Dresden 2011 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 43: Mechanical Properties II
MM 43.3: Vortrag
Donnerstag, 17. März 2011, 18:30–18:45, IFW D
Mechanical Behaviour of Layered Nanocomposites — •Inga Knorr1, Susanne Seyffarth1, Tobias Liese1, Nicolas Cordero2, Hans-Ulrich Krebs1, and Cynthia A. Volkert1 — 1Institut für Materialphysik, Universität Göttingen — 2Centre des Matériaux, Mines Paris, Paristech
Multilayer thin films with dimensions at the nanometer scale represent a technologically important class of materials which can offer improved mechanical properties as a result of composite, interface and size effects. Here, sample series composed of polycrystalline metal and amorphous layers are investigated, with the goal of understanding the size-dependence of the layer mechanical properties as well as the deformation and failure modes of nanoscale composites. The specific samples have layer thicknesses between 5 and 300 nm and consist of Cu/Polycarbonate, Ti/amorphous ZrO2, and Cu/amorphous Pd78Si22 layers. Mechanical characterization is performed using Berkovich nanoindentation as well as micro-compression tests. Sample morphologies in the undeformed and deformed states are investigated with SEM and TEM. The three sample sets show some common trends in the mechanical behavior. For example, the metal layers show a slight increase in strength with decreasing thickness and grain size, but the effect is much weaker than expected. In addition, the samples often fail by localized shear band formation, which may be attributed to plastic strain induced weakening at the layer interfaces. Explanations for these trends as well as possible tactics for improving the mechanical performance of multilayer films will be discussed.