Three-Dimensional Atomic-Scale Imaging of Impurity Segregation to Line Defects
D. Blavette,
*
E. Cadel,
A. Fraczkiewicz,
A. Menand
Clouds of impurity atoms near line defects are believed
to affect the plastic deformation of alloys. Three-dimensional atom probe techniques were used to image these so-called Cottrell
atmospheres directly. Ordered iron-aluminum alloys (40 atomic percent
aluminum) doped with boron (400 atomic parts per million) were
investigated on an atomic scale along the 
001
direction. A boron
enrichment was observed in the vicinity of an 001 edge
dislocation. The enriched region appeared as a three-dimensional pipe 5 nanometers in diameter, tangent to the dislocation line. The
dislocation was found to be boron-enriched by a factor of 50 (2 atomic
percent) relative to the bulk. The local boron enrichment is
accompanied by a strong aluminum depletion of 20 atomic percent.
Sonde Atomique et Microstructures, Groupe de Métallurgie
Physique, UMR CNRS 6634, Faculté des Sciences de Rouen,
Université de Rouen, 76821 Mont-Saint-Aignan Cedex, France.
*
To whom correspondence should be addressed. E-mail:
blavette{at}univ-rouen.fr
Ecole des Mines de Saint-Etienne, Centre SMS, 158 Cours Fauriel, 42 100 Saint-Etienne, France.
