Probing structural changes during ductile fracture in metallic glasses via in situ straining inside a MeV transmission electron microscope

Title
Probing structural changes during ductile fracture in metallic glasses via in situ straining inside a MeV transmission electron microscope
Authors
장혜정S.Y. KimW.-J. MoonY.-M. KimE.S.ParkD.H. Kim
Keywords
Metallic glass; In situ straining; Ductile fracture; Shear band; Intrinsic toughening; Transmission electron microscope
Issue Date
2018-09
Publisher
Intermetallics
Citation
VOL 102-100
Abstract
Structural changes in the vicinity of a crack during ductile fracture in various metallic glasses (MGs) with the propensity of forming shear bands were investigated by in situ straining inside a MeV transmission electron microscope (TEM). During tensile loading, a plastic deformation zone with a width of ∼100 nm and shear bands with a width of ∼15 ± 5 nm developed from crack tips of ductile fracture in MGs. In particular, crack propagation by nanovoid formation and coalescence was observed in Ti40Zr29Cu9Ni8Be14 MG with the highest compressive plasticity (∼6.7 ± 0.5%) among the tested MGs, whereas this process was hardly observable in other MGs. This difference may be attributed to atomic scale heterogeneities in Ti40Zr29Cu9Ni8Be14 MG induced by icosahedral short range orders (ISRO), which cause pronounced shear band branching and thus delay fracture process. Meanwhile, no crystallization of MGs even with ISRO or with lower Tx (crystallization onset temperature) was observed during in situ straining inside the MeV TEM and uniaxial tensile test with ribbon samples; a possible effect of normal stress and nanovoid formation during in situ straining is discussed to compare with crystallization during uniaxial compression test of the same MGs. Our study provides an insight into intrinsic toughening of MGs and thus can give useful guidelines on how to delay ductile fracture processes of MGs by tuning nanovoid formation, taking advantage of structural features through customized design of MGs.
URI
http://pubs.kist.re.kr/handle/201004/68221
ISSN
0966-9795
Appears in Collections:
KIST Publication > Article
Files in This Item:
There are no files associated with this item.
Export
RIS (EndNote)
XLS (Excel)
XML


qrcode

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

BROWSE