COERCIVE SM2CO17 POWDER FOR THE BONDED MAGNET APPLICATION

Microstructure of ingots with nominal composition of Sm(Co0.68Cu0.065F exZry)(z), where x=0.25, 0.27 and 0.30, y = 0.01, 0.02 and 0.03 and z varies from 7.9 to 8.3, were examined at various homogenizing temperat ures and magnetic hardening treatments. It was found that the resultin g H-ci is strongly dependent upon the alloy composition and the homoge nizing temperature. In general, the H-ci increases as the homogenizing temperature is raised, peaks at a critical temperature, then decrease s with increasing homogenizing temperature. This critical temperature may coincide with the solidus curve of the liquid + 2:17 --> TbCu7 typ e disordered structure transformation. In general, the single phased m icrostructure achieved after the homogenizing treatment is necessary t o obtain the highest H-ci after magnetic hardening. For a fixed therma l treatment, the H-ci was found to increase with the Zr content.