3D dislocation dynamics: stress-strain behavior and hardening mechanisms in fcc and bcc metals

A dislocation dynamics (DD) model for plastic deformation, connecting the m acroscopic mechanical properties to basic physical laws governing dislocati on mobility and related interaction mechanisms, has been developed. In this model there is a set of critical reactions that determine the overall resu lts of the simulations, such as the stress-strain curve. These reactions ar e annihilation, formation of jogs, junctions, and dipoles and cross-slip. I n this paper, we discuss these reactions and the manner in which they influ ence the simulated stress-strain behavior of fee and bcc metals. In particu lar, we examine the formation (zipping) and strength of dipoles and junctio ns, and effect of jogs, using the dislocation dynamics model. We show that the strengths (unzipping) of these reactions for various configurations can be determined by direct evaluation of the elastic interactions. Next, we i nvestigate the phenomenon of hardening in metals subjected to cascade damag e. The investigated microstructure consists of small dislocation loops deco rating the mobile dislocations. Preliminary results reveal that these loops act as hardening agents, trapping the dislocations and resulting in increa sed yield stress. (C) 2000 Elsevier Science B.V. All rights reserved.