XPS Analysis of Ti6Al4V Oxidation Under UHV Conditions

Oxidation of Ti6Al4V is studied by X-ray photoelectron spectroscopy (XPS). Oxide layer growth was monitored on the Ti6Al4V surface for 24 hours. The surface was previously etched with Ar+ ions under ultra-high vacuum conditions. XPS spectra show that TiO and Ti2O3, together with Al2O3, were the earliest oxides formed. Vanadium, despite being detected in its elementary form in the bulk, was not found in any of its oxidized states. TiO2, directly related to the good performance of Ti6Al4V for biomedical applications, did not contribute significantly to the passive layer at the beginning; nevertheless, it was identified after the oxidation process progressed to a more advanced stage. This behavior indicates that reoxidation of Ti6Al4V permits auto-healing of its passive layer, with the presence of TiO2, even in conditions of low oxygen availability.