Investigation of in-situ synthesis of alumina reinforcement and comparative flexural behavior with respect to ex-situ Al2O3 reinforced copper composite

Abstract

Ex-situ and in-situ reinforced copper matrix composite samples containing 1.1 wt. % and 2 wt. % Al2O3 were produced by spark plasma sintering (SPS) at 830 °C and holding time of 30 min. In-situ reinforced sample was synthesized by a novel technique using the reaction between ball-milled copper oxide and Cu-10 wt. % Al filings as the additive and copper powder. The in-situ formation of alumina reinforcement was confirmed by SEM observation and EDS analysis. Morphology and distribution of reinforcement phase in different composite samples were studied. The in-situ reinforced composite sample showed superior flexural fracture strength and strain (349 MPa and 0.027, respectively). Different patterns of crack propagation were observed in the SEM images of fracture surfaces: the reinforcement’s interface path (due to the formation of undesired oxide phase) was dominant in the ex-situ samples, while the interface of in-situ reinforcements remained intact and the cracks originated in the agglomeration sites.