The effect of configurational entropy on mechanical properties of single BCC structural refractory high-entropy alloys systems

In the study of high-entropy alloys (HEAs), due to the enormous adjustment space of the content (5-35 at.%) of each principal element, the yield strength at room temperature (RT) of the alloys are basically difficult to estimate. Five kinds of Nb-Mo-Ta-W HEAs with the same component elements but in different contents were fabricated by vacuum arc melting (VAM). The crystal structures of five kinds of alloys are all single-phase solid solutions of BCC structure. The grain sizes of each alloy are about similar to 150 mu m and the substructures within the grain are typical dendritic. The calculated yield strength through solid solution strengthening (SSS) model by Senkov is in certain agreement with the experimental yield strength of five alloys. In our study, the concept of configurational entropy is brought in to optimize the model. In comparison with the calculated yield strength of original model, the variation trend curve of the optimized model was in better agreement with that in experiment. Moreover, the optimized SSS model has a certain universality to predict the mechanical properties in other refractory HEAs system with a single BCC structure composed of W, Nb, Mo, Ta, Zr, Hf, Ti, V element. This conclusion provides a theoretical basis for the design of chemical contents of BCC structural refractory HEAs systems.