Fracture toughness of copper-base alloys for fusion energy applications

Oxide-dispersion strengthened copper alloys and a precipitation-hardened co pper-nickel-beryllium alloy showed a significant reduction in toughness at elevated temperatures (250 degrees C) as compared to room temperature. This decrease in toughness was much larger than would be expected from the rela tively modest changes in the tensile properties over the same temperature r ange. However, a copper-chromium-zirconium alloy strengthened by precipitat ion showed only a small decrease in toughness at the higher temperatures. T he embrittled alloys showed a transition in fracture mode, from transgranul ar microvoid coalescence at room temperature to intergranular with localize d ductility at high temperatures. The Cu-Cr-Zr alloy maintained the ductile microvoid coalescence failure mode at all test temperatures. (C) 1999 Publ ished by Elsevier science B.V. All rights reserved.