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Science 6 June 2003:
Vol. 300. no. 5625, pp. 1550 - 1552
DOI: 10.1126/science.1084284
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Reports

Dimples on Nanocrystalline Fracture Surfaces As Evidence for Shear Plane Formation

A. Hasnaoui, H. Van Swygenhoven,* P. M. Derlet

Tensile experiments of fully dense nanocrystalline structures with a mean grain size of less than 100 nanometers demonstrate a considerable increase in hardness but a remarkable drop in elongation-to-failure, indicating brittle behavior. However, dimple structures are often observed at the fracture surface, indicating some type of ductile fracture mechanism. Guided by large-scale atomistic simulations, we propose that these dimple structures result from local shear planes formed around clustered grains that, because of their particular misorientation, cannot participate in the grain boundary accommodation processes necessary to sustain plastic deformation. This raises the expectation that general high-angle grain boundaries are necessary for good ductility.

Paul Scherrer Institute, CH-5232, Villigen-PSI, Switzerland

* To whom correspondence should be addressed. E-mail: helena.vs{at}psi.ch

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Plastic Deformation with Reversible Peak Broadening in Nanocrystalline Nickel.
Z. Budrovic, H. Van Swygenhoven, P. M. Derlet, S. Van Petegem, and B. Schmitt (2004)
Science 304, 273-276
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