Ab Initio Study of the Elastic and Mechanical Properties of B19 TiAl

Abstract

Abstract:A theoretical study of the structural, elastic, and mechanical properties of B19 TiAl intermetallic compound with orthorhombic structure has been carried out by using ab initio density functional theory calculations based on the projector augmented wave and the generalized gradient approximation. The optimized structure parameters are found to be in agreement with the available experimental data. The orthorhombic B19 structure of TiAl is found to be mechanically stable at ground state in terms of formation energy and single crystal elastic constants. Additionally, the polycrystalline bulk, shear and Young's moduli, Poisson's ratio, Cauchy pressure, and anisotropy factors are obtained from the single crystal elastic constants. At ground state, the B19 TiAl is found to not only have intrinsic brittleness in terms of Pugh's ratio, Poisson's ratio, and Cauchy pressure, but also exhibit elastic anisotropy in terms of elastic anisotropy factors and orientation dependence of Young's modulus.

Synthesis and Mechanical Characterization of Binary and Ternary Intermetallic Alloys Based on Fe-Ti-Al by Resonant Ultrasound Vibrational Methods

“…The percentage of titanium in an alloy is proportional to the Young’s modulus of this alloy. These results are in full agreement with the theoretically calculated values found in [ 52 ], and with the measured values reported in the literature (between 145 and 175 GPa) in [ 54 , 56 ].…”

“…The ab initio computations were done using the DFT method based on the full-potential (linearized) augmented plane-wave ((L)APW) and local orbitals (lo) method implemented in the WIEN2K software (K. Schwartz Technical Universität, Vienna, Austria) [ 51 ]. Calculations for [ 52 ] (difference with E was −1.1 percent) were performed using the density functional theory (DFT) based on the projector augmented wave and the generalized gradient approximations (GGA) as implemented in the Vienna Ab initio Simulation Package (VASP) (Universität Wien, Vienna, Austria) [ 53 ].…”

First-Principles Investigations on Structural and Elastic Properties of Orthorhombic TiAl under Pressure

“…The experimental and theoretical structural parameters are presented in Table 1. Note that the present lattice parameters and elastic constants are obtained by using the method of Wen et al [11]. From the selected-area electron diffraction patterns, the lattice parameters were estimated by Abe et al [2] to be a = 4.5 Å, b = 2.8 Å, and c = 4.9 Å, and by Ducher et al [5] to be a = 4.65 Å, b = 2.828 Å, and c = 4.94 Å, respectively.…”

“…Recently, Holec et al [10] investigated the preferential site occupations of ternary elements in the B19-TiAl. Most recently, Wen et al [11] investigated the structural stability and the elastic and mechanical properties of the B19-TiAl at ground state. However, to our knowledge, the influence of pressure on the structural, elastic, and mechanical properties of the B19-TiAl has not been reported so far.…”

First-Principles Calculations on Structural Property and Anisotropic Elasticity of γ1-Ti4Nb3Al9 under Pressure

“…Although the ground-state elastic properties of some constituent phases in high-Nb containing TiAl alloys have already been investigated in both theory and experiment [13,14,15,16,17,18,19,20,21,22], the elastic properties of various phases under pressure have rarely been studied. Up to now, the structural and elastic properties of $\gamma$-TiAl, ${\alpha }_2$-Ti${}_3$Al and B19-TiAl phases under pressure have been investigated by using first-principles calculations [23,24,25,26].…”