Micromechanism of cold deformation of two-phase polycrystalline Ti-Al alloy with void

Abstract

Cold deformation behavior of polycrystalline metallic material is affected by intrinsic defects such as dislocations, voids, inclusions etc. Existing studies on α 2 (Ti 3 Al) + γ(TiAl) two-phase Ti-Al alloy cover about deformation behavior mainly on macro scale. This paper focuses on the cold deformation mechanism of two-phase Ti-Al alloy at micro scale, and the role of voids in deformation process. Molecular dynamics simulations were performed to study the evolution of micro structure of material under uniaxial tension. Interaction between spherical nano voids with different size and position was also examined in the simulation. The results show that (1) In elastic stage, deformation of the two-phase is coordinated, but Ti 3 Al is more deformable; (2) In plastic stage, γ phase is the major dislocation source in two-phase alloy; (3) voids detracts the strength of the two-phase alloy, while the position of void affect the degree of this subtraction, voids located at the boundary of α 2 /γ phase have significant detraction to strength.