Numerical simulation of nano-cutting behaviors for polycrystalline γ-TiAl alloy: The effect of grain sizes

As one of the most potentially lightweight and high-temperature structural materials, grain size is a critical factor affecting the mechanical and cutting properties of γ-TiAl alloys during machining. In spite of the extensive research on the plastic removal and defect evolution of single-crystal γ-TiAl alloys, there are few studies on the atomic plastic flow of polycrystalline γ-TiAl alloys during nano-cutting, and it lacks a characterization method for the variation of subsurface damage with grain size. In this paper, the atomic plastic flow mechanism, defect evolution and distribution, average cutting force, and stress change during nano-cutting of the polycrystalline γ-TiAl alloy under the influence of grain size are analyzed based on the molecular dynamics simulation method. The results show that with grain refinement, the plastic removal mode of the material changes, the average subsurface damage layer depth (AveSSD) shows a trend of decreasing and then increasing, the average cutting force decreases, and the effect of grain boundaries on the hindrance of stress diffusion is significantly weakened. This suggests that grain refinement at the nanoscale might be an effective way to enhance the cutting performance of polycrystalline γ-TiAl alloys. These simulation results, provide atomic-level details for the machining removal of polycrystalline γ-TiAl alloy and can assist optimization of the nano-cutting process of polycrystalline γ-TiAl alloy.