Dynamic Monte Carlo simulation of surface composition changes on TiC and AuCu under Ar⁺ ion bombardment

A dynamic Monte Carlo simulation code has been developed to describe the dynamic processes of surface composition changes in multi-component materials during ion bombardment. This code containing the simulations of not only the kinetic collision processes describing the preferential sputtering but also the radiation-induced segregation and radiation-enhanced diffusion. We applied it to AuCu and TiC under 2 keV Ar⁺ ion bombardment. The results have indicated that the altered layer formation in TiC is caused by the preferential sputtering of the lighter atom, while in AuCu, the above three major factors all play significant roles in the formation of an altered layer enriched with Au atoms at the topmost atomic layer followed by a depletion layer of Au approaching to the bulk composition. These calculations have described the experimental results very well.