On Short-Range Order Strengthening and its Role in High-Entropy Alloys

Abstract

Short-range order (SRO) strengthening is one of the major strengthening mechanisms in alloys. Generally it is attributed to the the increased resistance to dislocation slip caused by breaking favorable bonds. This contribution may be strong for the first dislocation slipping in a slip plane, but it is certainly less strong for the following next dislocations. Present work discusses SRO strengthening with a different optic: with the focus on the dissipated energy due to the formation of a diffuse antiphase boundary (APB). In this sense, SRO strengthening becomes important to define the friction stress on gliding dislocations. Cluster Variation Method calculations of APB energies are used to estimate the strengthening effect in BCC alloys. The results are illustrated using VNbTaMoW and VNbTaWAl high-entropy alloys, with ab-initio derived parameters. The results show that the strengthening is intense in the range of concentrated solid solutions, and also, that this effect is strongly composition-dependent.