Utilizing potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS), the passive films properties of alloy C in borax solutions under open circuit potential condition were evaluated. The potentiodynamic polarization curves suggested that alloy C showed excellent passive behavior in borax solutions. The capacitance versus potential curves revealed that the passive films displayed p-type semiconductive characteristics, where the Ni(II) vacancies preponderated over the oxygen vacancies and interstitials. The EIS data showed that the equivalent circuit Rs[(RfsQfs)(Rf Qf )(Rmf Qmf )] by three time constants is applicable. These results also revealed that the measured value of polarization resistance increases with decreasing concentration of borax solutions.
