Dynamics of edge dislocation in Cu-Ni solid solution alloys at atomic scale

The mobility of edge dislocation in Cu-Ni solid solution alloys within a wide range of temperatures 100-1100 K and Ni concentrations 0-30 at% is studied by molecular dynamics simulation. Two different regimes of the influence of substitutional Ni atoms on the motion of edge dislocation are observed. In the first regime, in which the velocity of edge dislocation is much less than the shear sound speed, Ni atoms act as barriers and slow the dislocation down. In this regime, the dependence of the edge dislocation velocity on Ni concentration weakens with increasing temperature. In the second regime, in which the dislocation moves faster, with a speed closer to the shear sound speed, Ni atoms accelerate its motion. The latter result is a consequence of higher shear sound speed along the [110] direction of Cu-Ni solid solution alloy associated with higher Ni content. The distance between Shockley partial dislocations representing the core of edge dislocation is analyzed as a function of temperature and Ni concentration. The partial splitting increases with temperature and decreases with Ni concentration. The latter result might be important for predicting strain hardening mechanisms in Cu-Ni alloys.