Origin of reduced anisotropic deformation in hexagonal close packed Ti-Al alloy

The origin of low ductility in the hexagonal close-packed (hcp) metal system like Ti is high anisotropic critical resolved shear stress (CRSS) of different slip systems. To reduce the anisotropic deformation is a key for improving the mechanical performance. In the present study, Al alloying shows it can effectively weaken the anisotropic deformation of the hcp system. The relationship between Al alloying and anisotropic deformation was studied by X-ray diffraction, geometric phase analysis, and ab initio calculations. The atomic-scale mechanism behind the isotropic deformation of the Ti-Al alloy was shown that {10 − 10} prismatic planes were the preferred substitution planes for the Al atoms. The hardening trend of prismatic slip was faster compared to that of basal slip. A high CRSS rate and low CRSS starting point of prismatic slip contributed to the reduction in anisotropic deformation of the Ti-Al alloy.