CHEMISORPTION INDUCED SURFACE SEGREGATION IN Cu-Ni ALLOYS

Surface segregation in Cu-Ni alloys, induced by ambient gases, has been studied using the time-of-flight atom-probe and Auger Electron Spectroscope. The study was made on the basis of the recent result that Ni atoms segregate to the surface in the Ni solute (below 16at.% Ni) alloys. Annealing in CO and O2 caused enhancement of Ni segregation but the degree of Ni enrichment depended on the bulk composition of the specimens. In the case of O2, the initial oxidation process was also investigated using the Ni solute alloys