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Article: Elucidating how correlated operation of shear transformation zones leads to shear localization and fracture in metallic glasses: tensile tests on Cu-Zr based metallic-glass microwires, molecular dynamics simulations, and modelling

TitleElucidating how correlated operation of shear transformation zones leads to shear localization and fracture in metallic glasses: tensile tests on Cu-Zr based metallic-glass microwires, molecular dynamics simulations, and modelling
Authors
KeywordsMetallic glass
Shear localization
Stochastic deformation
Shear transformation zones
Shear bands
Issue Date2019
PublisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/ijplas
Citation
International Journal of Plasticity, 2019, v. 119, p. 1-20 How to Cite?
AbstractThe plastic deformation of metallic glasses (MG) is well-known to occur via shear transformation zones (STZs) on the scale of atomic clusters, yet fracture of MG takes place via shear bands of the micron scale. So far, understanding on how the operation of STZs leads to shear localization and fracture remains limited. In this work, tensile tests on Cu/Zr-based MG micro-wires show that both the first-yield and fracture stress exhibit the Weibull distribution, and fractography reveals that shear localization in the form of intense shear bands leads to shear fracture. Molecular dynamics (MD) simulations show that shear bands form via the correlated emergence and operation of discrete STZs close to one another. To describe how the stochastic yet correlated occurrence of the discrete STZs leads to shear localization, a model is constructed to relate the probability of the successive operation of discrete STZs, to their nucleation density. The model predicts that, if nucleation density of the STZs grows along the strain path, as prior shear events triggers the emergence of new STZs, then successive occurrence of discrete shear events speeds up rapidly to an asymptotic state which is exactly the condition of shear localization and shear banding. Furthermore, the MD results suggest an exponential growth law for the occurrence of the STZs along the strain path, which also gives predictions in good agreement with the experimental Weibull distributions of the first-yield stress of Cu/Zr-based MGs.
Persistent Identifierhttp://hdl.handle.net/10722/277348
ISSN
2020 Impact Factor: 7.081
2020 SCImago Journal Rankings: 2.620
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorGan, KF-
dc.contributor.authorJiang, SS-
dc.contributor.authorHuang, YJ-
dc.contributor.authorYin, HBC-
dc.contributor.authorSun, JF-
dc.contributor.authorNgan, AHW-
dc.date.accessioned2019-09-20T08:49:16Z-
dc.date.available2019-09-20T08:49:16Z-
dc.date.issued2019-
dc.identifier.citationInternational Journal of Plasticity, 2019, v. 119, p. 1-20-
dc.identifier.issn0749-6419-
dc.identifier.urihttp://hdl.handle.net/10722/277348-
dc.description.abstractThe plastic deformation of metallic glasses (MG) is well-known to occur via shear transformation zones (STZs) on the scale of atomic clusters, yet fracture of MG takes place via shear bands of the micron scale. So far, understanding on how the operation of STZs leads to shear localization and fracture remains limited. In this work, tensile tests on Cu/Zr-based MG micro-wires show that both the first-yield and fracture stress exhibit the Weibull distribution, and fractography reveals that shear localization in the form of intense shear bands leads to shear fracture. Molecular dynamics (MD) simulations show that shear bands form via the correlated emergence and operation of discrete STZs close to one another. To describe how the stochastic yet correlated occurrence of the discrete STZs leads to shear localization, a model is constructed to relate the probability of the successive operation of discrete STZs, to their nucleation density. The model predicts that, if nucleation density of the STZs grows along the strain path, as prior shear events triggers the emergence of new STZs, then successive occurrence of discrete shear events speeds up rapidly to an asymptotic state which is exactly the condition of shear localization and shear banding. Furthermore, the MD results suggest an exponential growth law for the occurrence of the STZs along the strain path, which also gives predictions in good agreement with the experimental Weibull distributions of the first-yield stress of Cu/Zr-based MGs.-
dc.languageeng-
dc.publisherPergamon. The Journal's web site is located at http://www.elsevier.com/locate/ijplas-
dc.relation.ispartofInternational Journal of Plasticity-
dc.rightsThis work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.-
dc.subjectMetallic glass-
dc.subjectShear localization-
dc.subjectStochastic deformation-
dc.subjectShear transformation zones-
dc.subjectShear bands-
dc.titleElucidating how correlated operation of shear transformation zones leads to shear localization and fracture in metallic glasses: tensile tests on Cu-Zr based metallic-glass microwires, molecular dynamics simulations, and modelling-
dc.typeArticle-
dc.identifier.emailNgan, AHW: hwngan@hku.hk-
dc.identifier.authorityNgan, AHW=rp00225-
dc.description.naturepostprint-
dc.identifier.doi10.1016/j.ijplas.2019.02.011-
dc.identifier.scopuseid_2-s2.0-85061905288-
dc.identifier.hkuros305438-
dc.identifier.volume119-
dc.identifier.spage1-
dc.identifier.epage20-
dc.identifier.isiWOS:000471088600001-
dc.publisher.placeUnited Kingdom-
dc.identifier.issnl0749-6419-

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