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

Melt-spun ribbons of Pr/sub x/Fe/sub 98-x-y-z/Co/sub y/Ti/sub 1.5/B/sub z/Si/sub 0.5/(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/sub 11/Fe/sub 68.5/ Co formula/sub 8/Ti/sub 1.5/B/sub 10.5/Si/sub 0.5/; wheel velocity: 10.0 m/s and annealing condition 600/spl deg/C for 5 min in Ar atmosphere; magnetic properties J/sub r/=0.8 T (8.0 kG), H/sub cJ/=1.57 MA/m (19.7 kOe), H/sub cB/=0.55 MA/m(6.9 kOe), (BH)/sub max/=111.2 kJ/m/sup 3/ (13.9 MGOe), H/sub k//H/sub cJ//spl times/100=24.9%, /spl alpha/(J/sub r/)=-04%//spl deg/C, /spl alpha/(H/sub cJ/)=-0.37%//spl deg/C and T/sub c/=403/spl deg/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 Pr/sub 11/Fe/sub 68.5/Co/sub 8/Ti/sub 1.5/B/sub 10.5/Si/sub 0.5/ ribbons annealed at 600/spl deg/C for 5 min. The magnetic properties of this bonded magnet were J/sub r/=0.60 T(6.0 kG), H/sub cJ/=1.53 MA/m(19.3 kOe), H/sub cB/=0.42 MA/m (5.2 kOe) and (BH)/sub max/=66.8 kJ/m/sup 3/ (8.4 MGOe). The irreversible losses of Pr/sub 11/Fe/sub 66.5/Co/sub 10/Ti/sub 1.5/B/sub 10.5/Si/sub 0.5/ and Pr/sub 11/Fe/sub 64.5/Co/sub 12/Ti/sub 1.5/B/sub 10.5/Si/sub 0.5/ bonded magnets were smaller than that of an MQP-O bonded magnet at 150/spl deg/C.