Structural and mechanical properties of multi-element (AlCrMoTaTiZr)Nx coatings by reactive magnetron sputtering

(AlCrMoTaTiZr)N-x high-entropy films were deposited on silicon wafer and cemented carbide substrates from a single alloy target by reactive RF magnetron sputtering under a mixed atmosphere of Ar and N-2. The effect of nitrogen flow ratio R-N on chemical composition, morphology, microstructure, and mechanical properties of the (AlCrMoTaTiZr)N-x films was investigated. Nitrogen-free alloy film had an amorphous structure, while nitride films with at least 37 at.% N exhibited a simple NaCl-type FCC (face-centered cubic) structure. Mixed structures occurred in films with lower nitrogen contents. Films with the FCC structure were thermally stable without phase decomposition at 1000 degrees C after 10 h. The (AlCrMoTaTiZr)N film deposited at R-N = 40% exhibited the highest hardness of 40.2 GPa which attains the superhard grade. The main strengthening mechanisms for this film were grain-size and solid-solution strengthening. A residual compressive stress of 1.04 GPa was small to account for the observed hardness. The nitride film was wear resistant, with a wear rate of 2.8 x 10(-6) mm(3)/N m against a loaded 100Cr6 steel ball in the sliding wear test. These high-entropy films have potential in hard coating applications. (C) 2010 Elsevier B.V. All rights reserved.