Atomic-Level Observation of Disclination Dipoles in Mechanically Milled, Nanocrystalline Fe

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Science  29 Mar 2002:
Vol. 295, Issue 5564, pp. 2433-2435
DOI: 10.1126/science.1067430

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Plastic deformation of materials occurs by the motion of defects known as dislocations and disclinations. High-resolution transmission electron microscopy was used to directly reveal the individual dislocations that constitute partial disclination dipoles in nanocrystalline, body-centered cubic iron that had undergone severe plastic deformation by mechanical milling. The mechanisms by which the formation and migration of such partial disclination dipoles during deformation allow crystalline solids to fragment and rotate at the nanometer level are described. Such rearrangements are important basic phenomena that occur during material deformation, and hence, they may be critical in the formation of nanocrystalline metals by mechanical milling and other deformation processes.

  • * On leave from the National Institute for Materials Science, Tsukuba, 305-0047, Japan.

  • To whom correspondence should be addressed. E-mail: jh9s{at}

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