Plastic Deformation of Bulk Amorphous Alloys

2000 ◽  
Vol 644 ◽  
Author(s):  
L.Q. Xing ◽  
T.C. Hufnagel ◽  
K.T. Ramesh
Keyword(s):  
Plastic Deformation ◽  
Plastic Strain ◽  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Serrated Flow ◽  
Perfectly Plastic ◽  
Elastic Loading ◽  
The Difference ◽  
Elastic Perfectly Plastic

AbstractWe have studied plastic deformation, including “serrated flow,” of bulk metallic glasses under quasi-static uniaxial compression. The deformation response is essentially elastic-perfectly plastic, but the “plastic” deformation actually consists of sections of elastic loading separated by abrupt load drops. The load drops are due to the formation of shear bands, which represent the primary mechanism of plastic deformationIn Zr-Ti-Cu-Ni-Al bulk metallic glasses, fracture occurs after about 1-2% plastic strain, but in Zr-Ta-Cu-Ni-Al metallic glass the plastic strain to failure can be as large as 6-7%. The difference appears to be due a strong tendency for the shear bands in this alloy to branch. The branching presumably reduces the stress concentration on the shear bands, retarding the onset of fracture. No evidence is seen for the formation of crystalline phases in this alloy.

scholarly journals The Prospects for Mechanical Ratcheting of Bulk Metallic Glasses

2003 ◽  
Vol 806 ◽  
Author(s):  
Wendelin J. Wright ◽  
R. H. Dauskardt ◽  
W. D. Nix
Keyword(s):  
Plastic Strain ◽  
Metallic Glasses ◽  
Room Temperature ◽  
Tensile Axis ◽  
Uniaxial Stress ◽  
Temperature Deformation ◽  
Steel Alloys ◽  
Cyclic Torsion ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

ABSTRACTThe major mechanical shortcoming of metallic glasses is their limited ductility at room temperature. Monolithic metallic glasses sustain only a few percent plastic strain when subjected to uniaxial compression and essentially no plastic strain under tension. Here we describe a room temperature deformation process that may have the potential to overcome the limited ductility of monolithic metallic glasses and achieve large plastic strains. By subjecting a metallic glass sample to cyclic torsion, the glass is brought to the yield surface; the superposition of a small uniaxial stress (much smaller than the yield stress) should then produce increments in plastic strain along the tensile axis. This accumulation of strain during cyclic loading, commonly known as ratcheting, has been extensively investigated in stainless and carbon steel alloys, but has not been previously studied in metallic glasses. We have successfully demonstrated the application of this ratcheting technique of cyclic torsion with superimposed tension for polycrystalline Ti–6Al–4V. Our stability analyses indicate that the plastic deformation of materials exhibiting elastic–perfectly plastic constitutive behavior such as metallic glasses should be stable under cyclic torsion, however, results obtained thus far are inconclusive.

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.

Instrumented indentation study of plastic deformation in bulk metallic glasses

2006 ◽  
Vol 21 (1) ◽  
pp. 75-81 ◽  
Author(s):  
W.H. Li ◽  
T.H. Zhang ◽  
D.M. Xing ◽  
B.C. Wei ◽  
Y.R. Wang ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Metallic Glasses ◽  
Deformation Behavior ◽  
Loading Rate ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Plastic Deformation Zone ◽  
Instrumented Indentation ◽  
Depth Sensing ◽  
Plastic Deformation Behavior

Mechanical properties and micro-plastic deformation behavior of five bulk metallic glasses (BMGs) were studied by instrumented indentation. These materials included La60Al10Ni10Cu20, Mg65Cu25Gd10, Zr52.5Al10Ni10Cu15Be12.5, Cu60Zr20Hf10Ti10, and Ni60Nb37Sn3 alloys. Remarkable difference in deformation behavior was found in the load–displacement curves of nanoindentation and pileup morphologies around the indents. Serrated plastic deformation depended on the loading rate was found in Mg-, Zr-, and Cu-based BMGs. The subsurface plastic deformation zone of typical alloys was investigated through bonded interface technique using depth-sensing microindentation. Large and widely spaced shear bands were observed in Mg-based BMG. The effect of loading rate on the indentation deformation behaviors in different BMGs was elucidated by the change of shear band pattern.

Defect Analyses of Deformed Zr-Cu-Ni-Al Bulk Metallic Glasses

2009 ◽  
Vol 283-286 ◽  
pp. 453-457
Author(s):  
Jung Hoon Yoo ◽  
Dae Hwang Yoo ◽  
Jung Hwa Seo ◽  
Ji Ling Dong ◽  
Young Sang Na ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plastic Deformation ◽  
Metallic Glasses ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
Electron Holography ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Localized Plastic Deformation

In Zr-Cu-Ni-Al bulk metallic glasses where there are no dislocations, localized plastic deformation in shear bands occurs largely by the formation and migration of defects such as voids, micropores, shear bands and local variations in composition. Thus, the investigation on defects is critical for the understanding and improvement of plastic deformation in metallic glasses. In this study, microstructures and nano defects in the Zr-Cu-Ni-Al BMGs are characterized by variety of techniques, such as X-ray diffractometry, high resolution transmission electron microscopy, scanning transmission electron microscopy and electron holography.

Deformation behaviors and mechanism of Ni–Co–Nb–Ta bulk metallic glasses with high strength and plasticity

2007 ◽  
Vol 22 (4) ◽  
pp. 869-875 ◽  
Author(s):  
Y.H. Liu ◽  
G. Wang ◽  
M.X. Pan ◽  
P. Yu ◽  
D.Q. Zhao ◽  
...  
Keyword(s):  
Metallic Glasses ◽  
Flow Behavior ◽  
Shear Bands ◽  
Bulk Metallic Glasses ◽  
High Strength ◽  
Serrated Flow ◽  
Crystalline Materials ◽  
Glass Forming ◽  
Deformation Behaviors ◽  
Strength And Plasticity

A class of Ni–Co–Nb–Ta bulk metallic glasses (BMGs) with a high glass-forming ability is developed. With proper compositional modification, the BMGs exhibit the enhanced plastic strain (up to 4%) and the ultimate strength (up to 3540 MPa). It is found that the interactions of shear bands such as intersecting, arresting, and branching, which normally are related to the plastic metallic glasses, can be observed both in the plastic and brittle Ni–Co–Nb–Ta BMGs. Obvious serrated flow behavior is observed during plastic deformation. The origins of the plasticity and the serrated flow in the Ni-based BMGs are analyzed in analogy to that in crystalline materials.

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

Crushing of an Elastic-Perfectly Plastic Ring or Tube Between Two Planes

1987 ◽  
Vol 54 (1) ◽  
pp. 159-164 ◽  
Author(s):  
C. Y. Wang
Keyword(s):  
Plastic Deformation ◽  
Numerical Integration ◽  
Mathematical Problem ◽  
Plastic Ring ◽  
Perfectly Plastic ◽  
Analytical Approximations ◽  
Original Shape ◽  
Thin Ring ◽  
Elastic Perfectly Plastic

A thin ring is crushed between two rigid planes. Due to plastic deformation the ring does not recover its original shape when the compression is removed. For an elastic-perfectly plastic flexural material, the ring undergoes two to five different stages. The mathematical problem is formulated and solved by exact numerical integration and accurate analytical approximations.

Structural features of plastic deformation in bulk metallic glasses

2015 ◽  
Vol 106 (3) ◽  
pp. 031903 ◽  
Author(s):  
S. Scudino ◽  
H. Shakur Shahabi ◽  
M. Stoica ◽  
I. Kaban ◽  
B. Escher ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Metallic Glasses ◽  
Bulk Metallic Glasses ◽  
Structural Features
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