INITIAL-STAGES OF OXIDATION OF THE NI3AL ALLOY - A STUDY BY X-RAY PHOTOELECTRON-SPECTROSCOPY AND LOW-ENERGY HE+ SCATTERING

The oxidation of the Ni3Al alloy at low oxygen pressure was studied by low energy He+ scattering and X-ray photoelectron spectroscopy. For exposures up to approximately 10 L of oxygen at 900 K the formation of A12O3 was observed. From a simulation of the relation of XPS and LEISS data for different mechanisms of growth of the oxide overlayer, we show that a linear relation of the LEISS signal to the XPS signal is expected if the layer grows forming islands of uniform thickness. The experimental results indicate that the thickness of the A12O3 islands is indeed uniform up to the completion of the monolayer. The thickness of the layer was found to be approximately 5 Å from an analysis of the XPS results. © 1990.