  Linear complexions are defect phases that form in the presence of
dislocations and thus are promising for the direct control of plasticity. In
this study, atomistic simulations are used to model the effect of linear
complexions on dislocation-based mechanisms for plasticity, demonstrating
unique behaviors that differ from classical dislocation glide mechanisms.
Linear complexions impart higher resistance to the initiation and continuation
of dislocation motion when compared to solid solution strengthening in all of
the face-centered cubic alloys investigated here, with the exact strengthening
level determined by the linear complexion type. Stacking fault linear
complexions impart the most pronounced strengthening effect, as the dislocation
core is delocalized, and initiation of plastic flow requires a dislocation
nucleation event. The nanoparticle and platelet array linear complexions impart
strengthening by acting as pinning sites for the dislocations, where the
dislocations unpin one at a time through bowing mechanisms. For the
nanoparticle arrays, this event occurs even though the obstacles do not cross
the slip plane and instead only interact through modification of the
dislocation's stress field. The bowing modes observed in the current work
appear similar to traditional Orowan bowing around classical precipitates but
differ in a number of important ways depending on the complexion type. As a
whole, this study demonstrates that linear complexions are a unique tool for
microstructure engineering that can allow for the creation of alloys with new
plastic deformation mechanisms and extreme strength.
