High magnetic properties of nanocomposite ribbons made with Mischmetals-Fe-Co-Ti-B alloys

Magnetic properties, phase constitution, and microstructure of melt spun R-lean and B-enriched Mischmetal (MM)-Fe-Co-Ti-B nanocomposites have been investigated. The thermal magnetic analysis show that only 2:14:1 and alpha-Fe [alpha-(Fe, Co)] phases appear for MM(A)(9.5)Fe78.5Ti2B10 and MM(A)(9)Fe79.5Co2.5Ti1B8 ribbons, while an additional Fe3B phase is present for R9.25Fe79.25Co2.5Ti1B8 [R=MM(A), MM(B), and MM(C)] ribbons. The magnetic properties of the above nanocomposites are determined not only by the phase constitution of MM-Fe-Co-Ti-B nanocomposites but also by the composition of MMs. Besides, fine grain size of 15-40 nm is almost unchanged for the ribbons with various MMs, giving rise to the strong exchange coupling effect between magnetic grains and the improved magnetic performance. In this study, the optimum magnetic properties of B-r = 9.6 kG, H-i(c)= 8.6 kOe, and (BH)(max) = 18.2 MG Oe can be achieved for MM(B)(9.25)Fe79.25Co2.5Ti1B8 nanocomposites. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3061993]