Study of loop-loop and loop-edge dislocation interactions in bcc iron

Recent theoretical calculations and atomistic computer simulations have sho wn that one-dimensional glissile clusters of self-interstitial atoms (SIAs) play an important role in the evolution of microstructure in metals and al loys under cascade damage conditions. Recently, it has been proposed that t he evolution of heterogeneities such as dislocation decoration and rafts ha s serious impacts on the mechanical properties on neutron-irradiated metals . In the present work, atomic-scale computer modelling (ASCM) has been appl ied to study the mechanisms for the formation of such microstructure in bcc iron. It is shown that glissile clusters with parallel Burgers vectors int eract strongly and can form extended immobile complexes, i.e., rafts. Simil ar attractive interaction exists between dislocation loops and an edge disl ocation. These two mechanisms may be responsible for the formation of exten ded complexes of dislocation loops below the extra half-plane of edge dislo cations. The interaction energies between loops and between an edge disloca tion and loops has been calculated as a function of distance using ASCM and the results for long-range interactions are in good agreement with the res ults of isotropic elasticity calculations. (C) 2000 Elsevier Science B.V. A ll rights reserved.