Investigation of the electronic structure of carbon-containing TiAl

Single-electron band structure calculations for non-defective and C-containing TiAl were undertaken within the local density approximation in order to address the role of C within the TiAl lattice. C was introduced either substitutionally or interstitially assuming hypothetical compositions based on the tetragonal TiAl structure. From the analysis of the density of states and the crystal orbital overlap population (COOP) of the respective phases, the lattice was found to be most stable when carbon was substituted for Al. When carbon entered interstitially, strong Ti-C interactions were favoured energetically, although Al-C interactions could also be formed.