Effect of pressure on the structure of Fe-N alloys formed by solid-state reaction

Fe-N alloys with crystalline structures different from those obtained at at mospheric pressure were produced by solid-state reaction between Fe and amo rphous boron nitride under high pressure. Two new paramagnetic Fe-N phases were obtained at temperatures above 800 K under pressures between 2.0 and 4 .0 GPa. One is of cubic structure with lattice constant of 6.114 Angstrom, and another is of orthorhombic structure with lattice constants of a = 8.44 3, b = 4.749, and c = 3.993 Angstrom. epsilon -Fe3Nx with N contents of 18. 1 to 21.4 at.%, which could not be obtained at atmospheric pressure, was pr oduced at pressures of 3.0 to 4.0 GPa and temperatures of 690 to 800 K. The mechanism of formation Of epsilon -Fe3Nx under high pressure is discussed.