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.

Compressive properties of bulk metallic glass with small aspect ratio

2007 ◽  
Vol 22 (2) ◽  
pp. 501-507 ◽  
Author(s):  
F.F. Wu ◽  
Z.F. Zhang ◽  
S.X. Mao
Keyword(s):  
Plastic Deformation ◽  
Aspect Ratio ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Deformation Behavior ◽  
Shear Bands ◽  
Compressive Load ◽  
Small Aspect Ratio ◽  
Compressive Properties ◽  
Deformation Ability

The quasi-static compressive deformation behavior of a Vitreloy 1 bulk metallic glass (BMG) with an aspect ratio of 0.25 was investigated. It is found that the friction and the confinement at the specimen–loading platen interface will cause the dramatic increase in the compressive load, leading to higher compressive strength. In particular, the BMG specimens show great plastic-deformation ability, and plenty of interacted, deflected, wavy, or branched shear bands were observed on the surfaces after plastic deformation. The formation of the strongly interacted, deflected, wavy, or branched shear bands can be attributed to the triaxial stress state in the glassy specimens with a very small aspect ratio.

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.

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.

Propagation of shear bands in a Cu47.5Zr47.5Al5 bulk metallic glass

2008 ◽  
Vol 23 (1) ◽  
pp. 6-12 ◽  
Author(s):  
K.B. Kim ◽  
J. Das ◽  
M.H. Lee ◽  
S. Yi ◽  
E. Fleury ◽  
...  
Keyword(s):  
Fracture Surface ◽  
Stress Field ◽  
Shear Band ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Elastic Properties ◽  
Work Hardening ◽  
Shear Bands ◽  
Propagation Mode ◽  
Cast State

We report a novel finding of slither propagation of shear bands on the fracture surface of a Cu47.5Zr47.5Al5 bulk metallic glass (BMG). The nanoscale heterogeneities in the as-cast state are aggregated along shear bands with irregular morphology. Such heterogeneities create a fluctuating stress field during shear band propagation leading to a slither propagation mode. The slither propagation of 10 to 15 nm wide shear bands is effective to improve both the plasticity and the “work-hardening-like” behavior of BMGs if the size, the morphology, and the elastic properties of the heterogeneities are intimately intercalated during solidification.

scholarly journals Microstructure and Mechanical Properties of Cu-Ni-Zr-Ti Bulk Metallic Glass Composites by Spark Plasma Sintering

2021 ◽  
Vol 59 (5) ◽  
pp. 281-288
Author(s):  
Da Woon Shin ◽  
Hong Min ◽  
Jin Kyu Lee
Keyword(s):  
Plastic Deformation ◽  
Shear Band ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Glass Matrix ◽  
Shear Bands ◽  
Glass Composites ◽  
Bulk Metallic Glass Composites ◽  
Plasma Sintering ◽  
Spark Plasma

In the present study, Cu54Ni6Zr22Ti18 bulk metallic glass composites were developed by spark plasma sintering(SPS) using gas atomized Cu54Ni6Zr22Ti18 metallic glass powders and Ta powders. Metallic glass composites with Ta phase were fabricated by SPS. The successful consolidation of Cu54Ni6Zr22Ti18 metallic glass matrix composites with the Ta phase was achieved through the strong bonding due to the plastic deformation of the Ta powder and the super-plastic behavior of the metallic glass powder in the supercooled liquid state during SPS. The deformed Ta phases were well distributed in the Cu54Ni6Zr22Ti18 metallic glass matrix. The compressive fracture strength and total strain were 1770 Mpa and 10.2%, respectively, for the Cu54Ni6Zr22Ti18 bulk metallic glass composite with 40 wt% Ta phases. The uniformly dispersed deformed Ta phase in the Cu54Ni6Zr22Ti18 metallic glass matrix effectively impedes the propagation of the first shear band and generates a second shear band, causing a crossing of the shear bands, resulting in an improvement in plastic strain. This increase in plastic deformation is related to the fact that the deformed Ta phase, uniformly distributed in the Cu54Ni6Zr22Ti18 metallic glass matrix, acts as a source of shear bands and at the same time effectively suppresses the movement of the shear bands, dispersing the stress and causing wide plastic deformation.

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.

Initiation and evolution of shear bands in bulk metallic glass under tension—An in situ scanning electron microscopy observation

2009 ◽  
Vol 24 (9) ◽  
pp. 2924-2930 ◽  
Author(s):  
Qingping Cao ◽  
Feng Xu ◽  
Jingwei Liu ◽  
Lianyi Chen ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Yield Strength ◽  
Shear Band ◽  
Metallic Glass ◽  
Bulk Metallic Glass ◽  
Shear Bands ◽  
Maximum Pressure ◽  
Scanning Electron

The initiation and evolution of shear bands in Zr64.13Cu15.75Ni10.12Al10 bulk metallic glass tensile samples has been investigated in situ by scanning electron microscopy. The initial shear band originates from the highest stressed area, and does not propagate during further tension, which is attributed to the weakening of the stress field in front of the shear band tip, possibly caused by atomic rearrangement and local temperature rise. As a result, multiple shear bands occur in sequence with gradually increased length and offset. This result is due to the fact that the stress in front of the tip of the initial shear band does not concentrate again during further tension above the shear yield strength. Numerical analysis was carried out to investigate the stress distribution under tension, suggesting that the maximum pressure-dependent shear stress criterion overestimates the yield strength, while the shear plane criterion describes the conditions for the formation of shear bands well.

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.

Localized Shear Deformation and Fracture in a Zr-Based Bulk Metallic Glass

2007 ◽  
Vol 539-543 ◽  
pp. 2094-2099
Author(s):  
Tatsuya Morikawa ◽  
Tetsuro Kawada ◽  
Kenji Higashida
Keyword(s):  
Metallic Glass ◽  
Shear Deformation ◽  
Bulk Metallic Glass ◽  
Shear Bands ◽  
Step Height ◽  
Bending Test ◽  
Crystalline Materials ◽  
Apparent Fracture Toughness ◽  
Surface Steps ◽  
Localized Shear Deformation

Behaviors of fracture and deformation in a Zr-Al-Ni-Cu bulk metallic glass(BMG) was investigated by using three-point bending tests. Apparent fracture toughness obtained by bending test was 40MPam1/2 which is comparable to the value of ductile crystalline metals. This high toughness of the BMG should be understood by the crack-tip plasticity as well as crystalline metals. It is well known that plastic deformation occurs very inhomogeneously when BMGs are deformed at room temperature. Such inhomogeneity is manifested by the appearance of surface steps caused by localized shear deformation. In the present study, the surface steps due to the localized shear bands near a fracture surface have been examined in detail by using SEM and AFM, where much attention has been paid on the variation of the surface step height measured along the localized shear band. The variation of the step height indicates the gradient of plastic shear deformation, and it can be understood, in principle, as the introduction of elastic singularities corresponding dislocations in the case of crystalline materials.

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