The oxidation kinetics of AMZ4 (Zr59.3Cu28.8Al10.4Nb1.5 at %) bulk metallic glass powder were investigated under both isothermal and isobaric conditions using thermogravimetric analysis (TGA) and simultaneous TGA-DSC at high temperature. The key parameters such as oxidation temperature and oxygen partial pressure (P(O2)) were systematically varied. Morphology, phase composition, and microstructure before and after oxidation were analysed using SEM, EDX, and XRD. Initially, the AMZ4 particles exhibited a spherical morphology, smooth surfaces, and an amorphous structure. After oxidation, the particles showed roughened surfaces, and oxide layer formation, with coverage depending on the oxidation environment. The oxidation conditions under isobaric condition were explored at ramp temperatures from 25°C to 650°C, and P(O2) ranging from 0.00008% to 20%. The AMZ4 powders were oxidized in isothermal and isobaric conditions at different temperature (385°C, 435°C, and 485°C) and P(O2) (0.00008%, 3%, 6.67%, and 20%) for a constant dwell time of 3 hours. An increase in P(O2) correlated with greater weight gain (∆m/mo), with the highest oxidation content observed at 20%. The results demonstrate that the oxidation kinetics of AMZ4 powder are strongly dependent on both temperature and oxygen concentration, providing insights into its high-temperature behaviour and potential thermal stability.

Keywords: Bulk metallic glass; High temperature oxidation; Thermogravimetric analysis; Powder technology