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Analysis of local microstructure after shear creep deformation of a fine-grained duplex γ-TiAl alloy / D. Peter in Acta materialia, Vol. 58 N° 19 (Novembre 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6431–6443 Titre : Analysis of local microstructure after shear creep deformation of a fine-grained duplex γ-TiAl alloy Type de document : texte imprimé Auteurs : D. Peter, Auteur ; G.B. Viswanathan, Auteur ; A. Dlouhy, Auteur Année de publication : 2011 Article en page(s) : pp. 6431–6443 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Titanium  aluminides  Shear  creep  deformation  Transmission  electron  microscopy  Dislocations  Twinning Résumé : The present work characterizes the microstructure of a hot-extruded Ti–45Al–5Nb–0.2B–0.2C (at.%) alloy with a fine-grained duplex microstructure after shear creep deformation (temperature 1023 K; shear stress 175 MPa; shear deformation 20%). Diffraction contrast transmission electron microscopy (TEM) was performed to identify ordinary dislocations, superdislocations and twins. The microstructure observed in TEM is interpreted taking into account the contribution of the applied stress and coherency stresses to the overall local stress state. Two specific locations in the lamellar part of the microstructure were analyzed, where either twins or superdislocations provided c-component deformation in the L10 lattice of the γ phase. Lamellar γ grains can be in soft and hard orientations with respect to the resolved shear stress provided by the external load. The presence of twins can be rationalized by the superposition of the applied stress and local coherency stresses. The presence of superdislocations in hard γ grains represents indirect evidence for additional contributions to the local stress state associated with stress redistribution during creep. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410005094 [article] Analysis of local microstructure after shear creep deformation of a fine-grained duplex γ-TiAl alloy [texte imprimé] / D. Peter, Auteur ; G.B. Viswanathan, Auteur ; A. Dlouhy, Auteur . - 2011 . - pp. 6431–6443. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 19 (Novembre 2010) . - pp. 6431–6443 Mots-clés : Titanium  aluminides  Shear  creep  deformation  Transmission  electron  microscopy  Dislocations  Twinning Résumé : The present work characterizes the microstructure of a hot-extruded Ti–45Al–5Nb–0.2B–0.2C (at.%) alloy with a fine-grained duplex microstructure after shear creep deformation (temperature 1023 K; shear stress 175 MPa; shear deformation 20%). Diffraction contrast transmission electron microscopy (TEM) was performed to identify ordinary dislocations, superdislocations and twins. The microstructure observed in TEM is interpreted taking into account the contribution of the applied stress and coherency stresses to the overall local stress state. Two specific locations in the lamellar part of the microstructure were analyzed, where either twins or superdislocations provided c-component deformation in the L10 lattice of the γ phase. Lamellar γ grains can be in soft and hard orientations with respect to the resolved shear stress provided by the external load. The presence of twins can be rationalized by the superposition of the applied stress and local coherency stresses. The presence of superdislocations in hard γ grains represents indirect evidence for additional contributions to the local stress state associated with stress redistribution during creep. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410005094