Microstructure Analysis of Sintered Nd-Fe-B Magnets Improved by Tb-Vapor Sorption

Abstract

The surface treatment with Tb-vapor sorption improves the magnetic properties of small-sized magnets. Microstructure of the Tb-treated magnets was investigated by transmission electron microscopy (TEM). By applying the Tb-treatment, the diffusion of Tb through grain boundaries occurred even inside the magnets, and then a thin and continuous wetting-layer phase was formed at the boundaries between the Nd2Fe14B grains. The results suggest that the formation of the thin and continuous wetting-layer phase leads to the improvement in magnetic properties.