Application of TEM and SNMS in the study of thermally grown alumina scales

Abstract

The oxidation behaviour of several alumina-forming alloys containing reactive elements was investigated at 1100°C in air under atmospheric pressure. Analytical techniques were applied to characterise the corrosion products and to understand the role of reactive elements on the alumina scale growth. Secondary neutral mass spectrometry was used to determine the in-depth compositional profile of the element composing the oxide scale, as well as the oxygen isotope, after sequential oxidation experiments using ¹⁶O₂ and ¹⁸O₂ enriched environments. Transmission electron microscopy revealed the microstructure of the oxide scale and located the reactive elements within the Al₂O₃ scale or at the metal–oxide interface. The combination of both techniques led to a better understanding of the oxide scale growth mechanism.