Chemical state of segregants at Al2O3/alloy interfaces studied using mu XPS

The adherence of an oxide layer that forms on alloy surfaces as a result of high temperature oxidation often depends on the composition and structure of the oxide/alloy interface. This work follows previous Auger studies on t wo Al2O3/alloy interfaces after removal of the external alumna layer in vac uum. An attempt was made to use micro X-ray photoelectron spectroscopy to e xamine the chemical state of impurities and solutes that segregated to the interface during oxidation and cooling. Both alloys were iron-based: FeCrAl and FeAl. It was found that on the FeCrAl, S was saturated along with Cr a nd C co-segregation, forming a multi-layer structure with enriched chromium sulfide at the oxide side and chromium carbide at the alloy side. On the F eAl, segregated sulfur only partially covered the interface, but was also p resent as a sulfide. The different interfacial chemistry between these two systems demonstrated the complexity that can exist under the dynamic oxidat ion conditions. (C) 2001 Elsevier Science B.V. All rights reserved.