**Solute/screw dislocation interaction energy parameter for strengthening
in bcc dilute to high entropy alloys**

A Ghafarollahi and F Maresca and WA Curtin, MODELLING AND SIMULATION IN MATERIALS SCIENCE AND ENGINEERING, 27, 085011 (2019).

DOI: 10.1088/1361-651X/ab4969

Strengthening, i.e. increased stress required to move a dislocation, in
dilute or complex alloys arises from the totality of the interaction
energies between the solutes and an individual dislocation. Prevailing
theories for strengthening in bcc alloys consider only solute
interactions in the core of the screw dislocation while computations
suggest longer-range interactions. Here, a full statistical solute/screw
interaction energy parameter relevant for predicting strengthening in
random bcc alloys is presented. The parameter is valid for any number of
constituent atoms and at any concentrations, thus including the range
from dilute binary alloys to high-entropy alloys. The interaction energy
parameter is then calculated for many bcc alloys in the Nb-Ta-V-Ti-Zr
family using the Zhou-Johnson EAM potentials to demonstrate the spatial
range of solutes contributing to this key quantity and to assess
accuracy of previous simplified models. The interaction energy parameter
is found to converge if solutes out to sixth neighbors are included
while the simplified models are generally not very accurate. A recently-
proposed correlation between solute/dislocation interaction energy and
the solute/**111**/6 unstable stacking fault (USF) interaction energy is
then assessed in detail. A very good correlation is found between the
full interaction energy parameter introduced here and the solute/USF
interaction energy. This points toward a simplified approach to
estimating the interaction energy parameter using first-principles
methods.

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