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SUMMARY:IMX Talks - Grain Boundaries are Natural Brownian Ratchets: direct
 ional GB anisotropy
DTSTART:20240626T150000
DTEND:20240626T160000
DTSTAMP:20260922T023514Z
UID:dd6af551beeebabf88a6af3d4b9594760280ef68fc16fb32f9cafbd2
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. David Srolovitz\, The University of Hong Kong\nThe motio
 n of grain boundaries (GBs\, i.e.\, natural defects in polycrystals separa
 ting single-crystal grains of different orientations) gives rise to micros
 tructure evolution of polycrystalline materials. \nClassical models for G
 B motion posit that GB velocity\, v=MF\, where M is a constant (temperatur
 e-dependent) mobility and F is the driving force. \nReversing the sign of
  F implies that the magnitude of the GB velocity is unchanged but with mot
 ion in the opposite direction. We show that this proposition is true only 
 under a very restrictive set of conditions and a large population of GBs p
 ossess directionally-anisotropic migration behavior. We develop a Markov-c
 hain Monte Carlo method that explains this phenomena and demonstrates that
  the inequivalence of back and forth motion leads to akin to ``Brownian ra
 tchets''. We demonstrate how non-equilibrium thermal/mechanical perturbati
 ons can give rise to directional GB migration and show how oscillating str
 ess or temperature accelerates grain growth. Finally\, we demonstrate this
  effect through a novel set of experiments in-situ in a transmission elect
 ron microscope.\n \n Bio : David Srolovitz is the author of over 500 re
 search papers on materials theory/simulations of defects\, microstructure\
 , deformation\, and film growth and has an h-index of 100 and garnered ~3
 6\,000 citations.  He is a Member of the US National Academy of Engineeri
 ng\, Fellow of MRS\, TMS\, ASM\, Institute of Physics and is the winner of
  the MRS Materials Theory Award.  He was a staff member at Exxon Corporat
 e Research and Los Alamos National Laboratory and the Executive Director o
 f the Institute for High Performance Computing in Singapore.  Previously\
 , a professor at Princeton University (department head\, institute directo
 r\, the University of Pennsylvania (institute director)\, the University o
 f Michigan\, Yeshiva University (dean)\, and the City University of Hong K
 ong (department head\, institute director). He has held faculty positions 
 in Materials Science\, Mechanical Engineering\, Aerospace Engineering\, Co
 mputer Science\, Physics\, Applied Physics and Applied Mathematics.
LOCATION:COVIZ 2 https://plan.epfl.ch/?q=med%2021124&dim_floor=2&lang=fr&d
 im_lang=fr&tree_groups=centres_nevralgiques_grp%2Cmobilite_acces_grp%2Cres
 tauration_et_commerces_grp%2Censeignement%2Cservices_campus_grp%2Cequ http
 s://epfl.zoom.us/j/66847763836?pwd=Qk099bbM2lJAjMG1dZCS991XdRaTaW.1
STATUS:CONFIRMED
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