Ti-Ti Bonding in γ-TiAl and f.c.c. Ti

Abstract The flow and fracture of high-temperature intermetallic alloys is strongly influenced by the propagation and cross-slip of ordinary and super dislocations. One factor associated with the poor ductility of TiAl is an apparently large Peierls stress, or lattice friction stress for the glide of ordinary (1/2(110)) dislocations. This Peierls relief is intimately related to the underlying crystal and electronic structure of TiAl, and specific bonding states have been identified by some investigators as contributing to the pinning of dislocations along certain line directions. In this study we quantify the relative strength of these bonds using several complementary electronic structure methods. Aspects of the electronic structure, equilibrium lattice constants and bond energies of γ-TiAl are compared with hypothetical f.c.c. Ti as obtained by the full-potential linearized augmented-plane-wave (FLAPW) method, the DMol molecular cluster method and the linear muffin-tin orbital (LMTO) Green function (GF)...