Regensburg 2007 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 2: SYM Micro- and Nanomechanics I

MM 2.3: Talk

Monday, March 26, 2007, 11:15–11:45, H16

Micro-Compression Testing of Metals — •Cynthia Volkert — Institut für Materialforschung II, Forschungszentrum Karlsruhe, 76021 Karsruhe, Germany

Smaller is stronger, at least for most metals. When either the sample size or grain size of a metal is decreased below one micrometer, the underlying mechanisms for deformation are changed and almost all mechanical properties, strength in particular, are influenced. The opportunity to tailor mechanical properties by changing the material length scale, and to combine this with desired electrical, magnetic or chemical properties, has been a major incentive for the development of nanostructured metals and composites for technological applications.

Recent developments in micro-mechanical testing methods using focused ion beam machining offer unique opportunities to systematically study deformation of small samples. This talk will focus on results from uniaxial compression tests on sub-micron columns of single crystal Au and nanoporous Au. The experiments confirm that smaller is stronger, with sub-micron specimen strengths close to theoretical values. In addition to high strength, the nanoporous Au exhibits macroscopic brittle behavior. Results from fracture testing of micron-sized, notched cantilever beams fabricated in nanoporous Au with a focused ion beam reveal that the material has mechanical properties similar to those of a porous ceramic. These trends will be discussed in terms of the inhibition of defect creation and motion in small volumes. Finally, an outlook of what can be achieved by tailoring length scales in various materials will be presented.