Event Scheduled for Apr 20, 2018
Event: MSE Seminar Speaker - Dr. Frederic Sansoz
Time: 09:45 am
Details of Event:
Materials Science and Engineering
Invites you to a seminar by
Dr. Frederic Sansoz
Professor, Department of Mechanical Engineering, The University of Vermont, Burlington
Friday, April 20, 2018
Institute of Materials Science Building, Room 20, at 9:45 a.m.
Refreshments will be served at 9:30 a.m.
“Small-scale Mechanics of Super-strong Silver Nanostructures”
Abstract: Nanoscale face-centered-cubic metals have become increasingly important engineering materials for energy-related applications, while fundamentally pushing the scientific frontiers of mechanics and materials science at the nanoscale. Examples vary from Ag nanowire networks for next-generation transparent conductive electrodes in flexible touchscreens, organic solar cells, and stretchable electronics, to structural metallic alloys strengthened by nanoscale interfaces resisting extreme environments. This seminar will present our latest research in understanding the small-scale mechanics of strength and superplasticity in nanoscale silver metals, by using combined large-scale molecular dynamics simulations and in-situ nanomechanical experiments. First, following the “smaller is stronger” trend, we will show unusual room-temperature super-elongation without softening in single-crystalline Ag nanowires over a sample diameter range between 15 nm and 50 nm, which extends far beyond the maximum size for pure surface diffusion-mediated deformation (e.g. Coble-type creep). Over this diameter range, it is observed experimentally and theoretically that crystal slip can serve as a stimulus to diffusional creep of atomic surface ledges. Second, the ability of twin boundaries in strengthening and maintaining ductility in bulk nanostructures has been well documented; yet most understanding of the origin of these properties relies on perfect-interface assumptions. We will show that growth twins in bulk nanotwinned metals are inherently defective with kink-like steps, and that these atomic-scale imperfections also play a key role in plastic deformation mechanisms and the Hall-Petch strength limit. Specifically, this talk will highlight the role of solute atom segregation as a fundamentally new mechanism of twin stability and strengthening in nanotwinned Ag containing trace concentrations of solute Cu atoms.
Bio: Frederic Sansoz is a professor of mechanical engineering and materials science at the University of Vermont. He earned his BS degree in mechanical and aerospace engineering and MS degree in materials science and engineering from the Ecole Nationale Supérieure de Mécanique et Aérotechnique in Poitiers, France in 1996, and a PhD degree with honors in materials science and engineering from Ecole des Mines in Paris in 2000. He was a post-doctoral fellow in mechanical engineering at the Johns Hopkins University until 2003. Sansoz received the National Science Foundation CAREER award in 2008. His research focuses on understanding the mechanics and physics of interface-dominated nanomaterials.
Target Audience: Not Available
Sponsored By: Materials Science and Engineering Department
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