Effect of the intergrain interactions on the coercivity and its angular dependence for Nd(FeCo)B sintered magnets

Abstract Effects of interactions between grains with different alignment degrees on the coercivity and its angular dependence for Nd 16 (Fe 0.8 Co 0.2 ) 78 B 6 sintered magnets have been studied. The experiments show that the intrinsic coercivity j H c decreases with enhancing grain alignment (decreasing alignment coefficient σ ), the coercivity j H c ( θ ) increases with increasing angle θ between the applied field and the texture axis of the magnets and the variation ratio is larger for the magnets with better grain alignment. The coercivity of the magnets should be determined by the critical field making the moment of individual grains reverse and the interactions between the grains. For the sintered magnets composed of the grains with μm size, the magnetostatic interaction between the grains is stronger than the exchange coupling interaction and it makes the coercivity of magnet increase with increasing alignment coefficient σ . Taking into account the intergrain interactions, the starting field theory of coercivity is in good agreement with the experimental results for Nd 16 (Fe 0.8 Co 0.2 ) 78 B 6 sintered magnets.