Research

Micro- and Nanomechanics and Micro- and Nanostructure Characterization

When the material grain size or the sample volume itself are reduced to the micron- and sub-micron regime, significant size effects on the mechanical properties arise due to the increased contribution of surfaces and interfaces. We aim to derive a mechanistic understanding of the interplay between sample or microstructure size, the presence of individual microstructural elements such as interfaces, grain boundaries or dislocations, and the resulting global material properties. This is achieved by a combination of sophisticated methods such as highly localized and miniaturized quantitative experiments performed within high-resolution electron microscopy techniques, temperature- and rate dependent thermo-mechanical microstructure analysis, and advanced nanoindentation techniques. Various interests in the field of Micro- and Nanomechanics concern:

• Miniaturized testing techniques (compression, tension, bending, fracture, fatigue, ...)
• Small scale sample preparation techniques
• Quantitative electron microscopy
• Size effects influencing material properties
• Dislocation plasticity in confined volumes
• Deformation mechanisms in nanoscale or nanostructured materials (slip, twinning, grain boundaries)
• Irradiation resistant materials by microstructural design
• Temperature dependent deformation mechanisms of single crystal and nanocrystalline fcc and bcc metals
• Thermal fatigue behavior and microstructural stability of metallic thin films
• Local depth-dependent residual stresses in complex layered structures
• Fracture processes and properties of small structures and multilayers
• Deformation mechanisms in hexagonal metals
• Temperature dependent deformation mechanisms in nanoporous materials

Methods

Size effects influencing material properties, dislocation plasticity in confined volumes, temperature and irradiation dependent deformation, thermal fatigue and fracture of small-scale structures and multilayers, in-situ micromechanical testing in the SEM, in-situ nanomechanical testing in the TEM, advanced nanoindentation techniques, digital image correlation methods

• In situ micromechanical experiments in the SEM
• In situ nanomechanical testing in the TEM
• Broad ion beam and FIB based material structuring
• Advanced nanoindentation techniques (e.g. elevated temperatures, rate dependencies)
• Digital image correlation techniques to measure local deformations and microstructural evolution
• Local determination of residual stresses with high depth resolution
• Miniaturized fracture testing in the SEM and TEM
• Novel laser-based fast thermo-mechanical heating/cycling techniques

Teaching

In-situ an In-operando Characterization Techniques in Materials Science (In-situ und in-operando Charakterisierungstechniken in der Werkstoffwissenschaft), Materialphysik I and III, Wissenschaftliche Arbeiten in der Materialphysik

• Introduction to Materials Science
• Materials Characterization
• Materials Physics I
• Materials Physics III
• Exercises to Materials Physics
• In-situ and in-operando characterization techniques in material science
• Exercises to In-situ and in-operando characterization techniques in material science
• Seminar Bachelor Thesis
• Seminar Master Thesis
• Scientific Work in Materials Physics

Projects

Advanced nanoindentation for the extraction of material flow curves, Microstructure and temperature effects on submicron plasticity of bcc metals, Femtosecond laser application in materials science, Deformation Mechanisms of Nano-Porous Hexagonal Metals, Measuring Local Residual Stresses and Fracture Toughness in Thin Films, High temperature mechanical testing of novel Cu-Nb nanocomposites, Fabrication and thermo-mechanical behavior of nanoporous materials, High cycle thermo-mechanical fatigue behavior of semiconductor thin films, EPPL - Enhanced Power Pilot Line, Nanofatigue

Publications