Berlin 2012 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 34: Topical Session Bulk Nanostrucured Materials VII - Mechanical Properties II

MM 34.2: Talk

Wednesday, March 28, 2012, 12:00–12:15, H 0107

Fatigue and crack propagation in SPD Cu with regard to microstructural stability — •Jelena Horky, Golta Khatibi, Brigitte Weiss, and Michael Zehetbauer — Physics of Nanostructured Materials, Faculty of Physics, University of Vienna, 1090 Wien, Austria

For broad commercial applications of SPD nanomaterials not only enhancements in strength and ductility but also in fatigue and crack propagation are important. Therefore, this work aimed to investigate these properties in HPT (High Pressure Torsion)-processed Cu of two different purities. Besides high cycle fatigue (HCF), the main focus was laid on crack propagation. In case of cyclic loading, not only the thermal stability of HPT Cu but also its microstructural one is highly affected by the purity. Concerning high cycle fatigue, the reduced stability of a homogeneously nanostructured high purity Cu leads to grain coarsening and deteriorated fatigue strength. However, in case of very small load amplitudes and the presence of a crack, grain coarsening leads to retardation of crack growth, in contrast to a bimodally structured high purity Cu which shows a stable microstructure during crack propagation. Moreover, low purity HPT Cu which shows no grain coarsening during HCF, coarsens in the vicinity of a growing fatigue crack, indicating that crack propagation rates are determined by various, partly interdependent factors like purity, grain size, initial strength of the material and thermal stability of the microstructure.

The work has been supported by the Austrian Science Fund, under Project No. S10403.