摘要：We investigated the effect of vacancy formation on brittle (D022) to ductile (L12-like) transition in Al3Ti using DFT calculations. The well-known pseudogap on the density of states of Al3Ti migrates towards its Fermi level from far above, via a W - M co-doping strategy, where M is Si, Ge, Sn or Pb respectively. In particular, by a W - M co-doping the underline electronic structure of the pseudogap approaches an octahedral (L12: t2g, eg) from the tetragonal (D022: eg, b2g, a1g, b1g) crystal field. Our calculations demonstrated that (1) a W-doping is responsible for the close up of the energy gap between a1g and b1g so that they tend to merge into an eg symmetry, and (2) all M-doping lead to a narrower gap between eg and b2g (moving towards a t2g symmetry). Thus, a brittle to ductile transition in Al3Ti is possible by adopting this W - M co-doping strategy. We further recommend the use of W-Pb co-doped Al3Ti to replace the less anodic Al electrode in Al-battery, due to its improved ductility and high Al diffusivity. Finally this study opens a new field in physics to tailor mechanical properties by manipulating electron energy level(s) towards higher symmetry via vacancy optimization.
