Regensburg 2025 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 26: Topical Session: Thermophysical Properties of Bulk Metallic Glasses and Bulk Metallic Glass-forming Liquids
MM 26.6: Vortrag
Donnerstag, 20. März 2025, 11:30–11:45, H10
Temperature dependence of cooperativ fluctuations in supercooled glass-forming metallic melts — •Jürgen Schawe1, Min Kyung Kwak2, Mihai Stoica1, Eun Soo Park2, and Jörg Löffler1 — 1ETH Zürich, Laboratory of Metal Physics and Technology, Zurich, Switzerland — 2Seoul National University, Department of Materials Science and Engineering, Seoul, Republic of Korea
The behavior of a supercooled glass-forming metal alloy depends on the cooperative atomic fluctuations caused by the dynamic heterogeneities in the melt. These spatial and temporal heterogeneities form dynamic clusters, which are regions of cooperative rearrangement (CRR). The time and temperature dependence of the CRR characterizes the α-relaxation. In this study, the correlation length ξ, characteristic of the CRR, is derived for Pt57.4Cu14.7Ni5.3P22.6 and Pd43Cu27Ni10P20 bulk metallic glasses by fast differential scanning calorimetry in a temperature range between the glass transition temperature Tg and Tg + 50K. It appears that while the composition of the alloy influences the macroscopic α-relaxation and vitrification kinetics, typically defined by Tg, 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 at Tg is about 3 nm for both metallic glasses. The temperature dependence of ξ correlates with the apparent activation energy of the α-relaxation and is the reason for their non-Arrhenius behavior.
Keywords: metallic glasses; glass transition; dynamic heterogeneities; supercooled melt; kinetics