Determination of the local environment of silicon and the microstructure of quaternary CrAl(Si)N films

Nanocomposite CrAlSiN compounds prepared by the cathodic arc evaporation technique were subjected to structural and mechanical characterization tests. X-ray diffraction, X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) were employed to investigate the effects of Si addition on the structure and phase development of the metastable NaCl structure of high aluminum CrAlN films. TEM studies revealed that partial substitution of the metal component by Si in CrAlN results in the nucleation of a wurtzite h-AlN phase even for amounts of silicon as low as ∼2–3 at.%. XAS measurements at the Cr and Si K-edges indicated that the local environment of Cr atoms is strongly affected by the Si addition, and that silicon may also be part of the crystalline phase. These results indicate the formation of complex Cr–Si–X compounds, where X can be N, Al or both, and the formation of composite nanocrystalline CrAlSiN films.