Nitrogen solubility in liquid Fe-V and Fe-Cr-Ni-V alloys

Nitrogen solubility in liquid Fe, Fe-V, Fe-Cr-V, Fe-Ni-V and Fe-18 pct Cr-8 pet Ni-V alloys has been measured using the Sieverts’ method for vanadium contents up to 15 wt pct and over the temperature range from 1775 to 2040 K. Nitrogen solution obeyed Sieverts’ law for all alloys investigated. Nitride formation was observed in Fe-13 pet V, Fe-15 pet V and Fe-18 pet Cr-8 pet Ni-10 pet V alloys at lower temperatures. The nitrogen solubility increases with increasing vanadium content and for a given composition decreases with increasing temperature. In Fe-V alloys, the nitrogen solubility at 1 atm N2 pressure is 0.72 wt pet at 1863 K and 15 pct V. The heat and entropy of solution of nitrogen in Fe-V alloys were determined as functions of vanadium content. The first and second order interaction parameters were determined as functions of temperature as: $$e_N^V = \frac{{ - 463.6}}{T} + 0.148 and e_N^{VV} = \frac{{17.72}}{T} - 0.0069$$ The effects of alloying elements on the activity coefficient of nitrogen were measured in Fe-5 pet and 10 pet Cr-V, Fe-5 pet and 10 pet Ni-V and Fe-18 pet Cr-8 pct Ni-V alloys. In Fe-18 pet Cr-8 pet Ni-10 pet V, the nitrogen solubility at 1 atm N2 pressure is 0.97 wt pet at 1873 K. The second order cross interaction parameters, e N Cr,V and e N Ni,V , were determined at 1873 K as 0.00129 and − 0.00038 respectively.