A very large number of materials, particularly intermetallics and ceramics, exhibit crystal structures which are very different from the simpler cubic and hexagonal crystals formed by pure metals. However, in spite of their wide application as reinforcement or bulk phases, plasticity in these more complex crystals is so far only poorly understood.
In many cases the complex structure and mostly large unit cells result in an increased resistance to dislocation motion and therefore pronounced brittleness. But this is by no means always the case and in particular not on all crystallographic planes of an anisotropic crystal.
The aim of the research conducted within the crystal plasticity group is therefore to extend our current understanding of the close relationship between crystal structure and plasticity to more complex crystals. In order to be able to test and analyse all materials in the same way, however brittle or ductile they might be, nanomechanical methods in conjunction with scanning and transmission electron microscopy are used and further developed, for example in the case of high temperature nanoindentation and microcompression in vacuum. Materials investigated in the group range from binary model systems with varying crystal structure for a constant combination of elements to hard coating and high temperature materials, such as borides, carbides or MAX-phases.
- High temperature nanomechanics in vacuum (prototype development)
- Nanoimpact and –scratch
- In-situ nano- und micromechanics
- Scanning electron microscopy
- FIB-based sample preparation and 3D-FIB/SEM analysis
- Transmission electron microscopy
- Theoretical approaches via DFT – in collaboration
- Korte-Kerzel, S., Microcompression of brittle and anisotropic crystals: recent advances and current challenges in studying plasticity in hard materials, in: MRS Communications (2017), 1-12.
- Schneider, A. S. et al., Influence of test temperature on the size effect in molybdenum small-scale compression pillars, in: Philosophical Magazine Letters (2013), 1-8.
- Walter, C. et al., Anomalous yielding in the complex metallic alloy Al13Co4, in: Acta Materialia 61/19 (2013), 7189-7196.
- Korte, S., Clegg, W. J., Studying plasticity in hard and soft Nb-Co intermetallics, in: Engineering of Advanced Materials 14/11 (2012), 991-997.
- Korte, S. et al., High temperature microcompression and nanoindentation in vacuum, in: Journal of Materials Research 27 (2012), 167-176.
- Korte, S. et al., Deformation of silicon – insights from microcompression testing at 25 – 500 °C, in: International Journal of Plasticity 27/11 (2011), 1853-1866.
- Korte, S., Clegg, W. J., Discussion of the dependence of the effect of size on the yield stress in hard materials studied by microcompression of MgO Philosophical Magazine 91/7-9 (2011), 1150-1162.
- Mathur, H. N., Maier-Kiener, V., Korte-Kerzel, S., Deformation in the γ-Mg 17 Al 12 phase at 25–278° C, in: Acta Materialia 113 (2016), 221-229.
- Korte, S., Clegg, W. J., Onset of plasticity in InxGa1−xAs multilayers, in: Acta Materialia 58/1 (2010), 59-66.
- Korte, S., Clegg, W. J., Micropillar compression of ceramics at elevated temperatures, in: Scripta Materialia 60/9 (2009), 807-810.