Clusters of self-interstitial atoms in the form of parallel crowdions were created directly in high-energy displacement cascades produced in metals by neutron irradiation. They were equivalent to small perfect dislocation loops and, in isolation in pure metals, undergo fast thermally-activated glide in the direction of their Burgers vector. Their strain field and ability to glide allows long-range interaction with other extended defects. Indeed, dislocations decorated by dislocation loops were commonly observed after neutron irradiation. Dislocations gliding under applied stress also encounter these mobile defects. These effects influence mechanical properties and require further investigation. This paper presents results from an atomic-scale study of Cu and a-Fe at 0 or 300K. Loop drag and breakaway effects were investigated for an edge dislocation under applied stress interacting with a row of self-interstitial atoms loops below its glide plane. The maximum speed at which a loop was dragged was lower in Cu than Fe, and the applied stress at which this occurred was also lower. These differences in the dynamics of cluster-dislocation interaction were determined by the atomic structure of the defects and cannot be investigated by continuum treatment.

Dynamic Properties of Edge Dislocations Decorated by Interstitial Loops in α-Iron and Copper. Y.N.Osetsky, D.J.Bacon, Z.Rong, B.N.Singh: Philosophical Magazine Letters, 2004, 84[11], 745-54