Super-hard (MoSiTiVZr)Nx high-entropy nitride coatings

High-entropy nitride coatings have become a promising alternative to traditional protective coatings due to their excellent mechanical properties, thermal stability, oxidation, and wear resistance. However, the design and fabrication of hard high-entropy nitride coatings remain a great challenge. In this study, (MoSiTiVZr)Nx high-entropy nitride coatings were deposited by reactive DC magnetron sputtering at different nitrogen flow. The chemical compositions, structures, hardness, damage-tolerance, friction and corrosion resistances of the coatings were investigated. With the increase of nitrogen content in the coatings, the phase structure transforms from an amorphous structure to a single face centered cubic structure, and all alloying elements form metal-nitrogen bonds. The coating with nitrogen content of 53.7 at% exhibits an ultrahigh hardness of 45.6 GPa and the best damage-tolerance and wear resistance. The coatings with low nitrogen contents show better corrosion resistance than 304 stainless steels, however, an increase in nitrogen content results in a slight decrease in corrosion resistance. The mechanism of the structures, mechanical properties and corrosion resistance of (MoSiTiVZr)Nx coatings are discussed in details.