Al-12Si-3Cu-1 Mg-1.78Ni alloy is widely used for piston parts in automobile industry. The present paper investigates the effect of aging time for 1-16 h at 180°C after solution treatment of the alloy at 500°C for 5 h, on alloys prepared by gravity casting and squeeze casting. The wear rate of the alloy shows a minimum at an intermediate aging time. The hardness and ultimate tensile strength showed a peak at intermediate aging time. Mechanical properties and wear resistance are found to be better in squeeze cast alloy. The result are explained based on the microstructure developed during casting process and on heat treatment for various durations.

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