Production of iron nitrides by mechanical alloying

The iron nitrides were prepared by mechanical alloying followed by solid state reaction. Mechanical alloying of alpha-Fe and epsilon-Fe3N powders resulted in the formation of alpha-Fe solid solution with the composition of Fe16N2. The mechanically alloyed powders, when annealed at low temperatures (100-200 degrees C), consisted of alpha'-Fe16N2, alpha-Fe, and epsilon-Fe3N phases and consisted of alpha'-Fe16N2, alpha-Fe, and gamma'-Fe4N phases when annealed at intermediate temperatures (300-500 degrees C). On the other hand, the mechanically alloyed powders consisted mostly of alpha'-martensite phase and showed a higher saturation magnetization than iron powders when annealed at high temperatures (700-800 degrees C). (C) 2000 American Institute of Physics. [S0021-8979(00)76908-8].