Copper Alloys From Metal Oxide Precursors for High Conductivity Applications

Abstract

Extrusion of oxide powders allows fabrication of thin-walled metal articles to produce controlled-geometry, low-density copper alloy architectures. Shapes formed with copper oxide powders mixed with alloying oxides are reduced and sintered to produce high relative densities in the thin walls. This technology has produced square-cell honeycomb extrusions, which are being characterized for heat sink applications. This effort is to determine the bulk properties of alloys produced by this type of thermo-chemical powder processing and to explain behavior based on the final chemistry and microstructure of the alloys. Compositions investigated include Cu, Cu–Ni, Cu–Ag, W–Cu, Cu–Invar, Cu–Al₂O₃, and Cu-Cr alloys. Alloys have been characterized for relative density, thermal conductivity, and grain size. Mechanical properties including tensile and yield strength and elongation were measured on Cu–Ni and Cu–Ag, and the results were analyzed based on porosity and composition of the alloys. Properties were compared to alloys made through conventional processing and powder metallurgy.

Keywords:

• Powder metallurgy
• Reduction
• Sintering
• Copper
• Thermal conductivity
• Honeycomb
• Cu–Ni
• Cu–Ag
• W–Cu
• Invar

Acknowledgments

This work is sponsored by the Defense Sciences Office of Defense Advanced Research Projects Agency (N00014-99-1-1016) under Dr. Leo Christodoulou and by the Office of Naval Research (N0014-99-1-0852) under Dr. Steven Fishman. The authors would like to thank Ben Dempsey for performing thermal diffusivity testing and Justin Clark for assisting with tensile testing.