Influence of Sm-rich Phase on Magnetic Properties of Surface Modified Sm-Fe-N Powder Prepared by Reduction-diffusion Process

This paper provides influence of Sm-rich phase on magnetic properties of Sm-diffused Sm2Fe17N3 powder prepared by reduction-diffusion process with Sm2Fe17 and Sm2O3 powder. The reduction-diffused powder was washed by Ethylene-Glycol (EG) or water in Glove-box (GB) or air, and the coercivity changing rate (Hc changes from after nitriding to after heat resistance test) was investigated. The coercivity of powders after heat resistance test depended on oxygen content of the powders. In the Sm-Fe-N powder, Sm-rich amorphous phase, which could be SmFe3 nitrided phase, existed at grain boundary and the amorphous SmFe3 nitrided phase can be easily oxidized during washing resulting in decreasing coercivity.