Spatial heterogeneity as the structure feature for structure–property relationship of metallic glasses

Zhu, Fan; Song, Shuangxi; Reddy, Kolan Madhav; Hirata, Akihiko; Chen, Mingwei

doi:10.1038/s41467-018-06476-8

Cited by 134 publications

(51 citation statements)

References 52 publications

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“…NMR signal processing was carried out using RMN, version 1.8.6 [50], which uses the dFT normalization convention Q(N) = 1/ √ N. Uncorrelated noise floors were established for both FID and MRE signals based upon Equation (A11) such that the enhancement of the graphitic signal by CPMG is given by Equation (2). A stretched exponential weighting function h(j) = exp[−(2(j + j 0 − 1)/a ) β ] with parameters a = 21281.5 and β = 0.571097, corresponding to the best fit envelope function measured by the integrated (CF) n _gr-PC echo intensities, was used unless otherwise specified.…”

Section: Methodsmentioning

confidence: 99%

“…The microstructure and heterogeneity of materials exert significant influence on their macroscopic properties. The bioavailability of active pharmaceutical ingredients in drugs [1], deformation behavior of metallic glasses [2], progression of strength during cement hydration [3], and electrical properties of carbon composites in Li-ion battery electrodes [4] are just a few of many exemplifying cases. Characterization of microstructure is therefore an important part of establishing structure-property relationships, but doing so in a way that quantifies the number of distinct species present on a molecular basis is challenging.…”

Section: Introductionmentioning

confidence: 99%

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Quantification of Uncoupled Spin Domains in Spin-Abundant Disordered Solids

Walder

Alam

2020

IJMS

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Materials often contain minor heterogeneous phases that are difficult to characterize yet nonetheless significantly influence important properties. Here we describe a solid-state NMR strategy for quantifying minor heterogenous sample regions containing dilute, essentially uncoupled nuclei in materials where the remaining nuclei experience heteronuclear dipolar couplings. NMR signals from the coupled nuclei are dephased while NMR signals from the uncoupled nuclei can be amplified by one or two orders of magnitude using Carr-Meiboom-Purcell-Gill (CPMG) acquisition. The signal amplification by CPMG can be estimated allowing the concentration of the uncoupled spin regions to be determined even when direct observation of the uncoupled spin NMR signal in a single pulse experiment would require an impractically long duration of signal averaging. We use this method to quantify residual graphitic carbon using 13 C CPMG NMR in poly(carbon monofluoride) samples synthesized by direct fluorination of carbon from various sources. Our detection limit for graphitic carbon in these materials is better than 0.05 mol%. The accuracy of the method is discussed and comparisons to other methods are drawn.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantification of Uncoupled Spin Domains in Spin-Abundant Disordered Solids

Walder

Alam

2020

IJMS

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“…In view of their distinct physical and chemical properties, metallic glasses have gained popularity in several scientific disciplines. Advanced synthesis and processing methods have been employed to modify the local structure of these glassy systems by the controlled introduction of defects, such as interfaces and precipitates [4][5][6][7][8][9][10][11][12][13][14] . The absence of long range ordering in metallic glasses complicates the understanding of their local structure 3 .…”

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confidence: 99%

“…Several structural models have been introduced to describe the local structure and to understand the origin of the unusual properties of metallic glasses compared to their crystalline counterparts 4,10 . In addition to long studied dense random packing of hard spheres and 'solid-like' and 'liquid-like' regions in MGs, cluster-based local ordering is a widely accepted model for structurally disordered, yet macroscopically homogeneous systems 11,19 . Tailoring the population of local structural motifs (or building blocks) in a controllable manner may help to improve and engineer selective properties of metallic glasses.…”

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confidence: 99%

Structural insights into metal-metalloid glasses from mass spectrometry

Baksi

Bag

Kruk

et al. 2020

Sci Rep

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Despite being studied for nearly 50 years, smallest chemically stable moieties in the metallic glass (MG) could not be found experimentally. Herein, we demonstrate a novel experimental approach based on electrochemical etching of amorphous alloys in inert solvent (acetonitrile) in the presence of a high voltage (1 kV) followed by detection of the ions using electrolytic spray ionization mass spectrometry (ESI MS). The experiment shows stable signals corresponding to Pd, PdSi and PdSi2 ions, which emerges due to the electrochemical etching of the Pd80Si20 metallic glass electrode. These fragments are observed from the controlled dissolution of the Pd80Si20 melt-spun ribbon (MSR) electrode. Annealed electrode releases different fragments in the same experimental condition. These specific species are expected to be the smallest and most stable chemical units from the metallic glass which survived the chemical dissolution and complexation (with acetonitrile) process. Theoretically, these units can be produced from the cluster based models for the MG. Similar treatment on Pd40Ni40P20 MSR resulted several complex peaks consisting of Pd, Ni and P in various combinations suggesting this can be adopted for any metal-metalloid glass.

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confidence: 99%

Revealing hidden supercooled liquid states in Al-based metallic glasses by ultrafast scanning calorimetry: Approaching theoretical ceiling of liquid fragility

et al. 2019

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Metallic glasses (MGs) are amorphous alloys with a number of unique properties that are attractive for the fundamental understanding of the nature and applications of disordered systems [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Generally, MGs might be grouped into two categories based on their glass forming ability (i.e., the ease of glass formation by cooling a liquid): in one case, large or bulk volumes may be slowly cooled to the glassy state from the melt. This category is usually called as bulk metallic glass formers [18][19][20][21][22]. In contrast, certain MGs, represented by aluminum (Al)- [23,24] and some iron (Fe)- [25,26] based MGs, can be synthesized mainly by rapid solidification processes such as melt spinning or vapor deposition. These MGs are often denoted as marginal MG-formers [23][24][25].With the rapid developments of MGs, many previously identified marginal glass formers have been successfully made into bulk metallic glasses by composition strategies (such as Fe-and Ni-based MGs) [8,25,26,28]. However, one remarkable exception is the family of Al-based MGs [23,24]. Although there have been continuous efforts in optimizing compositions and improving processing techniques since its first discovery [29] several decades ago, the glass forming ability of Al-MGs is still limited nowadays [23,30,31]. Recently, Wu et al. [30] reported that the hitherto best glass forming ability for Al-MGs is from Al 86 Ni 6.75 Co 2.25 Y 3.25 La 1.75 with a fully glassy rod of 1.5 mm in diameter. Although the glassy rod can reach 2.5 mm for the same composition after a refined fluxtreatment of the liquid [31], this critical size is still much smaller than those of typical Zr-based MGs (~75 mm) [32], Mg-MGs (25 mm) [18] and Pd-MGs (80 mm) [33]. Moreover, the glass forming ability of Al-MGs is very sensitive to compositions. Only a few percent change of the constituting elements would dramatically reduce this critical size [21,27,30,34,35]. Consequently, it is more difficult to develop Al-MGs than other MGs. Fundamentally, it remains to be a puzzling issue why the Al-MGs are so unique [27,30,36].Among several factors, one clue for the distinction between bulk glasses and marginal glass formers is based upon their supercooled liquids [19,23,26,27]. The change of the relaxation dynamics (e.g., viscosity, diffusivity or relaxation time) with the temperature is highly materialspecific. Angell introduced the concept of fragility (m) for the classification of glass-forming materials, which was defined as the apparent activation energy of relaxation time τ α normalized to glass transition temperature T g : m = dlog(τ α )/(dT g /T)| T=T g [37]. A stronger deviation from Arrhenius behavior (with a larger m value) corresponds to a more fragile system; otherwise, the system is strong [37][38][39][40]. Wang et al. [41] theoretically pointed out that the fragility index for non-polymeric glasses should have a lower limit m = 16.5, and an upper limit m~175.Recently, Johnson et al.[42] conducted a critical asses...

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Spatial heterogeneity as the structure feature for structure–property relationship of metallic glasses

Cited by 134 publications

References 52 publications

Quantification of Uncoupled Spin Domains in Spin-Abundant Disordered Solids

Quantification of Uncoupled Spin Domains in Spin-Abundant Disordered Solids

Structural insights into metal-metalloid glasses from mass spectrometry

Revealing hidden supercooled liquid states in Al-based metallic glasses by ultrafast scanning calorimetry: Approaching theoretical ceiling of liquid fragility

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