Processing and characterization of NiTi-based shape memory alloy thin films

In the present work, the properties of two NiTi-based shape memory alloy thin films, namely Ti50Ni25Cu25 ribbon and Ni-Ti-Hf thin films, and the influencing factors have been extensively studied. Major attention has been paid to rapid thermal annealing of the initially amorphous materials and their...

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Main Author: Tong, Yunxiang
Other Authors: Miao Jianmin
Format: Theses and Dissertations
Language:English
Published: 2008
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Online Access:https://hdl.handle.net/10356/13440
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-134402023-03-11T17:51:26Z Processing and characterization of NiTi-based shape memory alloy thin films Tong, Yunxiang Miao Jianmin Liu Yong School of Mechanical and Aerospace Engineering DRNTU::Engineering::Materials::Microelectronics and semiconductor materials In the present work, the properties of two NiTi-based shape memory alloy thin films, namely Ti50Ni25Cu25 ribbon and Ni-Ti-Hf thin films, and the influencing factors have been extensively studied. Major attention has been paid to rapid thermal annealing of the initially amorphous materials and their resulted properties, including crystallization behavior, microstructure evolution, transformation characteristics and constraint shape memory effect. As a result, the processing-microstructure-property relationship has been established, which provides guidelines on optimization of the properties. The crystallization behavior of NiTi-based thin films is characterized by a single-stage transformation. The addition of Cu reduces the crystallization temperature and activation energy of the initially amorphous alloy; whereas, the addition of Hf has a contrary effect. With the help of rapid thermal annealing, the initially amorphous Ti50Ni25Cu25 ribbon can be fully crystallized by annealing at 400 ºC for 30 s, which is significantly lower than the crystallization temperature under conventional thermal annealing. This is attributed to the assistance of the extra energy available from the higher internal stress field associated with free volume in amorphous state. DOCTOR OF PHILOSOPHY (MAE) 2008-10-20T08:18:12Z 2008-10-20T08:18:12Z 2008 2008 Thesis Tong, Y. X. (2008). Processing and characterization of NiTi-based shape memory alloy thin films. Doctoral thesis, Nanyang Technological University, Singapore. https://hdl.handle.net/10356/13440 10.32657/10356/13440 en 207 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 DRNTU::Engineering::Materials::Microelectronics and semiconductor materials
spellingShingle DRNTU::Engineering::Materials::Microelectronics and semiconductor materials
Tong, Yunxiang
Processing and characterization of NiTi-based shape memory alloy thin films
description In the present work, the properties of two NiTi-based shape memory alloy thin films, namely Ti50Ni25Cu25 ribbon and Ni-Ti-Hf thin films, and the influencing factors have been extensively studied. Major attention has been paid to rapid thermal annealing of the initially amorphous materials and their resulted properties, including crystallization behavior, microstructure evolution, transformation characteristics and constraint shape memory effect. As a result, the processing-microstructure-property relationship has been established, which provides guidelines on optimization of the properties. The crystallization behavior of NiTi-based thin films is characterized by a single-stage transformation. The addition of Cu reduces the crystallization temperature and activation energy of the initially amorphous alloy; whereas, the addition of Hf has a contrary effect. With the help of rapid thermal annealing, the initially amorphous Ti50Ni25Cu25 ribbon can be fully crystallized by annealing at 400 ºC for 30 s, which is significantly lower than the crystallization temperature under conventional thermal annealing. This is attributed to the assistance of the extra energy available from the higher internal stress field associated with free volume in amorphous state.
author2 Miao Jianmin
author_facet Miao Jianmin
Tong, Yunxiang
format Theses and Dissertations
author Tong, Yunxiang
author_sort Tong, Yunxiang
title Processing and characterization of NiTi-based shape memory alloy thin films
title_short Processing and characterization of NiTi-based shape memory alloy thin films
title_full Processing and characterization of NiTi-based shape memory alloy thin films
title_fullStr Processing and characterization of NiTi-based shape memory alloy thin films
title_full_unstemmed Processing and characterization of NiTi-based shape memory alloy thin films
title_sort processing and characterization of niti-based shape memory alloy thin films
publishDate 2008
url https://hdl.handle.net/10356/13440
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