Elastic Fields and Dislocation Pinning in Random Alloys with Short-Range Order

Abstract We extend an elastic model of random alloys to incorporate short-range order (SRO). Both the
amplitude and spatial correlations of solute-induced displacements and stresses are expressed as
corrections to the purely random case, involving coupling terms between solute misfit volumes
and Warren–Cowley parameters. Alloys with a clustering tendency exhibit stronger fields and
more extended correlations, whereas alloys that exhibit ordering show the opposite behavior.
Line-tension dislocation dynamics simulations reveal that SRO enhances dislocation pinning
in clustering systems while it induces softening in ordering systems. However, the additional
pinning due to dislocation-induced disruption of SRO, can counteract softening. This may
explain cases like CrCoNi, where lattice distortions decrease while the critical resolved shear
stress increases, thus challenging the traditional link between SRO and strengthening.