Air-Oxidation Behavior of a Cu60Hf25Ti15 Bulk Metallic Glass at 375–520 °C

The oxidation behavior of a Cu₆₀Hf₂₅Ti₁₅ bulk metallic glass was studied over the temperature range of 375–520 °C in dry air. The oxidation kinetics of the amorphous alloy generally followed the parabolic law at all temperatures, with an oxidation rate increasing with temperature. The oxidation rates of the amorphous alloy were much higher than those of polycrystalline pure-Cu, implying that the additions of Hf and Ti accelerated the oxidation reaction. The composition of the scales formed on the amorphous alloy was strongly temperature-dependent, since they consisted mostly of Cu₄O₃ and CuO with minor amounts of HfO₂ at T ≤ 450 °C, while mostly CuO with minor amounts of HfO₂ and Cu₂TiO₃ were detected at higher temperatures. In addition, nanocrystalline Cu₅₁Hf₁₄ and Cu₃Ti₂ phases were detected on the substrate after oxidation at T ≥ 450 °C, indicating the occurrence of phase transformation.