Interfacial effects during ion beam processing of metals

Microstructural changes of surfaces and interfaces were investigated at the atomic level by computer simulations. Molecular dynamics simulations were employed to examine the effects of self-atom bombardment of Au and Pt in the energy range 10–20 keV. It was observed that significantly more damage and atomic mixing were produced near surfaces than in corresponding recoil events in the bulk. Most damage is created by viscous flow of liquid metal onto the surface, although in some cases, micro-explosions were observed. Interfacial mixing and roughening during ion irradiation was simulated by Monte Carlo methods for multilayered structures of immiscible metals. It was observed that only few ballistic jumps relative to diffusion jumps are needed to roughen the interface, but that many more ballistic than diffusive jumps are needed to mix the layers.