Flow serration and shear-band viscosity during inhomogeneous deformation of a Zr-based bulk metallic glass

Song, Shuangxi; Nieh, T.G.

doi:10.1016/j.intermet.2009.03.005

Cited by 136 publications

(65 citation statements)

References 38 publications

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“…Moreover, the strain rates or time scales of loading often affect the spatiotemporal characteristics of shear bands [15,25,54]. In particular, a density fluctuation [17,55] and thus a viscosity drop [27,31,47] usually accompanies the shear-band evolution, implying the loss of short-to-medium-range order [19] or equivalently the coalescence of free volume [18,31] within the band.…”

Section: Local Evolution Model For Shear Bandmentioning

confidence: 99%

“…Therefore, it is still necessary to understand the nature of the shear-banding process in these glassy alloys. In this respect, areas of interest involve the geometrical configuration of shear bands, such as thickness [2,11,12], length and spacing [10,[13][14][15][16], the structural change [17][18][19] and temperature rise [19][20][21] that occurs in shear bands, the propagating mode [19,[22][23][24][25][26] and velocity of shear bands [27][28][29], and the deformation accommodated by shear bands, including plastic strain and its strain rate [30,31]. In fact, the critical plastic energy C c dissipated in a shear band prior to catastrophic fracture is of central importance in the development of ductile BMGs.…”

Section: Introductionmentioning

confidence: 99%

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Shear-band toughness of bulk metallic glasses

Jiang

Dai

2011

Acta Materialia

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Dynamic "forced" shear and quasi-static tensile tests were performed on a typical Vitreloy 1 bulk metallic glass (BMG). The nanoscale shear band is found to initiate in a local plastic region, then propagates with a well-defined front. A theoretical model that takes into account momentum, energy and free-volume balance is developed to quantitatively describe the dissipation system of shear-band propagation in the local plastic region. The analytical expressions for shear-localization time, shear-band thickness and critical energy dissipated within the band are obtained. Calculations demonstrate that the shear-band propagation process is dominated by the free-volume softening, rather than the thermal softening. The latter increases the band thickness slightly but decreases the corresponding critical dissipation energy somewhat. The concept of shear-band toughness is further introduced to measure the inherent resistance capability of materials to the propagation of shear bands in BMGs. These results assist in more comprehensively understanding the evolution mechanism of the shear bands, and in guiding alloy design to enhance the toughness of BMGs.

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Section: Local Evolution Model For Shear Bandmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Shear-band toughness of bulk metallic glasses

Jiang

Dai

2011

Acta Materialia

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“…The avalanches that comprise plastic deformation take place on short time scales (typically on the order of milliseconds in bulk metallic glasses (BMGs) and single crystals [20][21][22]), so experimental time resolution is important. There are two types of avalanche events observed for BMGs.…”

Section: Introductionmentioning

confidence: 99%

Avalanche statistics from data with low time resolution

et al. 2016

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Extracting avalanche distributions from experimental microplasticity data can be hampered by limited time resolution. We compute the effects of low time resolution on avalanche size distributions and give quantitative criteria for diagnosing and circumventing problems associated with low time resolution. We show that traditional analysis of data obtained at low acquisition rates can lead to avalanche size distributions with incorrect power-law exponents or no power-law scaling at all. Furthermore, we demonstrate that it can lead to apparent data collapses with incorrect power-law and cutoff exponents. We propose new methods to analyze low-resolution stress-time series that can recover the size distribution of the underlying avalanches even when the resolution is so low that naive analysis methods give incorrect results. We test these methods on both downsampled simulation data from a simple model and downsampled bulk metallic glass compression data and find that the methods recover the correct critical exponents.

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“…Based on the prior work, 5,18 it is known that BMGs experience initial shear softening and subsequent recovery in a shear-banding event. Theoretically, such a physical picture of shear-banding dynamics can be inferred from Eq.…”

mentioning

confidence: 99%