Initial oxidation of Ti-Al intermetallics: an in situ MXPS study

A photoelectron spectroscopy study of the initial oxidation behaviour of th e intermetallic Ti-54Al was undertaken to gain an insight into the early st ages of scale formation on this material. The required experiments were per formed at different substrate temperatures using various UHV precleaning pr ocesses, At ambient temperature, a rapid initial surface oxidation occurred , leading to the formation of a few monolayers of mixed oxides. No signific ant further changes were observed with higher oxygen load. In contrast, hig her substrate temperature led to a progressive oxidation of the samples. In dications for the onset of Al2O3/TiO2 alternating layered scale growth were evident. At elevated temperatures the oxidation behaviour of the samples, precleaned with either argon ion bombardment or laser irradiation, differed significantly. This observation may be of future importance in scheduling the pretreatment processes for Ti-Al-based intermetallics. (C) 2000 Elsevie r Science B.V. All rights reserved.