| Abstract Scope |
Intermetallic Ti-Al alloys exhibit good mechanical and physical properties at high temperatures, making them attractive for applications such as low-pressure turbine blades in aircraft engines. However, their insertion into industry has been limited by their poor room temperature ductility and fracture toughness. To design TiAl alloys with improved mechanical properties, a detailed understanding of the plastic deformation mechanisms is crucial, but currently lacking. In this work, we perform detailed atomistic simulations to investigate the behavior of dislocations in the γ-TiAl phase. Using a newly developed machine learning interatomic potential, we model the screw superdislocation core structures, critical resolved shear stress, mobility, cross-slip behavior, and their dependencies on alloy composition and temperature. We observe a dislocation locking mechanism via the transformation of the glissile planar core to a sessile non-planar core, which may be responsible for the anomalous yield strength of γ-TiAl within the range of operating temperatures. |