EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Two sintering processes were chosen as alternative and low-cost fabrication methods for Ni50Mn30Ga20 ferromagnetic shape memory alloy (FeSMA): a simple and single pressing and sintering route and the open die pressing (ODP) process were adopted for the consolidation of NiMnGa powders. The effects of the sintering processes parameters such as sintering time, powders size and cooling method, and the applied thermal treatments were investigated by means of microstructural observation through optical and SEM microscopy, differential scanning calorimetry (DSC), mechanical analysis including dynamic mechanical thermal analysis (DMTA) for the damping characterization, X-ray diffraction analysis and electrical resistivity measurements. Moreover, the physical characterization of the NiMnGa sintered samples allowed a complete investigation of the evolution of the thermoelastic martensitic transition from different points of view and a correlation between thermomechanical condition and functional properties. Finally, magnetic measurements provided a preliminary characterization of the magnetic transition of the alloy and they allowed the investigation of the effects of the microstructural condition induced by the sintering on the magnetic properties of the alloy. The achievements of this experimental study could be the preliminary step for the implementation of an alternative production process for NiMnGa alloy and for the optimization and combination of the functional transitions in order to exploit the coupling between structural and magnetic order.