Low and Moderate Temperature Oxidation of Atomically Clean Nickel, Chromium and Ni-Cr Alloys. Final Report

摘要

We have placed the Ni(110) crystal in the system and observed competitive surface segregation of carbon and phosphorous. After repeated sputter cleaning and heating, the surface concentrations of these segregated species was reduced. Oxygen would also react with these species at elevated temperature. The sample was reacted to form a passivating NiO layer then sputter-profiled using Ar exp + bombardment. The profiles suggest the preferential sputtering of oxygen from NiO and a transition layer of Ni-O between the NiO and Ni substrate. Our initial studies of the Ni-Cr alloys utilized a polycrystalline sample. The sample was sputter cleaned and annealed. Again surface segregation of trace impurities was observed. We also observed surface segregation of Cr from the bulk alloy. We have now formed a passivating oxide on the atomically clean surface, exposed it to atmospheric pressure gases and sputter profiled it with AES. (ERA citation 10:000886)