Structural stability and mechanical properties of Ti2AlX (XÂ =Â Hf, Re) intermetallics: A DFT study

Present work describes the structural stability and mechanical properties of B2, D019 and O phases of Ti2AlX (X = Hf, Re) intermetallics calculated using density functional theory (DFT) within generalized gradient approximation (GGA). The lattice constant values for all the three phases are computed. For Ti2AlHf, O phase is the most stable followed by D019 and B2 whereas for Ti2AlRe, O phase is the most stable followed by B2 and D019 phases. All the three phases in Ti2AlHf and Ti2AlRe have metallic bonding inferred from the positive Cauchy pressure and they satisfy the Born stability criteria in terms of elastic constants. Ductile deformation behaviour is expected based on the G/B ratios for these systems except O phase. The B2 phase exhibits very high anisotropy in comparison to those of D019 and O in both alloys and the anisotropy is higher in Ti2AlHf.