Ion-beam-induced amorphization

Ion beams are capable of inducing the formation of metastable amorphous phases in metallic systems, depending on the coupling between irradiation conditions, namely temperature, implanted species, energy and fluence, and target characteristics such as constituents, stoichiometry and structure. Experimental results obtained by the implantation technique are compared with those obtained by ion mixing, taking into account a number of systems extracted from the various classes of studied materials. Material parameters mainly of an atomistic, thermodynamic and electronic nature have been used to devise several empirical criteria and rules to explain and possibly to predict the ease of glass formation; they are examined both to find unifying concepts and to correlate these with the features of leading viewpoints on ion-beam-induced amorphization processes. An atomistic model of glass formation under irradiation, based on spike evolution and on preferential sputtering, is presented and discussed with reference to some experimental results. (orig.)