Berlin 2005 – scientific programme
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M: Metallphysik
M 32: Poster TU B (Symposium Tomographic Methods in Materials Research M-32.32-55)
M 32.26: Poster
Monday, March 7, 2005, 14:30–16:30, Poster TU B
Microstructure, phase sequence, and superelasticity in highly oriented MBE-grown NiTiCu shape memory thin films — •R. Hassdorf1, J. Feydt1, S. Thienhaus1, M. Boese2, L. Buforn3, N. Conté3, and M. Moske1 — 1Forschungszentrum caesar, 53175 Bonn, Germany — 2Universität Bonn, Institut für Anorganische Chemie, 53117 Bonn, Germany — 3CSM Instruments SA, 2034 Peseux, Switzerland
Using MBE deposition highly oriented NiTiCu shape memory thin films were accomplished. The austenite-martensite transition in these films, single or two-stage transformation depending on the quantity of the Cu additions, occurs with comparable transition temperatures as known for sputter-deposited films. Mechanical stress measurements reveal a deformation recovery in the order of 400 MPa. Superelasticity spans to about 3% strain as referred to spherical indentation data. The microstructure is remarkable in that the crystallites are oriented within ±5∘ along the film plane normal as observed by X-ray diffraction. The occurrence of this preferential order is deduced to the formation of a Ti-rich (Ti2Ni) phase at the film-substrate interface providing a highly oriented initial crystallization template. The results described in this study outline the perspectives for tailoring the microstructure and transformation performance of shape memory thin films, especially in regard to technological applications.
Supported by BMBF under contract no. 03N4031A.