ToF-SIMS depth profiling of alumina scales formed on a FeCrAl high-temperature alloy

The thickness and composition of thin oxide scales formed on a powder metallurgical FeCrAl alloy isothermally oxidised between 0.5 and 192 h at 900 degreesC have been investigated using time-of-flight secondary ion mass spectrometry (ToF-SIMS). The results show that the oxide scale grows according to a parabolic law during oxidation times up to 192 h. The oxide scales mainly consist of alumina, with the accumulation of Fe and Cr oxides both within the scale and at the oxide scale/metal substrate interface. Furthermore, elements such as Mg, Si, K, Ca, Ti, Mn, Ni and Zr are also found within the oxide scale which indicates that these elements may also influence the oxide scale growth rate and growth mechanisms. The results demonstrate the usefulness of ToF-SIMS analysis for characterisation of the initial stages of oxidation of FeCrAl alloys at elevated temperatures. (C) 2004 Elsevier B.V. All rights reserved.