The effect of Ti and C on the phase evolution and magnetic properties of Pr9FebalTixB11-yCy (x=0-4, y=0-11) nanocomposites

Phase evolution, microstructure, and magnetic properties of melt-spun Pr9FebalTixB11-yCy (x=0, 2.5, and 4, y=0-11) ribbons have been investigated. For Pr9FebalTixB11-yCy series ribbons, addition of Ti suppresses the formation of metastable Pr2Fe23B3 phase and ensures the existence of a large amount of magnetically hard Pr2Fe14B phase in the ribbons. However, the increase of C substitution in the Pr9FebalTi2.5B11-yCy (y=0-5.5) ribbons diminishes the B-r, H-i(c), and (BH)(max) monotonically, which comes from the increase of volume fraction of Pr2Fe17Cz and alpha-Fe phases and the rapid decrease of the 2:14:1 phase. Only in the higher Ti content Pr9FebalTi4B11-yCy ribbons, a slight C addition cannot only form the Pr2Fe14(B,C) phase but also refine the grain size, giving rise to the improvement of magnetic properties. The optimal properties of B-r=9.4 kG, H-i(c)=11.1 kOe, (BH)(max)=18.0 MGOe, alpha=-0.207%/degrees C, and beta=-0.612%/degrees C are achieved in Pr9FebalTi4B10.5C0.5 nanocomposites. (C) 2006 American Institute of Physics.