Diffusion mechanism of tools and simulation in nanoscale cutting the Ni-Fe-Cr series of Nickel-based superalloy

摘要

Nickel-based superalloy is widely used in aerospace field for its excellent comprehensive performance, such as oxidation resistance and high temperature resistance. The key surfaces of most of the heat-resistant parts are obtained by precision cutting or ultra-precision cutting. Nickel-based superalloy belongs to NixFeyCrz series alloy because its main component is nickel (Ni), iron (Fe) and chromium (Cr). However, the high cutting temperature generated in cutting process caused that chemically worn is easy to occur in cutting tools. The main manifestation is that the tool wear caused by the weakening of tool strength with the fusion between the workpiece and tool atoms at tool-chip interface. In order to study the mechanism of diffusion wear in precision cutting process, the cutting model that using silicon carbide tool to cut Nickel-based superalloy is established, and the Morse potential energy function between different atoms is calculated. The simulation of the cutting process is carried out by means of MD (molecular dynamic) method. Besides, the simulation results are visualized and the interaction mechanism between the tool and workpiece material in the process of cutting simulation is studied. The MSD (Mean Square Displacement) method is used to describe the diffusion process between the workpiece atoms in the silicon carbide more accurately. The diffusion activation energy of the Ni, Cr and Fe atoms are calculated. Furthermore, the vacancy formation energy and the interstitial atom formation energy of the three atoms in the complete silicon carbide lattice are also calculated. The results show that the main diffusion mechanism of Ni, Cr and Fe atoms in cutting tools is grain boundary (GB) diffusion. The present study can make a more perfect microcosmic explanation for tool wear mechanism.