Air-oxidation of a Zr50Cu43Al7 bulk metallic glass at 400–500°C

Abstract: Air-oxidation behavior of a Zr50Cu43Al7 bulk metallic glass (ZCA7-BMG) was studied over the temperature range of 400–500°C. The oxidation kinetics of the ZCA7-BMG generally followed a multiple-stage parabolic-rate law with its steady-state parabolic-rate constants (k p values) decreasing with increasing temperature, indicative of the occurrence of kinetics inversion. The scales formed on the ZCA7-BMG were strongly dependent on temperature, consisting mostly of tetragonal ZrO2 and CuO, and minor amounts of monoclinic ZrO2 and Cu2O at 400°C, while Cu2O was completely absent at T ⩾450°C. In addition, a minor amount of Al2O3 was further observed after the oxidation at 500°C, whose formation is responsible for the lowest oxidation rate, as compared to those at T ⩽450°C. [Copyright &y& Elsevier]