C in Air
Fe-25wt%Cr alloys were fabricated by combining Powder Metallurgy (PM) with hot-forging treatment, and their oxidation behavior at 1100°C in air was investigated systematically by using XRD, SEM and EDS, respectively. The results showed that a composite oxidation scale containing both Cr2O3 and FeCr2O4 formed on the surface of as-forged Fe-25wt%Cr alloys after oxidation at 1100°C in air for 100 hours. The oxidation process of Fe-Cr alloys could be obviously divided into two different stages, and the kinetics of two-stage oxidation agreed well with the parabolic law. The first could be corresponding to the formation of protective Cr2O3 layer, while the second could be thought as the growth of FeCr2O4 and the further oxidation of the inner Cr2O3 oxidation scale. The faster oxidation rate in the second stage could be attributed to both the diffusion of iron ions rapider than that of Cr in the Cr2O3 layer and the fast transport velocity of oxygen ions along the cracks.
Hyungsun Kim, Jian Feng Yang, Chuleol Hee Han, Somchai Thongtem and Soo Wohn Lee
H. Xie et al., "Oxidation Behavior of As-Forged Fe-25wt%Cr Alloys at 1100°C in Air", Materials Science Forum, Vol. 695, pp. 348-352, 2011