Structure and properties of two Al–Cr–Nb–Si–Ti high-entropy nitride coatings

Two high-entropy alloy nitride films, (Al23.1Cr30.8Nb7.7Si7.7Ti30.7)N50 and (Al29.1Cr30.8Nb11.2Si7.7Ti21.2)N50, were designed and prepared by reactive magnetron sputtering. The influences of substrate bias (from − 50 V to − 150 V) on chemical composition, microstructure, and mechanical properties of the deposited films were investigated. All the films have face-centered cubic NaCl-type structure. The (Al23.1Cr30.8Nb7.7Si7.7Ti30.7)Nx films deposited at − 100 V exhibit the highest hardness of 36.1 GPa, and the (Al29.1Cr30.8Nb11.2Si7.7Ti21.2)Nx films have its maximum hardness of 36.7 GPa at a substrate bias of − 150 V. Both (Al23.1Cr30.8Nb7.7Si7.7Ti30.7)Nx and (Al29.1Cr30.8Nb11.2Si7.7Ti21.2)Nx films have outstanding oxidation resistance at 900 °C.