Wear mechanism of diamond-cutting tool in nano-cutting polycrystalline γ-TiAl alloy based on molecular dynamics simulation

Abstract

The machining of γ-TiAl is susceptible to tool wear, and investigations into tool-wear mechanisms can contribute to enhancing machining efficiency and optimizing the surface integrity of workpieces. In this study, a molecular-dynamics method is employed to simulate the cutting process of polycrystalline titanium–aluminum alloys using a single-crystal diamond tool. The findings suggest that tool wear is induced by cutting forces and plastic deformation, with amorphization and diffusive wear as the primary mechanisms. Plastic deformation within the matrix facilitates interactions between internal dislocations in the grains, thus resulting in work hardening at the surface layer, increased cutting forces, and heightened susceptibility of the cutting edge to wear due to plastic deformation. Moreover, elevated temperatures and pressures in the cutting contact area induce atomic amorphization, which reduces both the strength and hardness of the tool while triggering structural phase transitions for certain atoms. Consequently, lattice distortion occurs within this region, thus causing matrix atoms to diffuse into the tool. The combined effect of amorphization and diffusion significantly exacerbates tool wear. This investigation provides valuable insights into wear mechanisms and guidance for enhancing the quality of γ-TiAl alloy.