Thermodynamic and mechanical stabilities of α- and β-Ta{sub 4}AlC{sub 3} via first-principles investigations

Journal Article · Sat Dec 07 04:00:00 EST 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4837636· OSTI ID:22258689

Duong, Thien; Arróyave, Raymundo ^[1]

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1. Department of Materials Science and Engineering, Texas A and M University, College Station, Texas 77843-3123 (United States)

Recently, it has been predicted that Ta{sub 4}AlC{sub 3} is likely to exhibit an (α–β) polymorphic transformation at temperatures above 1873 K. However, recent X-ray diffraction and transmission electron microscopy experiments suggest on the other hand that the α phase remains stable up to temperatures close to the limit of experimental capabilities and no transition has yet been observed. While the matter has already been settled experimentally, in this work, we re-investigate the phase stability problem in Ta{sub 4}AlC{sub 3} by using first-principles methods. The study was carried out by considering both thermodynamic and mechanical stabilities of the Ta{sub 4}AlC{sub 3} polymorphs. Particularly, finite-temperature Gibbs free energies and elastic properties of the polymorphs were calculated using density functional theory. Calculation results reveal that the α phase continue to be stable even at temperatures exceeding 1875 K, which is in agreement with experimental results reported in literature.

• OSTI ID: 22258689
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 21 Vol. 114; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
DENSITY FUNCTIONAL METHOD
ELASTICITY
FREE ENTHALPY
PHASE STABILITY
TRANSFORMATIONS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION