High Performance Pr-2(Fe,Co)(14)(C,B)-Type Nanocomposite Ribbons

The phase evolution, microstructure and magnetic properties of Pr9+xFe73-xCo10 B4C4 and Pr9+xFe71-xTi2Co10B4C4(x=0, 0.5, 1, 1.5) melt-spun ribbons have been investigated. All ribbons are mainly comprised of the 2:14:1, 2:17 and alpha-Fe phases. For the group of Pr9+xFe73-xCo10B4C4 ribbons, the coercivity increases with increasing of x while the remanence decreases with increasing of x. Optimal magnetic properties of (BR)(max) = 12.5MGOe for the Ti-free group have been obtained at x=1.5. When 2at. %Ti is substituted for Fe, the magnetic properties are remarkably enhanced. The coercivity and squareness of demagnetization curve of the Ti-substitution ribbons are substantially improved without a sacrifice of remanence (except for x=0), even the remanence obviously increasing at x=1.5. In this study the optimal magnetic properties when B-r=9.6kG, H-i(c) =10.2kOe, (BH)(max)= 17.4MGOe have been obtained in Ti-substituted Pr10.5Fe69.5Ti2CO10B4C4. Ti-substitution suppress the formation of 2:17 phase and prior growth of a-Fe phase during melt-spinning and annealing process, which optimize the grain size and the volume fraction magnetically of hard phase and soft phase. As a result, the intergranular exchange coupling substantially increases. These are the main reasons that the magnetic properties increase with increasing of Pr in Ti substituted Pr9+xFe71-xTi2Co10B4C4 (x=0-1.5) ribbons.