Local shear transformations in deformed and quiescent hard-sphere colloidal glasses

K. E. Jensen, D. A. Weitz, and F. Spaepen
Phys. Rev. E 90, 042305 – Published 10 October 2014
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Abstract

We perform a series of deformation experiments on a monodisperse, hard-sphere colloidal glass while simultaneously following the three-dimensional trajectories of roughly 50000 individual particles with a confocal microscope. In each experiment, we deform the glass in pure shear at a constant strain rate [(15)×105 s1] to maximum macroscopic strains (5%10%) and then reverse the deformation at the same rate to return to zero macroscopic strain. We also measure three-dimensional particle trajectories in an identically prepared quiescent glass in which the macroscopic strain is always zero. We find that shear transformation zones exist and are active in both sheared and quiescent colloidal glasses, revealed by a distinctive fourfold signature in spatial autocorrelations of the local shear strain. With increasing shear, the population of local shear transformations develops more quickly than in a quiescent glass and many of these transformations are irreversible. When the macroscopic strain is reversed, we observe partial elastic recovery, followed by plastic deformation of the opposite sign, required to compensate for the irreversibly transformed regions. The average diameter of the shear transformation zones in both strained and quiescent glasses is slightly more than two particle diameters.

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  • Received 15 May 2014

DOI:https://doi.org/10.1103/PhysRevE.90.042305

©2014 American Physical Society

Authors & Affiliations

K. E. Jensen*

  • Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA

D. A. Weitz

  • Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA and School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA

F. Spaepen

  • School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA

  • *Present address: Department of Mechanical Engineering and Materials Science, Yale University, New Haven, Connecticut 06511, USA; kjensen@post.harvard.edu
  • spaepen@seas.harvard.edu

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Issue

Vol. 90, Iss. 4 — October 2014

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