Thermodynamic Description of Ternary Fe-X-P Systems. Part 8: Fe-Si-P

A thermodynamic description of the Fe-Ti-P system is developed in the frame of a new Fe-X-P (X = Al, Cr, Cu, Mn, Mo, Ti, Ni, Ti, Si) database. The adjustable parameters of the binary sub-systems (Fe-P, Fe-Ti and Ti-P) are taken, in general, from earlier assessments (slightly modifying the Ti-P description) and those of the ternary system are optimized in this study using literature experimental thermodynamic and phase equilibrium data. The solution phases of the system (Liquid, bcc_A2, fcc_A1 and hcp_A3) are described with the substitutional solution model. The Fe-Ti and the Ti-P compounds (Fe2Ti, FeTi, Ti3P, Ti17P10, Ti5P3, Ti4P3, TiP and TiP2) are treated as stoichiometric phases. The same is true for the ternary phase FeTiP and for the white-P phase. Continuous solubility has been accepted between the isomorphic compounds Fe2P and Ti2P. The titanium solubility in the Fe3P phase has also been taken into account. Good or reasonable agreement between the calculated and the experimental thermodynamic and phase equilibrium data was obtained. This conformity has been shown by means of a number of graphical and numerical comparisons.