scholarly journals Guiding shear bands in bulk metallic glasses using stress fields: A perspective from the activation of flow units

2020 ◽  
Vol 102 (13) ◽  
Author(s):  
K. Kosiba ◽  
S. Scudino ◽  
J. Bednarcik ◽  
J. Bian ◽  
G. Liu ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Stress Fields ◽  
Flow Units

scholarly journals Erratum to “On the shear-affected zone of shear bands in bulk metallic glasses” [J. Alloys Compd. 837 (2020) 155494]

2020 ◽  
Vol 842 ◽  
pp. 155852
Author(s):  
Farnaz A. Davani ◽  
Sven Hilke ◽  
Harald Rösner ◽  
David Geissler ◽  
Annett Gebert ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses

Bulk Metallic Glasses

2008 ◽  
Vol 604-605 ◽  
pp. 229-238
Author(s):  
Marcello Baricco ◽  
Tanya A. Başer ◽  
Gianluca Fiore ◽  
Rafael Piccin ◽  
Marta Satta ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Metallic Glasses ◽  
Amorphous Alloys ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Rapid Quenching ◽  
Second Phase ◽  
Research Activity ◽  
Long Time ◽  
Geometrical Constraints

Rapid quenching techniques have been successfully applied since long time for the preparation of metallic glasses in ribbon form. Only in the recent years, the research activity addressed towards the synthesis of bulk metallic glasses (BMG), in form of ingots with a few millimetres in thickness. These materials can be obtained by casting techniques only for selected alloy compositions, characterised by a particularly high glass-forming tendency. Bulk amorphous alloys are characterised by a low modulus of elasticity and high yielding stress. The usual idea is that amorphous alloys undergo work softening and that deformation is concentrated in shear bands, which might be subjected to geometrical constraints, resulting in a substantial increase in hardness and wear resistance. The mechanical properties can be further improved by crystallisation. In fact, shear bands movement can be contrasted by incorporating a second phase in the material, which may be produced directly by controlled crystallisation. Soft magnetic properties have been obtained in Fe-based systems and they are strongly related to small variations in the microstructure, ranging from a fully amorphous phase to nanocrystalline phases with different crystal size. The high thermal stability of bulk metallic glasses makes possible the compression and shaping processes in the temperature range between glass transition and crystallisation. Aim of this paper is to present recent results on glass formation and properties of bulk metallic glasses with various compositions. Examples will be reported on Zr, Fe, Mg and Pd-based materials, focussing on mechanical and magnetic properties.

“Extended” shear bands in interior of Pd-based bulk metallic glasses

Rare Metals ◽  
2015 ◽  
Vol 37 (1) ◽  
pp. 54-58 ◽  
Author(s):  
Li Liu ◽  
He Song ◽  
Xiang-Jin Zhao ◽  
Wei Du ◽  
Tao Zhang
Keyword(s):  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses

Increasing the Fracture Strength and Strain of Bulk Metallic Glasses by Ultrasonic Nano-Crystal Surface Modification

2016 ◽  
Author(s):  
Chi Ma ◽  
Yalin Dong ◽  
Chang Ye
Keyword(s):  
Surface Modification ◽  
Fracture Strength ◽  
Metallic Glasses ◽  
Crystal Surface ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Localized Deformation ◽  
Untreated Sample ◽  
Nano Crystal ◽  
Surface Technique

A novel surface technique, ultrasonic nano-crystal surface modification (UNSM), was used to process BMGs (Bulk Metallic Glasses) to improve the fracture strength and strain. It has been found that the fracture strength and strain are increased by 14.6% and 15.3% respectively after UNSM. In addition, micro-defects (voids and cracks) are found at the surface layer of UNSM-treated specimen after fracture, while there are fewer micro-defects observed in the untreated sample. We attribute the improvement of fracture stress and strain to two mechanisms. First, the excess free volume generated in BMGs by UNSM helps the nucleation of shear bands and the redistribution of the localized deformation. Second, the compressive residual stress generate by UNSM can slow down crack propagation. Both mechanisms lead to the improvement of BMGs fracture strength and strain.

Enhance plasticity of bulk metallic glasses by geometric confinement

2007 ◽  
Vol 22 (9) ◽  
pp. 2384-2388 ◽  
Author(s):  
P. Yu ◽  
Y.H. Liu ◽  
G. Wang ◽  
H.Y. Bai ◽  
W.H. Wang
Keyword(s):  
Metallic Glasses ◽  
Mechanical Performance ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Simple Step ◽  
Geometric Confinement ◽  
Shrink Fit

We report that bulk metallic glasses (BMGs) with large plasticity can be obtained in conventional brittle BMGs by a shrink-fit metal sleeve. The mechanical performance especially the plasticity in the Zr41.2Ti13.8Cu12.5Ni10Be22.5 BMG with a shrink-fit copper sleeve is much enhanced. The approach results in the formation of the highly dense and frequent interacting and arresting events of shear bands and is the origin of the observed large global plasticity. The results present another simple step toward toughening the inherently brittle BMGs.

Effect of Cooling Rate, Tungsten Fiber Addition and Annealing on Deformation and Mechanical Properties of Zr-Based Bulk Metallic Glasses Under a Nanoindenter

2015 ◽  
Vol 1120-1121 ◽  
pp. 68-72
Author(s):  
Yi Si
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Cooling Rate ◽  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Tungsten Fiber ◽  
Nanoindentation Instrument ◽  
Scanning Electron ◽  
Fiber Addition

The deformation and mechanical properties of Zr-based bulk metallic glasses (BMGs) under a nanoindenter and the effect of cooling rate, the effect of cooling rate, tungsten fiber addition and annealing on them have been studied by means of a nanoindentation instrument and a scanning electron microscope (SEM). The results indicate that the deformation of Zr-based BMGs under a nanoindenter is characterized by multiple shear bands and viscous flow which confirms the existence of a amount of plastic deformation. For pure quenched Zr-based BMGs, the larger the size of samples or the nearer the location away from the surface of a same sample, the smaller the values of microhardness (Hv) and elastic modulus (E); Annealing and tungsten fiber addition enhance the values of Hv and E; meanwhile, they also significantly change morphology around a nanoindenter and the amount of plastic deformation. The mechanism of plastic deformation is preliminarily analyzed.

scholarly journals Plastic Dynamical Model for Bulk Metallic Glasses

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Shaowen Yao ◽  
Zhibo Cheng
Keyword(s):  
Metallic Glasses ◽  
Loading Rate ◽  
Testing Machine ◽  
Compressive Loading ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Experimental Results ◽  
Dynamical Model ◽  
Compression Tests ◽  
Rate Range

Based on previous experimental results of the plastic dynamic analysis of metallic glasses upon compressive loading, a dynamical model is proposed. This model includes the sliding speed of shear bands in the plastically strained metallic glasses, the shear resistance of shear bands, the internal friction resulting from plastic deformation, and the influences from the testing machine. This model analysis quantitatively predicts that the loading rate can influence the transition of the plastic dynamics in metallic glasses from chaotic (low loading rate range) to stable behavior (high loading rate range), which is consistent with the previous experimental results on the compression tests of a Cu50Zr45Ti5 metallic glass. Moreover, we investigate the existence of a nonconstant periodic solution for plastic dynamical model of bulk metallic glasses by using Manásevich–Mawhin continuation theorem.

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