Theoretical investigations on phase stability, elastic constants and electronic structures of D022- and L12-Al3Ti under high pressure

Phase stability, elastic and thermodynamic properties, and electronic structure of titanium trialuminide (Al3Ti) with Ll2 and D022 structures under pressure up to 40 GPa have been investigated using first-principles calculations. The equilibrium structure and formation energy show that L12-Al3Ti is stable when the pressure is higher enough, approximately above than 20–30 GPa. The elastic constants, anisotropy index and Debye temperature of both phases increase with the pressure going up, and L12-Al3Ti has better ductility, smaller anisotropy and lower Debye temperature than D022-A13Ti. The pressure-induced Ti-3d delocalization can strengthen its orbital hybridization with Al(s,p), which leads to stronger atomic bonding, and subsequently makes the L12-Al3Ti more stable under high pressure.

► High pressure stability of D022, L12-Al3Ti are studied using first-principles method.
► Structural, energetic and thermodynamic properties are calculated under 0–40 GPa.
► L12-Al3Ti is more stable than D022-Al3Ti when pressure is above 20–30 GPa.
► The dependence of elastic, anisotropy and Debye temperature are investigated.
► Ti-3d and Al-3p electron interaction is strengthened under high pressure.