Abstract
The effects of pressure on the structural and elastic properties of orthorhombic TiAl are investigated using first-principles calculations based on density functional theory within the projector augmented wave method. The calculated lattice parameters at 0 GPa are in good agreement with the available experimental data. The pressure dependence of the normalized lattice parameters and the single crystal elastic constants are investigated. By the elastic stability criteria under pressure, it is found that orthorhombic TiAl is mechanically stable under pressure up to 100 GPa. The elastic moduli and Poisson’s ratio under pressure up to 100 GPa are calculated using the Hill average method. The ductility/brittleness under pressure are evaluated, and a critical pressure for brittle-to-ductile transition is found to be 40 GPa. The elastic anisotropy and Debye temperature under different pressure are estimated from the calculations.
Highlights
Intermetallic alloys based on γ-TiAl are widely considered as promising high-temperature structural materials for aerospace and automotive applications because of their low density, high strength, and good high temperature resistances to creep, oxidation, and corrosion [1]
Starting from the optimized geometry of a unit cell at the given pressure, the elastic constants of the orthorhombic TiAl can be determined using the strain–stress relationship method embedded in the VASP
Note that the present lattice parameters and elastic constants are obtained by using the method of Wen et al [11]
Summary
Intermetallic alloys based on γ-TiAl are widely considered as promising high-temperature structural materials for aerospace and automotive applications because of their low density, high strength, and good high temperature resistances to creep, oxidation, and corrosion [1]. These alloys have the serious drawback of their low ductility that results in their limited hot workability. To our knowledge, the influence of pressure on the structural, elastic, and mechanical properties of the B19-TiAl has not been reported so far. We will use first-principles calculations to further investigate the structural, elastic, and mechanical properties of orthorhombic B19-TiAl under pressure.
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