Solid solution strengthening theories of high-entropy alloys

We present a review of solid solution strengthening models for random concentrated solid solutions of which high entropy alloys are an interesting subset. High entropy alloys (HEAs) usually refer to a class of multicomponent alloys in equal or near equal concentrations. These complex compositions break the conventional notion of solutes and solvents. Few attempts have been made to extend the conventional solute strengthening models to HEAs. Among these, the model based on an average effective medium, does not include any adjustable parameter, allows all model inputs to be computed by atomistic simulations, and has predicted the strength of fcc HEAs in good agreement with experiments. The basic concepts of this theory is explained and its capabilities are compared with few other existing models for solute strengthening of HEAs.