Séminaire : Olivier Pierron

Small-Scale Mechanical Testing with MEMS Devices

Small-scale mechanical testing has become a critical part of materials research, whether for discovering nanoscale phenomena in modern technological applications or for enabling minimally invasive approaches to collect mechanical data from bulk materials and calibrate / validate advanced models. In this talk, I will present and discuss several advanced, MEMS-based in-situ SEM/EBSD/TEM mechanical testing techniques to investigate the plasticity, creep and fatigue properties of a wide range of materials, including ceramics and metals. Our novel in-situ EBSD/SEM fatigue testing technique allows accelerated fatigue tests (109 cycles in one day) on metallic thin films to investigate fatigue-induced grain growth and the effect of solute segregation on grain size stability in the nanocrystalline regime, to develop fatigue-resistant metals. Our in-situ TEM technique enables nanoscale observation of defect-defect interactions (including dislocations, grain boundaries, irradiation-induced defects) and their role on deformation, while measuring concomitantly the stress-strain response and other signature parameters such as activation volume. Some of the key issues we are actively investigating with this approach include governing plastic deformation mechanisms in nanocrystalline/ultrafine grained metals, mechanically-induced grain growth and its role on plasticity, mechanical annealing of irradiation-induced damage, and the role of solute segregation on grain boundary stability. I will also discuss a MEMS device (currently in development) to perform in-situ SEM irradiation creep tests, a critical technique to qualify novel structural materials for next generation nuclear reactors.

Olivier Pierron is a Professor in the Woodruff School of Mechanical Engineering at Georgia Tech. He received the Engineering degree from École des Mines de Paris (France) in 2000. He received the M.S. and Ph.D. degrees in Materials Engineering from Penn State, in 2002 and 2005, respectively. His M.S. thesis focused on the influence of hydride blisters on the failure of Zircaloy-4, and his Ph.D. thesis investigated the fatigue degradation properties of silicon MEMS components. Prof. Pierron was a Senior Engineer at Qualcomm MEMS Technologies, Inc. (San Jose, CA) before joining Georgia Tech in May 2007 as an Assistant Professor. He is the recipient of the 2013 NSF CAREER Award, the 2014 Hetenyi Award (for Best Research Paper published in the journal Experimental Mechanics), the 2013 CETL/BP Junior Faculty Teaching Excellence Award, and the 2017 Sigma Xi Best Ph.D. Thesis Advisor Award. 

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