Regensburg 2013 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 13: Topical Session: Quasicrystals & Complex Metallic Alloys III

MM 13.7: Vortrag

Montag, 11. März 2013, 17:15–17:30, H25

Medium-range structure of Zr₅₀Cu₄₅Al₅ Bulk Metallic Glass from Fluctuation Electron Microscopy — •Paul Voyles^1,2,3, Jinwoo Hwang¹, Zenon Melgarejo¹, Irena Kalay⁴, Eren Kalay⁴, Matt Kramer⁴, and Don Stone¹ — ¹University of Wisconsin, Madison, United States — ²Forschungszentrum Jülich, Jülich — ³RWTH Aachen, Aachen — ⁴Ames Lab, Iowa, United States

By combining fluctuation electron microscopy data sensitive to medium-range order (MRO) with an empirical interatomic potential sensitive to short-range order (SRO) in a single hybrid reverse Monte Carlo structural refinement, we have found two types of structural order in Zr₅₀Cu₄₅Al₅ bulk metallic glass [1]. One structure consists of icosahedral nearest-neighbor SRO clusters, arranged in chains at the MRO length scale of  1 nm. The other structure is more crystal-like, consisting of SRO clusters with more 4- and 6-sided faces on their Voronoi polyhedra. The crystal-like SRO clusters organize into compact MRO clusters with distinct 4- and 6-fold rotational symmetry. Experimentally, structural relaxation shifts the cluster population from crystal-like to more icosahedral. In molecular dynamics, the structural models are stable under annealing at temperatures well below T_g. The structural evolution of the models through the simulated glass transition will be discussed.

[1] J. Hwang, Z. Melgarejo, Y. Kalay, I. Kalay, M. J. Kramer, D. S. Stone, P. M. Voyles, Phys. Rev. Lett. 108, 195505 (2012)