High-density deformation nanotwin induced significant improvement in the plasticity of polycrystalline γ-TiAl-based intermetallic alloys†
Intermetallic alloys with high melting point can mostly serve as promising high-temperature structural materials, but their intrinsic brittleness limits their further application. Herein, we developed a strategy to realize high strength and high plasticity simultaneously in Cr-rich γ-TiAl-based intermetallic alloys via introducing high-density deformation nanotwins. Non-equilibrium continuous casting followed by annealing in the (α + γ) phase region generated numerous Shockley partial dislocations and stacking faults as well as a number of α2 nanoparticles in the γ-TiAl phase. The substantial Shockley partial dislocations and stacking faults acting as effective heterogeneous nucleation sites favored the generation of high-density nanotwins in the as-annealed alloys during deformation, especially within the γ lamellae. This strategy can also be applied to other brittle alloys with a favorable twinning deformation mechanism and paves the way for the development of high-strength and high-ductility materials.