Magnetization Process in Co-Zr-B permanent-magnet materials

Co-Zr-B alloy ingots consisted of Co₂₃Zr₆ phase together with the small amounts of Co₅Zr and Co₃ZrB₂ phases. On the other hand, Co-Zr-B melt-spun ribbons consisted mostly of Co₅Zr phase and exhibited a high coercivity. Heat treatment of the Co-Zr-B melt-spun ribbons resulted in increased coercivity. These annealed Co-Zr-B melt-spun ribbons were magnetically isotropic. The maximum energy products (BH)_max values in excess of 4.7 MGOe were observed for the Co-Zr-B melt-spun ribbons annealed at 600°C for 1 h. The mechanism underlying the coercivity of the annealed Co-Zr-B melt-spun ribbon was found to be the pinning type from the initial magnetization curve.