Microstructure and magnetocaloric properties in melt-spun and high-pressure hydrogenated La0.5Pr0.5Fe11.4Si1.6 ribbons.

The effects of wheel speeds and high-pressure hydrogen treatment on phase evolution, microstructure, and magnetocaloric properties in La0.5Pr0.5Fe11.4Si1.6 melt-spun ribbons are studied in this work. The results reveal that the increase of wheel speed is beneficial to the formation of cubic NaZn13-type phase and the grain refinement. The optimized wheel speed for microstructural and magnetocaloric properties is 30 m/s. The largest entropy change of 18.1 J/kg⋅K at 190 K under a magnetic field change of 0 T–5 T is obtained in La0.5Pr0.5Fe11.4Si1.6 ribbons melt-spun at 30 m/s. After a high-pressure hydrogen treatment of 50 MPa, the Curie temperature of the ribbons prepared at 30 m/s is adjusted to about 314 K and the large –ΔSM of 17.9 J/kg⋅K under a magnetic field change of 0 T–5 T is achieved at room temperature with almost none hysteresis loss. The small thermal and magnetic hysteresis and the large –ΔSM make the La0.5Pr0.5Fe11.4Si1.6 hydride ribbons appropriate for magnetic refrigerant applications around room temperature. [ABSTRACT FROM AUTHOR]