Depicting Defects in Metallic Glasses by Atomic Vibrational Entropy

Due to the chaotic structure of amorphous materials,it is challengingto identify defects in metallic glasses. Here we tackle this problemfrom a thermodynamic point of view using atomic vibrational entropy,which represents the inhomogeneity of atomic contributions to vibrationalmodes. We find that the atomic vibrational entropy is correlated tothe vibrational mean-square displacement and polyhedral volume ofatoms, revealing the critical role of vibrational entropy in bridgingdynamics, thermodynamics, and structure. On this method, the localvibrational entropy obtained by coarse-graining the atomic vibrationalentropy in space can distinguish more effectively between liquid-likeand solid-like atoms in metallic glasses and establish the correlationbetween the local vibrational entropy and the structure of metallicglasses, offering a route to predict the plastic events from localvibrational entropy. The local vibration entropy is a good indicatorof thermally activated and stress-driven plastic events, and its predictiveability is better than that of the structural indicators.

Automated summary

This study tackles the challenge of identifying defects in metallic glasses by using atomic vibrational entropy from a thermodynamic perspective. The study reveals the critical role of vibrational entropy in bridging dynamics, thermodynamics, and structure in metallic glasses. The local vibrational entropy obtained by coarse-graining the atomic vibrational entropy in space effectively distinguishes between liquid-like and solid-like atoms and establishes a correlation with the structure of metallic glasses, offering a route to predict plastic events.