| Abstract Scope |
In this presentation, we investigate how chemical fluctuations and short-range order (SRO) affect dislocation motion in body-centered cubic (bcc) refractory multi-principal element alloys. We reveal a hierarchical, multilevel potential energy landscape for screw dislocation that imposes trapping forces and back stresses, hindering dislocation motion. The presence of SRO further increases energy barriers, with effects varying by mechanism. For edge dislocations, we identify a stress-dependent transition from SRO-impeded (strengthening) to SRO-enhanced (softening) motion, governed by the degree of chemical ordering and applied shear stress. Under increasing shear, SRO shows a more rapid reduction in activation enthalpy compared to random solid solutions (RSS), marking a crossover from strengthening to softening. This transition is driven by increased activation distance, which amplifies mechanical work and accelerates enthalpy decay. Lastly, we develop a neural network model to predict Peierls barriers across composition space, capturing both chemistry and structure features for accurate and efficient dislocation analysis. |