Documents disponibles écrits par cet auteur

α- to γ-Al2O3 martensitic transformation induced by pulsed laser irradiation / P.F. Yan in Acta materialia, Vol. 58 N° 11 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 11 (Juin 2010) . - pp. 3867–3876 Titre : α- to γ-Al2O3 martensitic transformation induced by pulsed laser irradiation Type de document : texte imprimé Auteurs : P.F. Yan, Auteur ; M.L. Sui, Auteur Année de publication : 2011 Article en page(s) : pp. 3867–3876 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Martensitic  phase  transformation  Ceramics  High-resolution  electron  microscopy  Twinning  Alumina Résumé : A martensitic transformation from the α to the γ phase of aluminum oxide was observed by transmission electron microscopy (TEM) upon rapid heating induced by pulsed laser irradiation. Two variants possessing a twin relationship were found in the product. High-resolution TEM reveals that the transformation is achieved via the glide of quarter partial dislocations on every other basal plane of α-Al2O3. The high thermal stress caused by pulsed laser irradiation is believed to be the main driving force of the phase transformation. This martensitic transformation is associated with a positive volume change and substantial shear strain. The overall shear strain could be minimized by the self-accommodating variants. These characteristics suggest potential application of the martensitic transformation for transformation toughening in ceramic materials. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964541000203X [article] α- to γ-Al2O3 martensitic transformation induced by pulsed laser irradiation [texte imprimé] / P.F. Yan, Auteur ; M.L. Sui, Auteur . - 2011 . - pp. 3867–3876. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 11 (Juin 2010) . - pp. 3867–3876 Mots-clés : Martensitic  phase  transformation  Ceramics  High-resolution  electron  microscopy  Twinning  Alumina Résumé : A martensitic transformation from the α to the γ phase of aluminum oxide was observed by transmission electron microscopy (TEM) upon rapid heating induced by pulsed laser irradiation. Two variants possessing a twin relationship were found in the product. High-resolution TEM reveals that the transformation is achieved via the glide of quarter partial dislocations on every other basal plane of α-Al2O3. The high thermal stress caused by pulsed laser irradiation is believed to be the main driving force of the phase transformation. This martensitic transformation is associated with a positive volume change and substantial shear strain. The overall shear strain could be minimized by the self-accommodating variants. These characteristics suggest potential application of the martensitic transformation for transformation toughening in ceramic materials. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S135964541000203X

Transmission electron microscopy study of stacking faults and their interaction with pyramidal dislocations in deformed Mg / B. Li in Acta materialia, Vol. 58 N° 1 (Janvier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 173–179 Titre : Transmission electron microscopy study of stacking faults and their interaction with pyramidal dislocations in deformed Mg Type de document : texte imprimé Auteurs : B. Li, Auteur ; P.F. Yan, Auteur ; M.L. Sui, Auteur Année de publication : 2010 Article en page(s) : pp. 173–179 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Dislocations  Stacking  fault  Magnesium  TEM Résumé : We present transmission electron microscopy (TEM) observations of stacking faults (SFs) and their interactions with pyramidal dislocations, in plastically deformed polycrystalline pure magnesium. We have observed well-defined fringes as well as streaking in diffraction patterns, typical of SFs. The basal SFs are decorated by a large number of dark speckles, which are created by the interaction with pyramidal dislocations that have both 〈c〉 and 〈a〉 components as revealed by our contrast analysis. The SFs do not appear to result from the splitting of unit dislocations, as the SFs are relatively wide and no dislocation nodes were observed. By tilting the specimen systematically inside TEM, the SFs and the associated dislocations in Mg are found to exhibit a rich variety of features in terms of their morphology and diffraction contrast. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005904 [article] Transmission electron microscopy study of stacking faults and their interaction with pyramidal dislocations in deformed Mg [texte imprimé] / B. Li, Auteur ; P.F. Yan, Auteur ; M.L. Sui, Auteur . - 2010 . - pp. 173–179. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 1 (Janvier 2010) . - pp. 173–179 Mots-clés : Dislocations  Stacking  fault  Magnesium  TEM Résumé : We present transmission electron microscopy (TEM) observations of stacking faults (SFs) and their interactions with pyramidal dislocations, in plastically deformed polycrystalline pure magnesium. We have observed well-defined fringes as well as streaking in diffraction patterns, typical of SFs. The basal SFs are decorated by a large number of dark speckles, which are created by the interaction with pyramidal dislocations that have both 〈c〉 and 〈a〉 components as revealed by our contrast analysis. The SFs do not appear to result from the splitting of unit dislocations, as the SFs are relatively wide and no dislocation nodes were observed. By tilting the specimen systematically inside TEM, the SFs and the associated dislocations in Mg are found to exhibit a rich variety of features in terms of their morphology and diffraction contrast. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409005904