Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals

NiTi alloys are very important in a number of applications since they demonstrate shape memory effect, which is due to the martensitic phase transition with the transition temperatures close to the room temperature. Many factors affect transition temperatures of the alloy, including a variation of i...

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Main Authors: Zhou, Kun, Babicheva, Rita I., Semenov, Alexander S., Dmitriev, Sergey V.
Other Authors: School of Mechanical and Aerospace Engineering
Format: Article
Language:English
Published: 2019
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Online Access:https://hdl.handle.net/10356/102840
http://hdl.handle.net/10220/49487
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-1028402023-03-04T17:19:55Z Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals Zhou, Kun Babicheva, Rita I. Semenov, Alexander S. Dmitriev, Sergey V. School of Mechanical and Aerospace Engineering Nanyang Environment and Water Research Institute Martensitic Phase Transformation Shape Memory Alloy Engineering::Mechanical engineering NiTi alloys are very important in a number of applications since they demonstrate shape memory effect, which is due to the martensitic phase transition with the transition temperatures close to the room temperature. Many factors affect transition temperatures of the alloy, including a variation of its chemical composition and thermo-mechanical treatment, which affects grain size, dislocation density, and other crystal structure parameters. It is well-known that the chemical composition of the alloys in grain boundaries can differ significantly from that in the bulk due to segregation of certain elements from the matrix to the grain boundaries. The effect of grain boundary segregations on the martensite transformation temperatures is still poorly understood. In the present molecular dynamics study, the possible effect of segregation of Ti or Ni atoms along Σ25 tilt grain boundary on the forward and reverse martensitic transformations is analyzed. The segregation is simulated by replacing the monoatomic Ti or Ni layer in the grain boundary with Ni or Ti layer, respectively. The results are compared to the case of no segregations. We analyze the initial relaxed and thermalized structures of the bi-crystals in austenite state as well as the temperature dependencies of potential energy per atom and volumetric dilatation. It is found that segregations may significantly decrease the start and finish temperatures of the martensitic transformation, and this effect is more pronounced for segregations of Ni. Published version 2019-07-30T06:26:02Z 2019-12-06T21:01:03Z 2019-07-30T06:26:02Z 2019-12-06T21:01:03Z 2019 Journal Article Babicheva, R. I., Semenov, A. S., Dmitriev, S. V., & Zhou, K. (2019). Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals. Letters on Materials, 9(2), 162-167. doi:10.22226/2410-3535-2019-2-162-167 2218-5046 https://hdl.handle.net/10356/102840 http://hdl.handle.net/10220/49487 10.22226/2410-3535-2019-2-162-167 en Letters on Materials © 2018 Institute for Metals Superplasticity Problems of Russian Academy of Sciences. All rights reserved. 6 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Martensitic Phase Transformation
Shape Memory Alloy
Engineering::Mechanical engineering
spellingShingle Martensitic Phase Transformation
Shape Memory Alloy
Engineering::Mechanical engineering
Zhou, Kun
Babicheva, Rita I.
Semenov, Alexander S.
Dmitriev, Sergey V.
Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals
description NiTi alloys are very important in a number of applications since they demonstrate shape memory effect, which is due to the martensitic phase transition with the transition temperatures close to the room temperature. Many factors affect transition temperatures of the alloy, including a variation of its chemical composition and thermo-mechanical treatment, which affects grain size, dislocation density, and other crystal structure parameters. It is well-known that the chemical composition of the alloys in grain boundaries can differ significantly from that in the bulk due to segregation of certain elements from the matrix to the grain boundaries. The effect of grain boundary segregations on the martensite transformation temperatures is still poorly understood. In the present molecular dynamics study, the possible effect of segregation of Ti or Ni atoms along Σ25 tilt grain boundary on the forward and reverse martensitic transformations is analyzed. The segregation is simulated by replacing the monoatomic Ti or Ni layer in the grain boundary with Ni or Ti layer, respectively. The results are compared to the case of no segregations. We analyze the initial relaxed and thermalized structures of the bi-crystals in austenite state as well as the temperature dependencies of potential energy per atom and volumetric dilatation. It is found that segregations may significantly decrease the start and finish temperatures of the martensitic transformation, and this effect is more pronounced for segregations of Ni.
author2 School of Mechanical and Aerospace Engineering
author_facet School of Mechanical and Aerospace Engineering
Zhou, Kun
Babicheva, Rita I.
Semenov, Alexander S.
Dmitriev, Sergey V.
format Article
author Zhou, Kun
Babicheva, Rita I.
Semenov, Alexander S.
Dmitriev, Sergey V.
author_sort Zhou, Kun
title Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals
title_short Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals
title_full Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals
title_fullStr Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals
title_full_unstemmed Effect of grain boundary segregations on martensitic transformation temperatures in NiTi bi-crystals
title_sort effect of grain boundary segregations on martensitic transformation temperatures in niti bi-crystals
publishDate 2019
url https://hdl.handle.net/10356/102840
http://hdl.handle.net/10220/49487
_version_ 1759857229306003456