First-principles investigation on shear deformation of a TiAl/Ti3Al interface and effects of oxygen

We have calculated the generalized stacking fault energies including the unstable stacking fault energy (γus) and the cleavage energy (γcl) at the clean and the oxygen-doped TiAl/Ti3Al interface using a first-principles method in order to investigate the mechanical properties of the interface. The [011¯](111) slip system exhibits the lowest γus and the largest γcl/γus among the selected four typical slip systems, showing that the shear deformation in this slip system is energetically favored. Oxygen at the TiAl/Ti3Al interface increases the stacking fault energies, and reduces γcl/γus for all the selected slip systems, suggesting the presence of oxygen reduce the ductility of the binary phase TiAl-Ti3Al alloy.

Graphical abstractThe shear deformation in the slip system is energetically favored, because this slip system exhibits the lowest among the selected four typical slip systems at the TiAl/Ti3Al interface. The presence of oxygen at the TiAl/Ti3Al interface leads to a reduction of the ductility, because oxygen increases the stacking fault energies, and reduces for all the selected slip systemsFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The presence of the Ti3Al phase can improve the ductility of the TiAl alloy. ► The shear deformation along [011¯](111) is energetically favored at the TiAl/Ti3Al interface. ► Oxygen at the TiAl/Ti3Al interface increases the stacking fault energies. ► Oxygen reduces the ratio of cleavage energy and unstable stacking fault energy. ► Oxygen reduces the ductility of the TiAl-Ti3Al alloy.