Ｃｒ‐Ｃｏ添加Ｆｅ３Ｂ／Ｎｄ２Ｆｅ１４Ｂ系交換スプリング磁石の磁気特性と安定性

概要

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The effect of co-addition of Cr and Co to Fe3B/Nd2Fe14B exchange-spring nanocomposite permanent magnets on the magnetic properties and their stability was investigated. It was found that HcJ of Fe3B/Nd2Fe14B exchange-spring magnets can be controlled in the range from 300 kA/m to 600 kA/m by adjusting the Cr and Nd concentrations. The squareness of the demagnetizion curves is improved by simultaneous addition of Cr and Co. Thermal stability is also improved by Cr addition: irreversible flux losses rate of the 5 at% Cr-doped Fe3B/Nd2Fe14B exchange-spring magnets were about 1 % after exposure to a temperature of 100°C. This type of magnets are less susceptible to oxidation because the rare-earth content is lower than that of conventional Nd2Fe14B isotropic powders. The higher packing density can be obtained because of the round shape of the pulverized Fe3B/Nd2Fe14B exchange-spring magnet. Consequently, Fe3B/Nd2Fe14B exchange-spring magnet powders are suitable for the injection-molding process in which the magnetic powders are exposed to high temperatures.
社団法人日本磁気学会の論文