Professor David Srolovitz from the Department of Mechanical Engineering collaborated with scholars from Hong Kong, China, Germany and USA and worked on the research for the topic “Grain boundaries are Brownian ratchets”. The research is published by Science on August 24, 2024.
Details of the publication:
Grain boundaries are Brownian ratchets
Caihao Qiu, Maik Punke, Yuan Tian, Ying Han, Siqi Wang, Yishi Su, Marco Salvalaglio, Xiaoqing Pan,
David J. Srolovitz and Jian Han
Article in Science
Abstract
We demonstrate that grain boundaries (GBs) behave as Brownian ratchets, exhibiting direction-dependent mobilities and unidirectional motion under oscillatory driving forces or cyclic thermal annealing. We observed these phenomena for nearly all nonsymmetric GBs but not for symmetric ones. Our observations build on molecular dynamics and phase-field crystal simulations for a wide range of GB types and driving forces in both bicrystal and polycrystalline microstructures. We corroborate these simulation results through in situ experimental observations. We analyze these results with a Markov chain model and explore the implications of GB ratchet behavior for materials processing and microstructure tailoring.
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