Molecular Dynamics Simulation Of Nano-indentation In Cu Single Crystal

Investigating on the mechanical properties of nano-crystal, specially measuring strength and revealing the behavior of transform in crystal, has great importance in either theory or practical field. In this work, molecular dynamics simulations are applied to investigate the loading procedure in nano-indentation of Cu single crystal (sc-Cu), and the results are compared and illustrated.In chapterâ… , the current research of transform behavior and mechanical properties in nano-crystal are introduced, we also make a list of achievement in the field of nano-indentation by molecular dynamics, most of all, of nano-indentation in Cu single crystal.In chapterâ…¡, the principle of molecular dynamics are introduced, potential functions are chosen to fit the simulation. Beside it, we discuss the details such as time step, calculating methods and so on, simulation procedure are also described in last. Subsquently, we put emphasis on the effect of size of substrate, loading speed and loading temperature on the mechanical properties during nano-indentation of Cu single crystal. The results shows that with substrate size increasing, the critical load for plastic transform with sc-Cu substrate goes up, the critical depth of plastic transform deepen, and Young modulus decreases. With loading speed increasing(from 5.7m/s to 20m/s), the critical load for plastic transform with sc-Cu substrate goes up, the critical depth of plastic transform deepen, but Young modulus makes little change. With loading temperature increasing(from 5K to 400K), the critical load for plastic transform with sc-Cu substrate goes down, the critical depth of plastic transform gets a decrement trends, and Young modulus makes little change.In chapterâ…¢, the effect of crystal orientations on the micro-deformation mechanism is investigated. It indicates that [100][010][001]orientation and [111][112][110] orientation has same mechanism, the deformation is dominated by the dislocation nucleation caused by the slip of the{111} plane. Under the [100][011][011] orientation, the deformation is dominated by the deformation twinning, the deformation twinning grows after a few dislocations emission along the slipplane.