Tensile behavior, microstructural evolution, and deformation mechanisms of a high Nb-TiAl alloy additively manufactured by electron beam melting

[Display omitted] •Tensile behavior and flow stress are sensitive to temperature and evaluated by the Chaboche model.•The brittle to ductile transition temperature is between 700 and 750 ℃.•The brittleness is related to the localization of deformation and stress concentrations.•Dynamic recovery and recrystallization are the primary processes for the ductile stage. To evaluate the tensile behavior, microstructural evolution, and deformation mechanisms of Ti-45Al-8Nb alloy additively manufactured by electron beam melting, uniaxial tensile experiments were performed at a constant strain rate of 2.5 × 10−4 s−1 at various temperatures. The experimental results indicated that the tensile behavior and flow stress are sensitive to temperature. The brittle to ductile transition temperature of Ti-45Al-8Nb alloy additively manufactured by electron beam melting is between 700 and 750 ℃. Below this temperature, the fracture was predominantly trans-granular, resulting in brittle failure. In addition, the brittle failure behavior is related to the localization of deformation within the grains and stress concentrations owing to plastic incompatibility at the interface of the α2+γ phases. However, above this temperature, the fracture transformed from the trans-granular type to the mixed mode of trans-granular and ductile dimples. Dynamic recovery and recrystallization are the primary processes leading to softening behavior. The flow behavior at elevated temperatures results from the competition between work hardening and softening. Furthermore, the Chaboche model was used to describe the tensile inelastic behavior at different temperatures.