A remarkable inversion of oxidation rate and unique oxide morphology of Cu60Zr40 metallic glass at 100–300 °C

Liu C.; Liu B.; Wang Z.; Wilde G.; Qiao Y.; Ye F.

Abstract

The oxidation of the Cu60Zr40 metallic glass in air was investigated over the temperature range of 100–300 °C, and a complex, non-monotonic oxidation behavior was observed. Particularly, the sample oxidized at 250 °C possessed the slowest oxidation rate given the fact of the thinnest oxides layer, indicating an inversion of the oxidation rate as function of oxidation temperature. This unique behavior is accompanied by topography change of the oxides on the surface and transition of the oxidation kinetics between parabolic and linear growth models. A large density of alternatively distributed zirconium oxide and metallic Cu-enriched sublayers formed at T ≤ 200 °C, while the amorphous zirconium oxide layer transferred to a stable crystalline state at T > 250 °C. The accelerating effect of the segregated Cu layers aligning with the poor protection capacity of the crystalline zirconium oxide should be responsible for the remarkable inversion of the oxidation rate of this glassy alloy.