Interaction and accumulation of glissile defect clusters near dislocations

Accumulation of nano-size prismatic defect clusters near slip-dislocations results from their mutual elastic interaction. We present here 3-D isotropic elasticity calculations for the interaction energy between radiation-induced nano-size prismatic loops and grown-in dislocation loops. The current treatment extends the work of Trinkaus et al. in two respects. First, a computational method for full 3-D analysis of interaction energies in bcc Fe and fcc Cu is developed. Second, the theoretical method of Kroupa is computationally implemented for rigorous calculations of force, torque and induced surface energy on defect clusters. It is shown that small clusters are trapped within a zone of ∼10 nm in bcc Fe, and ∼20 nm in fcc Cu at room temperature, in rough agreement with experimental observations. Clusters can be absorbed in the core of grown-in dislocations because of unbalanced moments, which provide sufficient energy for rotation of their Burgers vectors in a zone of 2–3 nm in Fe. Near the dislocation core (within a few nanometers), sessile defect clusters in Cu are shown to convert to a glissile configuration.