In this study effect of heat-treatment on the mechanical properties of aluminum-based piston alloys has been investigated. AlCu4MgNi alloys and AlSiCuMgNi alloys with 10%, 12%, 18% and 24% Si were utilized for this purpose. After melting, alloys have been cast in the metal mold at 800 degrees C and solidified. The solution treatment has been performed at 500 degrees C for 5 h and then quenched. The samples have been aged at 180 degrees C for 9 h to observe the effect of aging on hardness properties. (c) 2006 Elsevier Ltd. All rights reserved.