Experimental and theoretical study of tracer diffusion in a series of (CoCrFeMn)100-xNix alloys

Tracer diffusion of all constituting elements is studied at various temperatures in a series of (CoCrFeMn)(100-x)Ni-x alloys with compositions ranging from pure Ni to the equiatomic CoCrFeMnNi high-entropy alloy. At a given homologous temperature, the measured tracer diffusion coefficients change non-monotonically along the transition from pure Ni to the concentrated alloys and finally to the equiatomic CoCrFeMnNi alloy. This is explained by atomistic Monte-Carlo simulations based on a modified embedded-atom potentials, which reveal that local heterogeneities of the atomic configurations around a vacancy cause correlation effects and induce significant deviations from predictions of the random alloy model. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.