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

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.