|Dilatancy induced ductile-brittle transition of shear band in metallic glasses|
|曾繁.蒋敏强; Dai LH(戴兰宏)
|Source Publication||PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
|Abstract||Dilatancy-generated structural disordering, an inherent feature of metallic glasses (MGs), has been widely accepted as the physical mechanism for the primary origin and structural evolution of shear banding, as well as the resultant shear failure. However, it remains a great challenge to determine, to what degree of dilatation, a shear banding will evolve into a runaway shear failure. In this work, using in situ acoustic emission monitoring, we probe the dilatancy evolution at the different stages of individual shear band in MGs that underwent severely plastic deformation by the controlled cutting technology. A scaling law is revealed that the dilatancy in a shear band is linearly related to its evolution degree. A transition from ductile-to-brittle shear bands is observed, where the formers dominate stable serrated flow, and the latter lead to a runaway instability (catastrophe failure) of serrated flow. To uncover the underlying mechanics, we develop a theoretical model of shear-band evolution dynamics taking into account an atomic-scale deformation process. Our theoretical results agree with the experimental observations, and demonstrate that the atomic-scale volume expansion arises from an intrinsic shear-band evolution dynamics. Importantly, the onset of the ductile-brittle transition of shear banding is controlled by a critical dilatation.|
|WOS Keyword||FREE-VOLUME MODEL
; INHOMOGENEOUS DEFORMATION
|WOS Research Area||Science & Technology - Other Topics
|WOS Subject||Multidisciplinary Sciences
|Funding Organization||National Key Research and Development Program of China(2017YFB0702003)
; Strategic Priority Research Program of the Chinese Academy of Sciences(XDB22040302)
; Key Research Program of Frontier Sciences of the Chinese Academy of Sciences(QYZDJSSW-JSC011)
曾繁.蒋敏强,Dai LH. Dilatancy induced ductile-brittle transition of shear band in metallic glasses[J]. PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES,2018,474(2212).
曾繁.蒋敏强,&戴兰宏.(2018).Dilatancy induced ductile-brittle transition of shear band in metallic glasses.PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES,474(2212).
曾繁.蒋敏强,et al."Dilatancy induced ductile-brittle transition of shear band in metallic glasses".PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES 474.2212(2018).
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