LAUSR

Abstract The oxidation behaviour of Ni 60 Nb 30 Ta 10 metallic glass in air was investigated below its glass transition temperature (665 °C). The oxidation kinetics followed two-stage parabolic rate law at 450 and 550 °C. The parabolic rate constant increased with increase in the oxidation temperature. At 450 °C, a thin amorphous oxide film consisting predominantly Nb 2 O 5 and Ta 2 O 5, with traces of NiO and Ni 2 O 3 was observed on the surface. At 550 °C, oxidation induced outward diffusion of Ni 2+ and Ni 3+ ions resulted in a thick oxide layer, containing extensive cubic NiO and monoclinic Ni 2 O 3 with traces of metallic Ni on the surface. Interestingly, at 550 °C the Nb 2 O 5 and Ta 2 O 5 oxides were completely absent on the surface of the oxidised layer.