Coercivity and magnetic viscosity of NdDyFeB mechanically alloyed magnets

We studied the temperature dependence of coercivity and magnetic viscosity in NdDyFeB mechanically alloyed magnets for temperatures between 25 and 500 K. The results are discussed in terms of the so-called global model of coercivity which provides information about the magnetic properties in the activation magnetization volume /spl nu//sub a/ where magnetization reversal is initiated. The anisotropy increase as well as the reduction of the magnetization associated with the substitution of Dy for Nd are factors leading to the enhancement of the coercive field. However, the contribution of microstructural features should also be considered.