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MM: Fachverband Metall- und Materialphysik

MM 9: Liquid and Amorphous Metals - Brittle-to-ductile Transition

MM 9.1: Vortrag

Montag, 16. März 2020, 11:45–12:00, IFW D

Invar effect in Fe-based bulk metallic glasses — •Alexander Firlus, Robin Schäublin, Mihai Stoica, and Jörg F. Löffler — Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland

Ferromagnetic Fe-based bulk metallic glasses universally show a low coefficient of thermal expansion, which suddenly increases by a factor of ∼3 at the Curie temperature. This effect is known as Invar effect and it is usually seen in crystalline FeNi alloys. While it is clear that this is a magnetically driven effect, the physics behind it is still not understood. Up to now, the only explanations of the Invar effect are based on simulations and calculations that rely on a unit cell, but these have no base in amorphous materials. The strength of the Invar effect is particularly sensitive to the short-range order and Fe coordination. We thus aim to investigate the dynamics from the atomic scale to the macroscale for various alloys in different structural states. We correlate the structural data determined via transmission electron microscopy with studies on the magnetics to get a complete picture of the underlying mechanics of the Invar effect in Fe-based magnetic glasses.