Mapping of residual strains around a shear band in bulk metallic glass by nanobeam X-ray diffraction

Shahabi, H. Shakur; Scudino, Sergio; Kaban, I.; Stoica, M.; Escher, B.; Menzel, S.; Vaughan, Gavin; Kühn, U.; Eckert, J.

doi:10.1016/j.actamat.2016.03.035

Cited by 54 publications

(31 citation statements)

References 39 publications

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“…The long‐range stress fields proposed by Maass were thought to originate from the inherent shear‐band plane roughness (geometric incompatibility stresses), giving locally rise to compressive or tensile stresses that are frozen‐in at the moment the shear‐band propagation is arrested . Reports using X‐ray diffraction were able to support the existence of a long‐range signature by mapping out residual strain fields extending over tens of micrometers away from the shear‐band core or around shear bands in a damage zone ahead of a crack tip . Further proof was provided by Vinogradov et al, who experimentally determined a strain‐distribution map that was in good agreement with theoretically predicted displacement fields known for dislocations, as well as by Binkowski et al by local strain mapping …”

Section: Elastic and Structural Fluctuations Introduced By Deformationmentioning

confidence: 72%

“…To separate a long‐range distortion and/or structural damage, particularly when experiments are based on nanoindentation, is practically impossible. Also with X‐ray scattering, as presented by Shakur Shahabi et al, it is very challenging to reveal structural changes or gradients in the disordered solid away from the shear‐band core. A recent effort by Küchemann et al aimed at shedding additional light onto this matter by conducing site‐specific X‐ray photon correlation spectroscopy (XCPS) measurements on an as‐cast and deformed Zr 65 Cu 25 Al 10 MG.…”

Section: Elastic and Structural Fluctuations Introduced By Deformationmentioning

confidence: 99%

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Elastic Fluctuations and Structural Heterogeneities in Metallic Glasses

Liu

Maaß

2018

Adv Funct Materials

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Suppressing crystallization of a metallic melt results in a disordered solid, also known as a metallic glass. One may conclude that a metallic glass is free of defined structural length scales beyond some atomic-scale value that characterizes short-and medium-range order. While it is well known from atomistic modeling that a metallic glass is structurally heterogeneous, heterogeneities at such a small length scale can hardly be resolved in experiments. This review highlights experimental insights into elastic fluctuations and structural heterogeneities that emerge at scales between a few nanometers and tens to hundreds of micrometers. It distinguishes between structural and property fluctuations in as-cast metallic glasses, and heterogeneities introduced by elastic and inhomogeneous plastic deformation. As-cast glasses reveal elastic fluctuations across 3 orders of magnitude, suggesting a hierarchy of length scales that can be tuned by thermomechanical processing. Similarly, nanoscale strain localization into shear bands drives the formation of structural and elastic heterogeneities at both the nano-and the microscale. It is proposed that both types of fluctuations will allow one to quantitatively define structure-property relationships via measurable length scales-an approach that has largely contributed to the engineering success of crystalline metals.

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Section: Elastic and Structural Fluctuations Introduced By Deformationmentioning

confidence: 72%

Section: Elastic and Structural Fluctuations Introduced By Deformationmentioning

confidence: 99%

Elastic Fluctuations and Structural Heterogeneities in Metallic Glasses

Liu

Maaß

2018

Adv Funct Materials

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“…The width of the heat affected zone around a shear band is much larger 1 , 7 , and the liquid-like layer in the vicinity of a shear band can be as thick as a few micrometers 3 , 8 . In addition, radiotracer diffusion 5 , 9 , nanoindentation 10 – 13 , X-ray photon correlation spectroscopy 14 , and nanobeam X-ray diffraction 15 , 16 all imply a wider region is affected rather than the nanoscale shear band itself. Nonetheless, a variety of values on the width of the affected zone around a shear band have been deduced, ranging from submicrometer to hundreds of micrometers by different techniques 10 – 17 .…”

Section: Introductionmentioning

confidence: 99%

Shear-band affected zone revealed by magnetic domains in a ferromagnetic metallic glass

Shen

Luo

et al. 2018

Nat Commun

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Plastic deformation of metallic glasses (MGs) has long been considered to be confined to nanoscale shear bands, but recently an affected zone around the shear band was found. Yet, due to technical limitations, the shear-band affected zone (SBAZ), which is critical for understanding shear banding and design of ductile MGs, has yet to be precisely identified. Here, by using magnetic domains as a probe with sufficiently high sensitivity and spatial resolution, we unveil the structure of SBAZs in detail. We demonstrate that shear banding is accompanied by a micrometer-scale SBAZ with a gradient in the strain field, and multiple shear bands interact through the superimposition of SBAZs. There also exists an ultra-long-range gradual elastic stress field extending hundreds of micrometers away from the shear band. Our findings provide a comprehensive picture on shear banding and are important for elucidating the micro-mechanisms of plastic deformation in glasses.

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“…30 Similarly, plastic deformation can induce residual strains. 31,32 Frequently, these strain distributions are inhomogeneous, yielding MG "composites" with soft and hard areas that show an increased ductility. 18,19 Different approaches have been proposed for measuring the ellipticity in electron diffraction patterns of nanocrystalline and amorphous materials.…”

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confidence: 99%

Local nanoscale strain mapping of a metallic glass during in situ testing

Gammer

Ophus

Pekin

et al. 2018

Applied Physics Letters

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The local elastic strains during tensile deformation in a CuZrAlAg metallic glass are obtained by fitting an elliptic shape function to the characteristic amorphous ring in electron diffraction patterns. Scanning nanobeam electron diffraction enables strain mapping with a resolution of a few nanometers. Here, a fast direct electron detector is used to acquire the diffraction patterns at a sufficient speed to map the local transient strain during continuous tensile loading in situ in the transmission electron microscope. The elastic strain in tensile direction was found to increase during loading. After catastrophic fracture, a residual elastic strain that relaxes over time was observed.

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Mapping of residual strains around a shear band in bulk metallic glass by nanobeam X-ray diffraction

Cited by 54 publications

References 39 publications

Elastic Fluctuations and Structural Heterogeneities in Metallic Glasses

Elastic Fluctuations and Structural Heterogeneities in Metallic Glasses

Shear-band affected zone revealed by magnetic domains in a ferromagnetic metallic glass

Local nanoscale strain mapping of a metallic glass during in situ testing

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