Magnetic properties of high-coercivity melt-spun Pr-Fe-Co-Ti-B-Si system ribbons and their bonded magnets

Melt-spun ribbons of PrxFe98-x-y-zCoyTi1.5BzSi0.5(x = 10.0-13.0, y = 8.0-12.0, z = 7.0-14.0) alloys were prepared by the single roller liquid rapid-quenching method, and the effects of composition, wheel velocity, and annealing condition on the magnetic properties were studied. The optimum preparation conditions and some of the properties were as follows: composition: Pr-11 Fe-68.5 CO formula(8)Ti(1.5)B(10.5)Si(0.5); wheel velocity: 10.0 m/s and annealing condition 600 degrees C for 5 min in Ar atmosphere; magnetic properties J(r) = 0.8 T (8.0 W), H-cJ = 1.57 MA/m (19.7 kOe), H,B = 0.55 MA/m(6.9 kOe), (BH)(max) = 111.2 kJ/m(3) (13.9 MGOe), H-k/H-cJ x 100 = 24.9%, alpha(J(r)) = -04%/degrees C, alpha(H-cJ) = -0.37%/degrees C and T-c = 403 degrees C. From a TEM observation, the average particle size of this ribbon was found to be about 23 nm. The isotropic compression molding bonded magnets were prepared by using Pr11Fe68.5Co8Ti1.5B10.5Si0.5 ribbons annealed at 600 degrees C for 5 min. The magnetic properties of this bonded magnet were J(r), = 0.60 T(6.0 W), H-cj = 1.53 MA/m(19.3 kOe), HBcB = 0.42 MA/m (5.2 kOe) and (BH)(max) = 66.8 kJ/m(3) (8.4 MGOe). The irreversible losses of Pr11Fe66.5Co10Ti1.5B10.5Si0.5 and Pr11Fe64.5Co12Ti1.5B10.5Si0.5 bonded magnets were smaller than that of an MQP-O bonded magnet at 150 degrees C.