An attempt to solve Andersen's puzzle in surface segregation during alloy sputtering

The paper addresses CuPt alloy sputtering by Ar ions and discusses the well-known experiment performed by Andersen et al. 25 years ago, but not yet properly explained. The atomistic (binary-encounter) simulation has been applied to extract the concentrations of surface Cu and Pt atoms from the experimental data. The results of simulations favor segregation of Cu at all bombarding energies studied experimentally (1.25-320 keV). It has been shown that some mysterious results of the experiment can be explained by a reconstruction of the surface undergoing sputtering. For forecasting purposes, the sputtering of CuPt alloy with 0.25-1 keV Ar ions is also considered.