Simple Approach for Evaluating the Possibility of Sluggish Diffusion in High-Entropy Alloys

The occurrence of sluggish diffusion (SD) in high-entropy alloys (HEAs) has been investigated experimentally and theoretically during the last decade, and currently, SD as a core effect of HEAs is being questioned. In this study, we propose a simple approach for evaluating the possibility of SD in HEAs based on the theoretical framework of atomic mobility functions in conjunction with the CALPHAD-based thermodynamics. The results obtained are as follows: (1) there is no relationship between configurational entropy and SD, (2) the influence of thermodynamic and mobility interactions among atoms on SD should become weaker with an increasing number of elements, and (3) the short-range order induced from the core effect of atomic distortion in HEAs may be related to SD.