Assessment of the Ti-Rich Corner of the Ti-Si Phase Diagram: The Recent Dispute About the Eutectoid Reaction

Abstract

Abstract The thermodynamic optimization of Ti-Si-X systems requires that their respective binary systems are constantly updated. The Ti-Si system has been experimentally investigated since the 1950s and these critical experimental data can be employed to calculate the Ti-Si phase diagram using thermodynamic modeling. The most recent assessment of the Ti-Si system was performed in 1998, showing the presence of stoichiometric Ti3Si as stable phase. In the light of the dispute over the stability of Ti3Si phase in the eutectoid reaction of the Ti-Si and Ti-X-Si systems, the present work assessed the Ti-rich corner of the "stable" (featuring Ti3Si phase) and "metastable" (featuring Ti5Si3 phase) Ti-Si phase diagrams. The phase boundaries, the values of the error of the least-square method of the optimization procedure and the relative standard deviation of the calculated variables of the assessed diagrams; and previous investigations were discussed in order to inspire further experimental work on the eutectoid reaction of the Ti-Si phase diagram.

Keywords

• Ti-Si phase diagram
• Ti-rich corner
• thermodynamic modeling
• sublattice model
• eutectoid reaction