Structural stability versus instability in irradiated metallic films

By the segregation-charge transfer (SCT) atomistic model, nucleation of crystalline or amorphous phases is modelled in binary alloy films, irradiated under conditions suitable to the formation of dense collision cascades. Off-equilibrium compositional and electronic density profiles develop at the interface between each cascade and the surrounding unperturbed crystalline matrix, as a consequence of interface enrichment of one of film constituents. Local charge transfer reactions (CTR), each involving a pair of dissimilar atoms of the initial alloy, are introduced to mimic system relaxation via formation of dimers of an effective compound. The energy cost to produce one such dimer, the difference of formation enthalpy between each effective compound and the corresponding initial alloy and the local strain associated with a CTR are calculated for a set of seventeen ion-bombarded alloys, out of which ten are vitrified and seven remain crystalline. Qualitative differences are found in the parameter trends between the two groups of alloys.