Low-temperature radiation embrittlement of copper alloys

The effect of low-temperature (T-irr less than 0.3T(melt)) irradiation on the tensile properties of copper and precipitation-hardened (PH) and dispersion-strengthened (DS) copper alloys was investigated. Samples were irradiated with fission neutrons at temperatures of 80 to 200 degrees C to doses of 0.6 to 5 dpa. Irradiation at temperatures <150 degrees C resulted in significant hardening and accompanying embrittlement in all of the materials. By comparing the present results with literature data, it is concluded that severe radiation embrittlement occurs in copper alloys irradiated at temperatures less than or equal to 100 degrees C for doses above similar to 0.01 to 0.1 dpa. On the other hand, irradiation at temperatures above 150 degrees C causes only moderate embrittlement for doses up to similar to 5 dpa. It is recommended that the minimum operating temperature for copper alloys intended for structural applications in fusion energy systems should be 150 degrees C, unless uniform elongations <1% can be accommodated in the design.