First-principles study on structural, elastic and thermal properties of γγ-TiAl and α2α2-Ti3Al phases in TiAl-based alloy under high pressure Read More: http://www.worldscientific.com/doi/abs/10.1142/S0217979217500795

Chaoyan Zhang^{*, †}

Hua Hou^{*, ‡}

Yuhong Zhao^*

Xiaomin Yang^*

Yaqiong Guo^*

^*College of Materials Science and Engineering, North University of China, Taiyuan 030051, P. R. China

^†School of Mechatronic Engineering, Xuzhou College of Industrial Technology, Xuzhou 221100, P. R. China

^‡Corresponding author.

Received: 3 September 2016

Revised: 23 November 2016

Accepted: 4 December 2016

Published: 22 February 2017

Abstract:


 The structural, elastic and thermal properties of 
$\gamma$-TiAl and α2${\alpha }_2$-Ti₃Al phases in the TiAl-based alloy under pressure were reported using CASTEP program based on the density functional theory. The calculated equilibrium parameters and elastic constants are in good agreement with experimental and the available theoretical data. The results indicate that under the same pressure, the α2${\alpha }_2$ phase in the direction along a$a$-axis is easier to be compressed than the γ$\gamma$ phase, while the compression along c$c$-axis of γ$\gamma$ phase is larger than that of α2${\alpha }_2$ phase; when the pressure is below 20 GPa, both the two phases are elastically stable, but the γ$\gamma$ phase have higher shear modulus and Young’s modulus, and the α2${\alpha }_2$ phase has better ductility and plasticity. Debye temperature, bulk modulus, thermal expansion coefficient and heat capacity of the γ$\gamma$ phase and α2${\alpha }_2$ phase under high pressure and high temperature were also successfully calculated and compared using the quasi-harmonic Debye model in the present work.

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