  The exceptional combination of strength and ductility in multi-component
alloys is often attributed to the interaction of dislocations with the various
solute atoms in the alloy. To study these effects on the mechanical properties
of such alloys there is a need to develop a modeling framework capable of
quantifying the effect of these solutes on the evolution of dislocation
networks. Large scale three-dimensional (3D) Discrete dislocation dynamics
(DDD) simulations can provide access to such studies but to date no relevant
approaches are available that aim for a complete representation of real alloys
with arbitrary chemical compositions. Here, we introduce a formulation of
dislocation interaction with substitutional solute atoms in fcc alloys in 3D
DDD simulations that accounts for solute strengthening induced by atomic misfit
as well as fluctuations in the cross-slip activation energy. Using this model,
we show that local fluctuations in the chemical composition of various
CrFeCoNi-based multi-principal element alloys (MPEA) lead to sluggish
dislocation motion, frequent cross-slip and alignment of dislocations with
solute aggregation features, explaining experimental observations related to
mechanical behavior and dislocation activity. It is also demonstrated, that
this behavior observed for certain MPEAs cannot be reproduced by assuming a
perfect solid solution. The developed method also provides a basis for further
investigations of dislocation plasticity in any real arbitrary fcc alloy with
substitutional solutes.
