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Nanowires: The long and short of breaking

13.09.2012
Mechanical failure of short nanowires is characterized by smooth, ductile deformations, while long nanowires fail catastrophically

Most materials will break when a force is applied to an imperfection in their structure — such as a notch or dislocation. The behavior of these imperfections, and the resulting breakage, differ markedly between small structures, such as nanowires, and larger, bulk materials.


Examples of failure in four different lengths of nanowire as a result of tensile stress. Only nanowire sections close to the fracture are shown. A short (188 nanometer (nm)) nanowire fails through gradual, ductile deformation (top). A long (1,503 nm) nanowire fails abruptly through a brittle or localized shear failure (bottom).

© 2012 American Chemical Society

However, scientists lacked complete understanding of the precise mechanics of nanowire breakages, owing in part to inconsistent behavior in experiments. These inconsistencies are now resolved thanks to numerical simulations by Zhaoxuan Wu and his co-workers at the A*STAR Institute for High Performance Computing, Singapore, and collaborators in the USA1.

The researchers focused on metal nanowires with a so-called 'face-centered cubic crystal structure' because they exhibit two different failure modes. Previous experiments by other groups showed that these nanowires can break as the result of a ductile process, in which a narrow neck is formed smoothly and continuously before failure. Other experiments showed that the failure was caused by a brittle fracture, which happened suddenly. To complicate matters further, atom-scale simulations of these experiments predicted that only ductile necking should be occurring.

Most materials will break when a force is applied to an imperfection in their structure — such as a notch or dislocation. The behavior of these imperfections, and the resulting breakage, differ markedly between small structures, such as nanowires, and larger, bulk materials. However, scientists lacked complete understanding of the precise mechanics of nanowire breakages, owing in part to inconsistent behavior in experiments. These inconsistencies are now resolved thanks to numerical simulations by Zhaoxuan Wu and his co-workers at the A*STAR Institute for High Performance Computing, Singapore, and collaborators in the USA (1).

The researchers focused on metal nanowires with a so-called 'face-centered cubic crystal structure' because they exhibit two different failure modes. Previous experiments by other groups showed that these nanowires can break as the result of a ductile process, in which a narrow neck is formed smoothly and continuously before failure. Other experiments showed that the failure was caused by a brittle fracture, which happened suddenly. To complicate matters further, atom-scale simulations of these experiments predicted that only ductile necking should be occurring.

The A*STAR-affiliated researchers contributing to this research are from the Institute for High Performance Computing

Journal information

Wu, Z., Zhang, Y.-W., Jhon, M. H., Gao, H. & Srolovitz, D. J. Nanowire failure: long = brittle and short = ductile. Nano Letters 12, 910–914 (2012).

A*STAR Research | Research asia research news
Further information:
http://www.research.a-star.edu.sg
http://www.researchsea.com

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