Phase transformations and magnetocaloric effect in NiFeGa ferromagnetic shape memory alloy

In this work, Ni55Fe18Ga27 ferromagnetic shape memory alloy was prepared through a suction-casting method. The martensitic, magnetic transformation and magnetocaloric effect of Ni55Fe18Ga27 ferromagnetic shape memory alloy were studied using differential scanning calorimetry (DSC) and superconducting quantum interface device (SQUID) magnetometer. The temperature dependence of the magnetization and the DSC curves of the alloy showed that the martensitic transformation occurs above the Curie temperature (T-c) between two paramagnetic phases, and the martensitic phase transformation temperatures increase with increasing the annealing temperature in terms of the heating and cooling process. Furthermore, the magnetic entropy change in the polycrystalline Ni55Fe18Ga27 alloy has also been analyzed as function of temperature in different applied magnetic fields. It is found that maximum values of the magnetic entropy change take place in the vicinity of the martensitic phase transformation temperature. (c) 2008 Elsevier B.V. All rights reserved.