Dependence of surface composition of ZrNi intermetallic compounds on their bulk composition and heat treatment

Abstract

AbstractX‐ray photoelectron spectroscopy (ESCA) was used to study the dependence of Zr2Ni, ZrNi and ZrNi5 intermetallic compound surface compositions upon duration of heating in air at 200 °C. The changes in relative intensities of Zr 3d, Ni 3p and Ni 2p lines in the course of ion sputtering and their dependences on take‐off angle of photoelectrons were measured. The post‐oxidation surface composition was: Ni (NiO) in the uppermost layer, its content increased with the time of heating. The following layer was enriched with ZrO2. The minimum of Ni/Zr atomic ratio was observed for 10–40 Å depth, depending on intermetallic compound composition and heating time. The next layer was enriched with Ni and for 1000–1600 Å depth the stoichiometric bulk composition was attained. The formation of a Ni rich layer over ZrO2 is explained by Ni diffusion through the oxide film.