The microstructure and magnetization behaviors of (Pr8.2Fe86.1-xCoxB5.7)0.99Zr0.01 (x=0-10) nanocomposite magnets

Nanocomposite (Pr8.2Fe86.1-xCoxB5.7)(0.99)Zr-0.01 (x = 0-10) ribbons consisting of Pr-2(Fe,Co)(14)B and alpha-(Fe,Co) phases were prepared by a melt-spun technique. The microstructure and magnetic properties were studied. The results show that the Curie temperature increases drastically with increasing Co content. The optimal permanent magnetic properties are obtained at x = 2, and the value of H-ci, M-s, M-r, and (BH)(max) are 6.52 kOe, 150.2 emu/g, 120.9 emu/g, and 22.34 MGOe, respectively. Typical magnetization behaviors of nanocomposite magnets are found in these ribbons. The significant remanence enhancement indicates that a strong intergrain exchange coupling exists in all ribbons studied in this work. By Co substitution, the intergrain exchange coupling is enhanced significantly. The study of microstructure shows that the larger grains of Pr-2(Fe,Co)(14)B hard phase are surrounded by the smaller grains of alpha-(Fe,Co) soft phase with size about 10-20 nm in the ribbon with Co substitution. This kind of microstructure is in favor of exchange coupling between magnetically hard and soft phases and results in excellent magnetic properties. (c) 2011 American Institute of Physics. [doi:10.1063/1.3566074]