Analysis of high-temperature flexural behaviour of copper–alumina micro- and nanocomposites

Copper (Cu)-based composites were studied for their high-temperature mechanical response. Copper is a high temperature–high strength material when combined with harder reinforcements, which find applications in engine components. High-temperature flexural testing of copper–alumina (Al₂O₃) micro- and nanocomposites fabricated by powder metallurgy was carried out at temperatures of 100 and 250°C. The composition of micro- and nanocomposites varied as 5, 10 and 20 vol.% and 1, 3 and 5 vol.%, respectively. The variation in the flexural strength of the composites at high-temperature testing is reported and compared with the ambient test values here, and, subsequently, deformation mechanisms of the composites are discussed. Fractography was performed to predict the mode of failure. The ductile mode of failure in microcomposites is contradictory to quasicleavage in nanocomposites. Nanocomposites show higher flexural strength at 100°C compared to microcounterparts. Interfacial de-cohesion and particle pull out are the results of the thermal gradient across the matrix to the reinforcement.