Effects of substrate temperature and post-annealing on microstructure and properties of (AlCrNbSiTiV)N coatings

AlCrNbSiTiV nitride films were deposited by reactive radio-frequency magnetron sputtering from an AlCrNbSiTiV equimolar target. Effects of substrate temperatures from 100 °C to 500 °C and post-annealing on the chemical composition, microstructure and mechanical properties of the films were investigated. Experimental results indicate that all nitride films have a single face-centered cubic (NaCl-type) structure with the stoichiometric nitride ratio approximately as Al8Cr8Nb7Si9Ti9V8N50. Increasing the substrate temperature increases the grain size and the compressive residual stress, but decreases the lattice constant. The highest hardness of (AlCrNbSiTiV)N nitride films is 41 GPa, corresponding to the super-hard grade. Even annealing in a vacuum at 900 °C for 5 h caused no notable change in the crystalline structure, lattice parameter, grain size or hardness. The super-hard level and thermal stability of these multi-component coatings are discussed.