Molecular dynamics simulation of indentation-cutting on Ni and Cu by rigid Fe tool (Focus on combination of surface structure of tool and work)

Abstract

2D-like indentations are performed by molecular dynamics simulation as “nanometric indentation cutting”. A 90 degree triangle rigid bcc-Fe indenter with (001) or (110) surfaces is continuously drove into single crystalline fcc-Ni and Cu with free side surface, on three different top surfaces of (001), (110) and (111) of the work materials. Despite of large difference in the elastic constants, there is little difference in the repulsive force between Ni and Cu during cutting. This is because the plastic deformation or dislocation emission immediately occurs without large elastic deformation under the 2D-like infinite-length sharp blade, in contrast to spherical indenter in 3D indentation. Ni(001) work material shows drastic change in the cutting morphology by the tool surface; cleavage cracking occurs from a line defect ahead of the (001) tool while smooth cut at the tool end is observed on the (110) tool. The key of this difference is the atomic roughness of the tool surface; the rough (001) tool leads drag and rotation of the work surface, nucleating complicated small grains around the tool. The smooth (110) tool shows growth of single grain, in which the (111) plane is parallel to the cutting direction, at the front of the contact surface. Ni work also shows various deformation mode compared to Cu work, e.g. deformation by large grain growth normal to tool surface in the (110) work and kink formation by dislocation array in the (111) work, due to the high stacking fault energy.

Keywords

• indentation
• cutting
• tool surface
• dislocation
• kink