Systematic study of the microstructure and magnetocaloric effect of bulk and melt-spun ribbons of La–Pr–Fe–Si compounds

• Published in: Journal of magnetism and magnetic materials 2014-01, Vol.350, p.94-99
• Main Authors: Liu, J.J., Zhang, Y., Zhang, J., Xia, W.X., Du, J., Yan, A.R.
• Format: Article
• Language: English
• Subjects: Bulk; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Magnetic properties and materials; Magnetically ordered materials: other intrinsic properties; Magnetocaloric effect, magnetic cooling; Magnetocaloric property; Melt-spun ribbon; Microstructure; NaZn13-type La–Pr–Fe–Si compound; Physics
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2013.09.027

The microstructure evolution and the mechanism of the formation of NaZn13-type 1:13 phase of La0.6Pr0.5Fe11.4Si1.6 alloys during annealing were investigated. After annealing at 1373K for a proper period of time (15 days for the bulk alloy and 4h for melt-spun ribbons), almost pure 1:13 phase was obtained. But with an overlong annealing time, 1:13 phase began to decompose and macroscopic α-Fe dendrites and La-rich phases appeared. Magnetocaloric effects of both La0.6Pr0.5Fe11.4Si1.6 bulk and melt-spun ribbons were also systematically studied. It was found that bulk sample exhibited larger thermal and magnetic hysteresis losses as a result of strong first-order transition, yet still showed higher magnetic entropy change and refrigerant capacity than those of melt-spun ribbons. By applying a field change of 0–5T, the magnetic entropy change and effective refrigerant capacity for bulk sample, respectively, were 25.2J/(kgK) and 474.1J/kg, while those of melt-spun ribbons turned out to be 21.9J/(kgK) and 458.5J/kg. •Microstructure evolution and mechanism of the NaZn13 phase formation of bulk and melt-spun ribbon of La0.6Pr0.5Fe11.4Si1.6 were investigated during annealing.•Both bulk alloy and melt-spun ribbon can get almost pure 1:13 phase after optimal annealing.•Bulk sample showed higher −ΔSM and RC than that of melt-spun ribbon and even has larger thermal and magnetic hysteresis losses.