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

Abstract 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.