Spatiotemporally inhomogeneous plastic flow of a bulk-metallic glass

Jiang, W. H.; Fan, G. J.; Liu, F.X.; Wang, G.Y.; Choo, Hahn; Liaw, Peter K.

doi:10.1016/j.ijplas.2007.01.015

Cited by 105 publications

(71 citation statements)

References 69 publications

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“…Based on systematical examination of the deformation and fracture in metallic glasses, Spaepen [8] first constructed a deformation map that distinguishes the plastic deformation into two basic modes: homogeneous and inhomogeneous. For the former, each volume element of the sample contributes to the macroscopic plastic strain [8]; for the latter, the strain is highly localized into a few nanoscale shear bands [9][10][11][12][13]. The deformation map has been subsequently extended by a number of other researchers [4,[14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

A thermoplastic forming map of a Zr-based bulk metallic glass

Chen

Jiang

et al. 2013

Acta Materialia

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A thermoplastic forming (TPF) map of a Zr 35 Ti 30 Be 26.75 Cu 8.25 bulk metallic glass was constructed through systematic hot-embossing experiments, spanning a wide range of strain rates and temperatures in the supercooled liquid region. By comparison with the corresponding deformation map, it is found that Newtonian flow, non-Newtonian flow and inhomogeneous flow regions correspond well to fully filled, partially filled and non-filled regions, respectively, in the hot-embossing TPF map. Furthermore, the spatio-temporally homogeneous flow facilitates the thermoplastic formabillity of the Zr-based bulk metallic glass, which is rationalized in terms of free volume theory as well as by finite element simulations. Finally, our results are corroborated by potential application tests.

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Section: Introductionmentioning

confidence: 99%

A thermoplastic forming map of a Zr-based bulk metallic glass

Chen

Jiang

et al. 2013

Acta Materialia

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“…6,7,9 As a spatiotemporal behavior, the plastic dynamics is actually seriously affected by a loading rate. 10 So far, although some reports have found that high strain rate could reduce the amplitude of serration events of BMGs under nanoindentation and compression tests, [11][12][13][14] how the strain rates affecting the plastic dyanmics of BMGs remains unclearly. Since the serrated flow resulted from a competition between the loading process associated with loading rate and the internal relaxation process, 15 strain rate increasing must modify the time scale of the loading process and then causes the dynamic behavior shifting.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of serrated flow in a bulk metallic glass

et al. 2011

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Under compression loading, bulk metallic glasses (BMGs) irreversibly deform through shear banding manifested as a serrated flow behavior. By using a statistical analysis together with a complementary dynamical analysis of the stress-time curves during serrated flow, we characterize the distinct spatiotemporal dynamical regimes and find that the plastic dynamic behavior of a Cu50Zr45Ti5 BMG changes from chaotic to self-organized critical behavior with increasing strain rate. This plastic dynamics transition with the strain rate is interpreted in the frame of the competence between the neighboring elastic strain field forming and relaxation processes.

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“…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. At nanoscale, these inelastic deformation and fracture is accommodated by atomic clusters called as shear transformation zones (STZs) (Argon, 1979;Falk and Langer, 1998) or tension transformation zones (TTZs) (Jiang et al, 2008a;Huang et al, 2014a).…”

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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Spatiotemporally inhomogeneous plastic flow of a bulk-metallic glass

Cited by 105 publications

References 69 publications

A thermoplastic forming map of a Zr-based bulk metallic glass

A thermoplastic forming map of a Zr-based bulk metallic glass

Dynamics of serrated flow in a bulk metallic glass

Nature of crack-tip plastic zone in metallic glasses

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