Dresden 2009 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 21: Magnetic Shape Memory Alloys I

MA 21.9: Vortrag

Mittwoch, 25. März 2009, 12:15–12:30, HSZ 103

Twinning behaviour of textured polycrystalline NiMnGa — •Robert Chulist¹, Martin Pötschke², Andrea Böhm³, Heinz-Günter Brokmeier⁴, Thomas Lippmann⁵, Carl-Georg Oertel¹, and Werner Skrotzki¹ — ¹Institut für Strukturphysik, Technische Universität Dresden, 01062 Dresden — ²Institut für Metallische Werstoffe, Leibniz-Institut für Festkörper und Werstoffforschung, 01069 Dresden — ³Fraunhofer-Institut für Werzeugmaschinen und Umformtechnik, 01187 Dresden — ⁴GKSS Forschungszentrum, 21494 Geesthacht — ⁵GKSS Forschungszentrum, 21502 Geesthacht

Magnetically actuated shape memory alloys such as NiMnGa have recently attracted special attention due to large strains achieved by the reorientation of martensitic twin variants in which twin boundaries are highly mobile. Until now, a magnetic field induced strain (MFIS) has been mainly reported for NiMnGa single crystals. Since for large-scale production growth of single crystals is economically unfavourable, it is necessary to investigate polycrystalline samples on their suitability for MFIS. Therefore, the texture of NiMnGa alloys obtained by the different fabrication processes has been measured by diffraction of high energy synchrotron radiation and neutrons. The twinning behaviour will be discussed with respect to type of texture, grain size, phase transformations including variant selection, and MFIS.