The influence of nitrogen fugacity on the phase equilibria of Me-N systems

Motivated by the thermodynamic assessment of the Ga-N and In-N binaries, we study a number of Me-N systems (Me=Al, B, Ga, In, Si, Ti, V and Zr) in the present paper. The nitrogen fugacity as a function of temperature and pressure, f(T,P), is taken into account. The expression for the nitrogen fugacity reported in the literature reveals a high pressure limit that differs from system to system. An approach for defining the high and the low pressure regions is proposed. Above the high pressure limit, a linear extrapolation expression for the nitrogen fugacity-pressure relation needs to be used. The influence of the nitrogen fugacity on the phase equilibria of Me-N systems is discussed and the corresponding phase stability diagrams are presented.