Abstract: The structure and magnetic properties of Co_80+xZr_20-x （x=0,1,2,3,4） alloys and the melt-ribbons were investigated by X-ray diffraction analysis and magnetic measurements. It was found that all the samples exhibited high-saturation magnetization. With increasing annealing temperature, the saturation magnetization values of all the samples increased largely in the experiment. The maximum value of saturation magnetization of melt-spun Co₈₁Zr₁₉ ribbons was 128 (A·m2)/kg, is obtained having been annealed at 750 ℃ for 2 h. For the melt-spun Co₈₂Zr₁₉ ribbons prepared at a velocity of 25 m/s, the maximum coercivity of 60 kA/m has been achieved. Owing to the high content of Co₅Zr phase in the ribbons, it can be approximately deduced that the hard magnetic properties are attributed to the existence of Co5Zr phase in the Co-Zr alloys. The coercivity mechanism of the samples is mainly determined by the nucleation of reversed domain.

Key words: Co-Zr alloys, hard magnetic property, coercivity, saturation magnetization