INTERGRANULAR MICROSTRUCTURE COERCIVE FIELD RELATIONSHIP IN ND16FE76B8 ALLOYS

It is shown that different structures of the regions surrounding the grains of the phi phase lead to different values of the coercive field. In particular a noticeable enhancement of coercitivity is reached when the intergranular region evolves from a nanocrystalline structure of grains (almost-equal-to 10 to 20 nm) of either phi, eta or Nd phase to a paramagnetic eutectic thin Nd-rich film (almost-equal-to 5 nm) which perfectly wets the phi grains. Therefore, the degree of exchange isolation has been found to govern the value of the coercive field.