Dresden 2011 – scientific programme
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MA: Fachverband Magnetismus
MA 25: Magnetic Shape Memory Alloys II (jointly with MM)
MA 25.1: Talk
Tuesday, March 15, 2011, 13:30–13:45, HSZ 103
Polycrystalline Ni-Mn-Ga: influence of microstructure and sample shape — •Jan Romberg1, Martin Pötschke1, Claudia Hürrich1, Stefan Roth1, Bernd Rellinghaus1, and Ludwig Schultz1,2 — 1IFW-Dresden — 2TU-Dresden
Ni-Mn-Ga ferromagnetic shape memory alloys (FSMAs) show strain up to 10% in magnetic field due to the motion of twin boundaries (MIR - magnetically induced reorientation). But, the large strain is only observed for single crystals. For technical application, polycrystals are of great interest because they are easier to produce und cheaper. But in polycrystals the grain boundaries can hinder twin boundary motion. It is known that in textured polycrystals MIR is possible.
We discuss the influence of microstructure and sample shape on the magnetically induced strain. Furthermore we worked out how to get large and yet textured grains and we developed an optimized mechanical training procedure in order to achieve large strain.