Christoph Robert Eduard Maass

Christoph Robert Eduard Maass
Christoph Robert Eduard Maass

Christoph Robert Eduard Maass

Assistant Professor
Materials Science and Engineering
408B Materials Science & Eng Bld
1304 W. Green
Urbana Illinois 61801
(217) 300-0665

metals, plasticity, small-scale mechanical testing, size effects, metallic glasses, structure-property relations

For more information

Academic and Scientific Experience

Professional Highlights

  • Robert Maass received a triple diploma in Materials Science and Engineering from the Institut National Polytechnique de Lorraine (INPL-EEIGM, France), Luleå Technical University (Sweden) and Saarland University (Germany) in 2005. In 2009, he obtained his PhD from the Materials Science Department at the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland. During his doctoral work, Robert designed and built an in-situ micro-compression set-up that he used to study small-scale plasticity with time-resolved Laue diffraction at the Swiss Light Source. From 2009-2011 he worked as a postdoctoral researcher at the Swiss Federal Institute of Technology (ETH Zurich) on plasticity of metallic glasses. Subsequently, he joined the California Institute of Technology as an Alexander von Humboldt postdoctoral scholar to continue his research on plasticity of metals. After working as a specialist management consultant for metals at McKinsey & Co., he transferred to the University of Göttingen as a junior research group leader. He joined the faculty of the University of Illinois at Urbana-Champaign as Assistant Professor of Materials Science and Engineering in 2015.

Courses Taught

  • MSE 406 - Thermal-Mech Behavior of Matls
  • MSE 595 - Materials Colloquium

Research Statement

Our research focuses on the fundamentals of plasticity across all length scales in both crystalline and amorphous materials. Plasticity of defect dominated materials is an old, but exciting problem with many unsolved questions. We are interested in plastic processes at the small scale that arise due to extrinsic or intrinsic confinements. Examples of such are the simple reduction of a materials dimension, or the mediation of global plastic deformation by only a tiny fraction of the material. In both cases unexpected scaling regimes can emerge, which can be exploited to tune a material’s resistance to plastic deformation – a property many of your daily life products are crucially reliant on. We combine traditional materials testing protocols with state-of-the-art nanoscale probing methods, and often design our own in-situ experiments to unravel micro structural processes underlying deformation. Current projects target spatiotemporal properties of collective deformation mechanisms in bulk metallic glasses and microcrystals, nano-scale structural characterization of deformation structures in amorphous metals, and microplasticity. All of these activities aim at understanding irreversible structural transitions and ways how to control them so that the next generation metallic components in your newest life-style gadget lasts even longer.

Selected Articles in Journals

  • Spatiotemporal slip dynamics during deformation of gold micro-crystals, G. Sparks, P. Sudharshan Phani, U. Hangen, R. Maaß, Acta Materialia 122, 109-119 (2017)
  • The stress statistics of the first pop-in or discrete plastic event in crystal plasticity, P.M. Derlet and R. Maaß, Journal of Applied Physics 120, 225101 (2016)
  • Critical stress statistics and a fold catastrophe in intermittent crystal plasticity, P.M. Derlet and R. Maaß, Physical Review E 94, 033001 (2016)
  • Unified Criterion for Temperature-Induced and Strain-Driven Glass Transition in Metallic Glass, H-B. Yu, R. Richert, R. Maaß, K. Samwer, Physical Review Letters 115, 135701 (2015)
  • Universal power-law strengthening in metals, P.M. Derlet and R. Maaß, Scripta Materialia 109, 19-22 (2015)
  • Long range stress fields and cavitation along a shear band in a metallic glass – The local origin of fracture, R. Maaß, P. Birckigt, C. Borchers, K. Samwer, C.A. Volkert, Acta Materialia 98, 94-102 (2015)
  • Dynamic properties of major shear bands in Zr-Cu-Al bulk metallic glasses, P. Thurnheer, R. Maaß, K.J. Laws, S. Pogatscher, J.F. Löffler, Acta Materialia 96, 428-436 (2015)
  • Strain induced fragility transition in metallic glass, H-B. Yu, R. Richert, R. Maaß, K. Samwer, Nature Communications 6, 7179 (2015)
  • Rate-dependent shear-band initiation in a metallic glass, D. Tönnies, K. Samwer, P.M. Derlet, C.A. Volkert, R. Maaß, Applied Physics Letters 106, 171907 (2015)
  • Slip statistics of dislocation avalanches under different loading modes, R. Maaß, M. Wraith, J.T. Uhl, J.R. Greer, K.A. Dahmen, Physical Review E 91, 042403 (2015)
  • Shear-band dynamics in metallic glasses (Invited Overview Article), R. Maaß and J.F. Löffler, Advanced Functional Materials 25, 2353–2368 (2015)
  • Crystal size effect in two dimensions – Influence of size and shape, R. Maaß, C.A. Volkert, P.M. Derlet, Scripta Materialia 102, 27-30 (2015)
  • Independence of slip velocities on applied stress in small-scale crystals, R. Maass, P.M. Derlet, J.R. Greer, Small 11, 341-351 (2015)
  • A probabilistic explanation for the size-effect in crystal plasticity, P.M. Derlet and R. Maass, Philosophical Magazine 95, 1829–1844 (2015)
  • A single shear band in a metallic glass – Local core and wide soft zone, R. Maass, K. Samwer, W. Arnold, C.A. Volkert, Applied Physics Letters 105, 171902 (2014)
  • Room Temperature Homogeneous Ductility of Micrometer-sized Metallic Glass, D. Tönnies, R. Maass, C.A. Volkert, Advanced Materials 26, 5715-5721 (2014)
  • Compositional dependence of shear-band dynamics in the Zr–Cu–Al bulk metallic glass system, P. Thurnheer, R. Maass, S. Pogatscher, J.F. Löffler, Applied Physics Letters 104, 101910 (2014)
  • Linking high and low temperature plasticity in bulk metallic glasses II: use of a log-normal barrier energy distribution and a mean field description of high temperature plasticity, P.M. Derlet and R. Maass, Philosophical Magazine 94, 2776-2803 (2014)
  • Deformation Response of Ferrite and Martensite in a Dual-Phase Steel, H. Ghassemi-Armaki, R. Maass, S. P. Bhat, S. Sriram, J. Greer, K.S. Kumar, Acta Materialia 62, 197-211 (2014)
  • Small Scale Plasticity: Insights into Dislocation Avalanche Velocities, R. Maass, P.M. Derlet, J.R. Greer, Scripta Materialia 69, 586-589 (2013)
  • Linking High and Low Temperature Plasticity in Bulk Metallic Glasses: Thermal Activation, Extreme Value Statistics, and Kinetic Freezing, P.M. Derlet and R. Maass, Philosophical Magazine 93, 4232 (2013)
  • Fatigue Deformation of Micro-sized Metallic Glass, D. Jang, R. Maass, G.Wang, P.K. Liaw, J.R. Greer, Scripta Materialia 68, 773-776 (2013)
  • Micro-plasticity and intermittent dislocation activity in a simplified micro structural model, P.M. Derlet and R. Maass, Modelling and Simulation in Materials Science and Engineering 21, 035007 (2013)
  • Ultra-high strength of dislocation free N3Al nano-cubes, R. Maass, L. Meza, B. Gan, S. Tin, J.R. Greer, Small 8, 1869-1875 (2012)
  • Shear-band arrest and stress overshoots during inhomogeneous flow in a metallic glass, R. Maass, D. Klaumuenzer, G. Villard, P.M. Derlet, J.F. Löffler, Applied Physics Letters 100, 071904 (2012)
  • Boson peak of model glass systems and its relation to atomic structure, P.M. Derlet, R. Maass, J.F. Löffler, European Journal of Physics B 85, 148 (2012)
  • Characterization of the dislocation structure evolution in Ni micropillars by in-situ Laue diffraction, R. Maass and M.D. Uchic, Acta Materialia 60, 1027-1037 (2012)
  • Thermal-activation model for freezing and elastic robustness of bulk metallic glass, P.M. Derlet and R. Maass, Physical Review B – Rapid Communications 84, 220201 (2012)
  • Single shear-band plasticity in a Zr-based bulk metallic glass at cryogenic temperature, R. Maass, D. Klaumuenzer, E. I. Preiß, P.M. Derlet, J.F. Löffler, Scripta Materialia 66, 231-234 (2012)
  • Probing shear-band initiation in metallic glasses, D. Klaumuenzer, A. Lazarev, R. Maass, F.D. Dalla Torre, J.F. Löffler, A. Vinogradov, Physical Review Letters 107, 185502 (2011)
  • Propagation dynamics of individual shear bands during inhomogeneous flow in a Zr-based bulk metallic glass, R. Maass, D. Klaumuenzer, J.F. Löffler, Acta Materialia 59, 3205-3213 (2011) – Nature Materials Research Highlight 10, 338 (2011)
  • Stick–slip behavior of serrated flow during inhomogeneous deformation of bulk metallic glasses, F.D. Dalla Torre, D. Klaumuenzer, R. Maass, J.F. Löffler, Acta Materialia 58, 3742-3750 (2010)
  • Temperature Dependent Shear Band Dynamics in a Zr-based Bulk Metallic Glass, D. Klaumuenzer, R. Maass, F.H. Dalla Torre, J.F. Löffler, Applied Physics Letters 96, 061901 (2010)
  • On the plasticity of small-scale nickel-titanium shape memory alloys, C.P. Frick, B.G. Clark, A.S Schneider, R. Maass, S. Van Petegem, H. Van Swygenhoven, Scripta Materialia 62, 492-495 (2010)
  • Smaller is stronger: the effect of strain hardening, R. Maass, S. Van Petegem, D. Ma, J. Zimmermann, D. Grolimund, F. Roters, H. Van Swygenhoven, D. Raabe, Acta Materialia 57, 5996-6005 (2009)
  • Time resolved Laue diffraction on metallic micropillars, R. Maass, S. Van Petegem, C.N. Borca, H. Van Swygenhoven, Materials Science and Engineering A 524, 40-45 (2009)
  • On the microstructure of nanoporous gold: an x-ray diffraction study, S. Van Petegem, S. Brandstetter, R. Maass, A.M. Hodge, B.S. El-Dasher, J. Biener, B. Schmitt, C.N. Borca, H. Van Swygenhoven, NanoLetters 9, 1158-1163 (2009)
  • In-situ time resolved Laue diffraction experiments during micro-compression experiments, R. Maass, S. Van Petegem, H. Van Swygenhoven, D. Grolimund, P.M. Derlet, Advances in Synchrotron Radiation 1, 157-157 (2008)
  • On the initial microstructure in metallic micropillars, R. Maass, S. Van Petegem, J. Zimmermann, C.N. Borca, H. Van Swygenhoven, Scripta Materialia 59, 471-474 (2008)
  • Crystal rotation in Cu single crystal micropillars - In situ Laue and electron backscatter diffraction, R. Maass, S. Van Petegem, D. Grolimund, H. Van Swygenhoven, D.Kiener, G. Dehm, Applied Physics Letters 92, 071905 (2008)
  • A strong micropillar containing a low angle grain boundary, R. Maass, S. Van Petegem, D. Grolimund, H. Van Swygenhoven, M.D. Uchic, Applied Physics Letters 91, 131909 (2007)
  • Time-resolved Laue diffraction of deforming micropillars, R. Maass, S. Van Petegem, H. Van Swygenhoven, P.M. Derlet, C.A. Volkert, D. Grolimund, Physical Review Letters 99, 145505 (2007)
  • Defect structure in micropillars using x-ray microdiffraction, R. Maass, D. Grolimund, S. Van Petegem, M. Willimann, M. Jensen, H. Van Swygenhoven, T. Lehnert, M.A.M. Gijs, C.A. Volkert, E.T. Lilleodden, R. Schwaiger, Applied Physics Letters 89, 151905 (2006)
  • Influence of hydrogen on the growth of FePt thin films, R. Maass, M. Weisheit, S. Faehler, L. Schultz, Journal of Applied Physics 100, 073910 (2006)
  • From micro- to macroplasticity, S. Brandstetter, H. Van Swygenhoven, S. Van Petegem, B. Schmitt, R. Maass, P.M. Derlet, Advanced Materials 18, 1545-1548 (2006)

Research Honors

  • TMS Young Leaders Professional Development award (2016)
  • Emmy Noether award by the German Research Foundation (2014)
  • Feodor von Lynen award by the Alexander von Humboldt Foundation (2011)
  • Young scientist award by the German Materials Research Society (2009)