A quantitative study of the hardness of a superhard nanocrystalline titanium nitride/silicon nitride coating

The hardness of nanocrystalline two-phase TiN/a-SiNx coatings has been measured by nanoindentation. An optimum hardness is found for the coatings containing 2-5 at.% silicon. In this regime the microstructure combines mechanical confinement effects with optimum load transfer between the phases as illustrated by finite element simulations.