AUTHOR=Perrin Alice , Hamaguchi Dai , Geringer Josina W. , Zinkle Steve , Yang Ying , Skutnik Steve , Poplawsky Jon , Katoh Yutai 

TITLE=Microstructure, electrical resistivity, and tensile properties of neutron-irradiated Cu–Cr–Nb–Zr

JOURNAL=Frontiers in Nuclear Engineering

VOLUME=Volume 3 - 2024

YEAR=2024

URL=https://www.frontiersin.org/journals/nuclear-engineering/articles/10.3389/fnuen.2024.1486694

DOI=10.3389/fnuen.2024.1486694

ISSN=2813-3412

ABSTRACT=High strength, high conductivity copper alloys that can resist creep at high temperatures are one of the primary candidates for efficient heat exchangers in fusion reactors. Cu-Cr-Nb-Zr alloys, which were designed to improve the strength and creep life of the ITER Cu-Cr-Zr reference alloys, have been found to have comparable electrical conductivity and tensile properties of Cu-Cr-Zr alloysThe measured creep rupture times for these improved alloys is about ten times higher than the ITER reference alloys at 90-125 MPa at 500℃. However, the effects of neutron irradiation on these alloys, and the ensuing material properties, have not been studied, and thus their utility in a fusion reactor environment is not well understood. This work characterizes the room temperature mechanical and electrical properties of a neutron irradiated Cu-Cr-Nb-Zr alloy and compares them to neutron irradiated ITER reference heat sink Cu-Cr-Zr alloy. Tensile specimens were neutron irradiated in the High Flux Isotope Reactor (HFIR) to 5 dpa between 275℃ and 325℃. Post-irradiation characterization included electrical resistivity measurements, hardness, and tensile tests. Microstructural evaluation used scanning electron microscopy, energy dispersive x-ray spectroscopy, and atom probe tomography to characterize the irradiation-produced changes in the microstructure and investigate the mechanistic processes leading to the post-irradiation properties. Transmutation calculations were validated with composition measurements from atom probe data and used to calculate contributions to the increase in electrical resistivity measured after irradiation. Comparisons with Cu-Cr-Zr alloys in the same irradiation heat found that the post-irradiated Cu-Cr-Nb-Zr alloys and Cu-Cr-Zr alloys had comparable electrical resistivity. While Cu-Cr-Nb-Zr alloys suffered more irradiation hardening than Cu-Cr-Zr, the overall tensile behavior deviated very little from non-irradiated values in the studied temperature range.