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Three-Dimensional Atomic-Scale Imaging of Impurity Segregation to Line Defects

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Science  17 Dec 1999:
Vol. 286, Issue 5448, pp. 2317-2319
DOI: 10.1126/science.286.5448.2317

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Abstract

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.

  • * 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.

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