Carbon release by selective alloying of transition metal carbides

TL;DR

This study combines theoretical calculations and experiments to show how alloying transition metals with TiC can control carbon release, enabling the design of nanocomposites with tailored properties for applications like low-friction coatings.

Contribution

It introduces a combined theoretical and experimental approach to manipulate carbon release in transition metal carbides through selective alloying.

Findings

Alloying with weak carbide-forming metals lowers carbide stability.

Alloying influences carbon distribution between carbide and matrix.

Late 3d transition metals are promising alloying elements for carbon release control.

Abstract

We have performed first principles density functional theory calculations on TiC alloyed on the Ti sublattice with 3d transition metals ranging from Sc to Zn. The theory is accompanied with experimental investigations, both as regards materials synthesis as well as characterization. Our results show that by dissolving a metal with a weak ability to form carbides, the stability of the alloy is lowered and a driving force for the release of carbon from the carbide is created. During thin film growth of a metal carbide this effect will favor the formation of a nanocomposite with carbide grains in a carbon matrix. The choice of alloying elements as well as their concentrations will affect the relative amount of carbon in the carbide and in the carbon matrix. This can be used to design the structure of nanocomposites and their physical and chemical properties. One example of applications is as low-friction coatings. Of the materials studied, we suggest the late 3d transition metals as the most promising elements for this phenomenon, at least when alloying with TiC.