Martensitic transformation and magnetic features in Ni-Fe-Mn-In Heusler alloy

The Ni50-xFexMn37In13(x=1, 3, 5) polycrystalline samples are prepared by arc melting method. The martensitic transformations and crystal structures for Ni50-xFexMn37In13(x=1, 3, 5) samples are systematically analyzed by measuring the structure and magnetism. The results show that the three samples present different structures at room temperature. In the mean time, with the increase of the content of Fe, the martensitic transformation temperature rapidly decreases, while the ferromagnetism is gradually enhanced for these alloys. Furthermore, both the magnetoresistance and the magnetocaloric effect are also investigated in Fe3 and Fe5 alloys. For an applied magnetic field of 3 T, it is found that the magnetoresistance effects of two samples are about -46% and -15%, while their isothermal entropy changes are about 6 J·kg-1 and 9.5 J·kg-1·K-1 during reverse martensitic transformation, respectively. Accompanied with the disappearing of a very wide transforming range and a slight magnetic hysteresis loss, the net refrigerating capacity of Fe3 sample reaches 96 J·kg-1 in the process of reverse martensitic transformation.