  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.
