Molecular dynamics simulation of the uniaxial tensile deformation of nanocrystalline copper
纳米晶铜单向拉伸变形的分子动力学模拟

Nanocrystalline (nc) materials are characterized by a typical grain size from 1 to 100 Din. The uniaxial tensile deformation of computer produced nc coppers is simulated by using molecular dynamics with Finnis-Sinclair potential. The mean grain size of simulated nc coppers is varied within the 5.38 to 1.79 urn range. With grain size decreasing, the mean atomic energy of nc systems and interior grain has increased, but that of grain boundaries has descended slowly. The Young's modulus depends strongly on the grain size, and decreases with decreasing grain size. The simulated nc coppers show a reverse Hall-Petch effect. Most of the plastic- deformation is due to grain boundary sliding, grain boundary motion, and grain rotation, and a minor part is caused by dislocation activities in the grains, which are consistent with experimental results. The dislocation activities begin to play a role in the large strain (over 5%); This role is progressively distinct with gram size increasing.