Effect of Light Element Impurities on the Edge Dislocation Glide in Nickel and Silver: Molecular Dynamics Simulation

Abstract

The influence of light element (C, N, O) impurities on the edge dislocation glide in fcc metals (Ni, Ag) is studied by molecular dynamics simulation. The introduction of impurity atoms is found to increase the dislocation glide threshold stress significantly, from 10 MPa in the pure metals at a temperature of 300 K to 1000–2000 MPa after the introduction of 10 at % impurity atoms. The increase in the threshold stress with the concentration of impurity atoms is shown to be caused by the Suzuki mechanism, i.e., the pinning of impurity atoms by the stacking fault between partial dislocations. The energies of binding of impurity atoms to stacking faults were determined for the metals under study. When temperature increases, the dislocation glide velocity in the pure metals decreases. After the introduction of impurity atoms, this dependence is reversed: the dislocation velocity increases gradually with temperature.