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MM: Fachverband Metall- und Materialphysik
MM 4: Mechanical Properties II
MM 4.2: Vortrag
Montag, 23. März 2009, 12:00–12:15, IFW B
Evolution of Vickers hardness during room temperature grain growth of nanocrystalline Palladium — •Christian Braun1, Jörg Schmauch1, Jürgen Markmann1,2, and Rainer Birringer1 — 1Universität des Saarlandes, FR 7.3 Technische Physik, Campus D2.2, 66123 Saarbrücken — 2Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, Institut für Nanotechnologie, 76344 Eggenstein-Leopoldshafen
Indentation methods provide a fast and reliable mean to characterize plastic deformation and hardness. Based on hardness values the Tabor relation allows one also to estimate yield strength. For polycrystalline coarse grained materials the Hall-Petch equation describes the relation between materials strength and its grain size. There are many studies, theory and experiment, around that corroborate that in nanometer-sized polycrystalline materials Hall-Petch behaviour prevails. Uncovering the physics of plastic flow in bulk nanocrystalline materials requires detailed studies of the scaling behaviour of yield stress versus grain size. With the recent discovery of room temperature grain growth in nc Palladium, it becomes feasible to investigate the scaling behaviour starting out from grain sizes below 10 nm up to the micrometer scale. In this study, we report about the evolution of Vickers hardness and strain rate sensitivity of nc Palladium during room temperature grain growth.