Dependence of the Mean Grain Size and Coercivity of Sintered Nd–Fe–B Magnets on the Initial Powder Particle Size

The grain size and magnetic properties of sintered Nd 14.3 Fe 78.9 TM 1.2 B 5.6 (TM: Co, Cu, Al, Ga) magnets have been examined in dependence on the powder particle size and distribution. The mean grain size decreases almost linearly with the mean particle size and seems to become more homogeneous with a decreasing width of the particle size distribution. The coercivity increases with decreasing grain size, which can be represented by a potential regression curve