Synthesis of α''-FeN ribbons with a porous structure.

The microstructure of FeCuB ribbons (∼20 μm thick) was modified to fabricate α''-FeN at a temperature as low as 160 °C. The ribbon samples were heat treated first at a temperature reaching 930 °C and then quenched down to room temperature. During the heat treatment, ribbon samples were oxidized, and hydrogen reduction was then conducted to remove the oxygen from the ribbon samples. The reduced ribbon samples had a porous structure, which improved the nitrogen diffusion efficiency and decreased the fabrication temperature of α''-FeN down to 160 °C. It was demonstrated that the techniques for microstructure control in this method including oxidation and reduction helped obtain the α''-FeN phase with high coercivity, thus manifesting this could be a promising technique for low-temperature nitridation on ribbons in general.