Controlled Formation and Mechanical Characterization of Metallic Glassy Nanowires

Nakayama, Koji S.; Yokoyama, Yoshihiko; Ono, Takahito; Chen, Luyang; Akiyama, Kotone; Sakurai, Takeshi; Inoue, Akihisa

doi:10.1002/adma.200902295

Cited by 47 publications

(47 citation statements)

References 27 publications

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“…Bulk metallic glasses are quite stable in the supercooled state and, after thermal processing, can be slowly cooled back to the strong glassy state with negligible volume shrinkage. Th is outstanding thermal formability of BMGs has recently been exploited for applications in nanotechnology and MEMS [71][72][73][74][75][76][77][78].…”

Section: Nanotechnology and Memsmentioning

confidence: 99%

“…Sputtered BMG fi lms have also been used to fabricate actuators and micro-cantilevers for MEMS applications [74]. Recently, the dimensions of BMG patterns and parts have been further reduced to scales on the order of tens of nanometers by superplastic deformation [76] and thermoplastic forming [78,79]. Metallic glass nanowires fabricated by these methods show interesting multi-harmonic oscillations with possible applications in mechanical and magnetic sensors.…”

Section: Nanotechnology and Memsmentioning

confidence: 99%

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A brief overview of bulk metallic glasses

2011

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Bulk metallic glasses, formed at very low critical cooling rates, are fundamentally diff erent from traditional amorphous alloys, which are usually formed at very high cooling rates in order to suppress the nucleation of crystalline phases. Th e high cooling rates required for the formation of traditional glassy alloys restrict the range of possible structures that can be prepared to powders, fi lms and ribbons. Of the extensive family of glasses, BMGs are probably the youngest, possessing a number of characteristics, such as amorphicity and high strength, that are shared by other glasses, including the most familiar window (oxide) glasses. However, the most important feature of BMGs that, along with other glasses, distinguish them from general amorphous materials is the glass transition that transforms supercooled liquids into a glassy state when cooled from high to low temperature and vice versa. Metallic glasses are therefore scientifi cally defi ned as amorphous alloys that exhibit a glass transition, from which derives their unique properties of extreme strength at low temperature and high fl exibility at high temperature, along with thermodynamic and physical properties that change abruptly at the glass transition temperature (T g ).Research on metallic glasses is closely related to that on metallic liquids. It is known that the atomic confi gurations of molten metals and alloys are disordered. Th e noncrystalline structure is expected to be retained if the liquids can be quenched at a suffi ciently high cooling rate to suppress the formation of equilibrium crystalline phases. Th e critical cooling rate required to freeze the liquid structure is estimated to be on the order of 10 5 -10 6 K s -1 for alloys. Th is assumption was proved experimentally in 1959 by a research group at Caltech, who reported the fi rst glassy alloy with a composition of Au 75 Si 25 produced by splat quenching [1]. In this pioneering work, the Au 75 Si 25 melt was quenched using a cold metal plate instead of the water or oil used traditionally. Th e good contact between liquid droplets and the cold metal avoids the formation of gaseous layers that limit the heat release during solidifi cation. Moreover, the droplets spread into a thin layer for rapid thermal diff usion when striking the solid, cold metal plate. X-ray diff raction analysis revealed the disappearance of all crystalline structure and the formation of a noncrystalline structure in the resultant micrometer-sized fl akes. Following this discovery, a large number of metallic glasses were found in various alloy systems, and rapid research progress was made in the search for new metallic glasses. Th is research was accelerated by the invention of a melt spinning method [2], a rapid cooling technique that can routinely quench liquid alloys as 10-50 μm thick ribbons at cooling rates of 10 3 -10 6 K s -1 by impinging a melt stream on a spinning copper wheel. Most glass-form alloys reported at that time were binary alloys, and their glass-forming ability was found to be strongl...

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Section: Nanotechnology and Memsmentioning

confidence: 99%

Section: Nanotechnology and Memsmentioning

confidence: 99%

A brief overview of bulk metallic glasses

2011

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“…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].…”

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confidence: 99%

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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“…Growing number of research activities are now focused on metallic glassy nanoobjects, for example, nanowires [59,60]. Nanowires have been used as barcodes for biological multiplexing, which could be visualized by an optical microscope [61].…”

Section: Direct Formation Of a Nanostructure On Depositionmentioning

confidence: 99%

Development of Functional Metallic Glassy Materials by FIB and Nanoimprint Technologies

Inoue

Louzguine‐Luzgin

Al-Marzouki

2013

Lecture Notes in Nanoscale Science and Technology

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Patterning techniques are very important in many areas of modern science and technology including applications. Production of micro-and nano-sized periodical structures has been intensively studied in the last years in order to generate one-, two-, and three-dimensional periodical structures in metals, polymers, and ceramics. The process of patterning commonly involves many individual steps before obtaining the desired structure. In general, a pattering method consists of the following elements: formation of a mask or muster, choice of transfer medium or replications of patterns, and choice of resist, which is usually a functional material capable of serving as the resist. Metallic glass is one of the promising materials for such a purpose. Recently, glassy alloys attracted much attention as imprinting materials because they soften on heating similar to polymers, but on subsequent cooling retain high hardness at room temperature and demonstrate good corrosion resistance [1]. It has been reported that a three-dimensional structure with several tens or hundreds of nanometer in characteristic length scale could be prepared using Pt-, Zr-, Au-based glassy alloy ribbon and Zr-based glassy alloy in bulk form [2][3][4][5] or in a thin film form [6]. In the present chapter we discuss usage of metallic glasses for nanoimprinting and other similar processes.

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Controlled Formation and Mechanical Characterization of Metallic Glassy Nanowires

Cited by 47 publications

References 27 publications

A brief overview of bulk metallic glasses

A brief overview of bulk metallic glasses

Dominant shear bands observed in amorphous ZrCuAl nanowires under simulated compression

Development of Functional Metallic Glassy Materials by FIB and Nanoimprint Technologies

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