Entropies in Alloy Design for High-Entropy and Bulk Glassy Alloys

High-entropy (H-E) alloys, bulk metallic glasses (BMGs) and high-entropy BMGs (HE-BMGs) were statistically analyzed with the help of a database of ternary amorphous alloys. Thermodynamic quantities corresponding to heat of mixing and atomic size differences were calculated as a function of composition of the multicomponent alloys. Actual calculations were performed for configurational entropy (S-config.) in defining the H-E alloys and mismatch entropy (S-sigma) normalized with Boltzmann constant (k(B)), together with mixing enthalpy (Delta H-mix) based on Miedema's empirical model and Delta parameter (delta) as a corresponding parameter to S-sigma/k(B). The comparison between Delta H-mix-delta and Delta H-mix-root S-sigma/k(B) diagrams for the ternary amorphous alloys revealed S-sigma/k(B) similar to (delta/22)(2). The zones S, S' and B's where H-E alloys with disordered solid solutions, ordered alloys and BMGs are plotted in the Delta H-mix-delta diagram are correlated with the areas in the Delta H-mix - S-sigma/k(B) diagram. The results provide mutual understandings among H-E alloys, BMGs and HE-BMGs.