Nanocomposite Ti–B–N coatings synthesized by reactive arc evaporation

Nanocomposite Ti–B–N coatings have been prepared by reactive arc evaporation from Ti–B compound targets. The highly ionized flux of film-forming species was utilized to synthesize a promising nanocrystalline metastable supersaturated solid solution of boron in TiN at lower nitrogen fractions. The combined results from elastic recoil detection, X-ray photoelectron spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy and selected area electron diffraction indicate that the additional nitrogen incorporated at higher partial pressures triggers the formation of a separate amorphous BN matrix phase surrounding the 6–8 nm sized face-centered cubic crystallites. A maximum in the hardness is obtained for the strained TiBN crystallites surrounded by a small fraction of boron synthesized at a nitrogen fraction of 0.1, while the formation of the amorphous BN phase leads to lower values.