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Phase stability and transformations in NiTi from density functional theory calculations / Karthik Guda Vishnu in Acta materialia, Vol. 58 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 745-752 Titre : Phase stability and transformations in NiTi from density functional theory calculations Type de document : texte imprimé Auteurs : Karthik Guda Vishnu, Auteur ; Alejandro Strachan, Auteur Article en page(s) : pp. 745-752 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : NiTi  Martensitic  phase  transformation  Density  functional  theory  (DFT)  Shape  memory  alloys  (SMA) Index. décimale : 669 Métallurgie Résumé : We used density functional theory to characterize various crystalline phases of NiTi alloys: (i) high-temperature austenite phase B2; (ii) orthorhombic B19; (iii) the monoclinic martensite phase B19′; and (iv) a body-centered orthorhombic phase (BCO), theoretically predicted to be the ground state. We also investigated possible transition pathways between the various phases and the energetics involved. We found B19 to be metastable with a 1 meV energy barrier separating it from B19′. Interestingly, we predicted a new phase of NiTi, denoted B19′′, that is involved in the transition between B19′ and BCO. B19′′ is monoclinic and can exhibit shape memory; furthermore, its presence reduces the internal stress required to stabilize the experimentally observed B19′ structure, and it consequently plays a key role in NiTi’s properties. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...] [article] Phase stability and transformations in NiTi from density functional theory calculations [texte imprimé] / Karthik Guda Vishnu, Auteur ; Alejandro Strachan, Auteur . - pp. 745-752. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 745-752 Mots-clés : NiTi  Martensitic  phase  transformation  Density  functional  theory  (DFT)  Shape  memory  alloys  (SMA) Index. décimale : 669 Métallurgie Résumé : We used density functional theory to characterize various crystalline phases of NiTi alloys: (i) high-temperature austenite phase B2; (ii) orthorhombic B19; (iii) the monoclinic martensite phase B19′; and (iv) a body-centered orthorhombic phase (BCO), theoretically predicted to be the ground state. We also investigated possible transition pathways between the various phases and the energetics involved. We found B19 to be metastable with a 1 meV energy barrier separating it from B19′. Interestingly, we predicted a new phase of NiTi, denoted B19′′, that is involved in the transition between B19′ and BCO. B19′′ is monoclinic and can exhibit shape memory; furthermore, its presence reduces the internal stress required to stabilize the experimentally observed B19′ structure, and it consequently plays a key role in NiTi’s properties. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235556%23 [...]

Phase stability and transformations in NiTi from density functional theory calculations / Karthik Guda Vishnu in Acta materialia, Vol. 58 N° 3 (Fevrier 2010) 

Public ISBD [article]  in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 745–752 Titre : Phase stability and transformations in NiTi from density functional theory calculations Type de document : texte imprimé Auteurs : Karthik Guda Vishnu, Auteur ; Alejandro Strachan, Auteur Année de publication : 2011 Article en page(s) : pp. 745–752 Note générale : Métallurgie Langues : Anglais (eng) Mots-clés : NiTi  Martensitic  phase  transformation  Density  functional  theory  (DFT)  Shape  memory  alloys  (SMA) Résumé : We used density functional theory to characterize various crystalline phases of NiTi alloys: (i) high-temperature austenite phase B2; (ii) orthorhombic B19; (iii) the monoclinic martensite phase B19′; and (iv) a body-centered orthorhombic phase (BCO), theoretically predicted to be the ground state. We also investigated possible transition pathways between the various phases and the energetics involved. We found B19 to be metastable with a 1 meV energy barrier separating it from B19′. Interestingly, we predicted a new phase of NiTi, denoted B19′′, that is involved in the transition between B19′ and BCO. B19′′ is monoclinic and can exhibit shape memory; furthermore, its presence reduces the internal stress required to stabilize the experimentally observed B19′ structure, and it consequently plays a key role in NiTi’s properties. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409006156 [article] Phase stability and transformations in NiTi from density functional theory calculations [texte imprimé] / Karthik Guda Vishnu, Auteur ; Alejandro Strachan, Auteur . - 2011 . - pp. 745–752. Métallurgie Langues : Anglais (eng) in Acta materialia > Vol. 58 N° 3 (Fevrier 2010) . - pp. 745–752 Mots-clés : NiTi  Martensitic  phase  transformation  Density  functional  theory  (DFT)  Shape  memory  alloys  (SMA) Résumé : We used density functional theory to characterize various crystalline phases of NiTi alloys: (i) high-temperature austenite phase B2; (ii) orthorhombic B19; (iii) the monoclinic martensite phase B19′; and (iv) a body-centered orthorhombic phase (BCO), theoretically predicted to be the ground state. We also investigated possible transition pathways between the various phases and the energetics involved. We found B19 to be metastable with a 1 meV energy barrier separating it from B19′. Interestingly, we predicted a new phase of NiTi, denoted B19′′, that is involved in the transition between B19′ and BCO. B19′′ is monoclinic and can exhibit shape memory; furthermore, its presence reduces the internal stress required to stabilize the experimentally observed B19′ structure, and it consequently plays a key role in NiTi’s properties. DEWEY : 669 ISSN : 1359-6454 En ligne : http://www.sciencedirect.com/science/article/pii/S1359645409006156