Dependence of the mechanical and structural properties of (Ti,Al)N films on the nitrogen content

(Ti,Al)N films with increasing nitrogen content were grown by reactive cosputtering and characterized by auger electron spectroscopy, grazing x-ray diffraction, polarization curves, electrochemical impedance spectroscopy, nanoindentation, and atomic force microscopy. For Ti/Al approximate to 1 the Ti1-xAlxN phase is always present, but lower nitrogen contents lead to an additional phase, probably alpha-Ti(Al), which causes a decrease in hardness and Young's modulus. The increase of nitrogen content results in a decrease of surface roughness or a more compacted surface coating, according to the impedance results.