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

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 830 700 °C with and holding time of 30 20 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 materials to 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 flexural fracture strength (349 MPa) and strain (0.027) of in-situ reinforced composite were significantly enhanced in addition that it entered the plastic zone. The in-situ reinforced composite sample showed superior flexural fracture strength and strain (349 MPa and 0.027, respectively). The fracture surfaces investigation revealed the effect of clean in-situ interfaces. 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.