Dresden 2017 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 55: Posters - Soft Matter, Glasses
DY 55.10: Poster
Thursday, March 23, 2017, 17:00–19:30, P1A
Irreversibility transition of colloidal polycrystals under cyclic deformation — •Pritam Kumar Jana1, Mikko J. Alava1, and Stefano Zapperi1,2,3,4 — 11COMP Centre of Excellence, Department of Applied physics, Aalto University, P.O. Box 11100, Aalto 00076, Finland — 2Center for Complexity and Biosystems, Department of Physics, University of Milano, via Celoria 16, 20133 Milano, Italy — 3ISI Foundation, Via Alassio 11/C, 10126 Torino, Italy — 4CNR-IENI, Via R. Cozzi 53, 20125 Milano, Italy
Recently, Tamborini et al. have investigated plasticity of colloidal polycrystals, which are prepared by crystallizing thermo sensitive block copolymer Pluronics F108 with a small amount of nanoparticles as impurities, under cyclic shear. [1] Guided by their experiment, we perform plastic deformation study on 2D polycrystalline samples using molecular dynamics simulations. Samples are prepared by reducing the temperature of binary Lennard-Jones liquids with a fixed cooling rate. A small amount of bigger particles, which basically acts as an impurity, creates dislocations in the system because of size mismatch. A string of dislocations are defined as grain boundaries and the amount of impurities can control the number of grains. In the next stage, samples are undergone a cyclic deformation where the maximum strain amplitude (γmax) is varied by changing the strain rate. For a small value of γmax, the system becomes quiescent within a few cycles whereas for larger γmax, particles move irreversibly which leads to the grain boundary motion and the annihilation of dislocations.
[1] Tamborini et al. PRL 113, 078301 (2014)