Equilibria bearing on the behavior of titanate phases during crystallization of iron silicate melts under strongly reducing conditions

Titanate phase relations at liquidus temperatures are determined for the CaAl2Si2O8-Fe2TiO4-FeTi2O5 system in contact with metallic iron by reflected- and transmitted-light microscopy, electron microprobe, and X-ray diffraction analyses. Results of critical equilibration runs are presented, various primary phase areas and liquidus isotherms are illustrated, and the geometry of the system is described. Three piercing points are determined, and it is noted that the compositional interrelations among coexisting crystalline and liquid phases as well as the sequence of the various titanate phases are indicative of the significant effects of the various cations on the relative stability of these phases. It is found that Al2O3 exerts a strong stabilizing effect on the phase assemblage of ulvospinel plus ferropseudobrookite relative to ilemite.