Defect formation in a two-layer Al/Ni crystal bombarded with ions having energies close to the sputtering threshold

Atomic collision cascades developed in an Al/Ni system, comprising a monolayer of Al atoms on the Ni(100) single crystal face bombarded at normal incidence by 25-or 50-eV Ar and Xe atoms, were simulated by means of molecular dynamics. It is shown that the number of Al atoms relocated within the first layer of the Al/Ni crystal markedly exceeds the number of analogous relocations in a nickel single crystal, which is explained by differences in the number of vacancies in the first layer of two systems, and in the lattice constants of Al and Ni.