Project leader: Daniel Kiener

Background

The ideal structural material should excel in strength and toughness. Strength describes the capability of a defect free component to carry load during operation, while toughness defines the load-bearing capability and ductility in the presence of a crack. For an energy-efficient and safe design, both quantities should be simultaneously high. Unfortunately, they are mutually exclusive, rendering their combination a Holy Grail in materials science. The reason for this incompatibility is rooted in the inverse strength-ductility paradigm. Focussing on metals, the strength is enhanced via microstructure refinement to the nanometer scale, but ductility and damage tolerance simultaneously drop dramatically. Safety-related or highly stressed components are thus made from rather soft metals, indicating tremendous economic impact conceivable. The objective of this project is to design new bulk materials that uniquely combine high strength and toughness. Severe plastic deformation will be employed to create novel nanostructured bulk metals and nanocomposites, utilizing atomistically informed alloy and interface design to promote plastic deformation. The largely unknown nanoscale processes that limit fracture toughness of nanostructured materials will for the first time be directly identified by quantitative nanomechanical fracture experiments performed in-situ in high resolution electron microscopes. Correlation of these unique insights with ab-initio calculations and energy-based elastic-plastic fracture mechanics computations will guide paths for further improvement of the fracture resistance. By combining a versatile synthesis technique with highly advanced in-situ nanomechanical testing permitting unique atomistic-level insights into nanoscale fracture processes and a scale-bridging modelling approach, new mechanism-based strategies to tailor innovative nanostructured metals and composites with unprecedented strength and toughness will be established.

Current Group Members

Research and technological achievements

  • Synthesis of grain boundary engineered powder-based W and W-Cu composites.
  • Theoretical mechanism-based model describing the temperature- and rate-dependent deformation behavior of nc bcc metals.
  • Grain boundary doping for nc W and W-Cu nanocomposites with C and B.
  • Determining the role of the substitutional alloying elements Re and Hf on nc W.
  • Experimental scheme linking macroscopic fracture properties to atomistic crack tip processes.
  • Studied confinement effects on metallic glasses and their relation to the respective fracture properties.
  • Synthesis of amorphous grain boundary phases to strengthen the softer copper phase using again the powder-based severe plastic deformation route.

Novel methodologies

  • Powder-based synthesis route using severe plastic deformation.
  • Reverse-phase dissolution to process an extremely strong nanocrystalline W nanofoam.
  • Capability to test specific interfaces in SEM and TEM.
  • Computer vision for tracking crack propagation in a semi-automated manner.
  • Continuously determine current crack lengths from the actual stiffness of a miniaturized fracture specimen.
  • Studied confinement effects on metallic glasses and their relation to the respective fracture properties.
  • Synthesis of amorphous grain boundary phases to strengthen the softer copper phase using again the powder-based severe plastic deformation route.

Publications

2021

D. Kiener, J. Jeong, M. Alfreider, R. Konetschnik, S.H. Oh, Prospects of Using Small Scale Testing to Examine Different Deformation Mechanisms in Nanoscale Single Crystals—A Case Study in Mg, Crystals 11, 2021, 61, 10.3390/cryst110100061.

J. Kappacher, O. Renk, D. Kiener, H. Clemens, V. Maier-Kiener, Controlling the high temperature deformation behavior and thermal stability of ultra-fine-grained W by re alloying, Journal of Materials Research, 2021, 10.1557/s43578-020-00026-z.

O. Glushko, D. Kiener, Einleitung von Ermüdungsschäden in ultrafein körnigen Metallfolien, Acta Materialia 206, 2021, 116599, 10.1016/j.actamat.2020.116599.

M. Wurmshuber, D. Frazer, M. Balooch, I. Issa, A. Bachmaier, P. Hosemann, D. Kiener, The effect of grain size on bubble formation and evolution in helium-beradiated cu-Fe-Ag, Materials Characterization 171, 2021, 110822, 10.1016/j.matchar.2020.110822.

M. Zhao, K. Schlueter, M. Wurmshuber, M. Reitgruber, D. Kiener, Open-Cell Wolfram Nanofoams: Scaling behavior and structural disorder dependence of Young es modulus and flow strength, Materials & Design 197, 2021, 109187, 10.1016/j.matdes.2020.109187.

 

2020

M. Burtscher, M. Alfreider, K. Schmuck, H. Clemens, S. Mayer, D. Kiener, In situ Frakturbeobachtungen verschiedener Grenzflächentypen innerhalb einer voll lamellaren intermetallischen TiAl-Legierung, Journal of Materials Research, 2020, 1–14, 10.1557/jmr.2020.306.

W. W. Glewski, P. Pitchai, K. Bochenek, G. Bolzon, R. Konetschnik, B. Sartory, R. Ebner, D. Kiener, M. Basista, Experimental and Numerical Investigation of the Deformation and Fracture Mode of Microcantilever Beams Made of Cr(Re)/Al2O3 Metal-Matrix Composite, Metall. Mater. Trans. A 51, 2020, 2377–2390, 10.1007/s11661-020-05687-3.

M. Zhao, M.J. Pfeifenberger, D. Kiener, Open-Cell Wolfram Nanofoams: Chloridionen induzierte Strukturmodifikation und mechanisches Verhalten, Ergebnisse in Physik 17, 2020, 103062, 10.1016/j.rinp.2020.103062.

J. Fan, W. Rao, J. Qiao, P.K. Liaw, D. Opu, D. Kiener, J. Eckert et al., Achieving work hardening by forming boundaries on the nanoscale in a Ti-based metallic glass matrix composite, Journal of Materials Science & Technology 50, 2020, 192–203, 10.1016/j.jmst.2020.02.036.

M. Alfreider, I. Issa, O. Renk, D. Kiener, Probing defect relaxation in ultra-fine grained Ta using micromechanical spectroscopy, Acta Materialia 185, 2020, 309–319, 10.1016/j.actamat.2019.12.011.

M. Alfreider, J. Zechner, D. Kiener, Addressing Fracture Properties of Individual Constituents Within a Cu-WTi-SiOx-Si Multilayer, JOM 72, 2020, 4551–4558, 10.1007/s11837-020-04444-6.

S. Lee, A. Vaid, J. Im, B. Kim, A. Prakash, J. Guénolé, D. Kiener, E. Bitzeck, S. Ho Oh, In-situ Observation of the Initiation of Plastizität by nucleation of prismatic dislocation loops, Nature communications 11, 2020, 2367, 10.1038/s41467-020-15775-y.

M. Alfreider, S. Kolitsch, S. Wurster, D. Kiener, Eine analytische Lösung zur korrekten Bestimmung von Risslängen über Auslegersteifigkeit, Materials & Design, 2020, 108914,10.1016/j.matdes.2020.108914.

M. Zhao, I. Issa, M.J. Pfeifenberger, M. Wurmshuber, D. Kiener, Tailoring ultra-strong nanocrystalline Wolfram Nanofoams by reverse phase dissolution, Acta Materialia 182, 2020, 215–225, 10.1016/j.actamat.2019.10.030.

J. Kappacher, A. Leitner, D. Kiener, H. Clemens, V. Maier-Kiener, Thermisch aktivierte Verformungsmechanismen und Feststofflösungsenthärtung in W-Re-Legierungen untersucht durch Hochtemperatur-Nanoeinbau,Materialien & Design 189, 2020, 108499, 10.1016/j.matdes.2020.108499.

D. Sorensen, E. Hintsala, J. Stevick, J. Pischlar, B. Li, D. Kiener, J.C. Myers, H. Jin, J. Liu, D. Stauffer,A.J. Ramirez, R.O. Ritchie, Intrinsische Zähigkeit des Schüttmetallglases Vitreloy 105 gemessen mit Mikro-Bindestellebalken, Acta Materialia 183, 2020, 242–248, 10.1016/j.actamat.2019.11.021.

 

2019

M. Wurmshuber, S. Doppermann, S. Wurster, D. Kiener, Ultrafeinkörnchen Wolfram von Hochdrucktorsion – Bulk Precursor versus Pulververarbeitungsroute, IOP Conf. Ser.: Mater. Sci. Eng. 580, 2019, 12051, 10.1088/1757-899X/580/1/012051.

I. Issa, A. Hohenwarter, R. Fritz, D. Kiener, Fraktureigenschaften von ultrafeinem Kornchrom korreliert mit einzelnen Dislokationsprozessen bei Raumtemperatur,J. Mater. Res. 34, 2019, 2370–2383, 10.1557/jmr.2019.140.

Y.Q. Wang, R. Fritz, D. Kiener, J.Y. Zhang, G. Liu, O. Kolednik, R. Pippan J. Sun, Frakturverhalten und Verformungsmechanismen in nanolaminierten kristallinen/amorphen Mikroauslegern, Acta Materialia 180, 2019, 73–83, 10.1016/j.actamat.2019.09.002.

A. Wat, J.I. Lee, C.W. Ryu, B. Gludovatz, J. Kim, A.P. Tomsia, T. Ishikawa, T. Ishikawa, J. Schmitz, A. Meyer, M. Alfreider, D. Kiener, E.S. Park, R.O. Ritchie, Bioinspired nacre-like alumina with a bulk-metallic glass-forming alloy as a compliant phase, Nature communications 10, 2019, 961, 10.1038/s41467-019-08753-6.

D. Kiener, R. Fritz, M. Alfreider, A. Leitner, R. Pippan, V. Maier-Kiener, Rate limiting deformation mechanisms of bcc metals in confined volumes, Acta Materialia 166, 2019, 687–701, 10.1016/j.actamat.2019.01.020.

O. Renk, V. Maier-Kiener, I. Issa, J.H. Li, D. Kiener, R. Pippan, Neal Hardening and elevated temperature strain rate sensitivity of nanostructured metals: Their relation to intergranular dislocation accommodation, Acta Materialia 165, 2019, 409–419, 10.1016/j.actamat.2018.12.002.

 

2018

I. Issa, M. Alfreider, D. Kozic, O. Kolednik, S. Sandfeld, D. Kiener, Linking Macroscopic Fracture Properties to Single Dislocation Processes, Microsc. Mikroanal. 24, 2018, 2184–2185, 10.1017/S1431927618011406.

M. Wurmshuber, D. Frazer, A. Bachmaier, Y. Wang, P. Hosemann, D. Kiener, Auswirkungen von Schnittstellen auf die Strahlungsreaktion und die zugrunde liegenden Defektrückgewinnungsmechanismen in nanostrukturierten Cu-Fe-Ag, Materials & Design 160, 2018, 1148–1157, 10.1016/j.matdes.2018.11.007.

R. Pippan, S. Wurster, D. Kiener, Frakturmechanik von Mikroproben: Grundlegende Überlegungen, Materialien & Design 159, 2018, 252–267, 10.1016/j.matdes.2018.09.004.

Acknowledgements

This project was funded by the European Research Council (ERC) (grant agreement no.: 771146)

Project duration

01.05.2018 - 30.04.2023

Downloads

All publications and download links can be found on ResearchGate or ORCiD.

Project Leader

Assoc. Prof. Dr. Daniel Kiener

daniel.kiener(at)unileoben.ac.at