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

• Published in: Fusion engineering and design Vol. 169; p. 112620
• Main Authors: Yi, Xiaoou, Du, Yufeng, Li, Yihang, Han, Wentuo, Liu, Pingping, Yoshida, Kenta, Toyama, Takeshi, Chen, Jiming, Zhan, Qian, Wan, Farong, Ohnuki, Somei, Nagai, Yasuyoshi
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.08.2021; Elsevier Science Ltd
• Subjects: CuCrZr/316LN; Diamond pyramid hardness; Enhanced diffusion; Explosion welding; Heat flux; Heat treatment; Interlayers; Mechanical properties; Microstructure; Neutron flux; Neutron irradiation; Neutrons; Radiation; Radiation damage; Structural integrity; Mechanical properties; Explosion welding; Neutron irradiation; CuCrZr/316LN; Microstructure
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2021.112620

•Explosion-welded CuCrZr/316LN joints were neutron irradiated to 0.3 dpa at Tirr < 190 °C. Good structural integrity has been maintained.•Black-spot contrasts dominated the damage microstructure on both sides of the CuCrZr/316LN interface. They were all under 4 nm in average size and achieved number densities on the order of 1022 m−3.•Radiation-enhanced diffusion might have favoured the dissolution of interlayers in pristine CuCrZr/316LN joints, and have accelerated the interfacial diffusion of key elements by at least two orders of magnitude.•The joint interface experienced an increase of Vickers hardness by ~ 21% after neutron irradiation. Heat treatments of 500 °C/1 h resulted in moderate softening, while 800 °C/1 h gave rise to a complete elimination of irradiation-induced hardening, respectively. 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.