Effects of nitrogen on the passivity of Fe-20Cr alloy

Abstract

Influences of nitrogen on the passivity of Fe-20Cr-(0, 1.1)N alloys were examined by in situ electrochemical techniques. Nitrogen was incorporated in the form of (Fe, Cr)-nitrides in the passive film, and Cr was enriched in the film of the alloy with nitrogen. Photocurrent analysis demonstrated that the structure of passive film formed on Fe-20Cr-1.1N alloy is Cr-substituted gamma-Fe2O3 with (Fe, Cr)-nitrides. Mott-Schottky analysis revealed that the film formed on Fe-20Cr-1.1N contained higher Cr6+ and lower Cr3+ vacancy concentrations compared with that on Fe-20Cr alloy. All of these results were associated with the enhanced protectiveness of the film on Fe-20Cr-1.1N. (c) 2008 Elsevier Ltd. All rights reserved.