Thermodynamics of Titanium, Nitrogen and TiN Formation in Liquid Iron

Abstract

Thermodynamics of titanium, nitrogen and TiN formation in liquid iron was investigated using the metal–nitride–gas equilibration under different nitrogen partial pressures in the temperature range of 1873–1973 K. The nitrogen solubility in liquid iron increased with increasing titanium content. Pure solid TiN was formed at critical contents of titanium and nitrogen in liquid iron. The experimental results were thermodynamically analyzed using Wagner's interaction parameter formalism to determine the first-order interaction parameter between titanium and nitrogen, the first-order self interaction parameter of titanium, and the equilibrium constant for the dissolution of pure solid TiN in liquid iron given as follows.
e_N^Ti = −8507/T+4.18, e_Ti^N = −29110/T+14.3
e_Ti^Ti = 0.048(1873–1973 K)
TiN (s) = Ti+N
log K_TiN = −15780/T+5.63