Study of age hardening behavior of Al–4.5 wt%Cu/zircon sand composite in different quenching media – A comparative study

The age hardening behavior of Al–4.5%Cu alloy composite reinforced with zircon sand particulates and produced by stir casting route has been investigated in different quenching media viz, water, oil, and salt brine solution (7 wt%). Optical microscopy of the as cast alloy composite indicates that the matrix of the composite has the cellular structure. Copper rich CuAl2 precipitates have been found near particle matrix interface. The results of ageing demonstrate that the microhardness of age hardenable Al–Cu based alloy composites depend on the quenching medium in which they are heat treated. Salt brine quenching is faster as compared to water and oil, even if higher strength is obtained but cannot be used for complex shapes and thin sections where oil quenching is the alternative due to minimum distortion and cracking problems. Thermal cycling studies of the composite at 25–540 °C have been also carried out to determine the extent of quenching of the matrix after each solution heat treatment cycle while varying the quenching media.