Structure and magnetic properties of Pr 2 Fe 14 (C, B)/α-(Fe, Co)-type nanocomposite ribbons

The phase evolution, microstructure and magnetic properties of Pr x Fe 82- x-y Ti y Co 10 B 4 C 4 ( x =9—10.5; y =0, 2) melt-spun ribbons have been investigated. All ribbons are mainly comprised of the 2 ∶14 ∶1, 2 ∶17 and α-(Fe, Co) phases. For the group of Ti-free ribbons ( y =0), the coercivity increases with increasing x while the remanence decreases with increasing x . When 2 at.%Ti is substituted for Fe in the Ti-free ribbons, 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 =9), the remanence even obviously increases at x =10.5. The optimal magnetic properties of B r =9.6 kGs (1 Gs=10 -4 T), i H c =10.2 kOe (1 Oe=79.5775 A/m), ( BH ) max ＝17.4 MGOe have been obtained in Ti-substituted Pr 10.5 Fe 69.5 Ti 2 Co 10 B 4 C 4 group. The volume fraction of the 2 ∶14 ∶1 phase increases with increasing x , which leads to an increase of coercivity. Ti-substitution suppresses the grain growth of α-(Fe, Co) phase during annealing process, which makes the volume ratio of magnetically hard phase and soft phase and grain size tend to have optimal values, and the intergranular exchange coupling substantially enhances.