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

A photoelectron spectroscopy study of the initial oxidation behaviour of the intermetallic Ti–54Al was undertaken to gain an insight into the early stages of scale formation on this material. The required experiments were performed at different substrate temperatures using various UHV precleaning processes. At ambient temperature, a rapid initial surface oxidation occurred, leading to the formation of a few monolayers of mixed oxides. No significant further changes were observed with higher oxygen load. In contrast, higher substrate temperature led to a progressive oxidation of the samples. Indications for the onset of Al2O3rTiO2 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. q2000 Elsevier Science B.V. All rights reserved