Prior to deformation

1. CAREER: Microstructure & Size Effects on Metal Plasticity at Limited Length ScaleFrederic Sansoz, University of Vermont & State Agricultural College, DMR 0747658 Specific objectives: Tocharacterize the synergistic effects of twin boundaries, free surfaces and sample size on plasticity in FCC metal nanowires under external loading using atomistic simulations and atomic force microscopy experiments. Study of size effects in nanoscale metal plasticity requires a precise understanding of microstructure evolution during deformation in nanowires and nanopillars 10% compression Prior to deformation Large-scale molecular dynamics computer simulations enabled us to study the compression of Cu nanopillars less than 100 nm in diameter containing complex dislocation networks. The above atomistic simulation shows a progressive stage of dislocation starvation where the initial dislocation density has been reduced markedly after 10% deformation.

2. CAREER: Microstructure & Size Effects on Metal Plasticity at Limited Length ScaleFrederic Sansoz, University of Vermont & State Agricultural College, DMR 0747658 This project also has made broader impacts through… …Education Doctoral students: Undergraduate students: Training and education of graduate and undergraduate students in the fields of mechanical engineering and materials science are fully integrated to the research project. All current and former students who have already participated in the research are shown here. ZacharyBurchman (Now graduate student at Carnegie Mellon U) ChuangDeng (Now postdoc at MIT and 2010 Acta Award winner) Virginie Dupont (Now post-doctoral fellow at Los Alamos National Lab) Trevor Avant ErinWood EvanMalina …Dissemination of knowledge Our work is also to disseminate the new knowledge gained from our research through publication of scholarly articles and presentation at conferences. Some recent publications (among 13 publications total) include: C. Deng and F. Sansoz, “Effects of Twin and Surface Facet on Strain-rate Sensitivity of Gold Nanowires at Different Temperatures”, Physical Review B, 81, 155430 (2010). C. Deng and F. Sansoz, “Near-Ideal Strength in Gold Nanowires Achieved through Microstructural Design”, ACS Nano, 3, 3001-3008 (2009). C. Deng and F. Sansoz, “Fundamental Differences in the Plasticity of Periodically Twinned Nanowires in Au, Ag, Al, Cu, Pb and Ni”, Acta Materialia, 57, 6090-6101 (2009). V. Dupont and F. Sansoz, “Molecular Dynamics Study of Crystal Plasticity during Nanoindentation in Ni Nanowires”, J. Materials Research, 24 (3), 948-956 (2009).