In situ copper–alumina composites

We present a process for the production of Cu–Al matrix composites containing between 25 and 30 vol.% in situ Al2O3. The composites are prepared by pressing, heat-treating and hot working blended powders of Cu, Al and CuO packed into copper alloy cans. The evolution of the microstructure during in situ reaction is governed by the stable growth of alumina films; these mitigate the rate of reaction, preventing thermal runaway if samples are processed with sufficient thermal ballast. The resulting alumina is amenable to subsequent refinement and dispersion by hot working the composite, with reversed (extrusion/upsetting/extrusion) deformation giving best results. Cu7 wt.%Al containing homogeneously distributed micron-sized alumina particles thus produced has a tensile strength of 848±44 MPa and a tensile ductility of 2.2±0.8%.