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Microstructures and shape memory characteristics of dual-phase Co–Ni–Ga high-temperature shape memory alloys / Yan Li in Acta materialia, Vol. 58 N° 10 (Juin 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3655–3663 Titre : Microstructures and shape memory characteristics of dual-phase Co–Ni–Ga high-temperature shape memory alloys Type de document : texte imprimé Auteurs : Yan Li, Auteur ; Yan Xin, Auteur ; Liang Chai, Auteur Année de publication : 2011 Article en page(s) : pp. 3655–3663 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : Co–Ni–Ga  Dual  phases  Shape  memory  alloys  Martensitic  phase  transformation  Fracture Résumé : The influence of microstructure on mechanical properties and shape memory characteristics of Co–Ni–Ga high-temperature shape memory alloys were investigated in this study. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were employed to detect the microstructures. We found that these alloys were composed of dual phases, a non-modulated tetragonal L10 martensite and a face-centered cubic (fcc) γ phase. The martensite was twinned and well self-accommodated. The γ phase was a Co-based solid solution with 30% lower hardness than martensite. Although the fracture mode was intergranular, the strength and plasticity of the alloys increased markedly with the increasing volume fraction of the γ phase. The presence of the γ phase in grain boundaries rather than in the martensite is favorable to shape memory recovery. This was revealed by the maximum shape recovery strain over 5.0% that was obtained in the Co46Ni25Ga29 alloy, with the γ phase formed mainly in grain boundaries. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001461 [article] Microstructures and shape memory characteristics of dual-phase Co–Ni–Ga high-temperature shape memory alloys [texte imprimé] / Yan Li, Auteur ; Yan Xin, Auteur ; Liang Chai, Auteur . - 2011 . - pp. 3655–3663. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 10 (Juin 2010) . - pp. 3655–3663 Mots-clés : Co–Ni–Ga  Dual  phases  Shape  memory  alloys  Martensitic  phase  transformation  Fracture Résumé : The influence of microstructure on mechanical properties and shape memory characteristics of Co–Ni–Ga high-temperature shape memory alloys were investigated in this study. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were employed to detect the microstructures. We found that these alloys were composed of dual phases, a non-modulated tetragonal L10 martensite and a face-centered cubic (fcc) γ phase. The martensite was twinned and well self-accommodated. The γ phase was a Co-based solid solution with 30% lower hardness than martensite. Although the fracture mode was intergranular, the strength and plasticity of the alloys increased markedly with the increasing volume fraction of the γ phase. The presence of the γ phase in grain boundaries rather than in the martensite is favorable to shape memory recovery. This was revealed by the maximum shape recovery strain over 5.0% that was obtained in the Co46Ni25Ga29 alloy, with the γ phase formed mainly in grain boundaries. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645410001461