Authors: P. Heino and E. Ristolainen
Affilation: Tampere University of Technology, Finland
Pages: 475 - 478
Keywords: copper, molecular dynamics, dislocation, interatomic potential, stacking fault energy
We study the effects of thermally induced shear strain and stress in several nanoscale copper systems consisting of about 200k atoms with the effective-medium theory and molecular dynamics method. Both edge and screw dislocations are seen to initiate at the free boundaries on the (111) slip plane. In most cases dislocations are slower than the speed of sound, but a transition to super sonic edge dislocations was observed. In some cases dislocations initiated at the compressive side of the system other than at the tensile side. This was proposed to be caused by the dependence of the stacking fault energy on the state of strain. The results show that initially the stress is concentrated in the corners of the system, and later, when the structure has been plastically deformed, high stress regions are found in the center of the system. The minimum stress and strain at which plastic deformation occurred were 1.2GPa and 4.6%.