Berlin 2018 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 12: Topical Session (Symposium MM): Fundamentals of Fracture

MM 12.3: Vortrag

Montag, 12. März 2018, 16:30–16:45, TC 006

The brittle-ductile transition of tungsten single crystals at the micro-scale — •Johannes Ast, Jakob Schwiedrzik, Juri Wehrs, Johann Michler, and Xavier Maeder — Empa, Swiss Federal Laboratories for Materials Science and Technology, Feuerwerkerstrasse 39, 3602 Thun, Switzerland

Notched micro-cantilevers were prepared by focused ion beam (FIB) milling in a tungsten single crystal. This material has nearly perfect elastic isotropy, a limited amount of activated slip systems and detailed knowledge of the macroscopic fracture behaviour is available. The cantilevers have dimensions of 25 μm in length, 5-7 μm in thickness and crack length to thickness ratios a/w of ca. 0.4. Loading rate and temperature are known to influence the fracture behaviour decisively in bcc metals. Therefore displacement-controlled fracture tests were performed inside a scanning electron microscope in the temperature range between -90°C and 500°C. Applying the J-Integral technique to plot continuous crack resistance curves, the fracture toughness and brittle-to-ductile transition (BDT) temperatures, which depend on the applied loading rate, were determined. This allows a thorough investigation of the activation energy of the BDT at the micro-scale.