Nanoscale materials typically show highly increased strength and hardness. A common assumption is that these properties are due to the fact that nanosized crystals are statistically free of dislocations and that the nucleation stress for dislocations is very high in these materials. Nanocrystalline and nanoporous metals are model systems for experimental investigations of deformation mechanisms at the nanoscale.
Our research focuses on the preparation of nanocrystalline metals and alloys with extremely fine grain sizes (smaller than 10 nm) and on the investigation of deformation processes by means of analysis of texture and residual stresses.
This work is done in cooperation with partners of the DFG research group Plasticity of nanocrystalline metals (FOR 714).
H. Rösner, J. Markmann and J. Weissmüller
Deformation Twinning in Nanocrystalline Pd
Phil. Mag. Lett. 84 (2004) 321
J. Weissmüller and J. Markmann
Deforming Nanocrystalline Metals: New Insights, New Puzzles
Adv. Eng. Mat. 7 (2005), 202
C.A. Volkert, E.T. Lilleodden, D. Kramer and J. Weissmüller
Approaching the Theoretical Strength in Nanoporous Au
Appl. Phys. Lett. 89 (2006) 061920
H.-J. Jin, L. Kurmanaeva, J. Schmauch, H. Rösner, Y. Ivanisenko and J. Weissmüller
Deforming Nanoporous Metal: Role of Lattice Coherency
Acta Mater. 57 (2009) 2665
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High resolution transmission electron mi- croscopy picture of a twin in nano- crystalline palladium after deformation by rolling. Conventional Pd doesn't exhibit twinning because of its high stacking fault energy.