Smaller is tougher

Beaber, A. R.; Nowak, Jessica; Ugurlu, Ozan; Mook, William; Girshick, Steven L.; Ballarini, Roberto

doi:10.1080/14786435.2010.487474

Cited by 32 publications

(28 citation statements)

References 22 publications

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“…The elastic modulus and hardness were obtained from the respective indentations. Figure 4 shows the fracture toughness for the Si-SiC composite towers as a function of the tower diameter along with TEM in situ indented nanospheres and nanotowers from Beaber et al (2010) and ex situ indented nanospheres from Mook et al (2007). For the nanosphere and nanotower data from Beaber et al, fracture toughness was calculated using a work per unit fracture area approach while the nanosphere data from Mook et al approximated the crack size as the thickness of the oxide surrounding the sphere and used the Griffith criterion to evaluate the fracture toughness.…”

Section: Resultsmentioning

confidence: 99%

Dislocation plasticity and phase transformations in Si-SiC core-shell nanotowers

2010

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Vapor-liquid-solid (VLS) Si nanotowers were coated with nanocrystalline SiC to form a Si-SiC core-shell composite. Due to a mismatch in the coefficients of thermal expansion (CTE), the Si core was under a compressive stress following the deposition. The composite tower was then cross-sectioned using focused ion beam milling, exposing the Si core. Indentation into the Si showed an increased toughness as a function of diameter compared to similar sized Si nanotowers and nanospheres. This result is explained through enhanced dislocation and phase transformation plasticity in the Si core from the CTE compressive stresses.

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Section: Resultsmentioning

confidence: 99%

Dislocation plasticity and phase transformations in Si-SiC core-shell nanotowers

2010

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“…An increase in mechanical toughness has been attributed to nano-scale silicon crystal thin films, nanospheres, and nanopillar type materials [61] mentioned at the beginning of the current report [2,4]. Valiev et al [22][23][24] have described a full range of strength and related material properties that are improved at nano-scale dimensions.…”

Section: Discussionmentioning

confidence: 98%

Crystal Engineering for Mechanical Strength at Nano-Scale Dimensions

Armstrong¹

2017

Crystals

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Abstract:The mechanical strengths of nano-scale individual crystal or nanopolycrystalline metals, and other dimensionally-related materials are increased by an order of magnitude or more as compared to those values measured at conventional crystal or polycrystal grain dimensions. An explanation for the result is attributed to the constraint provided at the surface of the crystals or, more importantly, at interfacial boundaries within or between crystals. The effect is most often described in terms either of two size dependencies: an inverse dependence on crystal size because of single dislocation behavior or, within a polycrystalline material, in terms of a reciprocal square root of grain size dependence, designated as a Hall-Petch relationship for the researchers first pointing to the effect for steel and who provided an enduring dislocation pile-up interpretation for the relationship. The current report provides an updated description of such strength properties for iron and steel materials, and describes applications of the relationship to a wider range of materials, including non-ferrous metals, nano-twinned, polyphase, and composite materials. At limiting small nm grain sizes, there is a generally minor strength reversal that is accompanied by an additional order-of-magnitude elevation of an increased strength dependence on deformation rate, thus giving an important emphasis to the strain rate sensitivity property of materials at nano-scale dimensions.

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“…6(f). Still, comparing this data to a previously published compressive data set, 212 gave an indication that such specimen types could be utilized in this length scale regime down to 100 nm thicknesses. The values indicated from Fig.…”

Section: -15 Gerberich Et Almentioning

confidence: 99%

“…210) and GaAs. 211 We should point out, however, that some very small length scale studies of silicon nanospheres by both atomic force microscopy 134 and transmission electron microscopy 212 resulted in similar flow stress behavior. Considering dopant levels, extensive studies 205,213 have demonstrated that n-doping can favor enhanced dislocation velocities compared to intrinsic silicon.…”

Section: Future Nanomechanical Approaches To Brittleness Transitionsmentioning

confidence: 99%

Review Article: Case studies in future trends of computational and experimental nanomechanics

Tadmor

Kysar

Zimmerman

et al. 2017

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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With rapidly increasing numbers of studies of new and exotic material uses for perovskites and quasicrystals, these demand newer instrumentation and simulation developments to resolve the revealed complexities. One such set of observational mechanics at the nanoscale is presented here for somewhat simpler material systems. The expectation is that these approaches will assist those materials scientists and physicists needing to verify atomistic potentials appropriate to the nanomechanical understanding of increasingly complex solids. The five following segments from nine University, National and Industrial Laboratories both review and forecast where some of the important approaches will allow a confirming of how in situ mechanics and nanometric visualization might unravel complex phenomena. These address two-dimensional structures, temporal models for the nanoscale, atomistic and multiscale friction fundamentals, nanoparticle surfaces and interfaces a) Electronic

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Smaller is tougher

Cited by 32 publications

References 22 publications

Dislocation plasticity and phase transformations in Si-SiC core-shell nanotowers

Dislocation plasticity and phase transformations in Si-SiC core-shell nanotowers

Crystal Engineering for Mechanical Strength at Nano-Scale Dimensions

Review Article: Case studies in future trends of computational and experimental nanomechanics

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