Understanding adhesion at as-deposited interfaces from ab initio thermodynamics of deposition growth: thin-film alumina on titanium carbide

TL;DR

This paper extends an ab initio thermodynamics method to predict the composition and adhesion of thin-film alumina on TiC, resolving previous discrepancies between equilibrium predictions and experimental observations by accounting for nonequilibrium deposition conditions.

Contribution

The study introduces an extended AIT-DG method that incorporates nonequilibrium effects to accurately predict interface adhesion and composition in thin-film deposition.

Findings

The extended AIT-DG method predicts strong adhesion at the alumina/TiC interface.

Inclusion of nonequilibrium conditions significantly alters interface composition predictions.

The method aligns theoretical predictions with experimental observations of adhesion.

Abstract

We investigate the chemical composition and adhesion of chemical vapour deposited thin-film alumina on TiC using and extending a recently proposed nonequilibrium method of ab initio thermodynamics of deposition growth (AIT-DG) [Rohrer J and Hyldgaard P 2010 Phys. Rev. B 82 045415]. A previous study of this system [Rohrer J, Ruberto C and Hyldgaard P 2010 J. Phys.: Condens. Matter 22 015004] found that use of equilibrium thermodynamics leads to predictions of a non-binding TiC/alumina interface, despite the industrial use as a wear-resistant coating. This discrepancy between equilibrium theory and experiment is resolved by the AIT-DG method which predicts interfaces with strong adhesion. The AIT-DG method combines density functional theory calculations, rate-equation modelling of the pressure evolution of the deposition environment and thermochemical data. The AIT-DG method was previously used to predict prevalent terminations of growing or as-deposited surfaces of binary materials. Here we extent the method to predict surface and interface compositions of growing or as-deposited thin films on a substrate and find that inclusion of the nonequilibrium deposition environment has important implications for the nature of buried interfaces.