Effect of particle size on the magneto-caloric properties of Ni51Mn34In14Si1 alloy

We have systematically investigated the effect of particle size on the magneto-caloric properties of Ni51Mn34In14Si1 alloy. Arc melted Ni51Mn34In14Si1 alloy was milled to reduce the average particle size and then vacuum annealed to reduce the strain accumulated in the particles during milling. Annealed particles were sieved and magneto-caloric parameters of the particles of different size ranges were systematically measured. It was observed that with decreasing particle size, the magnetic entropy change (ΔSM) decreased but the refrigerant capacity (RC) increased to a maximum value and then decreased. The investigations reveal that the magneto-caloric parameters could be tuned over a wide range by changing the particle size of the alloy. RC (ΔSM) obtained is 40.4 J kg−1 (11.2 J kg−1 K−1) for the alloy with particle size ranging between 600 μm and 710 μm for an applied magnetic field change of 1.2 Tesla. These combined values of ΔSM and RC are the highest reported for any ferromagnetic shape memory alloy particle. These studies indicate that Ni51Mn34In14Si1 alloy particles with controlled particle size are potential candidates for magnetic refrigeration near room-temperature.