Delayed shear banding and evolution of local plastic flow in a metallic glass

2014 ◽  
Vol 105 (9) ◽  
pp. 091904 ◽  
Author(s):  
B. A. Sun ◽  
Z. Y. Liu ◽  
Y. Yang ◽  
C. T. Liu
Keyword(s):  
Metallic Glass ◽  
Plastic Flow ◽  
Shear Banding ◽  
Local Plastic

Strain-rate dependence of hardening and softening in compression of a bulk-metallic glass

2007 ◽  
Vol 22 (10) ◽  
pp. 2655-2658 ◽  
Author(s):  
W.H. Jiang ◽  
F.X. Liu ◽  
F. Jiang ◽  
K.Q. Qiu ◽  
H. Choo ◽  
...  
Keyword(s):  
Flow Stress ◽  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Plastic Flow ◽  
Shear Banding ◽  
Constant Strain Rate ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Plastic Flow Stress

We investigated the effect of strain rate on the plastic-flow stress of a Zr-based bulk-metallic glass in quasistatic compression. The results indicate that the plastic-flow stress is dependent on the strain rate: an increase in the strain rate leads to a decrease in the plastic-flow stress, and vice versa. However, simply loading, unloading, and reloading at a constant strain rate do not change the plastic-flow stress. This strain-rate dependence of the plastic-flow stress may be related to shear-banding operations.

Plastic flow in dynamic compression of a Zr-based bulk metallic glass

2006 ◽  
Vol 21 (6) ◽  
pp. 1570-1575 ◽  
Author(s):  
W.H. Jiang ◽  
F.X. Liu ◽  
D.C. Qiao ◽  
H. Choo ◽  
P.K. Liaw
Keyword(s):  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Plastic Flow ◽  
Dynamic Compression ◽  
Maximum Shear Stress ◽  
Shear Banding ◽  
Shear Bands ◽  
Free Volume Model ◽  
Geometrically Constrained

Using geometrically constrained specimens, the plastic flow behaviors of the as-cast and the relaxed Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 bulk metallic glass in the dynamic compression were investigated. Both alloys exhibit a significant plasticity in the dynamic compression. The plastic deformation in both alloys is still inhomogeneous, which is characterized by the serrated plastic flow and the formation of shear bands. Free volumes affect the shear banding and the plastic flow. The reduced free volume results in the deviation of the shear banding direction from the maximum shear stress. The relaxed alloy exhibits the obvious stress overshoot, which is consistent with the theoretical prediction using a free volume model.

scholarly journals Non-trivial avalanches triggered by shear banding in compression of metallic glass foams

2020 ◽  
Vol 476 (2240) ◽  
pp. 20200186
Author(s):  
H. Lin ◽  
C. lu ◽  
H. Y. Wang ◽  
L. H. Dai
Keyword(s):  
Metallic Glass ◽  
Scaling Laws ◽  
Waiting Times ◽  
Shear Banding ◽  
Shear Bands ◽  
Mean Field ◽  
Structural Disorder ◽  
Aftershock Sequence ◽  
Atomic Scale ◽  
Characteristic Time Scale

Ductile metallic glass foams (DMGFs) are a new type of structural material with a perfect combination of high strength and toughness. Owing to their disordered atomic-scale microstructures and randomly distributed macroscopic voids, the compressive deformation of DMGFs proceeds through multiple nanoscale shear bands accompanied by local fracture of cellular structures, which induces avalanche-like intermittences in stress–strain curves. In this paper, we present a statistical analysis, including distributions of avalanche size, energy dissipation, waiting times and aftershock sequence, on such a complex dynamic process, which is dominated by shear banding. After eliminating the influence of structural disorder, we demonstrate that, in contrast to the mean-field results of their brittle counterparts, scaling laws in DMGFs are characterized by different exponents. It is shown that the occurrence of non-trivial scaling behaviours is attributed to the localized plastic yielding, which effectively prevents the system from building up a long-range correlation. This accounts for the high structural stability and energy absorption performance of DMGFs. Furthermore, our results suggest that such shear banding dynamics introduce an additional characteristic time scale, which leads to a universal gamma distribution of waiting times.

scholarly journals Atomic-scale viscoplasticity mechanisms revealed in high ductility metallic glass films

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hosni Idrissi ◽  
Matteo Ghidelli ◽  
Armand Béché ◽  
Stuart Turner ◽  
Sébastien Gravier ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Metallic Glasses ◽  
Shear Banding ◽  
Atomic Scale ◽  
Microscopy Imaging ◽  
Rate Dependent ◽  
Imaging And Spectroscopy ◽  
Shear Transformation Zones ◽  
The Impact ◽  
Glass Films

Abstract The fundamental plasticity mechanisms in thin freestanding Zr65Ni35 metallic glass films are investigated in order to unravel the origin of an outstanding strength/ductility balance. The deformation process is homogenous until fracture with no evidence of catastrophic shear banding. The creep/relaxation behaviour of the films was characterized by on-chip tensile testing, revealing an activation volume in the range 100–200 Å3. Advanced high-resolution transmission electron microscopy imaging and spectroscopy exhibit a very fine glassy nanostructure with well-defined dense Ni-rich clusters embedded in Zr-rich clusters of lower atomic density and a ~2–3 nm characteristic length scale. Nanobeam electron diffraction analysis reveals that the accumulation of plastic deformation at room-temperature correlates with monotonously increasing disruption of the local atomic order. These results provide experimental evidences of the dynamics of shear transformation zones activation in metallic glasses. The impact of the nanoscale structural heterogeneities on the mechanical properties including the rate dependent behaviour is discussed, shedding new light on the governing plasticity mechanisms in metallic glasses with initially heterogeneous atomic arrangement.

scholarly journals Numerical Study on the Fatigue Limit of Metallic Glasses under Cyclic Tension-Compression Loading

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1732
Author(s):  
Jinfeng Yan ◽  
Wenjun Meng ◽  
Zhi Chen ◽  
Hong Guo ◽  
Xianguo Yan
Keyword(s):  
Fatigue Life ◽  
Metallic Glass ◽  
Fatigue Limit ◽  
Free Volume ◽  
Strain Amplitude ◽  
Numerical Study ◽  
Hydrostatic Stress ◽  
Shear Banding ◽  
Engineering Application ◽  
Free Volume Theory

Numerical study was performed to determine the fatigue limit of metallic glass under tension-compression cyclic loading. A revised free-volume theory which considers the hydrostatic stress was utilized to make the predictions. Systematical simulations showed that a higher strain amplitude is prone to making the sample completely damaged earlier. However, lower strain fluctuations could result in a longer fatigue life. Shear banding evolution history described by free-volume localization could reasonably explain the mechanical responses of different samples. In addition, compressive loading could give rise to a higher stress than that under tensile loading because of hydrostatic stress contribution. In the end, a correlation between fatigue life and applied strain amplitude was plotted which could supply a guidance for designing the engineering application of metallic glass under periodic loading.

scholarly journals Strain-hardening and suppression of shear-banding in rejuvenated bulk metallic glass

Nature ◽  
2020 ◽  
Vol 578 (7796) ◽  
pp. 559-562 ◽  
Author(s):  
J. Pan ◽  
Yu. P. Ivanov ◽  
W. H. Zhou ◽  
Y. Li ◽  
A. L. Greer
Keyword(s):  
Metallic Glass ◽  
Strain Hardening ◽  
Bulk Metallic Glass ◽  
Shear Banding
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