Internal oxidation in dry and wet conditions for oxygen permeability of Fe–Ni alloys at 1150 and 1100 °C

摘要

The design of new austenitic alloys based on the Fe–Ni–Cr system requires knowledge of their oxygen permeability. Data are available for pure Fe and Ni but not for Fe–Ni alloys. Wagner’s model for internal oxidation is used to evaluate the oxygen permeability in Fe–Ni alloys. Internal oxidation of Fe–Ni–Cr alloys carried out at 1150 and 1100 °C in Rhines packs and H2/H2O mixtures is described. Internal oxidation produces zones of FeCr2O4 and Cr2O3 precipitates, according to parabolic kinetics. Permeabilities are deduced taking into account interfacial diffusion contributions. Oxygen permeability decreases with nickel addition in a non-ideal way, and oxygen permeability in nickel-rich alloys is independent of the studied environments. However, the oxygen permeability in iron at the highest temperature studied is increased in H2/H2O.