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First-Principles Study of a New Higher-Order MAX Phase of Ti₅Al₂C₃

X.-K. Qian, X.-K. Qian, X.-K. Qian, H.-Y. Wu, H.-P. Zhu, S.-H. Ma, T. Jiang

Journal of Ceramic Science and Technology, Vol. 7, No. 1 (2016), pp. 47-52

DOI: 10.4416/JCST2015-00027

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Abstract

The crystal structure of a new phase plays an important role in understanding its properties. The structure, elastic and electronic properties of Ti5Al2C3 are studied based on first-principles calculations. The simulated lattice parameter and internal coordinates are found to be in good agreement with the experimental values. It is shown that this new phase is mechanically stable. The elastic properties are estimated from the individual elastic constants with the help of Hill's approximation. The bulk modulus, shear modulus, Young's modulus, Poisson's ratio, theoretical density and Debye temperature of Ti5Al2C3 are calculated to be 147 GPa, 124 GPa, 290 GPa, 0.17, 4.12 g/cm3 and 759 K, respectively. The band structure and DOS reveal that Ti5Al2C3 is conductive. At the Fermi level (Ef), the energy band is contributed mainly by the Ti 3d state and secondarily by the Al 3p state. Ti-Al hybridizations are located just below the Ef and are weaker than the Ti-C bonds, which are much deeper in energy.

Keywords

Ti5Al2C3, first-principles, mechanical stability, electronic structure

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