High throughput optimization of hard and tough TiN/Ni nanocomposite coatings by reactive magnetron sputter deposition

TL;DR

This study developed a high throughput combinatorial approach to optimize TiN/Ni nanocomposite coatings, revealing a specific composition range with superior mechanical properties and microstructure.

Contribution

It introduces a novel combinatorial synthesis and analysis methodology for rapidly identifying optimal TiN/Ni coating compositions with enhanced properties.

Findings

Nanocomposite microstructure forms between 8-12 at.% Ni.

Optimal microstructure improves hardness and toughness.

Higher Ni contents weaken coating integrity.

Abstract

A combinatorial thin-film synthesis approach combined with a high throughput analysis methodology was successfully applied to synthesize TiN/Ni coatings with optimum mechanical properties. The synthesis approach consists of the deposition of TiN/Ni coatings with the Ni content ranging from around 0 to 20 at.%. by reactive magnetron sputtering with a well-defined composition gradient, so that almost all possible compositions are produced in one single coating under identical conditions, removing uncertainties from processing conditions. The analysis methodology continuously screened the microstructure, residual stresses, hardness and fracture toughness of TiN/Ni coatings. The results show that a nanocomposite microstructure of equiaxed nanograins of crystalline {\delta}-TiN embedded in a Ni rich amorphous phase is formed in the composition window between 8 and 12 Ni at.%. This microstructure offers a superior combination of hardness and toughness and a simultaneous reduction of residual stresses with respect to TiN coatings grown in the same conditions. Higher Ni contents are however detrimental because they compromise the integrity of the coatings.