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

1999; American Association for the Advancement of Science; Volume: 286; Issue: 5448 Linguagem: Inglês

10.1126/science.286.5448.2317

1095-9203

D. Blavette, E. Cadel, Anna Fraczkiewicz, A. Menand,

Diamond and Carbon-based Materials Research

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.