Shear-band cavities and strain hardening in a metallic glass revealed with phase-contrast x-ray tomography

Liu, C.; Das, A.; Wang, W.; Küchemann, Stefan; Kenesei, Péter; Maaß, R.

doi:10.1016/j.scriptamat.2019.05.021

Cited by 20 publications

(12 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our own conclusion was that the long-range signature measured via nanoindentation hardness maps originated from position-dependent residual stresses, of which the in-plane component is known to cause changes in the measured hardness. [66] These residual stresses were proposed to emerge when shear occurs over a non-planar shear-band plane, [27] locally giving rise to either tensile or compressive stress states. That means, no structural change was ascribed to the long-range softening (or hardening).…”

Section: B Effective Barrier Energies Across Numerous Alloy Systemsmentioning

confidence: 99%

“…With the absence of any other internal damage mechanisms, this shear-band aging response should allow a number of serration-cycles that mainly (ignoring moments due to lateral shear) is limited by the physical dimension of the specimen. Final fracture after a small number of serrations must therefore be promoted by other damage processes, such as internal micro-cracking, [26,27] than shear itself. Another consequence of an increasing v XH is therefore that the aging time during reloading shortens, thereby reducing the serration stress-amplitude towards T crit (negative strain-rate sensitivity).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Beyond Serrated Flow in Bulk Metallic Glasses: What Comes Next?

Maaß

2020

Metall Mater Trans A

Self Cite

View full text Add to dashboard Cite

This manuscript is based on an oral contribution to the TMS 2020 annual meeting and is dedicated to Prof. Peter Liaw, who for decades has shown great interest in serrated plastic flow. Here we will focus on the case of bulk metallic glasses, and begin with briefly summarizing some aspects of serrated and non-serrated inhomogeneous flow—a phenomenon that has perplexed materials scientists for decades. Four directions of research are identified that emerged out of the desire to fundamentally understand the intermittent inhomogeneous flow response. These research directions gear away from the phenomenological stress–strain behavior but put the underlying shear defect into focus. Unsolved problems and future research topics are discussed.

show abstract

Section: B Effective Barrier Energies Across Numerous Alloy Systemsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Beyond Serrated Flow in Bulk Metallic Glasses: What Comes Next?

Maaß

2020

Metall Mater Trans A

Self Cite

View full text Add to dashboard Cite

show abstract

“…These are regions of shear localization that manifest the intrinsic mechanism that mediates plastic deformation in metallic glasses [18][19][20]. Considerable effort has been dedicated a e-mail: urbassek@rhrk.uni-kl.de (corresponding author) URL: http://www.physik.uni-kl.de/urbassek/ to the understanding of shear-band initiation and propagation [18,[21][22][23]. A shear band is a nanometer-sized plane that undergoes severe shear rearrangements [20] but may reach several hundred micrometers into the amorphous matrix [24][25][26].…”

Section: Introductionmentioning

confidence: 99%

“…The severe shear rearrangement causes the disruption of the icosahedral network and leads to significant density changes [27,28]. Shear bands generated with various deformation mechanisms have been studied both experimentally [18,[21][22][23]29] and in simulations [30][31][32][33][34][35][36][37]. For the case of cutting simulations, the formation of a series of equidistant parallel shear bands in straight chips has been reported [6][7][8][9]; earlier cutting simulations [38][39][40] focused on the determination of cutting forces and did not report on the plasticity mechanisms.…”

Section: Introductionmentioning

confidence: 99%

Transition to chip serration in simulated cutting of metallic glasses

2021

View full text Add to dashboard Cite

Cutting of metallic glasses produces as a rule serrated and segmented chips in experiments, while atomistic simulations produce straight unserrated chips. We demonstrate here that with increasing depth of cut – with all other parameters unchanged – chip serration starts to affect the morphology of the chip also in molecular dynamics simulations. The underlying reason is the shear localization in shear bands. As the distance between shear bands increases with increasing depth of cut, the surface morphology of the chip becomes increasingly segmented. The parallel shear bands that formed during cutting do no longer interact with each other when their separation is $$\gtrsim $$ ≳ 10 nm. Our results are analogous to the so-called fold instability that has been found when machining nanocrystalline metals. Graphic abstract

show abstract

“…Nowadays, many synchrotron beamlines dedicated to imaging worldwide use established x-ray phase-contrast methods to generate two-and three-dimensional data for the visualization of the internal structure of specimens at different length scales, with applications in a broad range of disciplines, including materials science, biomedical imaging, paleontology, and geology (see, e.g., Refs. [12][13][14][15][16][17]). However, synchrotron sources are large-scale facilities with competitive access, and the use of x-ray phase-contrast imaging is still limited to a restricted user community.…”

Section: Introductionmentioning

confidence: 99%

X-ray phase imaging with the unified modulated pattern analysis of near-field speckles at a laboratory source

Zdora¹,

Zanette²,

Walker³

et al. 2020

Appl. Opt.

View full text Add to dashboard Cite

X-ray phase-contrast techniques are powerful methods for discerning features with similar densities, which are normally indistinguishable with conventional absorption contrast. While these techniques are well-established tools at large-scale synchrotron facilities, efforts have increasingly focused on implementations at laboratory sources for widespread use. X-ray speckle-based imaging is one of the phase-contrast techniques with high potential for translation to conventional x-ray systems. It yields phase-contrast, transmission, and dark-field images with high sensitivity using a relatively simple and cost-effective setup tolerant to divergent and polychromatic beams. Recently, we have introduced the unified modulated pattern analysis (UMPA) [Phys. Rev. Lett. 118, 203903 (2017)], which further simplifies the translation of x-ray speckle-based imaging to low-brilliance sources. Here, we present the proof-of-principle implementation of UMPA speckle-based imaging at a microfocus liquid-metal-jet x-ray laboratory source.

show abstract

Shear-band cavities and strain hardening in a metallic glass revealed with phase-contrast x-ray tomography

Cited by 20 publications

References 39 publications

Beyond Serrated Flow in Bulk Metallic Glasses: What Comes Next?

Beyond Serrated Flow in Bulk Metallic Glasses: What Comes Next?

Transition to chip serration in simulated cutting of metallic glasses

X-ray phase imaging with the unified modulated pattern analysis of near-field speckles at a laboratory source

Contact Info

Product

Resources

About