Modelling recrystallization and grain growth of tungsten induced by neutron displacement defects

A multi-scale model is developed for the long-term microstructural evolution of tungsten under cascade damage conditions and for different irradiation temperatures as they may occur in a divertor of a nuclear fusion reactor. In particular the competition between damage accumulation and recovery processes, including grain growth and recrystallization are captured. A mean-field model for recrystallization and grain growth is coupled to a cluster dynamics model for the evolution of the neutron damage. The displacement damage is produced in the form of defect clusters, for which a parameterized temperature-dependent scaling law is implemented. A physically-based grain nucleation model is implemented in the mean-field recrystallization model. The competition between the various temperature dependent mechanisms and their effects on the evolving microstructure is studied in the range of T= 1000 °C - 1400 °C.