Correlation between the elastic modulus and the intrinsic plastic behavior of metallic glasses: The roles of atomic configuration and alloy composition

Cheng, Yongqiang; Cao, Ajing; Ma, E.

doi:10.1016/j.actamat.2009.03.027

Cited by 343 publications

(170 citation statements)

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“…Both size-dependent [3,[7][8][9][10] and size-independent [12][13][14] shear banding behaviors in MG nanorods have been reported in experiments. Moreover, MD simulations on two-dimensional or threedimensional thin-slab geometry [15,16] show clear shear band formation, while MD simulations on three-dimensional nanowire samples show homogeneous flow [17,18]. Recently, Shi [11] proposed a new numerical sample preparation procedure termed "simulated casting", during which a molten liquid confined in a cylindrical container is quenched directly into a glassy nanowire.…”

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“…The force field parameters were fitted to match ab initio calculations of over thousands of configurations including various crystalline, liquid and glassy states. This ZrCuAl EAM potential has been validated against a large array of experimental and ab inito data, and has been extensively used to investigate the atomic-level structure, formation and deformation mechanisms of ZrCuAl bulk metallic glasses [16,18,20].…”

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Dominant shear bands observed in amorphous ZrCuAl nanowires under simulated compression

2012

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We observed the formation of dominant shear bands in model ZrCuAl metallic glass (MG) nanowires (18-nm-long) in molecular dynamics simulations, which implies size-independent incipient plasticity in MG materials. The MG nanowires were prepared using the simulated casting technique to ensure proper relaxation of sample surfaces. Under uniaxial compression, shear bands initiate at the surfaces and lead to reduced icosahedral short-range order. The shear band formation is sensitive to sample thermal-history, which calls for careful consideration of sample preparation effects in both experimental and numerical studies of sizeeffect in MG samples.Metallic glasses (MG), unlike other forms of glasses, have distinctive mechanical properties including large elastic strain limit and high tensile strength [1,2]. Metallic glasses, however, suffer from catastrophic failure upon free propagating shear bands. The formation of localized shear bands strongly compromises the practical usages of the metallic glasses for load-bearing applications. One promising way to overcome this shortcoming of metallic glasses is to reduce the sample size of MGs using Focused Ion Beam (FIB) [3] or hot extension [4]. It has been shown that MG in the form of nanowires can exhibit large tensile strain [5,6]. This is thought to be due to the limited spatial scale of nanowires which is insufficient for shear band propagation and maturation into runaway cracks [1].Although shear band propagation and maturation into cracks are likely size-dependent [1], it is still not clear whether the initiation of shear bands (incipient plasticity) is size-dependent. Both size-dependent [3,7-10] and size-independent [12-14] shear banding behaviors in MG nanorods have been reported in experiments. Moreover, MD simulations on two-dimensional or threedimensional thin-slab geometry [15,16] show clear shear band formation, while MD simulations on three-dimensional nanowire samples show homogeneous flow [17,18]. Recently, Shi [11] proposed a new numerical sample preparation procedure termed "simulated casting", during which a molten liquid confined in a cylindrical container is quenched directly into a glassy nanowire. This sample preparation technique is advantageous in comparison to the conventional cut-form-bulk procedure to obtain nanowire samples in computer simulation. Surfaces resulting from the traditional cut-from-bulk procedure are usually not sufficiently relaxed at the processing temperature, whereas in the simulated casting technique, surfaces are created from the melt directly and atoms on the surfaces are fully relaxed. For MG nanowires obtained from the cut-frombulk procedure, homogeneous deformation followed by necking was observed owing to unrelaxed surfaces [11]. By contrast, it was shown that MG nanowires obtained from the simulated casting, thus with relaxed surfaces, exhibit shear banding with a sample length longer than 13 nm, as a result of competition between elastic energy and shear band energy [11]. Interestingly, this critical length va...

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Dominant shear bands observed in amorphous ZrCuAl nanowires under simulated compression

2012

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“…A highly inhomogeneous deformation mode resulting in a major shear band has been observed in two-dimensional 4,19 and threedimensional thin-slab samples. 5,20,21 Nonetheless, cylindrical-shaped samples, which are most relevant to experiments, have shown nearly homogeneous flow until necking at high strains 22,23 and only exhibit shear bands upon the introduction of a surface notch. 24,25 The central question is whether the emergence of a shear band is a result of special dimensionality or sample geometry, and whether the absence of shear bands in cylindrical samples is due to the small sample size.…”

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Size-independent shear band formation in amorphous nanowires made from simulated casting

Shi

2010

Applied Physics Letters

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Molecular dynamics simulations indicate that surfaces strongly influence the strain localization behavior of amorphous nanowires in tension. A sample preparation routine that simulates casting was employed to facilitate the relaxation of the sample surface. Samples as short as 15 nm (7.5 nm in diameter)form dominant shear bands during deformation. The elastic energy release during plastic deformation is sufficient to provide the excess potential energy required for the shear band nucleation at rather small sample sizes. The results show that shear band formation is almost size-independent and is bounded only by its own length scale.

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“…Такие структурные изменения были объяснены с точки зрения свободного объема и конфигураци-онной потенциальной энергии [75,76]. Компью-терное моделирование показало, что изменения скорости охлаждения сплава Cu-Zr сопровожда-лись изменением доли икосаэдрических кластеров и их влиянием на пластичность [77].…”

Section: рис 2 схематическое изображение полос сдвигаunclassified

“…Также добавление элемента, повышаю-щего ν, обуславливает образование потенциально пластичного ОМС [78]. Изменение состава ОМС Zr 63-x Cu 24 Al x Ni 10 Co 3 , приводящее к соответствую-щим изменениям модуля упругости, объясняет ва-риации механических свойств с точки зрения внут-ренних структурных изменений [77], которые мо-гут быть весьма значительными [79]. Влияние ма-лой концентрации алюминия на упругие и пласти- Когда пространственно-однородное изменение температуры происходит в образце, имеющем в со-ставе более одной фазы, или поликристалличе-ском образце некубической фазы (с сильной ани-зотропией теплового расширения-сжатия), то де-формация неоднородна.…”

Section: рис 2 схематическое изображение полос сдвигаunclassified

Properties of Bulk Metallic Glasses

Luzgin¹,

Polkin²

2016

Izv.VUZ. Tsvet. Met.

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Металловедение и термическая обработка Izvestiya vuzov. Tsvetnaya metallurgiya • 6 • 2016 71 ВведениеМеталлические стекла, получаемые в виде тон-ких чешуек или лент, известны со второй полови-ны прошлого века [1]. Объемные металлические стекла (ОМС) с минимальным размером порядка 100-102 мм в каждом из 3 пространственных из-мерений [2] изначально были получены в системах Pd-Cu-Si и Pd-Ni-P, но ввиду исключительной дороговизны основного компонента (палладия) долгое время не представляли особого интере-са для ученых и инженеров. Впоследствии ОМС, полученные во многих других системах, включая технологически важные -на основе Fe, Mg, Ti и За последние несколько десятилетий открыто относительно небольшое число революционных материалов в области ме-талловедения и физики металлов, и объемные металлические стекла одни из них. Их прочность и твердость значительно выше, а модуль упругости ниже, чем кристаллических сплавов, что приводит к высокой энергии запасенной упругой деформации. Эти материалы также имеют очень хорошую устойчивость к коррозии. В настоящей работе исследованы свойства объемных металлических стекол, в частности тепловые, механические, магнитные, электрические показатели и коррозионная стойкость, а также приводятся области применения данных сплавов. Louzguine-Luzgin D.V., Pol'kin V.I. Properties of bulk metallic glassesA relatively small number of revolutionary discoveries were made in the field of metallurgy and metal physics in the last few decades, and bulk metallic glasses are one of them. The strength and hardness of bulk metallic glasses are much higher while moduli of elasticity are lower than those of crystalline alloys which results in high stored elastic strain energy. These alloys also have very good corrosion resistance. This article covers various properties of bulk metallic glasses, in particular thermal, mechanical, magnetic, electrical properties and corrosion resistance as well as applications of these alloys.Keywords: bulk metallic glasses, strength, ductility, application.

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Correlation between the elastic modulus and the intrinsic plastic behavior of metallic glasses: The roles of atomic configuration and alloy composition

Cited by 343 publications

References 50 publications

Dominant shear bands observed in amorphous ZrCuAl nanowires under simulated compression

Dominant shear bands observed in amorphous ZrCuAl nanowires under simulated compression

Size-independent shear band formation in amorphous nanowires made from simulated casting

Properties of Bulk Metallic Glasses

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