Effect of the excess entropy on the calculated activity interaction coefficient under the Miedema model and extrapolation method

Using the Miedema model combined with an extrapolation model to calculate activity interaction coefficients between alloy components has proven to be a viable approach. However, the influence of the excess entropy term on the model's calculated values has received limited detailed examination. In this paper, we investigate how excess entropy affects the model's calculated values in various alloy solutions by incorporating the Tanaka excess entropy relation within the framework of the Miedema model coupled with the Unified Extrapolation Model (UEM). A comparison with experimental values reveals the following: (1) For systems containing gaseous elements: predictions align better with experimental data when excess entropy is not considered, except in cases involving oxygen and some non-metallic elements (C, B, N, O, S). (2) For systems with non-metallic elements (e.g., C, Si): including excess entropy significantly improves alignment with experimental values. (3) For metallic solute systems: the effect of excess entropy is minimal and can generally be disregarded.