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Characterization of planar features in Mg–Y–Zn alloys / Y.M. Zhu in Acta materialia, Vol. 58 N° 2 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 464-475 Titre : Characterization of planar features in Mg–Y–Zn alloys Type de document : texte imprimé Auteurs : Y.M. Zhu, Auteur ; A.J. Morton, Auteur ; M. Weyland, Auteur Article en page(s) : pp. 464-475 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Magnesium  alloys  Precipitates  Stacking  faults  Dislocations  HAADF-STEM Index. décimale : 669 Métallurgie Résumé : The planar features in a Mg–8Y–2Zn–0.6Zr (wt.%) alloy solution-treated at 500°C for 1 h have been examined using conventional transmission electron microscopy and atomic-resolution high-angle annular dark-field scanning transmission electron microscopy. Three types of planar features are detected in the microstructure. The first type, which was previously reported to be an intrinsic stacking fault I1 bounded by a Frank partial dislocation, is shown to be the 14H precipitate phase that is associated with Shockley partial dislocations. The second type is also a precipitate phase that has a single unit cell height and is associated with Shockley partial dislocations. The third type of planar feature comprises small ribbon-like stacking faults. These stacking faults are determined as intrinsic I2 type bounded by two Shockley partial dislocations, which is further confirmed by computer simulation. The stacking fault energy associated with the faults is much smaller than that of pure magnesium. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Characterization of planar features in Mg–Y–Zn alloys [texte imprimé] / Y.M. Zhu, Auteur ; A.J. Morton, Auteur ; M. Weyland, Auteur . - pp. 464-475. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 2 (Janvier 2010) . - pp. 464-475 Mots-clés : Magnesium  alloys  Precipitates  Stacking  faults  Dislocations  HAADF-STEM Index. décimale : 669 Métallurgie Résumé : The planar features in a Mg–8Y–2Zn–0.6Zr (wt.%) alloy solution-treated at 500°C for 1 h have been examined using conventional transmission electron microscopy and atomic-resolution high-angle annular dark-field scanning transmission electron microscopy. Three types of planar features are detected in the microstructure. The first type, which was previously reported to be an intrinsic stacking fault I1 bounded by a Frank partial dislocation, is shown to be the 14H precipitate phase that is associated with Shockley partial dislocations. The second type is also a precipitate phase that has a single unit cell height and is associated with Shockley partial dislocations. The third type of planar feature comprises small ribbon-like stacking faults. These stacking faults are determined as intrinsic I2 type bounded by two Shockley partial dislocations, which is further confirmed by computer simulation. The stacking fault energy associated with the faults is much smaller than that of pure magnesium. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]

The 18R and 14H long-period stacking ordered structures in Mg–Y–Zn alloys / Y.M. Zhu in Acta materialia, Vol. 58 N° 8 (Mai 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 8 (Mai 2010) . - pp. 2936–2947 Titre : The 18R and 14H long-period stacking ordered structures in Mg–Y–Zn alloys Type de document : texte imprimé Auteurs : Y.M. Zhu, Auteur ; A.J. Morton, Auteur ; J.F. Nie, Auteur Année de publication : 2011 Article en page(s) : pp. 2936–2947 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Magnesium  alloys  18R  14H  Crystal  structure  Ordering Résumé : The 18R and 14H long-period stacking ordered structures formed in Mg–Y–Zn alloys are examined systematically using electron diffraction and high-angle annular dark-field scanning transmission electron microscopy. In contrast to that reported in previous studies, the 18R structure is demonstrated to have an ordered base-centred monoclinic lattice, with Y and Zn atoms having an ordered arrangement in the closely packed planes. Furthermore, the composition of 18R is suggested to be Mg10Y1Zn1, instead of the Mg12Y1Zn1 composition that is commonly accepted. The 14H structure is also ordered. It has a hexagonal unit cell; the ordered distribution of Y and Zn atoms in the unit cell is similar to that in the 18R and its composition is Mg12Y1Zn1. The 18R unit cell has three ABCA-type building blocks arranged in the same shear direction, while the 14H unit cell has two ABCA-type building blocks arranged in opposite shear directions. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000364 [article] The 18R and 14H long-period stacking ordered structures in Mg–Y–Zn alloys [texte imprimé] / Y.M. Zhu, Auteur ; A.J. Morton, Auteur ; J.F. Nie, Auteur . - 2011 . - pp. 2936–2947. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 8 (Mai 2010) . - pp. 2936–2947 Mots-clés : Magnesium  alloys  18R  14H  Crystal  structure  Ordering Résumé : The 18R and 14H long-period stacking ordered structures formed in Mg–Y–Zn alloys are examined systematically using electron diffraction and high-angle annular dark-field scanning transmission electron microscopy. In contrast to that reported in previous studies, the 18R structure is demonstrated to have an ordered base-centred monoclinic lattice, with Y and Zn atoms having an ordered arrangement in the closely packed planes. Furthermore, the composition of 18R is suggested to be Mg10Y1Zn1, instead of the Mg12Y1Zn1 composition that is commonly accepted. The 14H structure is also ordered. It has a hexagonal unit cell; the ordered distribution of Y and Zn atoms in the unit cell is similar to that in the 18R and its composition is Mg12Y1Zn1. The 18R unit cell has three ABCA-type building blocks arranged in the same shear direction, while the 14H unit cell has two ABCA-type building blocks arranged in opposite shear directions. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410000364