Shear band fracture in metallic glass: Hot or cold?

Qu, R.T.; Wang, S.G.; Li, G.J.; Wang, R.F.; Wang, X.D.; Wu, Shaojie; Zhang, Z.F.

doi:10.1016/j.scriptamat.2018.11.003

Cited by 20 publications

(3 citation statements)

References 33 publications

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“…SEM images showing the ribbon fracture morphology are presented in Figure 5. The dented morphology of the amorphous alloy sample was similar to that of other previously reported amorphous alloys [29,30]. Dent size can be positively correlated with plasticity; therefore, the toughness of the Mg 68 Zn 30 Ce 2 sample was superior to that of the Mg 66 Zn 30 Ce 4 sample, which was consistent with the actual results.…”

Section: Microscopic Mechanism Of Ductilitysupporting

confidence: 88%

Effect of Varying Ce Content on the Mechanical Properties and Corrosion Resistance of Low-Elastic-Modulus Mg-Zn-Ce Amorphous Alloys

Wang

Zhang

et al. 2022

Metals

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Magnesium alloys have good biocompatibility because they have mechanical properties similar to those of human bones, are biodegradable, and release non-toxic corrosion products and ions in the human body. In this study, a new type of Mg70−xZn30Cex (x = 2, 4, 6, and 8) amorphous magnesium alloy was prepared by copper roller melt-spinning, and the corresponding mechanical properties and corrosion resistance were studied. The results showed that when x = 4 and 6, the Mg-Zn-Ce amorphous alloys had decent amorphous forming abilities. The addition of Ce could effectively improve the ductility of the magnesium-based amorphous alloys with an elastic modulus of each sample ranging between 30 and 58 GPa, which was similar to that of human bones; thus, these materials could effectively prevent the stress shielding effect caused by excessive elastic modulus after implantation. Additionally, the addition of an adequate amount of Ce significantly improved the corrosion resistance of the alloy. The experimental results showed that the best corrosion resistance of the magnesium-based amorphous alloys was achieved when x = 6.

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Section: Microscopic Mechanism Of Ductilitysupporting

confidence: 88%

Effect of Varying Ce Content on the Mechanical Properties and Corrosion Resistance of Low-Elastic-Modulus Mg-Zn-Ce Amorphous Alloys

Wang

Zhang

et al. 2022

Metals

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“…Direct experimental evidence of temperature increase within SBs 1 – 4 supported an assumption that during a shear banding event, the temperature might exceed the glass transition temperature (T g ), bringing the material into a viscous state, which enables high shear displacements without rupture. However, it was convincingly demonstrated by several research groups that SBs can also stay cold, suggesting that heating is rather a consequence of rapid plastic deformation than the cause of it 5 – 11 . Another point of discussion is the SB propagation mode.…”

Section: Introductionmentioning

confidence: 99%

How to catch a shear band and explain plasticity of metallic glasses with continuum mechanics

Glushko,

Pippan,

Şopu

et al. 2024

Nat Commun

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Capturing a shear band in a metallic glass during its propagation experimentally is very challenging. Shear bands are very narrow but extend rapidly over macroscopic distances, therefore, characterization of large areas at high magnification and high speed is required. Here we show how to control the shear bands in a pre-structured thin film metallic glass in order to directly measure local strains during initiation, propagation, or arrest events. Based on the experimental observations, a model describing the shear banding phenomenon purely within the frameworks of continuum mechanics is formulated. We claim that metallic glasses exhibit an elastic limit of about 5% which must be exceeded locally either at a stress concentrator to initiate a shear banding event, or at the tip of a shear band during its propagation. The model can successfully connect micro- and macroscopic plasticity of metallic glasses and suggests an alternative interpretation of controversial experimental observations.

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“…The material flow in metallic glasses is a result of shear localization which leads to shear softening [16]. This softening is not caused by thermal effects [17,62,63] but by a volume increase (dilatancy) [16,23,64] which is related to rearrangements of atoms or clusters in space (topology). The material flow taking place in and around an in situ shear band differs from that of bulk samples in the respect that there is the possibility of strain and excess free volume relief (void condensation) towards the free surfaces [7] of the thin electron transparent foil.…”

mentioning

confidence: 99%

A comparison of in- and ex situ generated shear bands in metallic glass by transmission electron microscopy

Rösner,

Kübel,

Ostendorp

et al. 2021

Preprint

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Plastic deformation of metallic glasses performed at temperatures well below the glass transition proceeds via the formation of shear bands. In this contribution shear bands originating from in situ tensile tests of Al 88 Y 7 Fe 5 melt-spun ribbons conducted in a transmission electron microscope are compared with ones which had formed ex situ during cold rolling. The observed contrasts for shear bands generated in situ at the edges of thin electron-transparent foils are shown to be related to a meniscus-like foil thickness reduction. In comparison with ex situ samples, alternating contrast changes due to volume changes are missing and the shear band width is a factor of 15 larger. The meniscus-like shear band profile is accounted for by the thin foil allowing volume increase due to shear deformation to annihilate via the free surfaces of the thin foil and the sheared zones to widen.

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Shear band fracture in metallic glass: Hot or cold?

Cited by 20 publications

References 33 publications

Effect of Varying Ce Content on the Mechanical Properties and Corrosion Resistance of Low-Elastic-Modulus Mg-Zn-Ce Amorphous Alloys

Effect of Varying Ce Content on the Mechanical Properties and Corrosion Resistance of Low-Elastic-Modulus Mg-Zn-Ce Amorphous Alloys

How to catch a shear band and explain plasticity of metallic glasses with continuum mechanics

A comparison of in- and ex situ generated shear bands in metallic glass by transmission electron microscopy

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