Influence of solidification rate and heat treatment on magnetic refrigerant properties of melt spun Ni51Mn34In14Si1 ribbons

Influence of solidification rate and heat treatment on magnetic and magnetic refrigerant properties such as magnetic entropy change (ΔSM) and refrigerant capacity (RC) of melt spun ribbons of Ni51Mn34In14Si1 alloy is reported. The characteristic temperatures and magnetic refrigerant properties of as-spun ribbons decreased with increasing solidification rate. Higher solidification rate achieved by higher wheel speed yielded ribbons with partially ordered B2 austenite phase instead of the ordered L21 austenite structure. Structural properties improved and the characteristic temperatures increased upon heat treatment of the as-spun ribbons at elevated temperatures. Considerable enhancement in ΔSM and RC values were observed in 823 K heat treated ribbons obtained at lower solidification rate. A good combination of ∆SM (=14.1 J kg−1 K−1) and RC (=37.3 J kg−1) values were obtained at reasonably low magnetic field change of 1.2 T for the ribbons melt spun at a wheel speed of 16 m/s followed by annealing at 823 K for 1800 s.