In Situ X-Ray Observations of Dendritic Fragmentation During Directional Solidification of a Sn-Bi Alloy

Gibbs, John W.; Tourret, Damien; Gibbs, Paul J.; Imhoff, Seth D.; Gibbs, Meghan Jane; Walker, Brandon A.; Fezzaa, Kamel; Clarke, Amy J.

doi:10.1007/s11837-015-1646-7

Cited by 28 publications

(19 citation statements)

References 28 publications

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“…3(b,c) . A similar behavior was recently observed via in situ X-ray radiography for Sn-Bi dendrites 63 that were solidified parallel to gravity, in which the heavy elements formed large plumes ahead of the growth front. These plumes disturbed the stability of the growing dendrites, such that their growth velocity was highly inconsistent over time.…”

Section: Discussionsupporting

confidence: 82%

Probing the growth and melting pathways of a decagonal quasicrystal in real-time

Han

Xiao

Shahani

2017

Sci Rep

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How does a quasicrystal grow? Despite the decades of research that have been dedicated to this area of study, it remains one of the fundamental puzzles in the field of crystal growth. Although there has been no lack of theoretical studies on quasicrystal growth, there have been very few experimental investigations with which to test their various hypotheses. In particular, evidence of the in situ and three-dimensional (3D) growth of a quasicrystal from a parent liquid phase is lacking. To fill-in-the-gaps in our understanding of the solidification and melting pathways of quasicrystals, we performed synchrotron-based X-ray imaging experiments on a decagonal phase with composition of Al-15at%Ni-15at%Co. High-flux X-ray tomography enabled us to observe both growth and melting morphologies of the 3D quasicrystal at temperature. We determined that there is no time-reversal symmetry upon growth and melting of the decagonal quasicrystal. While quasicrystal growth is predominantly dominated by the attachment kinetics of atomic clusters in the liquid phase, melting is instead barrier-less and limited by buoyancy-driven convection. These experimental results provide the much-needed benchmark data that can be used to validate simulations of phase transformations involving this unique phase of matter.

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Section: Discussionsupporting

confidence: 82%

Probing the growth and melting pathways of a decagonal quasicrystal in real-time

Han

Xiao

Shahani

2017

Sci Rep

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“…Ignoring differences between the conditions already discussed above, it is striking that the normalised shape of the four distributions were similar. The distribution shape was similar to the fragmentation distributions recently reported for a Sn-Bi alloy 23 .…”

Section: Dendrite Fragmentation Distributionsupporting

confidence: 88%

“…Other subtleties may lie in the data, such as bi-modality or systematic differences in the position of peak fragmentation, but even with this comparatively large data set, further inferences were not supported safely by the data. Considering the present work and other recent comparable studies 23 , it is clear that a peak in fragmentation rate hundreds of microns into the mushy zone is a characteristic feature of quasi-static columnar dendritic arrays, independent ofsolidification direction or the presence or strength of an applied external field.…”

Section: Dendrite Fragmentation Distributionsupporting

confidence: 81%

The spatial and temporal distribution of dendrite fragmentation in solidifying Al-Cu alloys under different conditions

et al. 2016

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The directional columnar solidification of Al-Cu alloy dendrites was studied in-situ by synchrotron X-ray radiography to investigate the spatial and temporal distribution of dendrite fragmentation, without and with an applied pulsed electromagnetic field (PEMF) and in different solidification directions. The differing arrangements had a strong and reproducible influence on fragmentation behaviour that was rationalised using a model of solute-driven remelting of dendrite arms in microstructural regions of high vulnerability. Although absolute rates of fragmentation varied, all the fragmentation distributions had a characteristic peak in fragmentation rate at a distance of 500-800 µm into the mushy zone. Consistent with the need for solute-rich liquid flow for dendrite root re-melting, this peak was explained to occur under conditions where there was both comparatively steep liquid solute concentration gradients, measured directly from the radiographs, and relatively high permeability of the dendrite network to liquid flow.

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“…No facets were observed at the resolution of the images. Eventually the growth process terminates due to reduced driving forces [43] and/or solid diffusivities [44]. (The temperature-dependent Cr supersaturation and diffusion are dealt with further in the Supplemental Material [34].)…”

Section: Dynamic Observation Of Dendritic Quasicrystal Growth Upon Lamentioning

confidence: 99%

Dynamic Observation of Dendritic Quasicrystal Growth upon Laser-Induced Solid-State Transformation

et al. 2020

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We report the laser-induced solid-state transformation between a periodic "approximant" and quasicrystal in the Al-Cr system during rapid quenching. Dynamic transmission electron microscopy allows us to capture in situ the dendritic growth of the metastable quasicrystals. The formation of dendrites during solid-state transformation is a rare phenomenon, which we attribute to the structural similarity between the two intermetallics. Through ab initio molecular dynamics simulations, we identify the dominant structural motif to be a 13-atom icosahedral cluster transcending the phases of matter.

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In Situ X-Ray Observations of Dendritic Fragmentation During Directional Solidification of a Sn-Bi Alloy

Cited by 28 publications

References 28 publications

Probing the growth and melting pathways of a decagonal quasicrystal in real-time

Probing the growth and melting pathways of a decagonal quasicrystal in real-time

The spatial and temporal distribution of dendrite fragmentation in solidifying Al-Cu alloys under different conditions

Dynamic Observation of Dendritic Quasicrystal Growth upon Laser-Induced Solid-State Transformation

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