Al₂O₃/Cu composite fabricated by hot pressing and spark plasma sintering

The composite powders, in which the nano-Al₂O₃ particles are dispersed on the micrometer copper particles, were prepared by the mechanical alloying(MA). The shapes and size distributions of the composite powders were improved by the spherical process. The nanometer Al₂O₃/Cu composites were individually fabricated by the hot pressing (HP) and spark plasma sintering (SPS). The properties of the sintered composites with Al₂O₃ mass fractions of 0%, 0.5%, 1.0% and 1.5% were investigated, including density, electric conductivity and bending strength. The microstructures of the composite powders and fractures of the sintered samples were analyzed by SEM and the element analysis of micro-area. The results show that the bending strength of the composites increases and then decreases while the electric conductivity varies randomly with the increase of Al₂O₃ mass fraction. The SPS is superior to the HP, comparing the density, bending strength and electric conductivity of the composites with the same Al₂O₃ mass fraction. The ductile fracture occurs under bending loading.