Enhanced magnetocaloric effects of Ni-Fe-Mn-Sn alloys involving strong metamagnetic behavior.

Very recently, we reported that Fe-doped Ni 50-x Fe x Mn 38.0 Sn 12.0 alloys exhibited enhanced magnetization difference Δ M between the martensite and austenite phases. Of note is that the alloy with x = 4.2 exhibits a strong metamagnetic transition behavior, i.e. magnetic-field-induced reverse martensite transformation, which is favorable for the magnetocaloric effects. Here, the enhanced magnetocaloric effect related to metamagnetic transition in the selected Ni 35.8 Fe 4.2 Mn 38.0 Sn 12.0 alloy was reported. This alloy exhibits a high magnetization difference Δ M of ∼58 A·m 2 /kg between martensite and austenite phases owing to the magnetic and structural coupling. The doping of Fe leads to a strong metamagnetic behavior, with austenite peak temperature shift Δ A p / Δ H reaching −2.4 K/T. As a result, the magnetic entropy change Δ S m increases rapidly from a starting critical magnetic field ∼0.2 T and then saturates at various finishing critical magnetic fields, depending on the working temperature. A sizable peak Δ S m of 33.8 J/kg·K with a working temperature interval of 7 K is obtained under a magnetic field of 5 T, which is responsible for a high relative cooling power RCP of 237 J/kg. These results suggest that Ni 45.8 Fe 4.2 Mn 38.0 Sn 12.0 alloy may act as a potential solid-state magnetic refrigerant. [ABSTRACT FROM AUTHOR]