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

Natsuki Watanabe; Masaru Itakura; Noriyuki Kuwano; Deshan Li; Shunji Suzuki; Ken-ich Machida

doi:10.2320/matertrans.48.915

Natsuki Watanabe, Masaru Itakura, Noriyuki Kuwano, Deshan Li, Shunji Suzuki, Ken-ich Machida

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Keywords: grain boundary, coercivity, permanent magnet, neodymium-iron-boron sintered magnet, microstructure, terbium, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), electron energy loss spectroscopy (EELS)

JOURNAL FREE ACCESS

2007 Volume 48 Issue 5 Pages 915-918

DOI https://doi.org/10.2320/matertrans.48.915

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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.

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