Passivity of alloy 31 in green‐death solution

Abstract

The passivation behavior of alloy 31 was investigated as a function of passivation potential in a green‐death solution at 40 °C. The alloy 31 surface is in a stable passive state during cyclic potentiodynamic polarization. In potentiostatic polarization of alloy 31, passive current density increases with an increase in the passivation potential. Electrochemical impedance spectroscopy (EIS) and Mott–Schottky (M–S) analysis showed that a more defective n‐type semiconductive passive film forms as the potential increases. X‐ray photoelectron spectroscopy (XPS) revealed that passive film consists of mainly chromium and minor iron and nickel oxides. The increase of the applied potential is considered to be a reason for the change in passive film stability.