Fracture toughness of copper-base alloys for fusion energy applications

Abstract Oxide-dispersion strengthened copper alloys and a precipitation-hardened copper–nickel–beryllium alloy showed a significant reduction in toughness at elevated temperatures (250°C) as compared to room temperature. This decrease in toughness was much larger than would be expected from the relatively modest changes in the tensile properties over the same temperature range. However, a copper–chromium–zirconium alloy strengthened by precipitation showed only a small decrease in toughness at the higher temperatures. The embrittled alloys showed a transition in fracture mode, from transgranular microvoid coalescence at room temperature to intergranular with localized ductility at high temperatures. The Cu–Cr–Zr alloy maintained the ductile microvoid coalescence failure mode at all test temperatures.