scholarly journals Relation Between the Defect Interactions and the Serration Dynamics in a Zr-Based Bulk Metallic Glass

2020 ◽  
Vol 10 (11) ◽  
pp. 3892 ◽  
Author(s):  
Jamieson Brechtl ◽  
Zhong Wang ◽  
Xie Xie ◽  
Jun-Wei Qiao ◽  
Peter K. Liaw
Keyword(s):  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Compressive Strain ◽  
Multiscale Entropy ◽  
Compression Tests ◽  
Serrated Flow ◽  
Nanoindentation Hardness ◽  
Defect Interactions ◽  
Entropy Technique

For this study, the effects of thermal annealing and compressive strain rate on the complexity of the serration behavior in a Zr-based bulk metallic glass (BMG) was investigated. Here, as-cast and thermally-annealed (300 °C, 1 week) Zr52.5Cu17.9Ni14.6Al10Ti5 BMG underwent room-temperature compression tests in the unconstrained condition at strain rates of 2 × 10−5 s−1 and 2 × 10−4 s−1. The complexity of the serrated flow was determined, using the refined composite multiscale entropy technique. Nanoindentation testing and X-ray diffraction characterization were performed to assess the changes in the microstructure and mechanical properties of the BMG that occurred during annealing. The results indicated that the BMG did not crystallize during annealing in the prescribed heating condition. Nanoindentation tests revealed that annealing led to a significant increase in the depth-dependent nanoindentation hardness and Young’s modulus, which were attributed to the structural relaxation in the glass. Furthermore, both annealing and an increased strain rate resulted in a marked enhancement in the complexity of the serrated flow during compression. It was concluded that the increase in the sample entropy with increasing strain rate is related to an increase in the number of defect interactions during the serrated flow.

scholarly journals Strain rate dependence of plastic flow in Ce-based bulk metallic glass during nanoindentation

2007 ◽  
Vol 22 (2) ◽  
pp. 258-263 ◽  
Author(s):  
B.C. Wei ◽  
L.C. Zhang ◽  
T.H. Zhang ◽  
D.M. Xing ◽  
J. Das ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Loading Rate ◽  
Shear Banding ◽  
Rate Dependence ◽  
Strain Rate Dependence ◽  
Serrated Flow ◽  
Rate Dependent

The strain rate dependence of plastic deformation of Ce60Al15Cu10Ni15 bulk metallic glass was studied by nanoindentation. Even though the ratio of room temperature to the glass transition temperature was very high (0.72) for this alloy, the plastic deformation was dominated by shear banding under nanoindentation. The alloy exhibited a critical loading rate dependent serrated flow feature. That is, with increasing loading rate, the alloy exhibited a transition from less prominent serrated flow to pronounced serrated flow during continuous loading but from serrated to smoother flow during stepped loading.

Influence of Strain Rate on Mechanical Property of Zr52.5Cu17.9Ni14.6Al10Ti5 Bulk Metallic Glass at Room Temperature

2012 ◽  
Vol 616-618 ◽  
pp. 1721-1724
Author(s):  
Ya Juan Sun
Keyword(s):  
Mechanical Property ◽  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Room Temperature ◽  
Shear Bands ◽  
Side Surface ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Compression Tests

The mechanical property of Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass was investigated at different strain-rate range. It is indicated that the yield strength of the Zr52.5Cu17.9Ni14.6Al10Ti5 bulk metallic glass is insensitive to quasi-static strain rates ranging from 4×10-4 s-1 to 4×10-3 s-1. However, plasticity remarkably decreases with increasing strain rate under compression tests. The more shear bands were observed on the side surface of the fractured samples by SEM at low strain rate, which is contributed to the improved ductility.

In-Situ Observations of Shear Band Development during Deformation of a Bulk Metallic Glass

2000 ◽  
Vol 644 ◽  
Author(s):  
Paul A. El-Deiry ◽  
Richard P. Vinci ◽  
Nicholas Barbosa ◽  
T. C. Hufnagel
Keyword(s):  
Shear Band ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Shear Bands ◽  
Environmental Scanning ◽  
Compression Tests ◽  
Time Data ◽  
Band Formation ◽  
Serrated Flow ◽  
Stress Drops

AbstractWe have studied the development of shear band structure in a Zr57Ti5Cu20Ni8Al10 bulk metallic glass during deformation. In order to investigate the relationship between shear band development and serrated flow, we performed uniaxial compression tests in an environmental scanning electron microscope (ESEM). During the deformation, load-time data and surface images were simultaneously recorded. In the stress-time data, stress drops or “serrated flow” appear to correlate to new shear band formation. The majority of the shear bands we observed were at an angle of 45° with respect to the compression axis. In addition, we measured shear offset as a function of position along the shear band. We observed two different offset behaviors: Consistent offset along the length of a shear band, and offset that is localized into part of the band. The localized offset behavior could be evidence for dislocation-like displacement increments, or could be the result of a transition in the failure mode.

Effect of Strain Rate on Compressive Behavior of a ZrCuNiAl Bulk Metallic Glass at Room Temperature

2021 ◽  
Vol 1016 ◽  
pp. 1569-1575
Author(s):  
Zhi Ping Guo ◽  
Chuan Ting Wang ◽  
Yong He ◽  
Yuan He ◽  
Lei Guo ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Temperature Rise ◽  
Room Temperature ◽  
Dynamic Compression ◽  
Rate Sensitivity ◽  
Compression Tests ◽  
Compressive Behavior ◽  
Negative Strain Rate Sensitivity

In this study, quasi-static and dynamic compression tests were performed on a ZrCuNiAl bulk metallic glass. The results demonstrated that the ZrCuNiAl bulk metallic glass changed from plastic deformation without strain rate effect to brittle fracture with negative strain rate sensitivity. The fracture surface morphology was related to the strain rate and temperature rise. The modified cooperative-shear model was determined to describe the effect of strain rate and temperature rise on the yield stress of ZrCuNiAl bulk metallic glass.

scholarly journals Negative Strain Rate Sensitivity Induced by Structure Heterogeneity in Zr64.13Cu15.75Ni10.12Al10 Bulk Metallic Glass

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 339
Author(s):  
Xiang Wang ◽  
Zhi Qiang Ren ◽  
Wei Xiong ◽  
Si Nan Liu ◽  
Ying Liu ◽  
...  
Keyword(s):  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Strain Rate Sensitivity ◽  
Critical Role ◽  
Rate Sensitivity ◽  
Confined Compression ◽  
Negative Strain Rate Sensitivity ◽  
Cast Specimen ◽  
Structure Heterogeneity

The negative strain rate sensitivity (SRS) of metallic glasses is frequently observed. However, the physical essence involved is still not well understood. In the present work, small-angle X-ray scattering (SAXS) and high-resolution transmission electron microscopy (HRTEM) reveal the strong structure heterogeneity at nanometer and tens of nanometer scales, respectively, in bulk metallic glass (BMG) Zr64.13Cu15.75Ni10.12Al10 subjected to fully confined compression processing. A transition of SRS of stress, from 0.012 in the as-cast specimen to −0.005 in compression processed specimen, was observed through nanoindentation. A qualitative formulation clarifies the critical role of internal stress induced by structural heterogeneity in this transition. It reveals the physical origin of this negative SRS frequently reported in structurally heterogeneous BMG alloys and its composites.

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.

Impacting behavior of bulk metallic glass powder at an abnormally high strain rate during kinetic spraying

2007 ◽  
Vol 449-451 ◽  
pp. 911-915 ◽  
Author(s):  
Sanghoon Yoon ◽  
Changhee Lee ◽  
Hanshin Choi ◽  
Hwíjun Kim ◽  
Jungchan Bae
Keyword(s):  
Metallic Glass ◽  
High Strain Rate ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Glass Powder ◽  
High Strain ◽  
Kinetic Spraying

scholarly journals Strain rate-dependent compressive deformation behavior of Nd-based bulk metallic glass

2005 ◽  
Vol 13 (8) ◽  
pp. 827-832 ◽  
Author(s):  
L.F. Liu ◽  
L.H. Dai ◽  
Y.L. Bai ◽  
B.C. Wei ◽  
G.S. Yu
Keyword(s):  
Metallic Glass ◽  
Strain Rate ◽  
Bulk Metallic Glass ◽  
Deformation Behavior ◽  
Compressive Deformation ◽  
Rate Dependent
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