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

  • Thermally activated deformation processes in body-centered cubic Cr - How microstructure influences strain-rate sensitivity
    V. Maier, A. Hohenwarter, R. Pippan, D. Kiener
    Scr. Mater.106, 42-45 (2015)
  • In Situ TEM Microcompression of Single and Bicrystalline Samples: Insights and Limitations
    P.J. Imrich, C. Kirchlechner, D. Kiener, G. Dehm
    JOM67, 1704-1712 (2015)
  • Small scale mechanical testing of irradiated materials
    P. Hosemann, C. Shin, D. Kiener
    JOURNAL OF MATERIALS RESEARCH30, 1231-1245 (2015)
  • Microstructure and mechanical properties of CuxNb1-x alloys prepared by ball milling and high pressure torsion compacting
    M.D. Abad, S. Parker, D. Kiener, M.M. Primorac, P. Hosemann
    Journal of Alloys and Compounds, 117-125 (2015)
  • Internal and external stresses: In situ TEM compression of Cu bicrystals containing a twin boundary
    P.J. Imrich, C. Kirchlechner, D. Kiener, G. Dehm
    Scr. Mater.100, 94-97 (2015)
  • X-ray nanodiffraction reveals stress distribution across an indented multilayered CrN-Cr thin film
    M. Stefanelli, R. Daniel, W. Ecker, D. Kiener, J. Todt, A. Zeilinger, C. Mitterer, M. Burghammer, J. Keckes
    Acta Materialia, 24-31 (2015)
  • Elevated temperature mechanical properties of novel ultra-fine grained Cu-Nb composites
    M.M. Primorac, M.D. Abad, P. Hosemann, M. Kreuzeder, V. Maier, D. Kiener
    Mater. Sci. Eng. A-Struct. Mater. Prop. Microstruct. Process.625, 296-302 (2015)
  • Fabrication and thermo-mechanical behavior of ultra-fine porous copper
    M. Kreuzeder, M.-D. Abad, M.-M. Primorac, P. Hosemann, V. Maier, D. Kiener
    Journal of Materials Science, 634-643 (2015)
  • Influence of metastable retained austenite on macro and micromechanical properties of steel processed by the Q&P process
    H. Jirková, B. Mašek, M. F.-X. Wagner, D. Langmajerová, L. Kucerová, R. Treml, D. Kiener
    Journal of Alloys and Compounds, 163-168 (2014)
  • Critical assessment of the determination of residual stress profiles in thin films by means of the ion beam layer removal method
    R. Schöngrundner, R. Treml, T. Antretter, D. Kozic, W. Ecker, D. Kiener, R. Brunner
    Thin Solid Films, 321-330 (2014)