Study On Nano-cutting Chareacteristics And Deformation Mechanism Of Cu-Ni Alloy

Cu-Ni alloys with nanoscale microstructures generally have better catalysis.Nano-scale or nano-scale microstructures can be obtained by means of diamond tool cutting.Therefore,it is important to study the deformation characteristics and removal mechanism of workpiece materials during nano-cutting.Based on the theory of molecular dynamics,the molecular dynamics model of Cu-Ni alloy nano-cutting was constructed.The nano-cutting characteristics and deformation mechanism of Cu-Ni alloy were analyzed from the perspective of internal atom motion law.According to the current research status of nano-cutting mechanism and the characteristics of Cu-Ni alloy molecular dynamics model,the nano-cutting process of Cu-Ni alloy was studied by the following aspects.Firstly,the effect of the crystal orientation of the surface of Cu-Ni alloy on the nano-cutting process was studied.The Cu-Ni alloy is composed of a plurality of single crystal Cu grains having different crystal orientations and a grain boundary structure containing Ni elements.Therefore,the crystal orientation of the surface of the Cu-Ni alloy is mainly the surface crystal orientation of the single crystal Cu crystal in the alloy.In this paper,a molecular dynamics model of single crystal Cu nanomachining in five different crystal orientations is established.The cutting model which can describe the relative spatial position between the cutting direction and the crystal orientation of the workpiece surface is used to effectively analyze the influence mechanism of the crystal orientation of the workpiece surface on the nano-cutting process.For example,the material accumulation area of the workpiece surface,the propagation direction and stress distribution law of the internal defect structure of the workpiece,the cutting force of different crystal orientations.The surface of the single crystal Cu was etched by atomic force microscopy,and the experimental results and theoretical calculation results of the material accumulation on the surface of the workpiece were analyzed.Finally,explained why the cutting model can effectively analyze the nano-cutting process.Secondly,the influence of grain boundary structure on the nano-cutting process was studied.The nano-cutting molecular dynamics model of bicrystal Cu was constructed by Poisson-Voronoi method.The main research contents are as follows: the effect of grain boundary structure on the material accumulation area of workpiece surface during nano-cutting process Mechanism,the law of the change of cutting force at the grain boundary,the change of grain boundary structure during the nano-cutting process.The results show that the grain boundarystructure affects the nano-cutting process through the interaction with the internal dislocation plane of the grain,in the process of nano-cutting twin-crystal Cu,the cutting force changes at the grain boundary according to the crystal orientation of the grains on both sides of the grain boundary.Then,based on the twin-crystal Cu molecular dynamics model,the nano-cutting model of the twin-crystal Cu-Ni alloy was constructed by MC/MD method.The effect of Ni element on the grain boundary on the nano-cutting process was investigated.The results show that the Ni element segregated on the grain boundary makes the stress at the grain boundary larger,which increases the hindrance of the grain boundary structure to the dislocation structure.