Solute-strengthening in metal alloys with short-range order

Abstract

Recent surging interest in strengthening of High Entropy Alloys (HEAs) with possible chemical ordering motivates the development of new theory. Here, an existing theory for random alloys that accounts for solute-dislocation and solute–solute interactions is extended to include strengthening due to short-range order (SRO). Closed form expressions are presented for the yield strength and energy barrier of dislocation motion in alloys with SRO based on inputs of atomic misfit volumes, average lattice and elastic constants, the SRO parameters, and effective pair interactions between solutes. The theory shows both the long-established athermal strengthening effect of SRO as well as a notable effect of SRO on the misfit volume strengthening, which can increase or decrease strength. The generalized solute-strengthening theory is the most comprehensive to date that is applicable to macroscopically homogeneous single-phase alloys using inputs that can be measured, computed, or estimated.