It was recalled that, when irradiated, metals suffered significant internal damage accumulation and the degradation of mechanical properties. The damage took the form of a high number-density of nano-sized defect clusters (stacking-fault tetrahedra or interstitial loops). The alteration in mechanical properties was seen as a hardening response, and as localized plastic deformation in defect-free channels. Discrete dislocation dynamics were used to model these effects. It set up a framework for the elastic interaction between gliding dislocations and defect clusters, and prescribed a scheme for loop unfaulting and absorption into dislocations. It was shown here that stacking-fault tetrahedra represented weaker pinning points for dislocation motion than did parent dislocation loops. It was also shown that an appreciable yield drop could be attributed to a high density of defects which decorated the dislocations. Strong obstacles caused dislocations in Cu to double cross-slip continually, thus causing the formation of

defect-free channels. The correlation between yield stress increase, and defect number-density, was in excellent agreement with experiment.

Localized Deformation and Hardening in Irradiated Metals - Three-Dimensional Discrete Dislocation Dynamics Simulations. T.A.Khraishi, H.M.Zbib, T.Diaz de la Rubia, M.Victoria: Metallurgical and Materials Transactions B, 2002, 33[2], 285-96