In traditional body-centered cubic (bcc) metals, the core properties of screw
dislocations play a critical role in plastic deformation at low temperatures.
Recently, much attention has been focused on refractory high-entropy alloys
(RHEAs), which also possess bcc crystal structures. However, unlike
face-centered cubic high-entropy alloys (HEAs), there have been far fewer
investigations on bcc HEAs, specifically on the possible effects of chemical
short-range order (SRO) in these multiple principal element alloys on
dislocation mobility. Here, using density functional theory, we investigate the
distribution of dislocation core properties in MoNbTaW RHEAs alloys, and how
they are influenced by SRO. The average values of the core energies in the RHEA
are found to be larger than those in the corresponding pure constituent bcc
metals, and are relatively insensitive to the degree of SRO. However, the
presence of SRO is shown to have a large effect on narrowing the distribution
of dislocation core energies and decreasing the spatial heterogeneity of
dislocation core energies in the RHEA. It is argued that the consequences for
the mechanical behavior of HEAs is a change in the energy landscape of the
dislocations which would likely heterogeneously inhibit their motion
