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Cavitation in materials with distributed weak zones: Implications on the origin of brittle fracture in metallic glasses

Singh, I and Guo, TF and Murali, P and Narasimhan, R and Zhang, YW and Gao, HJ (2013) Cavitation in materials with distributed weak zones: Implications on the origin of brittle fracture in metallic glasses. In: JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS, 61 (4). pp. 1047-1064.

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Official URL: http://dx.doi.org/10.1016/j.jmps.2012.12.001

Abstract

Several experimental studies have shown that fracture surfaces in brittle metallic glasses (MGs) generally exhibit nanoscale corrugations which may be attributed to the nucleation and coalescence of nanovoids during crack propagation. Recent atomistic simulations suggest that this phenomenon is due to large spatial fluctuations in material properties in a brittle MG, which leads to void nucleation in regions of low atomic density and then catastrophic fracture through void coalescence. To explain this behavior, we propose a model of a heterogeneous solid containing a distribution of weak zones to represent a brittle MG. Plane strain continuum finite element analysis of cavitation in such an elastic-plastic solid is performed with the weak zones idealized as periodically distributed regions having lower yield strength than the background material. It is found that the presence of weak zones can significantly reduce the critical hydrostatic stress for the onset of cavitation which is controlled uniquely by the local yield properties of these zones. Also, the presence of weak zones diminishes the sensitivity of the cavitation stress to the volume fraction of a preexisting void. These results provide plausible explanations for the observations reported in recent atomistic simulations of brittle MGs. An analytical solution for a composite, incompressible elastic-plastic solid with a weak inner core is used to investigate the effect of volume fraction and yield strength of the core on the nature of cavitation bifurcation. It is shown that snap-cavitation may occur, giving rise to sudden formation of voids with finite size, which does not happen in a homogeneous plastic solid. (c) 2012 Elsevier Ltd. All rights reserved.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the PERGAMON-ELSEVIER SCIENCE LTD, ENGLAND.
Keywords: Brittle metallic glasses; Cavitation behavior; Heterogeneous plastic solids; Nanoscale strength distributions; Continuum analysis
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Depositing User: Francis Jayakanth
Date Deposited: 29 Apr 2013 11:58
Last Modified: 29 Apr 2013 11:58
URI: http://eprints.iisc.ac.in/id/eprint/46459

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