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Directional grain growth from anisotropic kinetic roughening of grain boundaries in sheared colloidal crystals

Gokhale, Shreyas and Nagamanasa, Hima K and Santhosh, V and Sood, AK and Ganapathy, Rajesh (2012) Directional grain growth from anisotropic kinetic roughening of grain boundaries in sheared colloidal crystals. In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 109 (50). pp. 20314-20319.

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Official URL: http://dx.doi.org/10.1073/pnas.1210456109

Abstract

The fabrication of functional materials via grain growth engineering implicitly relies on altering the mobilities of grain boundaries (GBs) by applying external fields. Although computer simulations have alluded to kinetic roughening as a potential mechanism for modifying GB mobilities, its implications for grain growth have remained largely unexplored owing to difficulties in bridging the widely separated length and time scales. Here, by imaging GB particle dynamics as well as grain network evolution under shear, we present direct evidence for kinetic roughening of GBs and unravel its connection to grain growth in driven colloidal polycrystals. The capillary fluctuation method allows us to quantitatively extract shear-dependent effective mobilities. Remarkably, our experiments reveal that for sufficiently large strains, GBs with normals parallel to shear undergo preferential kinetic roughening, resulting in anisotropic enhancement of effective mobilities and hence directional grain growth. Single-particle level analysis shows that the mobility anisotropy emerges from strain-induced directional enhancement of activated particle hops normal to the GB plane. We expect our results to influence materials fabrication strategies for atomic and block copolymeric polycrystals as well.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to NATL ACAD SCIENCES, WASHINGTON,USA
Keywords: colloids;grain boundary migration;anisotropic grain growth
Department/Centre: Division of Physical & Mathematical Sciences > Physics
Depositing User: Francis Jayakanth
Date Deposited: 22 Jan 2013 06:17
Last Modified: 22 Jan 2013 06:17
URI: http://eprints.iisc.ac.in/id/eprint/45668

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