Critical Poisson’s ratio for plasticity in Fe–Mo–C–B–Ln bulk amorphous steel

Gu, Xiaojun; McDermott, Amanda G.; Poon, S. J.; Shiflet, G. J.

doi:10.1063/1.2206149

Cited by 211 publications

(141 citation statements)

References 7 publications

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“…2,3,[27][28][29] For metallic glasses that are intrinsically brittle with little or no accumulated strain, they would exhibit far less liquid-like fracture in surface morphologies or diminishing scales in the vein-patterns. 30) Furthermore, the homogeneous deformation as seen in the tensile simulation suggests that the shear localization may not be the only mechanism for deformation in metallic glasses at low temperatures. However, we should realize that maintaining the stringent conditions in experiments as those in the simulation is highly improbable.…”

Section: )mentioning

confidence: 99%

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Free Volume Evolution in Metallic Glasses Subjected to Mechanical Deformation

2007

Mater. Trans.

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We define the Turnbull-Cohen free volume as the critical excess of the Voronoi volume of an atom less its core volume. Using molecular dynamics simulation we calculated the free volume change in two model binary metallic glasses undergoing tension and shear deformation. We show that the free volume change is an integral part of the deformation process; and the shear localization manifested as a shear band is directly related to the inhomogeneous distribution of the free volumes. Shear band formation may consist of two stages: the initial free volume production in the amorphous solids and the liquefaction of the regions with accumulated deformation strains. We show, for the first time, the formation of voids and the ''vein'' patterns on fracture surfaces at atomic scales; they are the combined result of the free volume change and loading and sample conditions.

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Section: )mentioning

confidence: 99%

“…This crucial property and its connection to the free volume change are currently under investigation. 30) …”

Section: )mentioning

confidence: 99%

Free Volume Evolution in Metallic Glasses Subjected to Mechanical Deformation

2007

Mater. Trans.

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“…13,14 Recently, it was reported that the ductility of BMGs was closely related to their Poisson's ratio. [15][16][17] For example, Ptbased BMG with high Poisson's ratio of about 0.41 shows an excellent compressive ductility. 15 Nivikov and Sokolov 18 reported that Poisson's ratio of a glass at room temperature correlates with the fragility of liquids at high temperature.…”

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confidence: 99%

Thermophysical and elastic properties of Cu50Zr50 and (Cu50Zr50)95Al5 bulk-metallic-glass-forming alloys

Fan

Freels

Choo

et al. 2006

Applied Physics Letters

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By employing a containerless high-temperature high-vacuum electrostatic levitation technique, the thermophysical properties, including the ratio between the specific heat capacity and the hemispherical total emissivity, the specific volume, and the viscosity, of Cu 50 Zr 50 and ͑Cu 50 Zr 50 ͒ 95 Al 5 bulk-metallic-glass ͑BMG͒-forming liquids have been measured. Compared with Cu 50 Zr 50 , the improved glass-forming ability of ͑Cu 50 Zr 50 ͒ 95 Al 5 can be attributed to its dense liquid structure and its high value of viscosity. Additionally, the relationship between the viscosity of various BMG forming liquids at the melting temperature and the elastic properties of the corresponding glasses at room temperature will be compared. © 2006 American Institute of Physics. ͓DOI: 10.1063/1.2408634͔The processing, the thermophysical, and mechanical properties of low-cost Cu-based bulk-metallic glasses ͑BMGs͒ have been intensively studied recently. [1][2][3][4][5] The Cubased BMGs exhibit extraordinarily high strength and good compressive ductility, which are comparable with the Zrbased BMGs. In order to frustrate the crystal formation during the copper-mold casting process, previous studies indicate that BMG alloys should typically consist of at least three components, which have varying atomic sizes. 6 However, it was reported recently that binary Cu-Zr alloys can be cast into bulk amorphous structures with sample diameters up to 2 mm. 7-10 Subsequent studies reveal that small amounts of Al additions ͑several at. %͒ further increase its glass-forming ability ͑GFA͒ in the ternary Cu-Zr-Al alloys. 11 Das et al. 12 reported that both Cu 50 Zr 50 and ͑Cu 50 Zr 50 ͒ 95 Al 5 BMGs exhibit good compressive ductility at room temperature. Most strikingly, the Cu 50 Zr 50 and ͑Cu 50 Zr 50 ͒ 95 Al 5 BMGs exhibit "strain hardening" effects during the compressive tests, which were not expected for the BMG alloys since there is no dislocation activities in the amorphous structure. Strain hardening is a desirable factor for the prevention of the strain localization. Nevertheless, the localized deformation within the shear bands was still primarily responsible for the observed plasticity in both Cu 50 Zr 50 and ͑Cu 50 Zr 50 ͒ 95 Al 5 BMGs. 12 Therefore, the precise mechanisms responsible for the plastic deformation of the Cu 50 Zr 50 and ͑Cu 50 Zr 50 ͒ 95 Al 5 BMGs require further investigations. 13,14 Recently, it was reported that the ductility of BMGs was closely related to their Poisson's ratio. [15][16][17] For example, Ptbased BMG with high Poisson's ratio of about 0.41 shows an excellent compressive ductility. 15 Nivikov and Sokolov 18 reported that Poisson's ratio of a glass at room temperature correlates with the fragility of liquids at high temperature. This correlation was recently challenged by Yannopoulos and Johari 19 by compiling extensive experimental data covering various glass-forming systems. In this letter, in an effort to further understand the relationship between the fragility and the elastic properties of glass-...

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“…The Poisson ratio v is considered as an indicator to predicate the ductile-brittle behavior of metallic materials. In some literature, bulk metal glasses are reported to have good ductility with the v > 0.31 [44]. The Poisson ratio of the present HEAs is v = 0.36-0.37.…”

Section: Cubic Elastic Constantsmentioning

confidence: 77%

Ab Initio Predicted Alloying Effects on the Elastic Properties of AlxHf1−xNbTaTiZr High Entropy Alloys

Tian

2015

Coatings

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Abstract:Using ab initio alloy theory, we investigate the equilibrium bulk properties and elastic mechanics of the single bcc solid-solution AlxHf1−xNbTaTiZr (x = 0-0.7, 1.0) high entropy alloys. Ab initio predicted equilibrium volume is consistent with the available experiment. We make a detailed investigation of the alloying effect of Al and Hf on the equilibrium volume, elastic constants and polycrystalline elastic moduli. Results imply that the partial replacement Hf with Al increases the stability of the bcc phase and decreases the ductility of the AlxHf1−xNbTaTiZr HEAs. The inner ductility of Al0.4Hf0.6NbTaTiZr is predicted by the calculations of ideal tensile strength.

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Critical Poisson’s ratio for plasticity in Fe–Mo–C–B–Ln bulk amorphous steel

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Cited by 211 publications

References 7 publications

Free Volume Evolution in Metallic Glasses Subjected to Mechanical Deformation

Free Volume Evolution in Metallic Glasses Subjected to Mechanical Deformation

Thermophysical and elastic properties of Cu50Zr50 and (Cu50Zr50)95Al5 bulk-metallic-glass-forming alloys

Ab Initio Predicted Alloying Effects on the Elastic Properties of AlxHf1−xNbTaTiZr High Entropy Alloys

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