Adiabatic magnetocaloric effect in Ni35Mn35In15 ribbons.

Heusler-type Ni-Mn-based metamagnetic shape memory alloys (MetaMSMAs) are promising candidates for magnetic refrigeration. To increase heat exchange rate and efficiency of cooling, the material should have a high surface/volume ratio. In this work, the typical Ni50Mn35In15 MetaMSMA was selected to fabricate thin ribbons by melt-spinning. The characteristic transformations of the ribbons were determined by calorimetry, X-ray diffraction, scanning electron microscopy and thermomagnetization measurements. The inverse and conventional magnetocaloric effects (MCEs) associated with the martensitic transformation (MT) and the ferromagnetic transition of the austenite (TCA), respectively, were measured directly by the adiabatic method (ΔTad) and indirectly by estimating the magnetic entropy change from magnetization measurements. It is found that the ribbons exhibit large values of ΔTad = 1.1K at μ0ΔH = 1.9 T, in the vicinity of the MT temperature of 300K for inverse MCE, and ΔTad = 2.3K for conventional MCE at TCA = 309 K. This result strongly motivates further development of different MetaMSMA refrigerants shaped as ribbons. [ABSTRACT FROM AUTHOR]