Influence of ion energy on properties of Mg alloy thin films formed by ion beam sputter deposition

New approaches in alloy development which promise improvements include both amorphous materials and very fine-grained alloys. Due to very high cooling rates, thin film deposition is one possible route to obtain amorphous or fine-grained material. In the present contribution, the magnesium alloys AZ91, AM50, AE42 and chemically pure (cp) Mg were used as sputter targets for ion beam sputter deposition. Argon ions with an energy between 800 and 1200 eV were used for sputtering while Si(100) served as substrate material. Very dense and microcrystalline textured films were obtained. These films exhibited improved corrosion behaviour with higher polarization resistance and an extended passive region compared to the as-cast alloys. The corrosion resistance scaled with the Al content of the films, which was lower than in the used target alloys, most probably caused by a sputter angle distribution depending strongly on the specific atomic species.