Deriving Metastable Pourbaix Diagrams of Stainless Steels Using Density Functional Theory Calculations

Abstract

This paper presents a novel method for deriving metastable Pourbaix diagrams of Fe-Cr alloys using Density Functional Theory calculations, with the objective of providing a more comprehensive understanding of the thermodynamic equilibria within passive films, considering the metallurgical characteristics of the alloys and the electrochemical polarization conditions. By using advanced numerical tools and optimization algorithms provided by the Materials Project Database, we have developed an approach that incorporates nonequilibrium effects as a corrective factor for the chemical equilibria observed in passive films. Our findings highlight the significant role of nucleation conditions, particularly for the Cr2O3 oxide, in stabilizing the inner layers of the passive films. Lastly, the method was used to investigate the impact of pulsed polarization conditions on AISI 304 stainless steel and proposed a reaction scheme elucidating the enhanced corrosion protective properties of the passive film.