Property Changes of Fe-N Prepared by Reduction-Sintering Method with Quenching

A process of reduction from α-Fe
₂
O
₃
, nitrification in ammonia and sintering was used to obtain dense single-phase Fe
₄
N, and changes in the material thus obtained with quenching were investigated. It was found that quenching from temperatures of 550°C and above brings about a slight decrease in saturation magnetization, due to intermixing of hexagonal iron nitride. In attempts to lower the nitrogen content, the ammonia pressure was lowered and samples quenched from 650°C; this also resulted in lower saturation magnetization, and the division of the Fe
₄
N into hexagonal iron nitride and α-Fe.