On the mechanism and the length scales involved in the ductile fracture of a bulk metallic glass

Tandaiya, Parag; Narasimhan, R.; Ramamurty, Upadrasta

doi:10.1016/j.actamat.2012.11.033

Cited by 91 publications

(69 citation statements)

References 45 publications

(82 reference statements)

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“…Some BMGs exhibit good fracture toughness while some exhibit poor fracture toughness. The former is called ductile BMG and the latter is the brittle one, which has been mentioned by Ramamurty group in their recent papers [56][57][58]. Here, DBT of BMGs was defined as the transition of microscopic fracture feature and macroscopic fracture mode.…”

Section: Discussionmentioning

confidence: 99%

The ductile to brittle transition behavior in a Zr-based bulk metallic glass

Jiang

et al. 2015

Materials Science and Engineering: A

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Section: Discussionmentioning

confidence: 99%

The ductile to brittle transition behavior in a Zr-based bulk metallic glass

Jiang

et al. 2015

Materials Science and Engineering: A

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“…MGs fracture by the break-up of a crack tip, the zone ahead of the crack tip is highly strained and its viscosity is reduced due to structural evolution. The strainsoftening yields a liquid-like plastic zone or shear band ahead of the crack tip, and the crack front is expected to act as meniscus (Wang et al, 2007;Tandaiya et al, 2013). When an infinitesimal perturbation of this meniscus reaches a critical wavelength l c for meniscus instability, it grows and advances the crack front into the plastic zone, leading to the formation of vein patterns.…”

Section: Plastic Zone Size and Shapementioning

confidence: 99%

“…Their intrinsic inability to undergo finite plastic straining under tension greatly impedes MGs from wide structural usage. The underlying deformation and fracture physics, being one of the most fundamental problems of MGs, has attracted substantial research effort for the last decades (Spaepen, 1975;Argon and Salama, 1976;Ravichandran and Molinari, 2005;Schuh et al, 2007;Jiang et al, 2008a;Raghavan et al, 2009;Tandaiya et al, 2009;Xu et al, 2010;Chen et al, 2011;Jang et al, 2011;Greer et al, 2013;Tandaiya et al, 2013;Narayan et al, 2014;Narasimhan et al, 2015). Due to their special atomic structures, MGs may go through ductile failure via shear banding (Dai et al, 2005;Jiang et al, 2008b;Chen and Lin, 2010;Chen et al, 2013;Greer et al, 2013) or brittle fracture by cavitation (Jiang et al, 2008a;Murali et al, 2011a;Singh et al, 2013Singh et al, , 2014.…”

Section: Introductionmentioning

confidence: 99%

Nature of crack-tip plastic zone in metallic glasses

Chen

Dai

2016

International Journal of Plasticity

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a b s t r a c tThe fracture of metallic glasses(MGs) can be induced by shear banding in a ductile mode or by cavitation in a brittle way. Plastic zone in front of a crack tip, which is greatly involved with localized shear band, cavitation and the resultant fracture morphology, is a key clue to unveil the secrets of the intrinsic ductility and fracture. However, the characteristics of plastic zone, i.e., stress and strain distributions, size and shape, have not been clearly unraveled for MGs so far. In this paper, an analytical solution of the plastic zone for mode I crack under plane strain condition is derived through J-integral based on a slip line field analysis and shape approximation, by taking pressure-sensitivity, dilatancy, and structural evolution into account. Two length scales of the plastic zone, i.e. the maximum radius R max and the radius along the crack line direction R x , are revealed to control shear flow instability and cavitation, and therefore failure modes. According to shear transformation zone (STZ) based free volume evolution dynamics, the critical values of the mode I stress intensity factor and the plastic zone size at crack initiation are obtained. The effects of Poisson's ratio, pressure sensitivity, and dilatancy on the stress/strain distributions, and the size of plastic zone are elucidated. It is found that larger Poisson's ratio and smaller dilatancy lead to higher fracture toughness and 'slender' critical plastic zone, facilitating a good ductility. The internal correlations of the fracture pattern (i.e. dimple structure) with the plastic zone are established, where the size of the fracture pattern is quantitatively characterized by the critical length of plastic zone. To be further, a shape change of the critical plastic zone from 'slender' (apt to shear plastic flow) to 'chubby' (inclined to cavitation) is revealed with increasing dilatancy or decreasing Poisson's ratio, which might shed light on the underlying mechanism of ductile-to-brittle transition in MGs.

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“…This unique combination may lead to an abnormal mechanism of fragmentation. According to recent studies by Tandaiya et al [18,19], crack initiates and then stably grows inside one dominant shear band in bending tests of BMGs with a notch, which shows that shear bands are precursors of cracks. Fracture of Zr-based BMGs into a few fragments has been discovered in split-Hopkinson pressure bar [20,21] and anvil-onrod impact tests [12,22].…”

Section: Introductionmentioning

confidence: 99%

“…Actually, there are two dissipation sources in the shear-band propagation and crack extension. According to quasistatic testing of four-point-bend notched BMGs by Tandaiya et al [19], the estimated energy release rate under mode II is J c ¼ 8.4 N mm…”

mentioning

confidence: 99%