Berlin 2015 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 4: Liquid and Amorphous Metals I: Fragility and Dynamics of Metallic Glasses

MM 4.4: Vortrag

Montag, 16. März 2015, 11:00–11:15, H 0107

Interatomic Repulsion Controls the Fragility of Supercooled Metallic Melts — •Johannes Krausser and Alessio Zaccone — Department of Physics, Technische Universität München, 85748 Garching, Germany

We present an analytic scheme to connect the fragility and glass-forming properties of metallic glasses to the pseudopotential between ionic cores in the metal. This is achieved by a suitable approximation of the repulsive part of the interaction and by using non-affine lattice dynamics to obtain analytical expressions for the shear modulus, viscosity, and fragility in terms of the pseudopotential. Employing a one-parameter fit to experimental data for various alloys, we were 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 (due to Pauli exclusion). This leads, for the first time, to a simple closed-form expression for the fragility of the supercooled liquid metal in terms of atomic-scale interaction parameters. In particular, a relationship of linear proportionality is found between the fragility and the energy scales of both the screened Coulomb repulsion and the valence electron repulsion due to Pauli exclusion. The new fundamental law that we discovered opens up opportunities to fabricate alloys with tailored thermo-elastic and glass-forming properties by tuning the interatomic interaction parameters via the electronic structure and chemical composition of the alloy.