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MM: Fachverband Metall- und Materialphysik

MM 25: Liquid and Amorphous Metals - Structure

MM 25.1: Vortrag

Dienstag, 17. März 2020, 11:45–12:00, IFW D

TEM in-situ investigation of local dynamics in amorphous alloys — •Katharina Spangenberg, Sven Hilke, Martin Peterlechner, and Gerhard Wilde — Institute of Materials Physics, University of Münster, Germany

The investigation of the amorphous atomic structure in metallic glasses (MGs) is essential for production and design of MGs as engineering materials. Unlike crystals, MGs have no long-range order, but may consist of distinct atomic structures often summarized as medium-range order (MRO). The degree and type of MRO in amorphous materials can be measured by fluctuation electron microscopy (FEM) using the evaluation of spatial fluctuations in diffraction from nanoscale volumes or intensity variations in dark field images. It has been experimentally shown that the dynamics of MGs in terms of atomic mobility are related to their mechanical properties and connect to the underlying mechanisms of plastic deformation. Therefore, spatial maps of atomic fluctuations can be evaluated to give insight into typical time and length scales of these rearrangements. In this sense, electron correlation microscopy (ECM) is able to investigate dynamics and relaxation phenomena at the atomic scale. The focus of the presented study is the atomic structure of nanostructured MGs using the techniques of ECM in TEM. The dynamics of nanostructured MGs are analysed at different temperatures. Different sample preparation routes are presented and the possibilities of in-situ sample analysis, which enables an observation of the microstructure and reactions at the atomic level upon e.g. heat or mechanical treatment, are discussed.