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Development of novel grain morphology during hot extrusion of magnesium AZ21 alloy / M. A. Azeem in Acta materialia, Vol. 58 N° 5 (Mars 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 5 (Mars 2010) . - pp. 1495–1502 Titre : Development of novel grain morphology during hot extrusion of magnesium AZ21 alloy Type de document : texte imprimé Auteurs : M. A. Azeem, Auteur ; A. Tewari, Auteur ; S. Mishra, Auteur Année de publication : 2011 Article en page(s) : pp. 1495–1502 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Magnesium  alloy  Extrusion  Dynamic  recrystallization  Annealing  Electron  backscattering  diffraction  (EBSD) Résumé : Microstructure and microtexture evolution during static annealing of a hot-extruded AZ21 magnesium alloy was studied. Apart from fine recrystallized equiaxed grains and large elongated deformed grains, a new third kind of abnormal grains that are stacked one after the other in a row parallel to the extrusion direction were observed. The crystallographic misorientation inside these grains was similar to that of the fine recrystallized grains. The large elongated grains exhibited significant in-grain misorientation. A self-consistent mechanistic model was developed to describe the formation of these grain morphologies during dynamic recrystallization (DRX). The texture of pre-extruded material, although lost in DRX, leaves a unique signature which manifests itself in the form of these grain morphologies. The origin of abnormal stacked grains was associated with slow nucleation in pre-extruded grains of a certain orientation. Further annealing resulted in large secondary recrystallized grains with occasional extension twins. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007599 [article] Development of novel grain morphology during hot extrusion of magnesium AZ21 alloy [texte imprimé] / M. A. Azeem, Auteur ; A. Tewari, Auteur ; S. Mishra, Auteur . - 2011 . - pp. 1495–1502. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 5 (Mars 2010) . - pp. 1495–1502 Mots-clés : Magnesium  alloy  Extrusion  Dynamic  recrystallization  Annealing  Electron  backscattering  diffraction  (EBSD) Résumé : Microstructure and microtexture evolution during static annealing of a hot-extruded AZ21 magnesium alloy was studied. Apart from fine recrystallized equiaxed grains and large elongated deformed grains, a new third kind of abnormal grains that are stacked one after the other in a row parallel to the extrusion direction were observed. The crystallographic misorientation inside these grains was similar to that of the fine recrystallized grains. The large elongated grains exhibited significant in-grain misorientation. A self-consistent mechanistic model was developed to describe the formation of these grain morphologies during dynamic recrystallization (DRX). The texture of pre-extruded material, although lost in DRX, leaves a unique signature which manifests itself in the form of these grain morphologies. The origin of abnormal stacked grains was associated with slow nucleation in pre-extruded grains of a certain orientation. Further annealing resulted in large secondary recrystallized grains with occasional extension twins. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409007599