Permanent Magnetic Properties of Melt-Spun YCo5Cx Ribbons

Ribbons of nominal compositions YCo5Cx (x = 0, 0.2, 0.4, 0.6) are prepared by melt spinning at surface velocities v=5, 10, 15, 20, 25, 30 and 35 m/s. YCo5 ribbon is crystallized in a single YCo5 phase of hexagonal CaCu5 structure. A small quantity of YCoC2 phase appears in the ribbons with C addition besides the YCo5 phase. With the increase of x the lattice constant c increases and a along with the unit cell volume decreases. The largest values of iHc=888 kA/m and (BH)max =58.4 kJ/m3 at present for the YCo5 ribbon system were obtained with x=0.4 and v=20 m/s. The improvement of the permanent magnetic properties is rooted in the refinement of the microstructure and the appearance of the YCoC2 phase which can act as domain wall pinning centers.