First-principles investigation on shear deformation of a TiAl/Ti ₃Al interface and effects of oxygen

We have calculated the generalized stacking fault energies including the unstable stacking fault energy (γ _us) and the cleavage energy (γ _cl) at the clean and the oxygen-doped TiAl/Ti ₃Al interface using a first-principles method in order to investigate the mechanical properties of the interface. The [011](111) slip system exhibits the lowest γ _us and the largest γ _cl/γ _us among the selected four typical slip systems, showing that the shear deformation in this slip system is energetically favored. Oxygen at the TiAl/Ti ₃Al interface increases the stacking fault energies, and reduces γ _cl/γ _us for all the selected slip systems, suggesting the presence of oxygen reduce the ductility of the binary phase TiAl-Ti ₃Al alloy.