Oxidation behavior of sputter-deposited Ti–Ni thin films at elevated temperatures

The isothermal oxidation kinetics of sputter-deposited equiatomic Ti–Ni thin films in pure oxygen from 823 to 923 K is studied using thermo-gravimetric analysis. The structure, composition-depth distribution and surface morphology of oxidized Ti–Ni thin films are investigated by X-ray diffraction (XRD), Auger electron spectroscopy (AES) and atomic force microscope (AFM), respectively. The results show that the oxidation kinetics of Ti–Ni thin films obeys a near-parabolic law. TiO2, TiNi3 and parent B2 phase are the compositions of oxidized Ti–Ni thin films. A double-layered scale including the outermost layer and the Ni-rich layer is formed outside the B2 matrix of oxidized Ti–Ni thin films. Moreover, thermal oxidation induces a surface smoothening of Ti–Ni thin films and surface roughness of oxidized Ti–Ni films decreases with the increasing oxidation temperature.