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

The evolution of microstructure, density and hardness of Cu–Al2O3 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 N2, H2 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–Al2O3 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.% Al2O3 was conventionally sintered in N2, Ar and H2 atmosphere respectively. However, maximum hardness value of 125 has been achieved for the Cu–5 vol.% Al2O3 nanocomposite prepared by spark plasma sintering. It has been observed that Cu–Al2O3 metal matrix composite (MMC) shows poor mechanical properties when it is conventionally sintered in N2 or Ar atmosphere compared to that in H2 atmosphere.

The evolution of microstructure, density and hardness of Cu–Al2O3 metal matrix composites with different techniques of sintering has been demonstrated here. The effect of sintering atmosphere has also been discussed. Synthesis of microcomposites was carried out by reinforcing 5, 10 and 15 vol.% of alumina powder particle (average size ∼5.71 μm) in copper matrix via conventional sintering using H2 and N2 atmospheres. Nanocomposites of 1, 5, 7 vol.% alumina (average size <50 nm) reinforced in copper matrix was 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. The fabrication of Cu–Al2O3 metal matrix microcomposites and nanocomposites via conventional route and spark plasma sintering routes are studied and compared. Maximum Vickers hardness of 60 and 80 are obtained when the Cu–15 vol.% Al2O3 is conventionally sintered in N2 and H2 atmosphere respectively. However, maximum hardness value of 125 is achieved for the Cu–5 vol.% Al2O3 nanocomposite prepared by spark plasma sintering. It has been observed that Cu–Al2O3 metal matrix composite (MMC) shows poor mechanical properties when it is conventionally sintered in N2 atmosphere than H2 atmosphere.Figure optionsDownload as PowerPoint slideHighlights
► Better matrix–reinforcement interfacial bonding and compatibility in hydrogen atmosphere than nitrogen atmosphere.
► An improvement in density and hardness under hydrogen atmosphere than in nitrogen atmosphere is manifested.
► Spark plasma sintering method results in higher density and hardness values than conventional sintering.