Atomic simulation for the effect of nano-cutting parameters on the 3D surface morphology of polycrystalline γ-TiAl alloy

Abstract

γ-TiAl alloy is one of the most potentially lightweight and high-temperature structural materials, and its machined surface quality has a significant effect on member service performance. Despite the extensive research on plastic removal and defect evolution under different cutting parameters, the forming mechanism of surface topography is not perfect under different cutting parameters. It is necessary to study the variation law of surface topography under the influence of different cutting parameters from the atomic scale. To this end, the influence of cutting depths and cutting speeds on the machined surface topography is investigated during nano-cutting of polycrystalline γ-TiAl alloys based on molecular dynamics simulation methods, and the effect of defective grain boundaries on cutting force fluctuations is analyzed. The results show that the effect of grain boundary on material deformation and dislocation obstruction is the main reason for the peak cutting force; with the increase of cutting depth, the average cutting force and friction coefficient increase, and both Sa and Sq show an increasing trend, which is the result of the joint action of plowing effect and grain boundary distribution; Sa and Sq show a decreasing and then increasing trend with the increase of cutting speed, and the critical cutting speed is 200 m s−1. This indicates that a smaller cutting depth and an appropriately higher cutting speed can effectively improve the surface quality of the polycrystalline γ-TiAl alloy, and optimize its nano-cutting process.