Ion Beam Mixing

Abstract

Ion beam mixing is a new method which combines vapour deposition of thin layers and their subsequent bombardment using an inert-gas heavy-ion beam. The collision cascades induce intermixing between deposited layers and also with the substrate material. This method is capable of producing many alloy phases with no limitation of the alloy composition. The basic mechanisms of ion mixing have been extensively studied in recent years. Originally most of the attention has been focused on ballistic effects or radiation enhanced diffusion. However, it is now accepted that in the low or intermediate temperature range, where ion mixing is generally made, thermal spike mixing is the dominant mechanism and that chemical effects play an important role in phase formation. The different mechanisms of ion mixing will be presented and the main models reviewed and compared with experimental results. Of great interest is the formation of metastable or new alloys which could not be formed by conventional techniques. Typical examples of new metastable crystalline, quasi-crystalline or amorphous phase will be also presented.