Dresden 2014 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 23: Electron Microscopy I - Nanomaterials
MM 23.4: Talk
Tuesday, April 1, 2014, 11:00–11:15, IFW D
Characteristics of shear bands in metallic glasses investigated by analytical TEM — •Vitalij Schmidt, Harald Rösner, Martin Peterlechner, and Gerhard Wilde — Institut für Materialphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Str. 10, 48149 Münster
In metallic glasses the entire deformation flow is restricted to narrow regions called shear bands. They are associated with a structural change compared to the surrounding matrix due to local distortion, most likely resulting in enhanced free volume. Therefore deformation properties of metallic glasses are determined by shear band characteristics which are a current object of research.
We present investigations of shear bands with a new approach that combines high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) with electron energy loss spectroscopy (EELS) and energy dispersive x-ray (EDX) analysis. It is thereby possible to correlate dark-field intensity and local density by Δ ρ = ISB − IM/IM, where Δ ρ is the difference in density, ISB and IM are the HAADF intensities of the shear band and the matrix, respectively.
Cold-rolled Al88Y7Fe5 melt-spun ribbons show shear bands having frequent contrast changes. Density measurements approve a continuous variation throughout the band*s length implying different propagation velocities within the bright and dark parts.