Interatomic repulsion softness directly controls the fragility of supercooled metallic melts
Samwer, Konrad H
Proceedings of the National Academy of Sciences (PNAS)
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Krausser, J., Samwer, K. H., & Zaccone, A. (2015). Interatomic repulsion softness directly controls the fragility of supercooled metallic melts. Proceedings of the National Academy of Sciences (PNAS), 112 13762-13767. https://doi.org/10.1073/pnas.1503741112
We present an analytic scheme to connect the fragility and viscoelasticity of metallic glasses to the effective ion–ion interaction in the metal. This is achieved by an approximation of the short-range repulsive part of the interaction, combined with nonaffine lattice dynamics to obtain analytical expressions for the shear modulus, viscosity, and fragility in terms of the ion–ion interaction. By fitting the theoretical model to experimental data, we are able to link the steepness of the interionic repulsion to the Thomas–Fermi screened Coulomb repulsion and to the Born–Mayer valence electron overlap repulsion for various alloys. The result is a simple closed-form expression for the fragility of the supercooled liquid metal in terms of few crucial atomic-scale interaction and anharmonicity parameters. In particular, a linear relationship is found between the fragility and the energy scales of both the screened Coulomb and the electron overlap repulsions. This relationship opens up opportunities to fabricate alloys with tailored thermoelasticity and fragility by rationally tuning the chemical composition of the alloy according to general principles. The analysis presented here brings a new way of looking at the link between the outer shell electronic structure of metals and metalloids and the viscoelasticity and fragility thereof.
metallic glasses, fragility of liquids, supercooled liquids, glass transition, liquid metals
The support of the Technische Universität München Institute for Advanced Study, funded by the German Excellence Initiative and the European Union 7th Framework Programme under Grant Agreement 291763, is acknowledged.
External DOI: https://doi.org/10.1073/pnas.1503741112
This record's URL: https://www.repository.cam.ac.uk/handle/1810/252765
Attribution-NonCommercial 2.0 UK: England & Wales
Licence URL: http://creativecommons.org/licenses/by-nc/2.0/uk/
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