Atomic Transport in Nanocrystalline Materials

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dc.contributor.authorChellali Mohammed Reda
dc.date.accessioned2022-12-07T09:52:11Z
dc.date.available2022-12-07T09:52:11Z
dc.date.issued2013-02-10
dc.description.abstractTriple junctions, singular topological defects of the grain boundary structure, which can get a dominant role for grain growth and atomic transport in nanocrystalline matter. In my thesis the atomic transport along triple junctions and grain boundaries has been studied using the three dimensional atom probe tomography technique in nanocrystalline Ni-Cu and Ni-Bi systems. In the completely miscible Ni-Cu system, we could demonstrate that in the triple junctions of nanocrystalline Cu the diffusivity of Ni is 100-300 times higher diffusivity than in standard high angle grain boundaries. The measurements also revealed that the chemical (or segregation) width of grain boundaries unexpectedly varies with temperature. This segregation layer at the grain boundaries grows from the 0.7 nm at 563 K to 2.5 nm at 643 K. This variation is not controlled by simple volume diffusion. It was proven by kinetic analysis that the effective transport width has to possess a significant dependence on temperature. The transport product of triple junction diffusivity has been accurately measured as a function of temperature.
dc.formatpdf
dc.identifier.urihttps://dspace.univ-oran1.dz/handle/123456789/3085
dc.language.isofr
dc.publisherUniversité Oran1 Ahmed Ben Bella
dc.subjectTriple junction, Grain boundary, Segregation, Nanocrystalline, Atom probe Tomography, Ni/Cu, Ni/Bi, Embrittlement, Ductility, Alloy
dc.titleAtomic Transport in Nanocrystalline Materials
grade.Co-rapporteurLEI ZHENG, Professeur adjoint, Université de Münster Allemagne
grade.ExaminateurBelaïdi Abdelkader, Professeur, ENSET d’Oran
grade.ExaminateurBelhadji Maamar, Professeur, Université d'Oran
grade.ExaminateurBourahla Ahmed, Maitre de Conférences-A-, Université de Mostaganem
grade.OptionSciences de l’environnement et climatologie
grade.PrésidentSebbani Mohamed, Professeur, Université d'Oran
grade.RapporteurHamou Ahmed, Professeur, Université d'Oran
l'article.1.DateParutionAugust2011
l'article.1.RevueScripta Materialia
l'article.1.RéférenceScripta Mater. (2011), doi10.1016/j.scriptamat.2011.05.002
l'article.1.TitreTriple junction and grain boundary diffusion in the Ni/Cu system
l'article.2.DateParution13 December 2012
l'article.2.RevueUltramicroscopy
l'article.2.RéférenceUltramicroscopy (2013), http//dx.doi.org/10.1016/j.ultramic.2012.12.002
l'article.2.TitreNano-analysis of grain boundary and triple junction transport in nanocrystalline Ni/Cu
la.MentionTrès Honorable
la.SpécialitéPhysique
la.coteTH3965
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