B2 Phases and their defect structures: Pact II. Ah initio vibrational and electronic free energy in the Al-Ni-Pt-Ru system

Raymundo Arroyave, Sara Prins, Zi-kui Liu

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1 Scopus citations

Abstract

In this work, we calculate the finite temperature thermodynamic properties of the binary B2 phases in the Al-Ni-Pt-Ru system, particularly the B2 RuAl phase in the Pt-Al-Ru ternary, through the incorporation of the vibrational and electronic contributions to the total free energy. The harmonic approximation is used to consider the atomic vibrations, with the quasi-harmonic correction to account for volume expansion effects on the vibrational entropy as the temperature increases. The vibrational entropy calculations are incorporated through the supercell approach. The calculated phonon dispersion curves show that the B2 PtRu structure is mechanically unstable at low temperatures, while B2 PtAl is marginally stable. The thermal electronic contribution is added to the total free energy. Finally, the formation enthalpies and entropies of B2 RuAl are calculated as a function of temperature.

Original languageEnglish (US)
Article numberS5.13
Pages (from-to)529-534
Number of pages6
JournalMaterials Research Society Symposium - Proceedings
Volume842
StatePublished - 2005

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials

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