High temperature micro-deformation behavior of continuous TiNb fiber reinforced TiAl matrix composite investigated by in-situ high-energy X-ray diffraction

The continuous TiNb fiber reinforced TiAl matrix composite possesses improved mechanical properties whereas the micro-deformation mechanism remains to be elucidated. This work dynamically analyzed the high-temperature compressive process of TiNb_f/TiAl composite by in situ high-energy X-ray diffraction (HEXRD) method. Results indicated β-TiNb and interfacial α₂ phase both contained two fiber textures whose formation obeyed the special sequences. Only <110> fiber texture in γ matrix and <0001> fiber texture in α-TiNb existed. The elastic-plastic (E-P) stresses of β-TiNb and α-TiNb grains were higher than macroscopic yield stress σ_y, especially α-TiNb presented significant strengthening effect. But E-P stresses of γ grains were all lower, especially the [200] and [202] orientated γ grains tended to yield easier along LD direction. Interfacial α₂ grains would enter E-P stage earlier due to stress concentration, indicating to share loading effectively. Both fiber and interface can play an important reinforcing role at the initial deformation. However, the fiber degradation at the later stage of work hardening would make it lose the strengthening effect. The load capacity of α₂ interface can maintain the strongest until the true strain reaching 22.16%. This work can provide a fundamental understanding of macro-deformation of TiNb_f/TiAl composite from the perspective of micromechanical behavior.