The Cooperativity of Atomic Fluctuations in Highly Supercooled Glass-Forming Metallic Melts

High Resolution Image Download MS PowerPoint Slide The behavior of supercooled glass-forming metals depends on the cooperative atomic fluctuations caused by dynamic heterogeneities in the melt. These spatial and temporal heterogeneities form dynamic clusters, which are regions of cooperative rearrangement (CRR). In this study, the macroscopic kinetics and the correlation length ξ, of the CRR, are derived for Pt 57.4 Cu 14.7 Ni 5.3 P 22.6 and Pd 43 Cu 27 Ni 10 P 20 metallic glass-formers by fast differential scanning calorimetry near the glass transition. While the alloy composition influences the α-relaxation and vitrification kinetics, typically defined by the glass transition, as well as the limiting temperature of the Vogel–Fulcher–Tammann–Hesse equation and the fragility index, it has no significant influence on the correlation length of the cooperative atomic motions. In agreement with many other materials, ξ is about 3 nm at the glass transition for both metallic glasses. The temperature dependence of ξ correlates with the apparent activation energy of the α-relaxation and is the reason for its non-Arrhenius behavior.