Study Of Structural Changes And Tempertature Field In Nanofabrication Process Of Single Crystal Copper

The Nanofabrication Technology is the manufacturing techniques of various microstructures in nanometer scale, and indicat the development of scientific and technology of the country. It provided technical support and guarantee for national defense strategy. Its accuracy has become an indicator of the development level of nano-technology.However, the development of nano-machining technology is restricted with processing theory and measurement, especially with the lack of subsurface formation mechanism. But the nanostructure's formation of sub-surface structure is impacted the mechanical properties and dimensional accuracy. So the discussing of the subsurface formation mechanism in nanostructure and the changes of the subsurface organizational structure has important significance.In addition, in the nanofabrication, the thermal deformation of nanostructure is an important factor the impact of the precision of nanofabrication.Firstly, based on reading the literature, we made a comprehensive evaluation of the research status of subsurface deformation in nanofabrication. We established the molecular dynamics model of nano-cutting process, then we researched the mechanism of materials removal and subsurface formation mechanism in nanofabrication, and analysis the changes of the stress distribution and nanostructure atoms' order. The simulation results show that: in the nano-cutting process of single crystal copper, the dislocation formed in the nanostructure surface and extended. In the tool and workpiece contact area ,the stress become higher. In cutting process, the atoms order of nanostructure was reduced.Secondly, we analysis the material structure change of nanostructure in nanofabrication by the built mode and the simulation results l in the previous and using spherical harmonic function. We researched that how the different cutting direction and cutting speed is impacted on the sub-surface of nanostructure in nanofabrication, as well as the indentation depth and indenter radius impacted sub-surface structure change in nano-indentation process. Simulation results show that: In the surface of nanostructure have similar icosahedral structure are appeared. There is also the close-packed structure and defect FCC structure appeared. For different cutting direction and cutting speed, the subsurface damage layer has different sizes. And the proportion of icosahedral structure and defect FCC structure atoms is different.In nanoindentation process, there is defect FCC structure appeared. And as the indentation depth and indenter radius larger, the proportion of these atoms increased, the others almost unchanged.Finally, we researched the temperature field of nanostructure in nanofabrication. We represented the temperature of workpiece atoms using statistical temperature of statistical thermodynamics, and study the different cutting parameters impact on the temperature distribution of nanostructure. Study the relationship between the structural changes of workpiece and the cutting process temperature distribution. In the nano-cutting process, the temperature field of the components is showing the concentric distribution with the center is the tool tip and components maximum temperature is between 300 and 700 degrees.With the cutting speed and cutting depth increases, the maximum temperature of nanostructure becomes higher, and the rise of temperature increased, the occurrence of thermal deformation is greater. The atomic structure of nanostructure is changed flow the change of the nanostructure's temperature.