First-principles study of point defects and Si site preference in Al3Ti

The formation energies of various point defects in Al3Ti(D022) have been calculated by using first-principles calculation. The effects of vacancies on Si site preference were examined to better understand Si substitution behavior in Al3Ti. The results show that, under Al-rich condition, the formation energy of antisite AlTi is the lowest than those of other point defects, and Ti vacancy is more preferred than Al vacancy. But Si prefers to occupy Al vacancy compared with Ti vacancy which causes a finite solubility of Si in Al3Ti system. The calculation is instructive for the further improvements of process of Si removal.

► For antisites in Al3Ti, formation energy of AlTi is lowest under Al-rich condition.
► The most probable vacancy in Al3Ti is Ti vacancy under Al-rich condition.
► Al vacancy formation is more preferred than Ti vacancy formation under Ti-rich condition.
► Al vacancy is helpful to Si doping in Al3Ti.