PUB - Publikationen an der Universität Bielefeld

The interface diffusion was studied in ultrafine-grained Nd2Fe14B which shows an intergranular melting transition owing to an excess amount of Nd. Below the intergranular melting transition, the interface diffusion of Fe-59 is similar to grain boundary diffusivities in bcc Fe. The microstructure and intergranular melting transition show characteristic variations with the Nd excess which sensitively affects the diffusivity at and above the melting transition. In Nd2Fe14B with high Nd excess, which contains extended Nd-rich triple junctions, the melting transition occurs at ca. 950 K in one step leading to an abrupt increase of the diffusion coefficient. In Nd2Fe14B with low Nd excess, which is free from additional phases at triple junctions, the diffusion coefficient above the melting transition increases gradually. Interface diffusion is found to have no rate-controlling influence on the hot-deformation used for the generation of magnetic anisotropy.