Crystal structure, phase stability, and electronic structure of Ti-Al intermetallics

Ti3Al

T. Hong, T. J. Watson-Yang, X. Q. Guo, Arthur J Freeman, T. Oguchi, Jian Hua Xu

Research output: Contribution to journalArticle

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Abstract

A potentially useful high-temperature intermetallic compound Ti3Al is investigated theoretically by the self-consistent linear muffin-tin orbitals (LMTO) and full-potential linearized augmented-plane-wave (FLAPW) methods within the local-density approximation. Structural properties were calculated for the naturally observed structure, D019, and for two other similar structures, D022 and L12. The LMTO-calculated Wigner-Seitz radii are 2.98 a.u. for all three structures, in excellent agreement with the experimental value (2.99 a.u.) of the observed D019 structure, while the values from the FLAPW method are 2.94 a.u. for the three structures, showing an agreement within about 2%. The calculated formation energies are 0.29, 0.27, and 0.29 eV/atom by the LMTO, and 0.28, 0.25, and 0.27 eV/atom by the FLAPW for the D019, D022, and L12 structures, respectively. The calculated bulk moduli are 1.2 Mbar for all the phases done by the LMTO and FLAPW except the D019 phase from the LMTO calculations, where the value is 1.3 Mbar. These calculated formation energies and bulk moduli agree well (to 10%) with experimental data. The FLAPW-calculated c/a ratio for the D019 and D022 structures are 0.807 and 2.131, respectively. The value for the D019 structure is within 1% of the observed value (0.8007) and the value for the D022 structure is significantly lower than the observed value (2.234) for TiAl3. Charge-density plots for D019 and L12 show quite localized charge distributions in both phases. The covalent character of the bonding is not significant, which may be a good sign for ways to improve its poor ductility.

Original languageEnglish
Pages (from-to)1940-1947
Number of pages8
JournalPhysical Review B
Volume43
Issue number3
DOIs
Publication statusPublished - 1991

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Phase stability
Tin
Intermetallics
Electronic structure
intermetallics
tin
plane waves
Crystal structure
electronic structure
orbitals
crystal structure
energy of formation
bulk modulus
Elastic moduli
Orbital calculations
Local density approximation
Atoms
Charge distribution
Charge density
ductility

ASJC Scopus subject areas

  • Condensed Matter Physics

Cite this

Crystal structure, phase stability, and electronic structure of Ti-Al intermetallics : Ti3Al. / Hong, T.; Watson-Yang, T. J.; Guo, X. Q.; Freeman, Arthur J; Oguchi, T.; Xu, Jian Hua.

In: Physical Review B, Vol. 43, No. 3, 1991, p. 1940-1947.

Research output: Contribution to journalArticle

Hong, T. ; Watson-Yang, T. J. ; Guo, X. Q. ; Freeman, Arthur J ; Oguchi, T. ; Xu, Jian Hua. / Crystal structure, phase stability, and electronic structure of Ti-Al intermetallics : Ti3Al. In: Physical Review B. 1991 ; Vol. 43, No. 3. pp. 1940-1947.
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abstract = "A potentially useful high-temperature intermetallic compound Ti3Al is investigated theoretically by the self-consistent linear muffin-tin orbitals (LMTO) and full-potential linearized augmented-plane-wave (FLAPW) methods within the local-density approximation. Structural properties were calculated for the naturally observed structure, D019, and for two other similar structures, D022 and L12. The LMTO-calculated Wigner-Seitz radii are 2.98 a.u. for all three structures, in excellent agreement with the experimental value (2.99 a.u.) of the observed D019 structure, while the values from the FLAPW method are 2.94 a.u. for the three structures, showing an agreement within about 2{\%}. The calculated formation energies are 0.29, 0.27, and 0.29 eV/atom by the LMTO, and 0.28, 0.25, and 0.27 eV/atom by the FLAPW for the D019, D022, and L12 structures, respectively. The calculated bulk moduli are 1.2 Mbar for all the phases done by the LMTO and FLAPW except the D019 phase from the LMTO calculations, where the value is 1.3 Mbar. These calculated formation energies and bulk moduli agree well (to 10{\%}) with experimental data. The FLAPW-calculated c/a ratio for the D019 and D022 structures are 0.807 and 2.131, respectively. The value for the D019 structure is within 1{\%} of the observed value (0.8007) and the value for the D022 structure is significantly lower than the observed value (2.234) for TiAl3. Charge-density plots for D019 and L12 show quite localized charge distributions in both phases. The covalent character of the bonding is not significant, which may be a good sign for ways to improve its poor ductility.",
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