Regensburg 2007 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 14: SYM Micro- and Nanomechanics II

MM 14.4: Talk

Tuesday, March 27, 2007, 11:30–11:45, H16

Bulge Testing of Thin Films in an Atomic Force Microscope — •Elmar W. Schweitzer and Mathias Göken — University Erlangen-Nürnberg, Department of Materials Science and Engineering, Institute of General Material Properties, Martensstraße 5, 91058 Erlangen, Germany

Bulge testing of thin membranes is a method, which allows to record stress-strain-curves of thin films without any substrate influence. Pressure is applied to one side of a free standing sample membrane and the deflection as a function of the applied pressure is recorded. Another advantage compared to nanoindentation is a better definition of the stress state in the sample which can be influenced by choosing an appropriate membrane shape.

As soon as the sample dimension reaches the order of magnitude, where physical phenomena, e.g. dislocation motion, come into play, interesting effects can be observed. For example thin metal films show an increase in strength with decreasing film thickness. Furthermore grain boundaries play a more important role, because their volume fraction increases as well.

A self designed bulge test apparatus, which can be incorporated into a Dimension 3100 AFM will be presented. The device can be operated as a standard bulge tester, i.e. pressure-deflection-data of the membrane in question can be recorded. In addition to that, topography images of the loaded membrane surface can be taken to study plasticity effects on a local scale.