ABSTRACT In this paper, the hardness property during natural age hardening phenomenon for aluminum based alloy has been studied. Different factors play role in aging hardening of aluminum. In this study, the chosen factors were percentages of copper and nickel in aluminum alloys. The specimens were manufactured using casting process, and then heat treatment was carried out for all produced samples together at 550 °C for 3 h before quenching in water. Finally, the specimens were left at room temperature for 936 hours (39days) to allow solute atoms to defuse and form coherent phases to allow the age hardening to take place. The results show that the hardness increased with time in the first 300 hour after the quenching time, and then it remained constant for the rest of the 936 hours. Furthermore, the hardness did not drop until the end of 936 hours which means the over-aging status was not achieved. To get full analysis of the natural aging, design of experiment technique was used to study the effect of %Cu, %Ni and aging time.
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M. Hamasha, A. Mayyas, A. Hassan and M. Hayajneh, "The Effect of Time, Percent of Copper and Nickel on Naturally Aged Al-Cu-Ni Cast Alloys," Journal of Minerals and Materials Characterization and Engineering, Vol. 11 No. 2, 2012, pp. 117-131. doi: 10.4236/jmmce.2012.112009.
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