Study of the wear behaviour of Al–4.5% Cu–3.4% Fe in situ composite: Effect of thermal and mechanical processing

Al–Cu-based MMCs reinforced by Al–Fe intermetallics are investigated for their wear behaviour. The composite (Al–4.5 mass% Cu–3.4 mass% Fe) was produced by solidification processing where the Al–Fe-based intermetallic formed in situ in a matrix of mainly Al–Cu alloy. The effects of thermal and mechanical processing, viz., as-cast condition, solution treatment, aging and hot rolling on the wear behaviour of the composites were examined. The composites were characterized by optical microscopy, SEM, microhardness measurements and X-ray diffraction. The wear behaviour of the composites was studied in a pin-on-disc type wear apparatus. The as-cast in situ composite exhibited the highest wear rate. The wear rate of the (cast + solution treated + aged) composite was about 4.5 times and that of the (rolled + solution treated + aged) composite about 9.5 times lower than the wear rate of the as-cast composite. Hot-rolling + solution treatment + ageing of the MMC was found to yield the lowest wear rate among all processing conditions investigated. Worn surface revealed that mainly abrasive wear took place in all cases. The extent of abrasive wear was largest in the as-cast MMC as evidenced by deep groves on the worn surface as well as by the highest weight loss. Dark patches of presumably transfer layer were found in some cases, particularly on the (rolled + solution treated + aged) samples. Attempt has been made to relate the wear behaviour of the in situ MMC to their microstructures and to the microhardness of the matrix and the reinforcing phase.