Vibration Effects on the Structural Stability of Al-Ti Intermetallics by First-principles Calculations

The structural stability of the intermetallics AlTi3, Al2Ti, Al3Ti4 and Al3Ti in the Al-Ti system has been investigated using density functional theory (DFT) and density functional perturbation theory (DFPT). The calculated ground-state convex hull is in agreement with the experimental researches. Al3Ti4 (hP7) is metastable at 0 K and may be stabilized as the temperature increases due to the effects of the vibration entropy. For Al2Ti, r-Al2Ti is stable at 0 K and h-Al2Ti is stabilized by the vibration entropy at high temperatures. Al3Ti (tI16) is unstable considering vibration effects and Al3Ti (tI8) is the most stable structure at 0 K.