Configurational Entropy Effects on Glass Transition in Metallic Glasses

Configurational entropy (S_conf) is known to be a key thermodynamic factor governing a glass transition process. However, this significance remains speculative because S_conf is not directly measurable. In this work, we demonstrate the role of S_conf theoretically and experimentally by a comparative study of a Zr-Ti-Cu-Ni-Be high-entropy metallic glass (HE-MG) with one of its conventional MG counterparts. It is revealed that the higher S_conf leads to a glass that is energetically more stable and structurally more ordered. This is manifested by ab initio molecular dynamics simulations, showing that ∼60% fewer atoms are agitated above T_g, and experimental results of smaller heat capacity jump, inconspicuous stiffness loss, insignificant structural change during glass transition, and a more depressed boson peak in the HE-MG than its counterpart. We accordingly propose a model to explain that a higher S_conf promotes a faster degeneracy-dependent kinetics for exploration of the potential energy landscape upon glass transition.