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The influence of lattice vibrations and electronic free energy on phase stability of titanium silicides and Si solubility in hcp titanium: A DFT study

Authors: 

A.I. Kartamyshev, D.O. Poletaev, A.G. Lipnitskii

Source title: 
Calphad, 65: 194-203, 2019 (ISI)
Academic year of acceptance: 
2019-2020
Abstract: 

In this paper, we evaluated the influence of vibrational and electronic free energy on the thermodynamic phase stability of the Ti5Si3, Ti3Si, Ti6Si3, and other silicides in the binary Ti-Si system and the solubility of Si in 27.png-Ti within the density functional theory and harmonic approximation. We showed, that vibrational and electronic free energy thermodynamically stabilize the Ti3Si silicide and destabilize the Ti6Si3 silicide with respect to the Ti5Si3 and 27.png-Ti. According to our calculations, the transition from equilibrium of Si solid solution with the Ti5Si3 silicide to the equilibrium of Si solid solution with the Ti3Si silicide should be at ~ 900 K. The account of both the vibrational and electronic free energy increase the calculated solubility limit of Si in 27.png-Ti and make it closer to the experimental one.