Regensburg 2013 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 53: Topical Session: Fundamentals of Fracture - Novel Experimental Techniques II

MM 53.1: Talk

Thursday, March 14, 2013, 11:45–12:00, H4

Investigation of the fracture behavior of Tungsten at the micro scale — •Nicola Julia Schmitt¹, Christoph Bohnert^{1, 2}, Christoph Eberl¹, Oliver Kraft¹, and Sabine Maria Weygand² — ¹Institute for Applied Materials, Karlsruhe Institute of Technology, 76344 Eggenstein-Leopoldshafen (Germany) — ²Department of Mechanical Engineering and Mechatronics, Karlsruhe University of Applied Sciences, 76133 Karlsruhe (Germany)

Tungsten promises great potential as structural material in power generation due to its high melting point. One challenge however, is to deal with its ductile-to-brittle transition far above room temperature which limits its application. Studies at the macro scale have shown that microstructural characteristics have a big influence on the fracture toughness of tungsten. Moreover, it was shown that tungsten can be fairly ductile at small scale for sample sizes below 100 µm. To deepen the insight into the underlying fracture mechanisms, tests are carried out at the micro scale, which are supported by finite element simulations.

To investigate the influence of the crystal orientation and grain boundaries two different types of beams were tested, namely single crystal microbeams with different orientations and bi-crystalline microbeams with varied grain boundary orientations. The micro bending beams with 30 µm in width and 200 µm in length have been fabricated and notched by a combined method of micro-electro-discharging machining and focused ion beam. Fracture experiments are conducted by using a nanoindentation system. First results indicate that fracture is rather brittle when the notch is aligned an expected cleavage plane.