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Phase Formation and Structural Sequence of Highly-Oriented MBE-Grown NiTiCu Shape Memory Thin Films
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Ralf Hassdorf1), Jürgen Feydt1), René Pascal1), Sigurd Thienhaus1), Markus Boese2), Tobias Sterzl1), Bernhard Winzek1) and Michael Moske1)
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1) Center of Advanced European Studies and Research (caesar)
2) Institut für Anorganische Chemie, Universität Bonn
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We present a study demonstrating the capability for controlled shape memory thin film growth using molecular beam epitaxy. Here, NiTiCu alloy films were grown which are known to exhibit the martensitic transformation well above room temperature. Remarkably, the microstructure of these films was found to be very different compared to conventionally sputtered polycrystalline films: here, the crystallites are highly oriented within ±3° along the film plane normal. Moreover, a splitting of the martensite orientation is detected indicating the selection of two specific sets of martensite variants. Mechanical stress measurements reveal a high ratio of recoverable stress even for films below 500 nm thickness. These results open up the possibility to specifically modify the microstructure and crystallographic orientation of shape memory thin films and thus suggest promising characteristics, especially in regard to their superelastic behavior.
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Keyword: shape memory alloy, martensitic transformation, thin film, molecular beam epitaxy, phase formation
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Received: March 11, 2002
Accepted: April 15, 2002 ,
Published online: September 06, 2005 |
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Copyright (c) 2005 The Japan Institute of Metals |
 Reference
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