Synthesis and characterization of copper–alumina metal matrix composite by conventional and spark plasma sintering

Abstract

The evolution of microstructure, density and hardness of Cu–Al 2O 3 metal matrix composites with different techniques of sintering have been demonstrated here. The effect of sintering atmosphere on the interfacial compatibility of matrix and reinforcement has also been discussed. Synthesis of microcomposites was carried out by reinforcing 5, 10 and 15 vol.% of alumina powder particles (average size ∼5.71 μm) in copper matrix via conventional sintering using N 2, H 2 and Ar atmospheres. Nanocomposites of 1, 5, 7 vol.% alumina (average size <50 nm) reinforced in copper matrix were fabricated by powder metallurgy route using spark plasma sintering technique. These micro- and nano-composites have been characterized by X-ray diffraction and scanning electron microscopy followed by density and hardness measurements. Cu–Al 2O 3 metal matrix micro- and nanocomposites fabricated by conventional and spark plasma sintering routes were studied and compared. Maximum Vickers hardness of 60, 75 and 80 was obtained when the Cu–15 vol.% Al 2O 3 was conventionally sintered in N 2, Ar and H 2 atmosphere respectively. However, maximum hardness value of 125 has been achieved for the Cu–5 vol.% Al 2O 3 nanocomposite prepared by spark plasma sintering. It has been observed that Cu–Al 2O 3 metal matrix composite (MMC) shows poor mechanical properties when it is conventionally sintered in N 2 or Ar atmosphere compared to that in H 2 atmosphere.