Change in the Local Atomic Structure of the Fe–Ni Alloy Due to Irradiation by Argon Ions

In this work, the surface of the N18 alloy was modified with argon ions in a repetitively pulsed regime. In situ electron spectroscopy methods were used to study changes in the chemical composition and local atomic structure caused by ion action on the surface. The chemical composition was determined by Auger electron spectroscopy using argon ion profiling. The analysis of the local atomic structure was carried out by the method of spectroscopy of extended thin structures of electron energy losses. The excitation spectra of the iron M_2,3-edge and the K-edge of oxygen were obtained in the geometry of backscattering from the surface. The variation in the energy of the incident electron beam made it possible to obtain a signal from the excitation of oxygen and iron atoms from the same depth. The analysis of experimental data was carried out by the method of solving the inverse problem for finding pair correlation functions using regularization according to Tikhonov. The study of the local atomic structure was carried out at profiling depths of 5, 25, and 50 nm. It is shown that the ion-modified layer within the projective range of argon ions consists mainly of iron oxides. At a profiling depth of 50 nm, the parameters of the local environment of Fe atoms are close to those of unoxidized iron. Nickel as a result of surface diffusion is found at a depth of more than 50 nm.