Neutron irradiation response of explosion-welded CuCrZr/316LN joints for ITER application

Abstract

Explosion-welded CuCrZr/316LN joints, which serve as key joining components in enhanced-heat-flux type first wall panels of ITER, have been neutron irradiated in the BR2 reactor (Belgium) at <190 °C, up to 0.3 dpa. The joints have maintained good structural integrity after irradiation and were free of void swelling. Radiation defects featuring black-spot contrasts were produced on both sides of the CuCrZr/316LN interface. They were on the order of 1022 m−3 in number density and all less than 4 nm in average size. Radiation-enhanced diffusion might have favoured the dissolution of interlayers which were characteristic of pristine CuCrZr/316LN joints, and accelerated the diffusion of key elements (e.g. Cu, Fe) across the interface. The joint interface experienced an increase of Vickers hardness by ~ 21% (∆Hv = 48) after neutron irradiation. Heat treatments of 500 °C/1 h resulted in moderate softening of the interface, while 800 °C/1 h gave rise to a complete elimination of irradiation-induced hardening effect, respectively.