A Molecular-Dynamics Study of the Influence of Carbon, Nitrogen, and Oxygen Impurities on the Edge Dislocation Slip in Aluminum and Nickel

The influence of C, N, and O impurities on the slip of an edge dislocation in Al and Ni has been studied by the molecular-dynamics method using the Mishin EAM potentials. Introduction of impurity atoms into the metal lattice leads to a significant increase in the threshold dislocation-slip stress (by about two orders of magnitude with the introduction of 5 at % impurity atoms), which is due to pinning of impurity atoms at a stacking fault between partial dislocations (the Suzuki mechanism). The binding energies of impurity atoms with stacking faults have been found for the metals under consideration. The dislocation-slip rate in pure metals decreases with an increase in temperature; however, an inverse dependence is observed upon the introduction of impurity atoms: the dislocation velocity, in contrast, gradually increases with temperature.