Fracture of Brittle Metallic Glasses: Brittleness or Plasticity

Xi, Xuekui; Zhao, Dongdong; Pan, M. X.; Wang, W. H.; Wu, Yue; Lewandowski, John J.

doi:10.1103/physrevlett.94.125510

Cited by 507 publications

(314 citation statements)

References 29 publications

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“…While the shear response of amorphous solids has received a significant amount of attention in the theoretical physics and molecular simulation literature over the past decade [1-8], significantly less attention has been devoted to hydrostatic loading in such systems [9,10]. This omission appears significant since experimental studies in metallic glass (MG) and other amorphous solids reveal nanocavities [11,12] that form during or subsequent to deformation and strongly implicate cavitation in the physics of the fracture process zone, even when the fracture behavior is relatively brittle [13][14][15]. The importance of cavitation in fracture is supported by recent molecular dynamics (MD) simulations in glassy Cu 50 Zr 50 and Fe 80 P 20 [16].…”

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confidence: 99%

Cavitation in Amorphous Solids

Guan

Spector

et al. 2013

Phys. Rev. Lett.

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Molecular dynamics simulations of cavitation in a Zr 50 Cu 50 metallic glass exhibit a waiting time dependent cavitation rate. On short time scales nucleation rates and critical cavity sizes are commensurate with a classical theory of nucleation that accounts for both the plastic dissipation during cavitation and the cavity size dependence of the surface energy. All but one parameter, the Tolman length, can be extracted directly from independent calculations or estimated from physical principles. On longer time scales strain aging in the form of shear relaxations results in a systematic decrease of cavitation rate. The high cavitation rates that arise due to the suppression of the surface energy in small cavities provide a possible explanation for the quasibrittle fracture observed in metallic glasses. DOI: 10.1103/PhysRevLett.110.185502 PACS numbers: 63.50.Lm, 62.20.mm, 64.70.pe Amorphous materials, commonly termed glasses when quenched from the melt, occur in every class of material including ceramics, metals, and polymers. While the shear response of amorphous solids has received a significant amount of attention in the theoretical physics and molecular simulation literature over the past decade [1-8], significantly less attention has been devoted to hydrostatic loading in such systems [9,10]. This omission appears significant since experimental studies in metallic glass (MG) and other amorphous solids reveal nanocavities [11,12] that form during or subsequent to deformation and strongly implicate cavitation in the physics of the fracture process zone, even when the fracture behavior is relatively brittle [13][14][15]. The importance of cavitation in fracture is supported by recent molecular dynamics (MD) simulations in glassy Cu 50 Zr 50 and Fe 80 P 20 [16].Theory and simulation studies have been applied to understand this process in liquids more commonly than in glasses. Two recent studies [17,18] simulated the process of homogeneous nucleation in liquids in comparison with experimental data. These studies observed evidence of the curvature dependence of the surface energy on the measured cavitation rate, an effect that has itself been the subject of a significant amount of study [19][20][21][22]. One particularly notable contribution from simulation was the mapping out of the point at which the gas-liquid spinodal dips below the glass line and the glass must become unstable to cavitation [23].Continuum mechanics approaches to modeling the kinetics of cavitation have been developed over many years by numerous researchers [6,[24][25][26][27][28][29][30]. Often preexisting cavities are assumed to exist due to voids, inclusions, or intersections of grains, and the effect of surface energy is neglected. Various assumptions have been considered regarding the plastic constitutive behavior around the cavity [6,[24][25][26][27][28][29][30]. In these cases, because plastic and elastic energy both scale with the volume of the void, above a critical stress cavity growth becomes unbounded. Here, as in some earlier ...

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confidence: 99%

Cavitation in Amorphous Solids

Guan

Spector

et al. 2013

Phys. Rev. Lett.

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“…However, the deformation behaviors observed for the x=3, 4 alloys are very different from those with x=1, 2. Flat facets and flutes with fatal cracks are observed on the fracture surface, as shown in Figure 4(d); these are generally features of brittle materials such as Mg-and Fe-based BMGs [24]. It can be concluded that the alloys have a transition from ductility to brittleness when the Sn content increases from 2 to 3 at.%.…”

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Effect of Sn addition on the glass-forming ability and mechanical properties of Ni-Nb-Zr bulk metallic glasses

Zhang

Wang

et al. 2011

Chin. Sci. Bull.

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The effect of tin (Sn) addition on the glass forming ability (GFA) and mechanical properties of the Ni-Nb-Zr ternary alloy system has been studied. The addition of Sn improves the GFA; Ni 61 Nb 35.5-x Zr 3.5 Sn x (in at.%) alloys with x=1 can be cast into amorphous samples at least 3 mm in diameter using a copper mold injection-casting method. The critical size for glass formation decreases to 2 mm when x=5 because Ni 2 SnZr phase precipitates readily. The addition of Sn is also effective in enhancing the stability of the supercooled liquid; a maximum supercooled liquid region of 48 K was attained for the Ni 61 Nb 30.5 Zr 3.5 Sn 5 alloy. Compression tests reveal that the Ni 61 Nb 33.5 Zr 3.5 Sn 2 alloy possesses the best mechanical properties, with yield strength ~3180 MPa, fracture strength ~3390 MPa and plastic strain ~1.3%. The fracture surfaces examined by scanning electron microscopy indicate that the alloys have a transition from ductility to brittleness in fracture behavior. The combination of high GFA, high thermal stability, high strength and compressive plasticity makes these alloys potentially attractive for engineering applications. Bulk metallic glasses (BMGs) have attracted much attention from scientists and engineers over the past few decades, since they possess such promising properties as high yield strength, hardness and elastic strain limit, along with relatively high fracture toughness, fatigue resistance and corrosion resistance [1][2][3]. In the case of Ni-based alloys, glassy rods up to several millimeters in diameter have been successfully fabricated from many alloy systems, such as, etc. These Ni-based bulk metallic glassy alloys have been reported to exhibit high strength (ranging up to 3000 MPa), high thermal stability (glass transition temperature generally around 880 K) [9,10], and excellent corrosion resistance [11]. The combination of superior properties enables them to have promising applications as engineering materials, such as for pressure sensors and micro-geared motors [12]. However, the achievement of a higher GFA for Ni-based amorphous alloys is still a challenging subject. So far the maximum dimension of Ni-based metallic glassy samples without noble elements is only 5 mm, which is much lower than that for other alloy systems, such as Zr-, Mg-, Ti-, Cu-, or Fe-based BMGs. Furthermore, most of the Ni-based BMGs exhibit a narrow supercooled liquid region (less than 40 K), which is not sufficient for processing. Thus, the development of new Ni-based BMGs with higher GFA as well as wide supercooled liquid region is of great importance. It was reported that BMG samples up to 3 mm were fabricated in the Ni-Nb-Sn [8] and Ni-Nb-Zr [13] alloy systems. The composition regions for glass formation in these simple ternary systems are located in the range of Ni 60 Nb 40-x Sn x (3

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“…Формирование полос сдвиговой деформации [35,36] приводит к появлению ступенек на боко-вой поверхности образца, что показано на рис. 4.…”

Section: рис 2 схематическое изображение полос сдвигаunclassified

“…В случае, когда сдвиг обусловлен релакса-цией упругой энергии образца, значительное по-вышение температуры может возникнуть в резуль-тате локализованного течения. Локальный нагрев в полосах сдвига, в зависимости от температуры, напряжения и скорости деформации, может сти-мулировать переход от неоднородной деформации образца под нагрузкой к однородному течению [35,40]. И тем не менее есть основания полагать, что значительный нагрев образца происходит толь-ко в местах концентрации полос сдвига -вблизи микротрещин или у поверхности разрушения [39].…”

Section: рис 2 схематическое изображение полос сдвигаunclassified

“…Большинство ОМС показывают умеренно отрицательную темпера-турную зависимость электропроводности, хотя и демонстрируют металлический тип связи. Тем не менее было показано, что температурный коэф-фициент сопротивления стеклообразных сплавов Pd 40 Ni 40-x Cu x P 20 меняется с отрицательного на по-ложительный при увеличении содержания Cu [13]. Значения температуропроводности (а) и тепло-проводности (λ) ОМС при комнатной температуре также представлены в табл.…”

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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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Fracture of Brittle Metallic Glasses: Brittleness or Plasticity

Cited by 507 publications

References 29 publications

Cavitation in Amorphous Solids

Cavitation in Amorphous Solids

Effect of Sn addition on the glass-forming ability and mechanical properties of Ni-Nb-Zr bulk metallic glasses

Properties of Bulk Metallic Glasses

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