Air Oxidation of a Ni 53 Nb 20 Ti 10 Zr 8 Co 6 Cu 3 Glassy Alloy at 400–550 °C

Air-oxidation behavior of a Ni 53 Nb 20 Ti 10 Zr 8 Co 6 Cu 3 amorphous ribbon was studied at 400–550 °C. The oxidation kinetics of the amorphous alloy followed a two-stage parabolic rate law with its oxidation rates steadily increasing with temperature. The steady-state oxidation rate constants of the alloy were faster than those of pure Ni. Triplex scales formed on the glassy alloy, containing an outer layer of NiO. The scales formed in the intermediate layer consisted of Nb 2 O 5 , NiO, and uncorroded α-Ni, while an additional Nb 2 Zr 6 O 17 phase was also detected in the inner layer. The formation of multilayered scales is responsible for the faster oxidation for the Ni6-AR.