Thermodynamic descriptors to predict oxide formation in aqueous solutions

TL;DR

This paper introduces the maximum driving force (MDF) as a thermodynamic descriptor to predict oxide formation and corrosion behavior in aqueous solutions, using DFT calculations and experimental data.

Contribution

It formulates MDF as a novel thermodynamic descriptor for predicting oxide stability across various materials and environmental conditions, including complex alloys.

Findings

MDF effectively describes corrosion trends in nickel thin films.

Depth-dependent chemical potentials improve understanding of subsurface oxidation.

The approach aids in predicting oxide formation in multielement alloys.

Abstract

We formulate the maximum driving force (MDF) parameter as a descriptor to capture the thermodynamic stability of aqueous surface scale creation over a range of environmental conditions. We use formation free energies, $\Delta_f G$s, sourced from high-throughput density functional theory (DFT) calculations and experimental databases to compute the maximum driving force for a wide variety of materials, including simple oxides, intermetallics, and alloys of varying compositions. We show how to use the MDF to describe trends in aqueous corrosion of nickel thin films determined from experimental linear-sweep-voltometry data. We also show how to account for subsurface oxidation behavior using depth-dependent effective chemical potentials. We anticipate this approach will increase overall understanding of oxide formation on chemically complex multielement alloys, where competing oxide phases can form during transient aqueous corrosion.