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

Abstract

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 (H_c 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.