Separating the Role of Mixing-Entropy on the Dynamics of Glass-Forming Liquids.

While the concept of high entropy has gained prominence in materials design, disentangling specific impacts of entropy on material properties from the enthalpy of mixing remains elusive. It is demonstrated that the role of entropy can be distinguished from the dynamics of glass-forming liquids through micro-alloying. Based on experiment analysis of 79 compositions, liquid fragility is found to consistently decreases under two conditions: i) when the alloying content x is minimal, irrespective of the elements used; or ii) when increasing the diversity of alloying elements at a constant x, namely the high-entropy micro-alloying. These observations are consistent with thermodynamic principles that favor an entropy-dominated regime over enthalpy. These findings elucidate the subtle impact of mixing entropy on material properties and provide evidence of the entropy nature of glass transition.