Recent progress in experimental investigation of neutron irradiation response of tungsten

In order to facilitate its application as plasma facing material, neutron irradiation response of tungsten (W) has been extensively studied by employing fission reactors. In this article, the major findings of the microstructural evolution and thermo-mechanical property degradation of W following neutron irradiation in various reactors are summarized by reviewing the papers published in 2019–2021 from the US-Japan joint projects on fusion materials research and the EUROfusion program. Microstructural development of W following irradiation has been well documented as functions of irradiation temperature, dose, and neutron spectrum. Detailed characterization of the primary defect features, i.e., dislocations, voids, and precipitates, enables a better understanding of the interactions between displacement damage and solid transmutant elements. Irradiation hardening and embrittlement are the primary degradation phenomena of W exposed to neutrons, manifested by hardness and yield strength increase, ductility loss at high doses, and shift of the ductile to brittle transition temperature (DBTT). It is believed that the segregation and precipitation of the solid transmutant elements dominantly contributes to the property deterioration. Predicting W performance in real fusion neutron irradiation environments based on the current understanding of W response to fission neutrons remains an open question.