Screw dislocation mobility in a face-centered cubic solid solution with short-range order

The effect of short-range ordering (SRO) on screw dislocation mobility in Ni-10%Al is investigated using molecular dynamics simulations. We find that the onset of SRO results in a change of the threshold stress as well as a decrease in the damping in the regime where the dislocation velocity and shear stress are linearly related. The presence of a diffuse anti-phase boundary (DAPB), a region of broken SRO formed from dislocation slip, decreases the stress threshold for dislocation motion and does not significantly change the linear damping at the temperatures studied. The results in this study suggest that screw dislocations in concentrated face-centered cubic alloys move faster in a DAPB than in a random alloy, due to both a decrease in threshold stress and damping in the linear regime. It also highlights the importance of differentiating the effect of SRO on mobility for mesoscale modeling of dislocations in such alloys.