Berlin 2015 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 41: Electron Microscopy
MM 41.6: Vortrag
Mittwoch, 18. März 2015, 17:00–17:15, TC 006
Comparison of medium-range order in shear bands and matrix of a metallic glass by fluctuation electron microscopy — •Vitalij Schmidt1, Harald Rösner1, Martin Peterlechner1, Paul Voyles2, and Gerhard Wilde1 — 1Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany — 2Materials Science and Engineering, University of Wisconsin-Madison, 1509 University Ave, Madison, WI53706, USA
The deformation behavior of metallic glasses is yet not fully understood. For temperatures well below the glass transition and high strains the plastic flow is restricted to narrow areas called shear bands while the surrounding amorphous matrix seems unaffected. Thus modifications of the local medium-range order (MRO) are likely to be expected in the shear bands. In order to analyze the structural modifications in shear bands directly, melt-spun and subsequently cold-rolled Al88Y7Fe5 ribbons were selected and prepared for transmission electron microscopy (TEM) by electro-polishing. The thin foils exhibit shear bands with contrast changes along their propagation direction observed by high-angle annular dark-field (HAADF)-STEM. Fluctuation electron microscopy has been used to characterize the deformed metallic glass samples by analyzing sets of nanobeam-diffraction patterns. Azimuthal profiles are extracted from the variance of these sets resulting in a measure for the MRO. Different parts of the observed shear bands are compared with the surrounding matrix showing differences in MRO with respect to the contrast changes.