Mechanical characterization of materials at small length scales

Pantano, Maria F.; Espinosa, Horacio D.; Pagnotta, Leonardo

doi:10.1007/s12206-011-1214-1

Cited by 79 publications

(32 citation statements)

References 176 publications

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“…[330][331][332][333][334]. The first key element when testing freestanding thin films or nanowires is the extraction, manipulation and positioning of the specimens.…”

Section: Fracture Testing Methods Of Freestanding Specimensmentioning

confidence: 99%

Failure of metals III: Fracture and fatigue of nanostructured metallic materials

2016

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a b s t r a c tPushing the internal or external dimensions of metallic alloys down to the nanometer scale gives rise to strong materials, though most often at the expense of a low ductility and a low resistance to cracking, with negative impact on the transfer to engineering applications. These characteristics are observed, with some exceptions, in bulk ultra-fine grained and nanocrystalline metals, nano-twinned metals, thin metallic coatings on substrates and freestanding thin metallic films and nanowires. This overview encompasses all these systems to reveal commonalities in the origins of the lack of ductility and fracture resistance, in factors governing fatigue resistance, and in ways to improve properties. After surveying the various processing methods and key deformation mechanisms, we systematically address the current state of the art in terms of plastic localization, damage, static and fatigue cracking, for three classes of systems: (1) bulk ultra-fine grained and nanocrystalline metals, (2) thin metallic films on substrates, and (3) 1D and 2D freestanding micro and nanoscale systems. In doing so, we aim to favour cross-fertilization between progress made in the fields of mechanics of thin films, nanomechanics, fundamental researches in bulk nanocrystalline metals and metallurgy to impart enhanced resistance to fracture and fatigue in high-strength nanostructured systems. This involves exploiting intrinsic mechanisms, e.g. to enhance hardening and rate-sensitivity so as to delay necking, or improve grain-boundary cohesion to resist intergranular cracks or voids. Extrinsic methods can also be utilized such as by hybridizing the metal with another material to delocalize the deformation -as practiced in stretchable electronics. Fatigue crack initiation is in principle improved by a fine structure, but at the expense of larger fatigue crack growth rates. Extrinsic toughening through hybridization allows arresting or bridging cracks. The content and discussions are based on experimental, theoretical and simulation results from the recent literature, and focus is laid on linking microstructure and physical mechanisms to the overall mechanical behavior.

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“…[330][331][332][333][334]. The first key element when testing freestanding thin films or nanowires is the extraction, manipulation and positioning of the specimens.…”

Section: Fracture Testing Methods Of Freestanding Specimensmentioning

confidence: 99%

Failure of metals III: Fracture and fatigue of nanostructured metallic materials

2016

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“…If polysilicon is considered as structural material, an amplifier with a pair of 250 µm long, 6 µm wide, and 22 µm thick beams 1 , with inclination angle θ=2° fulfills both requirements. In fact, according to the last of expressions (10), kA=289 N/m, while according to equation (14), such geometry allows to achieve an amplification ratio (without any sample) v2/u1=19.44. In particular, it is interesting to note that with this amplification ratio, it is possible to achieve a sample displacement bigger than 1µm (one of the design constraints) with a small actuator displacement (~60 nm), and thus a small temperature increase (~20°C from figure 2b), while being able to apply forces bigger than 200 µN.…”

Section: Design Of the Mechanical Amplifiermentioning

confidence: 99%

“…Among these, the most promising techniques are based on Micro-ElectroMechanical Systems (MEMS) technology. The most important advantage they offer relies on the compatibility of MEMS devices with Scanning/Transmission Electron Microscope (SEM/TEM) chambers, which enable for real-time imaging of the sample deformation, while providing high displacement and force resolution [10].…”

Section: Introductionmentioning

confidence: 99%

Design of a bent beam electrothermal actuator for in situ tensile testing of ceramic nanostructures

Pantano

Pugno

2014

Journal of the European Ceramic Society

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Abstract.A necessary condition to include nanoscale materials in the design of highly performing as well as reliable electrical and electromechanical devices is the availability of a sufficiently deep knowledge of their mechanical behavior. Up to date, the most powerful tools for mechanical characterization of nanosamples are properly designed microelectromechanical systems (MEMS), due to their compatibility with Scanning/Transmission Electron Microscopy (SEM/TEM) and high resolution force/displacement measurements. Herein, we report about the design of a MEMS platform for in situ SEM tensile testing of nanoscale samples. This is characterized by a very compact structure, based only on a bent beam electrothermal actuator, which performs both actuating and sensing functions. The size of the structural components of the present device is chosen with the aim of testing ceramic nanowires, but the resulting configuration can be applied also for other material samples.

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“…Young's modulus size effect is of interest because it is an essential input for finite element method (FEM) modelling [1]. Focused ion beam (FIB) has the ability to machine a range of geometries for testing bulk mechanical properties along specific crystallographic orientations, or properties of interesting regions such as grain boundaries [2], [3].…”

Section: Introductionmentioning

confidence: 99%

In-situ micro bend testing of SiC and the effects of Ga⁺ ion damage

Robertson

Doak

Zhou

et al. 2017

J. Phys.: Conf. Ser.

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Abstract. The Young's modulus of 6H single crystal silicon carbide (SiC) was tested with micro cantilevers that had a range of cross-sectional dimensions with surfaces cleaned under different accelerating voltages of Ga + beam. A clear size effect is seen with Young's modulus decreasing as the cross-sectional area reduces. One of the possible reasons for such size effect is the Ga + induced damage on all surfaces of the cantilever. Transmission electron microscopy (TEM) was used to analyse the degree of damage, and the measurements of damage is compared to predictions by SRIM irradiation simulation.

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Mechanical characterization of materials at small length scales

Cited by 79 publications

References 176 publications

Failure of metals III: Fracture and fatigue of nanostructured metallic materials

Failure of metals III: Fracture and fatigue of nanostructured metallic materials

Design of a bent beam electrothermal actuator for in situ tensile testing of ceramic nanostructures

In-situ micro bend testing of SiC and the effects of Ga⁺ ion damage

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Mechanical characterization of materials at small length scales

Cited by 79 publications

References 176 publications

Failure of metals III: Fracture and fatigue of nanostructured metallic materials

Failure of metals III: Fracture and fatigue of nanostructured metallic materials

Design of a bent beam electrothermal actuator for in situ tensile testing of ceramic nanostructures

In-situ micro bend testing of SiC and the effects of Ga+ ion damage

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In-situ micro bend testing of SiC and the effects of Ga⁺ ion damage