| Abstract Scope |
In this work, we investigate how chemical fluctuations and short-range order (SRO) affect dislocation cores and energy barriers in bcc refractory multi-principal-element alloys. Compared with pure metal, chemical fluctuations produce variable, asymmetric screw core structures and nonperiodic dislocation trajectories. Local chemical environments can pre-bias the core, shifting it toward or away from the next easy-core position and thereby lowering or raising the energy barrier. These variations create a hierarchical, rugged energy landscape. 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 to SRO-enhanced 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, marking a crossover from strengthening to softening. This transition is driven by increased activation distance, which amplifies mechanical work and accelerates enthalpy decay. |