(Al1.5CrNb0.5Si0.5Ti)N-x high-entropy nitride coatingswere designed and investigated in this study. Nitride coatings are deposited under a sufficient amount of nitrogen at 415 degrees C on Si by direct current magnetron reactive sputtering from a non-equimolar Al1.5CrNb0.5Si0.5Ti high-entropy alloy target. The effects of substrate bias (V-s) on film structure and mechanical properties are studied. All these coatings have a single NaCl-type face-centered cubic structure and nearly stoichiometric ratio of (Al1.5CrNb0.5Si0.5Ti)(50) N-50. A distinct refinement of microstructure of the films is observedwhen V-s varies from 0 V to - 100 V. Typical columnar structure transits into a dense and featureless structure and grain size decreases from 70 nm to 5 nm. Similar refinement remains at larger bias(-150 or -200 V). At the same time, the residual compressive stress increases from near zero to -3.9 GPa at -150 V and then decreases to -3.2 GPa at -200 V. The hardness increases from 12 GPa at 0 V, peaks at 36 GPa at -100 V, and then decreases to 26 GPa at -200 V. The structural evolution strengthening mechanism are discussed and compared with equimolar high-entropy nitrides. (C) 2012 Elsevier B.V. All rights reserved.