Large low-field magnetocaloric effect in a directionally solidified Ni50Mn18Cu7Cu25 alloy

Magnetic refrigeration based on the magnetocaloric effect (MCE) is conceived as a promising alternative to the conventional gas compression/expansion technique. For potential applications, the magnetic refrigerants exhibiting high-performance at low field are in great need. In this work, we present large MCE obtained in a directionally solidified polycrystalline Ni50Mn18Cu7Ga25 alloy with the co-occurrence of magnetic transition and martensitic transformation. Such a strong magneto-structural coupling yields large magnetic entropy change of −12.8 Jkg−1K−1 and adiabatic temperature variation of 1.6 K at an external magnetic field change of 1.5 T. It is demonstrated that the fabrication of Ni-Mn-Ga based alloys through composition tuning and directional solidification could be an economical processing route to improve magnetocaloric properties.