Abstract
When a film of a binary metallic alloy is bombarded by ions under conditions favourable to the development of dense collision cascades, it explores kinetic and thermodynamic regions not accessible by other techniques. In this work the main characteristics of the atomistic segregation-charge transfer model, for interpreting phase nucleation under irradiation, are outlined. A local non-equilibrium com-positional profile evolves at the interface between each single cascade and the crystalline matrix driven by the preferential migration to the interface of one of the film constituents. Concurrently, a charge density profile evolves, which can be non-equilibrium over the timescale for cascade quenching. Relaxation to (meta)stable eauilibrium is simulated by a charge transfer reaction, involving a couple of dissimilar atoms of the original alloy, which are ionized and form a dimer of an effective alloy. The model is used to evaluate both the amount of energy required to introduce an effective alloy dimer into the matrix and the local strain suffered by the target as a consequence of ion formation by a charge transfer reaction. Both structure stability parameter threshold values are found for a set of seven amorphized and five crystalline alloys under ion bombardment and they make it possible to separate crystalline from vitrified alloys.