Regensburg 2002 – wissenschaftliches Programm

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DS: Dünne Schichten

DS 6: Strukturbildung und -chararkterisierung II

DS 6.2: Vortrag

Montag, 11. März 2002, 11:30–11:45, HS 32

Highly oriented MBE-grown NiTiCu shape memory thin films — •S. Thienhaus¹, R. Hassdorf¹, J. Feydt¹, R. Pascal¹, M. Boese², A. Sehrbrock¹, and M. Moske¹ — ¹Forschungszentrum caesar, 53111 Bonn — ²Universität Bonn, Institut für Anorganische Chemie, 53117 Bonn

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 only two specific 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 for tailoring microstructure and crystallographic orientation of shape memory thin films and thus suggest promising characteristics, especially in regard to their superelastic behavior.