Non-equilibrium Solute Capture in Passivating Oxide Films

TL;DR

This paper investigates the formation of non-equilibrium oxide phases during metal oxidation, combining experimental and theoretical approaches to predict solute capture at moving interfaces, which challenges traditional equilibrium models.

Contribution

It introduces a scientific framework for understanding and predicting non-equilibrium oxide phases formed during oxidation processes, expanding beyond classical equilibrium assumptions.

Findings

Experimental evidence of non-equilibrium oxide phases

Theoretical model predicting solute capture at interfaces

Implications for various electrochemical processes

Abstract

If all humans vanished tomorrow, almost every metal structure would collapse within a century or less, the metal converting to an oxide. In applications ranging from the mature technology of nuts and bolts to high technology batteries, nuclear fuels and turbine engines, protective oxide films are critical to limiting oxidation. To date models of these oxide films have assumed that they form thermodynamic equilibrium stable or metastable phases doped within thermodynamic solubility limits. Here we demonstrate experimentally and theoretically the formation of unusual non-equilibrium oxide phases, that can be predicted using a scientific framework for solute capture at a moving oxide/substrate interface. The theory shows that solute capture is likely a generic process for many electrochemical processes, and suggests that similar phenomena yielding non-equilibrium phases can occur and be predicted for a wide range of other processes involving solid-fluid and solid-solid chemical reactions.