MAGNETIC HYSTERESIS IN FE-R-B POWDERS

The hard magnetic properties of Fe-R-B powders have been examined using various magnetic techniques. High coercivities were obtained in fine powders with a particle size around 1 mu m. A domain wall pinning process is suggested for the less anisotropic, Nd-containing samples where the domain walls are pinned at the particles surface. The initial magnetization curves, field dependence of coercivity and remanence curves of thermally demagnetized samples change significantly after ac and dc demagnetization indicating a more uniform domain wall pinning process in the ac and dc demagnetized samples. A magnetization rotation reversal process is suggested for the more anisotropic, heavy rare-earth containing powders.