Observation of Giant Diffusivity Along Dislocation Cores
Marc Legros,1
Gerhard Dehm,2
Eduard Arzt,3*
T. John Balk4
Diffusion of atoms in a crystalline lattice is a thermally activated
process that can be strongly accelerated by defects such as
grain boundaries or dislocations. When carried by dislocations,
this elemental mechanism is known as "pipe diffusion." Pipe
diffusion has been used to explain abnormal diffusion, Cottrell
atmospheres, and dislocation-precipitate interactions during
creep, although this rests more on conjecture than on direct
demonstration. The motion of dislocations between silicon nanoprecipitates
in an aluminum thin film was recently observed and controlled
via in situ transmission electron microscopy. We observed the
pipe diffusion phenomenon and measured the diffusivity along
a single dislocation line. It is found that dislocations accelerate
the diffusion of impurities by almost three orders of magnitude
as compared with bulk diffusion.
2 Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Department Materials Physics, University of Leoben, 8700 Leoben, Austria.
3 Max Planck Institute for Metals Research, 70569 Stuttgart, Germany.
4 Department of Chemical and Materials Engineering, University of Kentucky, Lexington, KY 40506, USA.
Present address: INM–Leibniz Institute for New Materials, 66123 Saarbrücken, Germany.
* To whom correspondence should be addressed. E-mail: legros{at}cemes.fr
