Assoc. Prof. Dr. Daniel Kiener

Function: Group Leader
Room: 412
Phone: +43 (0) 3842-804-412
E-Mail: daniel.kiener(at)unileoben.ac.at

 

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

Publications

  • An SEM compatible plasma cell for in situ studies of hydrogen-material interaction
    A. Massone, A. Manhard, W. Jacob, A. Drexler, W. Ecker, A. Hohenwarter, S. Wurster, D. Kiener
    Rev. Sci. Instrum.91, ARTN 043705 (2020)
  • Thermally activated deformation mechanisms and solid solution softening in W-Re alloys investigated via high temperature nanoindentation
    J. Kappacher, A. Leitner, D. Kiener, H. Clemens, V. Maier-Kiener
    Materials & Design189, ARTN 108499 (2020)
  • Open-cell tungsten nanofoams: Chloride ion induced structure modification and mechanical behavior
    M. Zhao, M. Pfeifenberger, D. Kiener
    Results Phys.17, ARTN 103062 (2020)
  • Experimental and Numerical Investigation of the Deformation and Fracture Mode of Microcantilever
    W. Weglewski, P. Pitchai, K. Bochenek, G. Bolzon, R. Konetschnik, B. Sartory, R. Ebner, D. Kiener, M. Basista
    Metallurgical and Materials Transactions A51A, ARTN 5687 (2020)
  • Probing defect relaxation in ultra-fine grained Ta using micromechanical spectroscopy
    M. Alfreider, I. Issa, O. Renk, D. Kiener
    Acta Materialia185, 309-319 (2020)
  • Intrinsic toughness of the bulk-metallic glass Vitreloy 105 measured using micro-cantilever beams
    D. Sorensen, E. Hintsala, J. Stevick, J. Pischlar, B. Li, D. Kiener, J. Myers, H. Jin, J. Liu, D. Stauffer, A. Ramirez, R. Ritchie
    Acta Materialia2020, 242-248 (2020)
  • Tailoring ultra-strong nanocrystalline tungsten nanofoams by reverse phase dissolution
    M. Zhao, I. Issa, M. Pfeifenberger, M. Wurmshuber, D. Kiener
    Acta MaterialiaElsevier182, 215-225 (2020)
  • Ultrafine-grained Tungsten by High-Pressure Torsion-Bulk precursor versus powder processing route
    M. Wurmshuber, S. Doppermann, S. Wurster, D. Kiener
    IOP Conference Series: Materials Science and Engineering580, ARTN 012051 (2019)
  • Fracture behavior and deformation mechanisms in nanolaminated crystalline/amorphous micro-cantilevers
    Y. Wang, R. Fritz, D. Kiener, J. Zhang, G. Liu, O. Kolednik, R. Pippan, J. Sun
    ElsevierActa Materialia180 (2019), 73-83 (2019)
  • Fracture properties of ultrafine grain chromium correlated to single dislocation processes at room temperature
    I. Issa, A. Hohenwarter, R. Fritz, D. Kiener
    Journal of Materials Research2019, 2370-2383 (2019)