Comparative study of the magnetocaloric effect in multiphase GdNiAl alloys: Single peak versus table-like profile in magnetic entropy changes

This paper presents a comparative analysis of the magnetic and magnetocaloric properties of multiphase Gd28Ni24Al48 and Gd33Ni13Al54 alloys. Both as-cast alloys are composed of GdNiAl2, GdNiAl and Ni-substituted GdAl2 ferromagnetic phases. The component ferromagnetic phases have closely adjacent ordering temperatures near 40 K, resulting in a reasonably large magnetic entropy change (ΔSM) for the Gd28Ni24Al48 alloy, while the widened ferromagnetic phase transitions contribute to the “table-like” ΔSM profile and considerable refrigerant capacity (RC) in the Gd33Ni13Al54 alloy. The above difference is principally due to the influence of the NiAl substitution on the transition temperatures of GdNiAl and GdAl2 phases. The −ΔSMs and RCs of 14.5 J/kgK, 500 J/kg and 9.2 K/kgK, 591 J/kg were obtained, for a 50 kOe field change, for the Gd28Ni24Al48 and Gd33Ni13Al54 alloys, respectively. The plateau-shaped −ΔSM and considerable RC qualify the Gd33Ni13Al54 alloy as a competitive refrigerant candidate for regenerative Ericsson cycle based magnetic refrigeration at low temperatures.