Mechanical Properties under Irradiation

One of the main computational tools to study the dynamic collective evolution of dislocations in a solid under an external loading at the mesoscopic scale is Discrete Dislocation Dynamics (DDD). In this simulation technique each dislocation is represented as an elastic entity, which obeys certain rules for motion and interaction with other dislocations, such as drag force upon gliding, cross-slip, junction formation etc. Based upon these rules, DDD simulations were used to study the role of the dislocation microstructure in strain hardening, nanoindentation, low-strain fatigue, crack-tip plasticity etc. However, in order to perform a quantitative creep deformation analysis in a DDD simulation, reliable rules for dislocation climb are requeired.
In the framework of this research, which is performed is collaborations with CEA/Saclay (Commissariat à l’Énergie Atomique) in France, a 3-dimensional Discrete Dislocation Dynamics simulation is coupled with the diffusion theory of point defects in order to introduce climb in this simulation technique. These simulations will demonstrate the irradiation-driven evolution of the dislocation network, such as irradiation-enhanced dislocation annealing, irradiation driven re-crystallization and irradiation induced plasticity at temperatures and stress levels where plastic strain does not show up in the absence of irradiation.

In the figure: Annealing of vacancy loops via bulk-diffusion climb (click image for animation).