Impact of varying Al concentrations on the solid solution formation of AlCoCuNiPt high-entropy alloy: a first-principles study

Abstract Much of the work on high-entropy alloys (HEA) focuses on establishing robust guidelines for designing the material. Despite these significant efforts, there’s still a need to contribute insights to understand how HEAs achieve a solid solution phase. Therefore, this study conducted first-principles investigations to examine the influence of varying Al concentrations on the preference of bulk structures of Al x CoCuNiPt, (with x ranging from 3.1% to 37.5%) to form solid solution. We have shown that increasing Al concentration reduces the tendency of Al x CoCuNiPt to form single-phase solid solution, which can be attributed to the enhanced charge transfer between Al and the other elements in the system. The increase in Al concentration also leads to significant unevenness in charge distribution, reducing the likelihood of AlCoCuNiPt forming a solid solution. A comparative analysis between Al x CoCuNiPt and Pd x CoCuNiPt underscores the critical role of comparable electronegativity among components in minimizing charge transfer and stabilizing the solid solution phase. These results highlight the potential of tuning composition to stabilize solid solutions even in systems with substantial electronegativity disparities, providing valuable insights into HEA design.