Modelling the brittle-to-ductile transition of high-purity tungsten under neutron irradiation

Tungsten becomes significantly more brittle when exposed to neutron irradiation, which can be detrimental for the functionality of plasma facing components in nuclear fusion reactors. A predictive model of the mechanical behaviour of irradiated tungsten is therefore vital in order to assess how the brittle-to-ductile transition temperature evolves under fusion conditions. To this end, a cluster dynamics model is used to describe the defect production in high purity tungsten under neutron irradiation. The resulting defect concentrations provide input for a crystal plasticity model, capable of describing the influence of irradiation induced defects on the mechanical properties of high-purity tungsten. Simulation results reveal a striking match with experimental data in terms of yield stress at various temperatures and irradiation levels. Moreover, also the brittle-to-ductile transition temperature is adequately described by incorporating a probabilistic cleavage model.