The effect of residual stress on Σ3(111) twin boundaries fracture behavior in γ-TiAl with molecular dynamics simulation

Abstract

In this paper, molecular dynamics (MD) simulations are performed to study the influence of residual stress on fracture behavior in γ-TiAl alloy with ∑3(111) twin boundaries. The tensile processes are simulated at 1, 300, 1050 K after the residual stress is introduced by prepressing. The evolution of microdefects during tensile fracture is observed, and the distribution of residual stress in three direction is characterized. Results show that the introduced residual stress is symmetrically distributed on both sides of ∑3(111) twin boundaries. The residual compressive stress can prevent the nucleation of micro-cracks and increase the yield strength. The fracture mode of the γ-TiAl alloy with ∑3(111) twin boundaries during tensile load at 1 K is the nucleation of microcracks at grain boundaries followed by intergranular fracture. The ∑3(111) twin boundaries have good thermal stability. The residual compressive stress is completely released and the amplitude of residual tensile stress increases at 1050 K, and the γ-TiAl alloy with ∑3(111) twin boundaries exhibits good ductility.