Analysis of Atomic-scale Free Volume in Bulk Metallic Glasses

Abstract

Research in metallic glasses is becoming popular due to their excellent material properties such as high strength, high hardness, wide elastic range, low internal friction. In these researches, the free volume of metallic glasses becomes an important research topic since it reflects the internal structure of metallic glasses which can affect both thermodynamic and mechanical behaviors. However, the main methods to probe the free volume is still mostly constrained by experimental approaches which are complicated, costly and time-consuming. Hence, computational approaches have been proposed to estimate the free volume of metallic glasses from computation rather than experiment. This paper provides a new method to compute and analyze the free volume quantitatively from atomic level by using Voronoi diagram of atoms. The unfilled space, which is the interstitial space not occupied by atoms in metallic glasses and also in the crystalline alloy with same composition, is computed by using the beta-decomposition based on the Voronoi diagram. Then, the free volume is calculated as the difference between them. We calculated the free volumes of six different kinds of metallic glasses and compared our result with the results from another method. We found that there is a reasonable difference between two results which indicates that our result is reasonable and acceptable.