Nanotwinned Materials for Energy Technologies
Personnel
Project Leader(s):
Richard LeSar
Principal Investigators:
Alexander King, Matthew Kramer, Richard LeSar, Mikhail Mendelev, Ryan Ott, Krishna Rajan
Overview
Nanotwinned metals and alloys are emerging as a particular form of nanoscaled material that can exhibit high strength coupled with improved thermal stability, both of which are yet unexplained. We propose an integrated experimental, modeling and simulation program to examine the underlying mechanisms of plasticity in nanotwinned samples. We will employ a range of methods to create systems with differing twin morphologies and microstructures. The characterization of these systems will be carried out using a range of techniques, from microscopy to synchrotron scattering to the use of an atom probe. Mechanical testing of these samples will be carried out in a novel tensile strain stage that enables accurate measurements of stress-strain behavior with concurrent in situ transmission electron microscopy (TEM) observations of evolving microstructures. The experiments will be coupled with a modeling and simulation program that includes atomistics, dislocation dynamics, and mesoscale simulations. The experiments will provide both realistic validation of models and a deeper understanding of fundamental mechanisms, enhancing the development of new understandings of deformation in nanotwinned materials. This program will not only shed new light on plasticity in nanotwinned materials by bridging the current gap between the experiments and modeling, but it will also greatly enhance our overall understanding of many collective and cooperative mechanisms of plasticity in these materials. The importance of this work, beyond the fundamental questions that will be answered, arises from the potential of these materials for use as structural materials in, for example, nuclear reactors.
Publications
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Wang Y M; Ott R T; Besser M F; Hamza A V . 2012. Temperature-dependent competing deformation mechanisms in nanocrystalline metals. Physical Review B. 85:144122. abstract
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Zhou C Z; LeSar R . 2012. Dislocation dynamics simulations of the Bauschinger effect in metallic thin films. Computational Materials Science. 54:350-355. abstract
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Zhou C Z; LeSar R . 2012. Dislocation dynamics simulations of plasticity in polycrystalline thin films. International Journal of Plasticity. 30-31:185-201. abstract
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Wang Y M; Ott R T; van Buuren T; Willey T M; Biener M M; Hamza A V . 2012. Controlling factors in tensile deformation of nanocrystalline cobalt and nickel. Physical Review B. 85:014101. abstract
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Saldana C; King A H; Stach E A; Compton W D; Chandrasekar S . 2011. Vacancies, twins, and the thermal stability of ultrafine-grained copper. Applied Physics Letters. 99:231911. abstract
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