Oxidation behavior of the (Cu78Y22)98Al2 bulk metallic glass containing Cu5Y-particle composite at 400–600 °C

The oxidation behavior of the (Cu78Y22)98Al2 bulk metallic glass containing ∼55% Cu5Y particles (CYA-composite) was studied over the temperature range of 400–600 °C in dry air. The results generally showed that the oxidation kinetics of the composite obeyed a two-stage parabolic-rate law, with its steady-state parabolic-rate constants (kp values) increased with temperature. In addition, the oxidation rates of the composite were significantly lower than those of the polycrystalline Cu–20%Y alloy. The scales formed on the composite consisted mostly of hexagonal-Y2O3 (h-Y2O3) and minor CuO, while significant amounts of Cu2O and CuO, with minor amounts of Y2O3 were detected for the Cu–20%Y alloy. It was found that the absence of Cu2O is responsible for the slower oxidation rates of CYA-composite.