An atomistic investigation of dislocation velocity in body-centered cubic FeCrAl alloys

Edge, screw, and mixed dislocation velocities in FeCrAl body-centered cubic alloy were investigated by classical molecular dynamics simulation at several temperatures for the < 111 > {110} type slip system. For screw orientation, the dislocation velocity as a function of applied shear stress was found to be zero up to a threshold stress, beyond which the velocity increases with applied shear stress. For edge and mixed orientations, the dislocation velocity as a function of applied shear stress was found to have four regimes: zero value below a threshold stress, slow glide regime just above the threshold stress, a linear regime, and a final nonlinear regime past a certain velocity with a relatively lower slope. Two main features of the dislocation velocity were observed in FeCrAl alloys. First is that the rate of increase of the velocity with the applied shear stress decreases with chromium concentration and aluminum concentration, and that the dependence of the dislocation velocity on the angle between direction of the Burgers vector and the dislocation line direction shows a sinusoidal-like behavior.