Berlin 2008 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 29: Mechanical Properties I
MM 29.3: Vortrag
Mittwoch, 27. Februar 2008, 14:30–14:45, H 0111
Determination of intrinsic stresses in thin films by nanoindentation — •Olena Chukhrai1, Andre Clausner1, Norbert Schwarzer2, and Frank Richter1 — 1Chemnitz University of Technology, Institute of Physics, Chemnitz, Germany — 2SIO - Saxonian Institute of Surface Mechanics, Eilenburg, Germany
Intrinsic stresses often occur in thin films as a result of the complex formation of the thin film structure. Therefore, simultaneous determination of intrinsic stress and yield strength are necessary. It was shown [1], that intrinsic stresses can be derived from nanoindentation data by combination of "pure normal" and mixed (normal and tangential) loading, in particular, when the concept of the "effectively shaped indenter" is used. A device for creation of biaxial stress in the samples which can be used together with our nanoindentation setup (UNAT, Asmec GmbH) was constructed, tested and utilized for the investigation of a highly elastic Ni/Ti alloy. We found that for the NiTinol hardness changed by more than 70% when the stress was varied between 0 and 0.9 GPa. Using our theoretical concept [1], the intentionally introduced biaxial stress could be taken into account and the yield strength could be determined. The next step was to apply for the samples with known biaxial stress a combination of "pure normal" and mixed loading with pointed indenter and to determine the intrinsic stress and the yield stress using our theory. The feasibility of the concept of simultaneous determination of intrinsic stresses and yield strength by nanoindentation was shown and it can now be used.
[1] Schwarzer N.: http://archiv.tu-chemnitz.de/pub/2006/0018/index.html