Regensburg 2010 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 29: Nanostructured Materials II

MM 29.2: Vortrag

Mittwoch, 24. März 2010, 12:15–12:30, H16

Mechanical testing of infiltrated nanoporous gold — •Eike Epler¹, Burkhard Roos¹, Marcus Jahn¹, Lorenz Holzer², and Cynthia A. Volkert¹ — ¹Institut für Materialphysik, Uni Göttingen, Germany — ²EMPA, Dübendorf, Switzerland

Recently, nanoporous (np) metal foams have attracted a lot of interest because of their unusual mechanical, electrical, chemical, and optical properties. The very high strength of np Au foams has been the topic of numerous studies and is attributed to a length scale effect, although the exact strengthening mechanisms are not known. Unfortunately, np Au also shows a very low fracture toughness, comparable to that of concrete. In our investigations, we copy nature and combine a brittle material, in this case the np foam, with a ductile material, in this case a polymer, with the goal of achieving a strong and tough composite. Open cell np gold with a relative density of 30% and ligament diameters of around 30nm has been infiltrated with two types of polymers and the elastic modulus, yield strength and fracture toughness of the composite have been measured using micro-mechanical testing methods in the nanoindenter. Results are compared to the uninfiltrated np structure and the bulk material. Additionally, it is possible to fabricate high quality SEM and TEM samples from the infiltrated material with focused ion beam machining, which was not possible in the uninfiltrated foam due to redeposition. The microscopy allows the defect content and foam morphology before and after deformation to be investigated and reveals that nano-twins play an important role in deformation.