Structural and dynamic heterogeneities in Cu50Zr50 and Ni50Zr50 Metallic Glasses

Structural heterogeneity plays a key role in the dynamics and physical properties of metallic glasses. To date, there has been a lack of an effective and general parameter to describe and compare structural heterogeneity among different alloys. In this study, we introduce a new parameter, the spatial heterogeneity coefficient, to quantify the microstructural heterogeneity among metallic glasses (MGs). Using it, we investigated the microstructural heterogeneity of Cu50Zr50 and Ni50Zr50 MGs. We found that the Cu50Zr50 alloy shows higher structural heterogeneity than Ni50Zr50 across all temperatures, as observed from both five- and four-fold symmetric perspectives. Concurrently, Cu50Zr50 displays stronger dynamic heterogeneity and stronger dynamics fragility as it approaches the glass transition. These characteristics endow Cu50Zr50 with a higher GFA than Ni50Zr50 MG. This study provides a novel approach to understanding the structural heterogeneity in MGs and its impact on their dynamic behavior.