Abstract
Relationship between magnetizability and grain size was investigated in Nd-Dy-Fe-Co-B-M (M=V or MO) sintered permanent magnets. Grain size distribution was measured by using a high speed image processor. It has been confirmed that addition of V or Mo results in a decrease in the average grain size and grain size distribution. Dependence of the relative open flux on the magnetizing force in these magnets revealed that a small grain is essential to obtain a good magnetizability and an enhanced coercivity. It is suggested that the local demagnetization field decreases when grain size decreases, leading to improvements both in magnetizability and coercivity of V or Mo-added Nd-Fe-B sintered magnets.
