Evolution of defects and deformation mechanisms in different tensile directions of solidified lamellar Ti-Al alloy

Two-phase gamma-TiAl/alpha(2)-Ti3Al lamellar intermetallics have attracted considerable attention because of their excellent strength and plasticity. However, the exact deformation mechanisms remain to be investigated. In this paper, a solidified lamellar Ti-Al alloy with lamellar orientation at 0 degrees, 17 degrees, and 73 degrees with respect to the loading direction was stretched by utilizing molecular dynamics (MD) simulations. The results show that the mechanical properties of the sample are considerably influenced by solidified defects and tensile directions. The structure deformation and fracture were primarily attributed to an intrinsic stacking fault (ISF) accompanied by the nucleated Shockley dislocation, and the adjacent extrinsic stacking fault (ESF) and ISF formed by solidification tend to form large HCP structures during the tensile process loading at 73 degrees. Moreover, cleavage cracking easily occurs on the gamma/alpha(2) interface under tensile deformation. The fracture loading mechanism at 17 degrees is grain boundary slide whereas, at 73 degrees and 0 degrees, the dislocation piles up to form a dislocation junction.