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Hidden order in serrated flow of metallic glasses

Sarmah, Ritupan and Ananthakrishna, G and Sun, BA and Wang, WH (2011) Hidden order in serrated flow of metallic glasses. In: Acta Materialia, 59 (11). pp. 4482-4493.

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Official URL: http://dx.doi.org/10.1016/j.actamat.2011.03.071


We report results of statistical and dynamic analysis of the serrated stress-time curves obtained from compressive constant strain-rate tests on two metallic glass samples with different ductility levels in an effort to extract hidden information in the seemingly irregular serrations. Two distinct types of dynamics are detected in these two alloy samples. The stress-strain curve corresponding to the less ductile Zr65Cu15Ni10Al10 alloy is shown to exhibit a finite correlation dimension and a positive Lyapunov exponent, suggesting that the underlying dynamics is chaotic. In contrast, for the more ductile Cu47.5Zr47.5Al5 alloy, the distributions of stress drop magnitudes and their time durations obey a power-law scaling reminiscent of a self-organized critical state. The exponents also satisfy the scaling relation compatible with self-organized criticality. Possible physical mechanisms contributing to the two distinct dynamic regimes are discussed by drawing on the analogy with the serrated yielding of crystalline samples. The analysis, together with some physical reasoning, suggests that plasticity in the less ductile sample can be attributed to stick-slip of a single shear band, while that of the more ductile sample could be attributed to the simultaneous nucleation of a large number of shear bands and their mutual interactions. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Item Type: Journal Article
Publication: Acta Materialia
Publisher: Elsevier Science
Additional Information: Copyright of this article belongs to Elsevier Science.
Keywords: Metallic glasses;Ductility;Intermittent flow;Chaos;Self-organized criticality
Department/Centre: Division of Chemical Sciences > Materials Research Centre
Date Deposited: 29 Jun 2011 09:59
Last Modified: 29 Jun 2011 09:59
URI: http://eprints.iisc.ac.in/id/eprint/38648

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