Properties of copper composites strengthened by nano- and micro-sized Al2O3 particles

Abstract

Abstract Electrolytic copper powder, inert gas atomized prealloyed copper powder containing 3.5 wt.% Al, and a mixture of copper and commercial Al2O3 powder particles (4 wt.% Al2O3) were milled separately in a high-energy planetary ball mill for up to 20 h in air. The milling was performed in order to strengthen the copper matrix by grain size refinement and Al2O3 particles. Milling in air of prealloyed copper powder promoted formation of fine dispersed Al2O3 particles by internal oxidation. Hot-pressing (800 °C for 3 h in argon at a pressure of 35 MPa) was used for compaction of milled powders. Compacts from 5 and 20 h milled powders were additionally subjected to high temperature exposure (800 °C for 1 and 5 h in argon) in order to examine their thermal stability and electrical conductivity. The effect of different size and the amount of Al2O3 particles on strengthening, thermal stability and electrical conductivity of the copper-based composites was studied. The results were discussed in terms of the effects of the grain size refinement along with micro- and nano-sized Al2O3 particles on the strengthening of the copper matrix.