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Constitutional and thermal defects in D019-SnTi3

C. Colinet, J. C. Tedenac, S. G. Fries.

Intermetallics, 16, 923-932, (2008)

Vacancy and antisite defect formation energies in D019-SnTi3 are calculated by an ab initio approach. Based on a statistical-thermodynamic model, the defect concentrations are calculated as function of temperature and deviation from stoichiometry. The constitutional defects are antisite Sn atoms and antisite Ti atoms in Sn-rich and Ti-rich SnTi3, respectively. The dominant thermal defects are composed of two antisites for stoichiometric alloys. For Sn-rich D019-SnTi3 alloys, the thermal defect is an interbranch where one antisite Sn atom is replaced by four Ti vacancies. For Ti-rich D019-SnTi3 alloys, the thermal defect is a five point defect comprising one antisite Ti and four Ti vacancies. The effective defect formation enthalpies are derived for different concentration regions of D019-SnTi3. The Gibbs energy as well as the Sn and Ti chemical potentials in the D019-SnTi3 are obtained as function of composition for various temperatures. The extension of the one phase domain of D019-SnTi3 in the Sn–Ti phase diagram is discussed.

Keyword(s): intermetallics; phase diagrams; point defects; site occupancy; ab initio calculations
DOI: doi:10.1016/j.intermet.2008.04.007
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