Enhanced annealing of the dislocation network under irradiation

In crystalline metals, the dislocation network is the main source of internal strain, while irradiation steadily injects new sources of internal strain (point defects, defect clusters). As a consequence, the evolution of the dislocation network is driven by irradiation. While the atomistic mechanisms by which the forcing proceeds have long been suggested, namely the partitioning of defect elimination between dislocations and other defect sinks, both in stationary or transient regimes, some of the macroscopic consequences, such as irradiation enhanced dislocation annealing and irradiation driven recrystallization, are left unexplained. In this work we show that dislocation sink strengths for point defects are altered in the presence of neighboring dislocations and their climb motion is coordinated with the dislocation microstructure. A climb model, which takes into account the dislocation network, provides the mechanism for coordinated climb, which is shown to ease dislocation annealing. In particular, we demonstrate that coordinated dislocation climb accelerates the annihilation of dislocation pairs with the opposite sign and the repulsion of dislocations of the same sign, thereby, among other things, promoting the annealing of small-angle tilt boundaries by subgrain rotation.