Hard Magnetic Property Improvement of Melt-Spun PrCo5 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.