Thermal evolution and high temperature annealing of dislocation microstructure

of an irradiated metal, described by an ensemble of interacting interstitial

dislocation loops, is explored using discrete dislocation dynamics simulations.

On the microscopic scale, the two fundamental processes driving microstructural

evolution are the pipe diffusion of atoms along the dislocation lines, resulting

in dislocation self-climb, and bulk diffusion of vacancies resulting in the conventional

dislocation climb. Simulations show that the coalescence and coarsening

of prismatic dislocation loop microstructure observed at lower temperatures is

driven primarily by dislocation self-climb. In tungsten, dislocation self-climb

gives rise to a pronounced change in the dislocation loop microstructure at temperatures close to 800 ⁰C [1],

whereas the same microstructural transformation in iron is predicted to occur at 270 ^₀C.