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MM: Fachverband Metall- und Materialphysik

MM 4: Mechanical Properties I

MM 4.1: Vortrag

Montag, 26. März 2012, 10:15–10:30, H 0106

In-situ TEM mechanical testing of nanocrystalline Cu — •Matthias Funk¹, Claiare Chisholm³, Anna Castrup², Daniel Kiener⁴, Andrew Minor³, and Christoph Eberl¹ — ¹KIT, Institute for Applied Materials, Kaiserstrasse 12, 76131 Karlsruhe, Germany — ²KIT, Institute of Nanotechnology, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany — ³Department of Materials Science and Engineering, University of California, Berkeley, USA — ⁴Austrian Academy of Science, Erich Schmid Insitute of Materials Science, Jahnstrasse 12, 8700 Leoben, Austria

For nanocrystalline (nc) materials deformation seems to be governed by processes at the grain boundaries. Therefore, it is necessary to observe the microstructural changes during deformation to fully understand the mechanisms involved. In-situ TEM tensile and cycling tests were conducted on sputtered nc Cu thin films with a thickness of 60 nm. The sputtered films were transferred onto a Push-to-Pull device to test it with an in situ Picoindenter. The continuous films were milled into an hour glass shape by the use of a FIB tool with a gage width and length of roughly 3 and 4 um. Videos were taken of the single cycles in combination with micrographs at the end of each cycle. The strain of up to 9% was analyzed with digital image correlation globally over the whole sample as well as locally. The ultimate tensile strength reached 2 GPa and the Youngs modulus round about 50 GPa. During cycling, grain coarsening was observed. The high observed strength and ductility will be discussed in the light of the microstructural changes during tensile and fatigue testing and the small testing volume.