Papers by Author: Martin Pötschke

Abstract: Textured polycrystalline Ni-Mn-Ga alloys were prepared by directional solidification. Alloys were chosen to have the 5M modulated martensitic structure after proper heat treatment. A two-side mechanical training decreased the twin boundary pinning stress. The stress-strain behaviour for the training process and the magnetically induced stress depends on the training direction. Magnetic field induced strain was demonstrated in samples with a plate-like geometry. The influence of the microstructure on the magneto-mechanical behaviour is discussed.

Abstract: Textured polycrystalline NiMnGa alloys were prepared by directional solidification. Alloys were chosen to have either the 7M or the 5M modulated martensitic structure after proper heat treatment. Mechanical training allowed to reduce the twin boundary pinning stress to below the magnetically induced stress. Thus, magnetic field induced changes in the mechanical behaviour could be demonstrated. The conditions of preparation and mechanical training will be discussed together with their influence on structure, microstructure, and the magneto-mechanical behaviour.