Perspectives of sensor alloys in nickel base systems

NiMnGa alloys have been an important material for sensor manufacture where the shape memory has been within martensitic range only and accepted as magnetic shape memory alloys. The acoustic - magneto - thermo-mechanical responses of NiMnGa compositions have introduced unique behavior to manufacture smart sensors. Most interest has appeared about study of compositions, which has shape recovery at room temperature. Highly brittle nature of single or poly-crystals have introduced many elements (Fe, Sn, Cu, Al, Gd, etc.) to induce ductility of crystals. The relative variations of crystallography, layered modulations (M) and transition temperatures developed have described to consider the martensitic systems for further unique developments. Magnetic field induced strains (MFIS) of ferromagnetic shape memory (FMSM) alloys have attracted combinations of properties by ferromagnetic elements substitutions. The strategies of ductility improvement have described NiFeGa alloys of similar characteristics. The interests mostly have concentrated on the activity of magnetic shape recovery at room temperature.