It was pointed out that, when a binary metallic alloy film was bombarded with ions under conditions which were favourable to the development of dense collision cascades, it entered kinetic and thermodynamic regions which were not accessible by using other techniques. The main characteristics of the atomistic segregation-charge transfer model for interpreting phase nucleation under irradiation were outlined here. A local non-equilibrium compositional profile evolved at the interface, between each single cascade and the crystalline matrix; driven by preferential migration to the interface of one of the film constituents. At the same time, a charge density profile evolved which could be non-equilibrium over the time-scale of cascade quenching. The relaxation to metastable equilibrium was simulated by assuming a charge-transfer reaction which involved a couple of dissimilar atoms of the original alloy that were ionised and formed, in effect, a dimer of alloy. The model was used to evaluate the amount of energy which was required to introduce an effective alloy dimer into the matrix, and the local strain which was suffered by the target as a result of ion formation via a charge-transfer reaction. Threshold values of both structure-stability parameters were found for a set of 7 amorphized and 5 crystalline alloys under ion bombardment. These made it possible to distinguish crystalline and vitreous alloys.

Modelling Structural Stability under Irradiation. P.M.Ossi: Philosophical Magazine B, 1999, 79[11-12], 2129-36