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.