Comparison of properties and microstructures of Tréfimétaux CuNiBe and Hycon 3HP^TM before and after neutron irradiation

The precipitation strengthened CuNiBe alloys are among the three candidate copper alloys that are being evaluated for application in the first wall, divertor, and limiter components of ITER. Generally, CuNiBe alloys have higher strength but poorerconductivity compared to CuCrZr and Cu-A1_2O_3 alloys.

Brush-Wellman Inc. has developed an improved version of their Hycon CuNiBe alloy that has higher conductivity while maintaining a reasonable level of strength. In the present work we have investigatedthe physical and mechanical properties of the Hycon 3HPTM alloy both before and after neutron irradiation and have compared its microstructure and properties with the European CuNiBe candidate alloy manufactured by Trefimetaux.

Tensile specimens of bothalloys were irradiated in the DR-3 reactor at Risø to displacement dose levels of up to 0.3 dpa at 100, 250 and 350 degC. Both alloys were tensile tested in vacuum in the unirradiated and irradiated conditions at 100, 250 and 350 degC and themicrostructures of the alloys were investigated using transmission electron microscopy.

Electrical resistivity measurements were made on tensile specimens be-fore and after irradiation; all measurements were made at 23 degC. Results of theseinvestigations are presented and discussed in terms of the sensitivity of these alloys to test temperature, which becomes increasingly problematic when the irradiation and test temperature reaches 250 degC and above.