Dresden 2014 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
MM: Fachverband Metall- und Materialphysik
MM 6: Microstructure and Phase Transformations I - Martensitic phase transformations
MM 6.4: Vortrag
Montag, 31. März 2014, 11:00–11:15, IFW B
Mesoscopic twinning of nanotwinned martensites in eptiaxial Ni-Mn-Ga films: A TEM study — •Christian Behler1,2,3, Anja Backen1, Hanuš Seiner4, Robert Niemann1,2, Sandra Kauffmann-Weiss1,3, Ludwig Schultz1,2, and Sebastian Fähler1,2,3 — 1IFW Dresden, P.O. Box 270116, 01171 Dresden, Germany — 2Technische Universität Dresden, Department of Physics, Institute for Solid State Physics, 01062 Dresden, Germany — 3Technische Universität Chemnitz, Faculty of Natural Sciences, Institute of Physics, D-09107 Chemnitz, Germany — 4Institute of Thermomechanics, ASCR, Dolejškova 1402/5, 182 00 Prague, Czech Republic
Ni-Mn-Ga magnetic shape memory (MSM) alloys have attracted much attention due to the high reversible strains realized by reorientation of martensitic variants by applying external magnetic fields (MIR). To optimize this effect a detailed knowledge about the microstructure is beneficial, since the MIR effect depends on the martensitic phase and the type of mesoscopic twin boundaries connecting the different martensitic variants. As model system epitaxial Ni-Mn-Ga films are investigated which show two different microstructures at the surface. Several cross-sections of both structures were prepared by FIB milling and analyzed by means of (High-Resolution) TEM to gain a complete 3D information about the film structure. We apply a nucleation scenario based on WLR theory to explain the precession of the martensitic transformation for each microstructure. It results in the characteristic formation of mesoscopic twin boundaries we observe in thin films.