2-17 rare earth-cobalt permanent magnets with coercive force up to 30 KOe

Sintered Sm(Cosub(.67)Cusub(.08)Fesub(.22)Zrsub(.03))sub(z) (Z=7.7-8.9) magnets with high coercive force have been prepared. The experiments showed that the important factors controlling magnetic hardness are mainly the amount of liquid phase additive, aging time at 820 0C and step treatment. Both coercivity and squareness of loops for the liquid phase sintered magnets appear to be much higher than those for the magnets without additive. It is specially interesting that the primary magnetization curves for the magnets described here show a behaviour different from that of the typical 2-17 magnets. In the present paper, both maximum sub(m)Hsub(c) of 33 KOe and maximum (BH)sub(max) of 27 MGOe have been obtained. The magnets are not easy to be magnetized to saturation even in a magnetic field up to 50KOe. (Author)