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.

Fine Crystalline Phase Dispersion in Zr-Based Bulk Metallic Glass by Laser Irradiation

2007 ◽  
Vol 26-28 ◽  
pp. 747-750
Author(s):  
R. Ikutomo ◽  
Masato Tsujikawa ◽  
Makoto Hino ◽  
Hisamichi Kimura ◽  
Kunio Yubuta ◽  
...  
Keyword(s):  
Wear Resistance ◽  
Shear Band ◽  
Metallic Glass ◽  
Laser Irradiation ◽  
Bulk Metallic Glass ◽  
Crystalline Phase ◽  
Shear Bands ◽  
High Strength ◽  
Band Formation ◽  
Phase Dispersion

Bulk metallic glass (BMG) exhibits remarkable properties such as high strength, good stiffness and good corrosion resistance. However, the wear resistance of amorphous metals is not excellent as expected their high strength. It is thought that large local shear bands easily change into cracks for debris formation. The effective obstruction of shear band formation might be applied to improve the wear resistance of BMG. In this study, we tried to suppress shear band deformation by fine crystalline phase dispersion formed by semi-conductor laser irradiation. The microstructures of irradiated Zr-based BMG specimens were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The fine dispersions of crystalline phases are observed in the amorphous matrix. The optimum condition for laser irradiation was discussed.

Effect of Structure Relaxation on the Plastic Deformation Behaviour in a Zr-Based BMG under Indenter

2009 ◽  
Vol 618-619 ◽  
pp. 437-441
Author(s):  
Hao Wen Xie ◽  
Peter D. Hodgson ◽  
Cui E Wen
Keyword(s):  
Plastic Deformation ◽  
Shear Band ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Free Volume ◽  
Cast Alloy ◽  
Deformation Behaviour ◽  
Shear Bands ◽  
Structure Relaxation ◽  
Effect Of Structure

Vickers and nano indentations were performed on a structurally relaxed Zr41Ti14Cu12.5Ni10Be22.5 bulk metallic glass (BMG), and the evolution of the shear bands in the relaxed BMG was investigated and compared to that in the as-cast alloy. Results indicate that the plastic deformation in the BMG with structure relaxation is accommodated by the semicircular (primary) and radial (secondary) as well as tertiary shear bands. Quantitatively, the shear band density in the relaxed alloy was much lower than that in the as-cast alloy. The annihilation of free volume caused by the annealing was responsible for the embrittlement of the sample with structure relaxation.

The more shearing, the thicker shear band and heat-affected zone in bulk metallic glass

2008 ◽  
Vol 23 (8) ◽  
pp. 2133-2138 ◽  
Author(s):  
H. Guo ◽  
J. Wen ◽  
N.M. Xiao ◽  
Z.F. Zhang ◽  
M.L. Sui
Keyword(s):  
Aspect Ratio ◽  
Shear Band ◽  
Metallic Glass ◽  
Shear Deformation ◽  
Bulk Metallic Glass ◽  
Heat Affected Zone ◽  
Shear Bands ◽  
Source Model ◽  
Ion Milling ◽  
Low Aspect Ratio

In a compression test for a Zr-based bulk metallic glass, a dominant shear band was preserved before fracture by a cylindrical stopper. A heat-affected zone (HAZ) ∼10 μm thick together with shear band was discovered in the center of the deformed sample by preferential ion milling. By using a low aspect ratio sample for compression, diverse micron-scaled HAZs among multiple shear bands were also revealed. Based on above experimental results and the isothermal source model, it was found that the thickness of shear band and its HAZ increased continuously with the progression of shear deformation.

Nanoscale multistep shear band formation by deformation-induced nanocrystallization in Zr-Al-Ni-Pd bulk metallic glass

2005 ◽  
Vol 87 (15) ◽  
pp. 151907 ◽  
Author(s):  
Junji Saida ◽  
Albertus Deny Heri Setyawan ◽  
Hidemi Kato ◽  
Akihisa Inoue
Keyword(s):  
Shear Band ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Shear Band Formation ◽  
Band Formation

Analysis of serrations and shear bands fractality in UFGs

2015 ◽  
Vol 24 (1-2) ◽  
pp. 1-9 ◽  
Author(s):  
Aggelos C. Iliopoulos ◽  
Nikolaos S. Nikolaidis ◽  
Elias C. Aifantis
Keyword(s):  
Shear Band ◽  
Shear Banding ◽  
Shear Bands ◽  
Ultrafine Grain ◽  
Strain Rates ◽  
Stress Strain ◽  
Band Formation ◽  
Serrated Flow ◽  
Multiple Shear Band ◽  
First Case

AbstractTsallis nonextensive statistics is employed to characterize serrated flow, as well as multiple shear band formation in ultrafine grain (UFG) size materials. Two such UFG materials, a bi-modal Al-Mg alloy and a Fe-Cu alloy, were chosen. In the first case, at low strain rates serrated flow emerges as recorded in the stress-strain graphs, whereas at high strain rates, extensive shear banding occurs. In the second case, multiple shear banding is the only mechanism for plastic deformation, but serrations in the stress-strain graph are not recorded. The analysis aims at the estimation of Tsallis entropic index qstat (stat denotes stationary state), as well as the estimation of fractal dimension. The results reveal that the distributions of serrations and shear bands do not follow Gaussian statistics as implied by Boltzmann-Gibbs extensive thermodynamics, but are approximated instead by Tsallis q-Gaussian distributions, as suggested by nonextensive thermodynamics. In addition, fractal analysis of multiple shear band images reveals a (multi)fractal and hierarchical profile of the spatial arrangement of shear bands.

scholarly journals Effect of Cold Rolling on the Evolution of Shear Bands and Nanoindentation Hardness in Zr41.2Ti13.8Cu12.5Ni10Be22.5 Bulk Metallic Glass

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1670
Author(s):  
Abhilash Gunti ◽  
Parijat Pallab Jana ◽  
Min-Ha Lee ◽  
Jayanta Das
Keyword(s):  
Shear Band ◽  
Metallic Glass ◽  
Cold Rolling ◽  
Bulk Metallic Glass ◽  
Shear Bands ◽  
Three Dimensional ◽  
Peak Loads ◽  
Nanoindentation Hardness ◽  
Band Spacing ◽  
Calorimetric Studies

The effect of cold rolling on the evolution of hardness (H) and Young’s modulus (E) on the rolling-width (RW), normal-rolling (NR), and normal-width (NW) planes in Zr41.2Ti13.8Cu12.5Ni10Be22.5 (Vitreloy 1) bulk metallic glass (BMG) was investigated systematically using nanoindentation at peak loads in the range of 50 mN–500 mN. The hardness at specimen surface varied with cold rolling percentage (%) and the variation is similar on RW and NR planes at all the different peak loads, whereas the same is insignificant for the core region of the specimen on the NW plane. Three-dimensional (3D) optical surface profilometry studies on the NR plane suggest that the shear band spacing decreases and shear band offset height increases with the increase of cold rolling extent. Meanwhile, the number of the pop-in events during loading for all the planes reduces with the increase of cold rolling extent pointing to more homogeneous deformation upon rolling. Calorimetric studies were performed to correlate the net free volume content and hardness in the differently cold rolled specimens.

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.

Shear band formation and ductility in bulk metallic glass

2005 ◽  
Vol 85 (23) ◽  
pp. 2671-2687 ◽  
Author(s):  
A. V. Sergueeva ◽  
N. A. Mara ◽  
J. D. Kuntz ◽  
E. J. Lavernia ◽  
A. K. Mukherjee *
Keyword(s):  
Shear Band ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Shear Band Formation ◽  
Band Formation
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