Nanomachining characteristics of textured polycrystalline NiFeCo alloy using molecular dynamics

Abstract

This work investigates the grinding process of a polycrystalline NiFeCo alloy through molecular dynamics (MD) simulation. The important factors that affect the grinding mechanics are cautiously investigated by analyzing the grinding force, resistance coefficient, local stress and strain, temperature, surface morphology, the evolution of structure and dislocation, which contain grinding velocity, machining depth, tool radius, and surface texture. The result shows that a higher machining velocity, greater grinding depth and tool radius lead to a larger grinding force and chipping volume, as well as a higher temperature of the substrate. While the grinding force, chipping volume, and temperature are the largest in the grinding of smooth surface compared to other surface textures due to the greater surface density. Moreover, the morphology of surface texture powerfully influences the pile-up volume, but slightly affects the shape of groove. The local shear strain and stress play a significant role in the grinding that explains the deformation mechanism in the substrate under the high pressure of cutting tool, and the grain boundary in polycrystalline is the control factor in the deformation behavior. Notably, the analysis of structure and dislocation evolution reveals that the nucleation and movement of dislocation caused plastic strain during the grinding show clearly the mechanism of subsurface damage. Besides, the dislocation motion is eliminated by grain boundary or interacts with each other to form new dislocation.