Thermodynamic assessment of Fe3Mn3Nb3N and Nb3C3Nsystems

In the present work the thermodynamic parameters of the Fe3Mn3Nb3N and Nb3C3N systems are assessed with the CALPHAD technique using a computerized optimization procedure (PARROT).Descriptions for most of the binary and ternary systems are already available so a selection between sets of parameters was made. An additional reassessment was needed for the Nb3N system with the aim to suppress unexpected appearance of the bcc phase at high pressures. The description of the Fe3Mn3Nb3N and Nb3C3N systems was made as an extrapolation from binary and ternary systems. The obtained set of parameters for the Fe3Mn3Nb3N system was tested against existing experimental data for the niobium nitride solubility.

► The unexpected appearance of the bcc phase was suppressed in the Nb3N system.
► The Fe3Mn3Nb3N and Nb3C3N systems were assessed using CALPHAD techniques.
► The calculations of NbN solubility gave consistent results with experimentaldata.