Energetic Study on Defect Structures in Nanocrystalline Aluminum and Copper by Atomic Simulations
Tomotsugu SHIMOKAWA, Tomoyuki HIRAMOTO, Toshiyasu KINARI and Sukenori SHINTAKU
Abstract:Atomic simulations of shear deformation of aluminum and copper nanocrystalline models are performed to determine the influences of defect plane energies on defect structures in nanocrystalline metals. In aluminum models with high stacking fault energy, deformation twins can be observed in the case of the specific crystal orientation which is the same one as that expected analytically. In this case, extrinsic stacking faults always form in the early stage of the formation of intrinsic stacking faults. It is also observed that new crystal slip generates in an extended stacking fault in another crystal orientation in aluminum. In order to clarify the appearance mechanism of these defects in aluminum, we use the dislocation theory and nudged elastic band method, and necessary conditions to form deformation twin in aluminum are discussed. Key Words:Molecular Dynamics, Atomic Simulation, Nanocrystalline Material, Deformation Twin, Partial Dislocation, Stacking Fault Energy, Plastic Deformation, Nudged Elastic Band Method