The motion of dislocations in irradiated materials

The motion of dislocations in irradiated materials has unique features that are not seen in unirradiated materials undergoing plastic deformation. In the present work, we show dislocation dynamics studies that reveal the single and collective aspects of dislocation motion in materials under displacement cascade damage. First, we investigate the dynamics of dislocation interaction with irradiation induced defect clusters in neutron-irradiated bcc iron. The critical stress to unlock dislocations from self-interstitial atom (SIA) cluster atmospheres and the reduced dislocation mobility associated with loop drag by gliding dislocations are determined. Microstructure of "defect clouds" along the grown-in dislocations generated by Kinetic Monte Carlo simulations were used as input. We introduced nonconservative dislocation climb motion into parametric dislocation dynamics by considering the osmotic force that arises from absorbing point defects at the climbing segment. The dislocation climb resulting from point defect absorption is simulated.