The oxidation behavior of an Fe61B15Zr8Mo7Co5Y2Cr2 bulk metallic glass at 650°C in various oxygen-containing environments

The oxidation behavior of an Fe 61 B 15 Zr 8 Mo 7 Co 5 Y 2 Cr 2 bulk metallic glass (Fe7-BMG) was investigated in three oxygen-containing atmospheres over the oxygen partial pressure range of 10 3 –10 5 Pa at 650 °C. The oxidation kinetics of the Fe7-BMG followed the parabolic rate law in all cases, indicating that solid-state diffusion is the rate-controlling step during oxidation. The oxidation rate constants ( k p values) increased with increasing oxygen partial pressure, implying a typical scaling behavior with a p-type semiconductivity. Duplex scales formed on the Fe7-BMG consisted of an outer layer of mostly iron oxides (Fe 2 O 3 /Fe 3 O 4 ) and minor amounts of B 2 O 3 , and a heterophasic inner layer of mostly tetragonal-ZrO 2 (t-ZrO 2 ) intermixed with non-oxidized intermetallic phases.