Recrystallization of Dispersion-Strengthened Copper Alloys

Abstract

Pure copper exhibits high electrical and thermal conductivities, but it has low strength at room temperature as well as at elevated temperatures. Dispersion-strengthened (DS) copper alloy exhibits a high strength without sacrificing its inherent high conductivities, and maintains excellent thermal and mechanical stability at elevated temperatures by retaining its microstructures (Nadkarni, 1984). These unique characteristics are mainly attributed to the presence of uniformly dispersed thermally stable particles, which are typically oxides. Unlike precipitation-hardened copper alloys, which lose their strength by heating above the initial aging temperatures, the non-metallic oxide particles in oxide DS copper alloys, such as alumina, silica, and beryllia, neither coarsen nor go into solution, effectively preventing recrystallization and consequent softening of the alloys. Alumina DS copper alloys are not recrystallized even after exposure to temperatures approaching the melting point of copper (Preston & Grant, 1961). This is due to the pinning effect of the nano-sized alumina particles on the movement of the boundaries and dislocations. A unique combination of high strengths and high conductivities at elevated temperatures makes alumina DS copper alloys good candidates for high temperature electric materials (e.g., electrodes, lead wires, and connectors) (Nadkarni, 1984) as well as potential components in nuclear energy applications (Sumino et al., 2009).