The quenching rate, which is dependent on the surface velocity (Vs) of Cu wheel during melt spinning, has significant influence on the formation of nanocomposite structure in the Fe52 Pt32 B18 melt-spun ribbons. The L 10 -FePt Fe2 B hard magnetic nanocomposite structure was formed at Vs =20-37 ms, while the soft magnetic fcc-FePt+amorphous phases were formed at Vs =40-50 ms. The ribbons melt spun at Vs =37 ms exhibit in-plane coercivity (Hci) =760 kAm, remanence (Br) =0.71 T, and energy product (BH)max =93.4 kJ m3. The Br =0.74-0.77 T, Hci =681-718 kAm, and (BH)max =101-108 kJ m3 were obtained for the ribbons melt spun at Vs =50 ms and annealed at 748-773 K for 900 s. The improvement in hard magnetic properties is due to the formation of more finer and homogeneous nanocomposite structure, which results in the enhancement in exchange coupling among the nanosized hard L 10 -FePt and soft Fe2 B magnetic phases.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy(all)