Characterisation of fresh surface oxidation films formed on pure molten magnesium in different atmospheres

This paper examines the early stages of surface oxidation of liquid magnesium under argon, air, and air mixed with protective fluorine-bearing gases. Surface film characteristics such as morphology, thickness and composition are determined. In all cases except argon the film was locally uniform with no evidence of specific nuclei. In air, the film thickness was 15–150 nm. Under fluorine-bearing gas mixtures the surface film was a mixed fluoride and oxide and more even: 70–100 nm thick under SF6 and 30–50 nm under 1,1,1,2-tetrafluoroethane. The latter had a substantially lower O:F ratio. Complete conversion of available fluorine into the film was indicated. 2010 Elsevier Ltd. All rights reserved.