(AlCrNiTiZr)N_x high-entropy nitride coatings with enhanced hardness via tailoring N₂ flow rates for anti-wear applications

(AlCrNiTiZr)N_x high-entropy nitride coatings with enhanced hardness are prepared by reactive magnetron cosputtering. The chemical composition, microstructure, as well as mechanical and tribological properties of the coatings are studied systematically. With N₂ flow rates from 0 to 16 SCCM, the nitrogen content of the coatings increases to 55.7 at. % and the phase structure changes from amorphous to face-centered cubic. The hardness of the coating increases, obviously, with an increase in the nitrogen content. When the nitrogen flow rate is 12 SCCM, the coating has the highest hardness of 31.77 GPa and the lowest wear rate of 1.23 × 10⁻⁵ mm³/(N m) at room temperature. The wear resistance results show that all the hardness, adhesion strength, and damage tolerance contribute to the coating’s wear resistance.