Experimental and theoretical study of tracer diffusion in a series of (CoCrFeMn)$_{100-x}$Ni$_x$ alloys

TL;DR

This study investigates tracer diffusion in a series of (CoCrFeMn)$_{100-x}$Ni$_x$ alloys, revealing non-monotonic diffusion behavior influenced by local atomic heterogeneities and correlation effects, supported by experiments and atomistic simulations.

Contribution

It combines experimental tracer diffusion measurements with atomistic Monte-Carlo simulations to explain diffusion anomalies in high-entropy alloys.

Findings

Tracer diffusion coefficients vary non-monotonically across compositions.

Local atomic heterogeneities cause significant deviations from random alloy predictions.

Simulation results support the influence of atomic configuration correlations on diffusion.

Abstract

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.