Hard Magnetic Property Improvement of Melt-Spun PrCo 5 Ribbons by Fe and C Doping

Magnetic properties and microstructure of melt-spun PrCo 5− x − y Fe x C y ( x = 0 and 0.3; y = 0–0.3) ribbons are studied. For PrCo 5 ribbons spun at lower wheel speed of 20 m/s, the coexistence of 2:17 phase with magnetic hard 1:5 phase leads to low coercivity of 0.6 kOe. Increasing wheel speed to 40 m/s imroves the coercivity to 3.3 kOe due to the increased volume fraction of 1:5 phase. Interestingly, magnetic properties of PrCo 5 ribbons melt spun at 40 m/s ( B r = 6.4 kG, i H c = 3.3 kOe, and ( BH ) max = 4.5 MGOe) are improved to B r = 6.1–6.5 kG, i H c = 7.8–13.5 kOe, ( BH ) max = 7.3–8.9 MGOe by doping C, and significantly enhanced to B r = 6.3 kG, i H c = 16.1 kOe, and ( BH ) max = 9.3 MGOe for C and Fe co-doped PrCo 4.6 Fe 0.3 C 0.1 ribbons. The structural and thermo-magnetic analysis confirms that the entrance of Fe and part of C into the crystal structure of 1:5 phase leads to the increase of Curie temperature. Doping proper C content not only uniformly refines grain size and, therefore, improves the squareness of demagnetization curve and ( BH ) max , but also increases the volume fraction of 1:5 phase, and thus enhances the coercivity. The increased volume fraction of 1:5 phase and the reduced magnetic domain size due to refined microstructure by co-doping Fe and C make PrCo 4.6 Fe 0.3 C 0.1 ribbons exhibit a high permanent magnetic performance. They are promising candidate materials for making bonded magnets.