Phase Stability of Iron Nitride FeN at High Pressure-Pressure-Dependent Evolution of Phase Equilibria in the Fe-N System.

Although the general instability of the iron nitride γ'-FeN with respect to other phases at high pressure is well established, the actual type of phase transitions and equilibrium conditions of their occurrence are, as of yet, poorly investigated. In the present study, samples of γ'-FeN and mixtures of α Fe and γ'-FeN powders have been heat-treated at temperatures between 250 and 1000 °C and pressures between 2 and 8 GPa in a multi-anvil press, in order to investigate phase equilibria involving the γ' phase. Samples heat-treated at high-pressure conditions, were quenched, subsequently decompressed, and then analysed ex situ.