TITLE:
The Effect of Time, Percent of Copper and Nickel on the Natural Precipitation Hardness of Al – Cu – Ni Powder Metallurgy Alloys Using Design of Experiments
AUTHORS:
Mohammad M. Hamasha, Ahmad T. Mayyas, Mohammed T. Hayajneh, Adel M. Hassan
KEYWORDS:
Al; Powder Metallurgy; solution treatment; Natural Precipitation hardening.
JOURNAL NAME:
Journal of Minerals and Materials Characterization and Engineering,
Vol.10 No.6,
May
10,
2011
ABSTRACT: In this investigation, the effect of time, percentage of copper and nickel on the hardness property
of aluminum based powder metallurgy alloys were studied. A full factorial analysis with four
levels for each factor was used. The samples were produced using powder metallurgy process,
and then subjected to natural aging where heat treatment was conducted for all samples together
at 550°C for 3 hours before quenching in water. Then, the samples were left at room
temperature for 936 hours (39 days) to allow traces atoms to diffuse and form coherent phases
which increase the hardness. It was found that the hardness was firstly increased with time for
about 300 hours after the quenching time, and then it tends to remain constant after that.
However, the hardness drop at overage stage was not observed until the end of 936 hours. To get
a full analysis of the natural aging we used design of experiment tool to study the effect of %Cu,
%Ni and aging time on the hardness. The results showed that the hardness was influenced
significantly by all considered factors and interactions between them.