Equilibria between Titanium Metal and Solutions of Titanium Dichloride in Fused Sodium Chloride

Thermal analyses of TiCl 3 and NaCl in closed titanium metal crucibles were made in the range from 0 to 100 wt % TiCl 2 . The melting point of TiCl 2 was confirmed to be 1025°C. The phase diagram of the system has two compounds and one eutectic. The eutectic point lies at 50.0 wt % TiCl 2 and 605°C. One compound, NaCl ‐ TiCl 2 , is formed by a peritectic reaction at 628°C; the other one, 2 NaCl ‐ TiCl 2 , decomposes in the solid state at 548°C. The free energy curves derived from the phase diagram indicate that liquid NaCl ‐ TiCl 2 melts have the highest stability at temperatures up to about 800°C at the composition 2 Na + 1 Ti + 4 C 1 , thus making probable the existence of [ TiCl 4 ] 2 − complex ions. At higher temperatures or in the presence of large cations, more complex ionic clusters are likely to exist.