Grain boundary self-diffusion in polycrystalline nickel of different purity levels / Sergiy V. Divinski in Acta materialia, Vol. 58 N° 2 (Janvier 2010)  

Public ISBD [article]  inActa materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 386-395 Titre : Grain boundary self-diffusion in polycrystalline nickel of different purity levels Type de document : texte imprimé Auteurs : Sergiy V. Divinski, Auteur ; Gerrit Reglitz, Auteur ; Gerhard Wilde, Auteur Article en page(s) : pp. 386-395 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Nickel Grain boundary diffusion segregation width Index. décimale : 669 Métallurgie Résumé : Grain boundary self-diffusion in Ni materials of two different purity levels (99.6 and 99.999 wt.%) was measured over wide temperature intervals using the radiotracer technique and applying the 63Ni radioisotope. The diffusion experiments were performed in both Harrison’s type B and type C kinetic regimes. The diffusional grain boundary width, δ, was found to be equal to 0.54 ± 0.1 nm, that is reasonably close to the accepted value of View the MathML source in face-centred cubic metals. The purer the material, the higher the grain boundary diffusivity and the lower the corresponding activation enthalpy of self-diffusion along general high-angle grain boundaries. Using the semi-empirical approach of Borisov et al., the average energy of high-angle grain boundaries was estimated to be about 0.79 and 0.98 J m−2 in the low- and high-purity Ni materials at room temperature, respectively. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Grain boundary self-diffusion in polycrystalline nickel of different purity levels [texte imprimé] / Sergiy V. Divinski, Auteur ; Gerrit Reglitz, Auteur ; Gerhard Wilde, Auteur . - pp. 386-395. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 386-395 Mots-clés : Nickel Grain boundary diffusion segregation width Index. décimale : 669 Métallurgie Résumé : Grain boundary self-diffusion in Ni materials of two different purity levels (99.6 and 99.999 wt.%) was measured over wide temperature intervals using the radiotracer technique and applying the 63Ni radioisotope. The diffusion experiments were performed in both Harrison’s type B and type C kinetic regimes. The diffusional grain boundary width, δ, was found to be equal to 0.54 ± 0.1 nm, that is reasonably close to the accepted value of View the MathML source in face-centred cubic metals. The purer the material, the higher the grain boundary diffusivity and the lower the corresponding activation enthalpy of self-diffusion along general high-angle grain boundaries. Using the semi-empirical approach of Borisov et al., the average energy of high-angle grain boundaries was estimated to be about 0.79 and 0.98 J m−2 in the low- and high-purity Ni materials at room temperature, respectively. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]

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Strain mapping along Al–Pb interfaces / Harald Rösner in Acta materialia, Vol. 58 N° 1 (Janvier 2010)  

Public ISBD [article]  inActa materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 162–172 Titre : Strain mapping along Al–Pb interfaces Type de document : texte imprimé Auteurs : Harald Rösner, Auteur ; Christoph T. Koch, Auteur ; Gerhard Wilde, Auteur Année de publication : 2010 Article en page(s) : pp. 162–172 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Misfit dislocation Strain mapping Size-dependent melting Focus series reconstruction Résumé : Local strains at particle–matrix hetero-interfaces in an Al–Pb composite produced by high-energy ball-milling were measured by means of geometric phase analysis (GPA) on the basis of high-resolution transmission electron microscope (HRTEM) images. A through-focus series of 10 experimental micrographs was used to retrieve the complex exit-face wave function and subsequently to calculate the components of the strain tensor using Pb as the reference lattice. The strain analysis revealed considerable strain for the interface regions with compressive strain for the Pb side and tensile strain for the Al side. The strained zones extend up to 2–3 lattice spacings on either side of the interface. The interface regions are not sheared or significantly rotated, which shows that the whole state of the interface is elastically strained but not plastically deformed. A new possible interpretation of the melting behaviour of the Pb particles in terms of the strains is discussed. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005898 [article] Strain mapping along Al–Pb interfaces [texte imprimé] / Harald Rösner, Auteur ; Christoph T. Koch, Auteur ; Gerhard Wilde, Auteur . - 2010 . - pp. 162–172. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 162–172 Mots-clés : Misfit dislocation Strain mapping Size-dependent melting Focus series reconstruction Résumé : Local strains at particle–matrix hetero-interfaces in an Al–Pb composite produced by high-energy ball-milling were measured by means of geometric phase analysis (GPA) on the basis of high-resolution transmission electron microscope (HRTEM) images. A through-focus series of 10 experimental micrographs was used to retrieve the complex exit-face wave function and subsequently to calculate the components of the strain tensor using Pb as the reference lattice. The strain analysis revealed considerable strain for the interface regions with compressive strain for the Pb side and tensile strain for the Al side. The strained zones extend up to 2–3 lattice spacings on either side of the interface. The interface regions are not sheared or significantly rotated, which shows that the whole state of the interface is elastically strained but not plastically deformed. A new possible interpretation of the melting behaviour of the Pb particles in terms of the strains is discussed. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005898

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