The Study of Oxidation on TiAl Surface with Photoemission Spectroscopy in Conjunction with Synchrotron Radiation

Abstract

The oxidation processes on a TiAl surface induced by a hyperthermal O₂ molecular beam (HOMB) with a translational energy of 2.2 eV was studied by X-ray photoemission spectroscopy in conjunction with synchrotron radiation. At a surface temperature of 300 K, the simultaneous growth of Al and Ti oxides accompanied with the segregation of Al₂O₃ near the surface was observed. The efficiency of oxidation for the HOMB incidence was smaller than that for O₂ backfilling (25 meV). Furthermore, the chemical compositions of oxide species (Al₂O₃, Ti₂O₃, TiO₂) on the TiAl surface were independent of the translational energy of incident O₂ molecule. The present results suggest that the oxidation on TiAl surface proceed via precursor molecular states.