Modeling the effect of short-range order on cross-slip in an FCC solid solution

Abstract

Short-range ordering (SRO) in single-phase face-centered cubic solid solution alloys has been linked to changes in mechanical behavior that are correlated with pronounced changes in deformation microstructure. More specifically, it has been linked with the rise of localized planar slip, which is associated with a glide softening effect due to the destruction of SRO in a slip plane by lead dislocations in an array. While the glide softening effect has been well studied, what remains less clear is the effect of SRO on cross-slip. While it is apparently suppressed in the planar slip mode, the energetic factors governing this phenomenon have not been investigated in detail. In this study, cross-slip in a model Ni-10%Al alloy is studied through the use of atomistic simulations, comparing configurations with random configurational disorder and SRO. The resulting cross-slip activation barriers are found to depend not only on the overall state of SRO in the alloy, but also on the presence or absence of a diffuse anti-phase boundary in the slip plane. The results from this study demonstrate an increase in the cross-slip energy barrier due to an increase in energy per unit length of the final state for dislocations in a planar slip array, and the possibility of correlated cross-slip, and suggest also a reduction in dynamic recovery with the onset of SRO.