Microstructure modification induced giant coercivity enhancement in Sm(CoFeCuZr)z permanent magnets

The magnetic domain evolution during the reversal process were investigated for Sm(Co0.665Fe0.25Cu0.06Zr0.025)7 magnets before and after Cu fine powders doping. As the field reduces to 0 T, reversed domains, which mostly lie around grain boundaries, were observed in the original magnets. On the other hand, few obvious reversed domains were observed in Cu powders doped magnets until the reverse filed increased to − 0.3 T, reversed domains were suddenly observed around some grain boundaries. It is therefore suggested that pinning force of the cellular phase near the grain boundary regions in the doped magnets is much stronger than that in the original magnets.219