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Advances in Materials Science and Engineering
Volume 2017, Article ID 1691465, 13 pages
https://doi.org/10.1155/2017/1691465
Research Article

Statistical Model for the Mechanical Properties of Al-Cu-Mg-Ag Alloys at High Temperatures

1Mechanical Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia
2Mechanical Engineering Department, King Abdulaziz University, Jeddah, Saudi Arabia
3Industrial Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia
4Physics & Astronomy Department, Faculty of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
5King Abdullah Institute for Nanotechnology (KAIN), King Saud University, Riyadh, Saudi Arabia

Correspondence should be addressed to E. A. El-Danaf; as.ude.usk@fanade

Received 2 March 2017; Revised 15 May 2017; Accepted 1 June 2017; Published 9 July 2017

Academic Editor: Markus Bambach

Copyright © 2017 A. M. Al-Obaisi et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Aluminum alloys for high-temperature applications have been the focus of many investigations lately. The main concern in such alloys is to maintain mechanical properties during operation at high temperatures. Grain coarsening and instability of precipitates could be the main reasons behind mechanical strength deterioration in these applications. Therefore, Al-Cu-Mg-Ag alloys were proposed for such conditions due to the high stability of Ω precipitates. Four different compositions of Al-Cu-Mg-Ag alloys, designed based on half-factorial design, were cast, homogenized, hot-rolled, and isothermally aged for different durations. The four alloys were tensile-tested at room temperature as well as at 190 and 250°C at a constant initial strain rate of 0.001 s−1, in two aging conditions, namely, underaged and peak-aged. The alloys demonstrated good mechanical properties at both aging times. However, underaged conditions displayed better thermal stability. Statistical models, based on fractional factorial design of experiments, were constructed to relate the experiments output (yield strength and ultimate tensile strength) with the studied process parameters, namely, tensile testing temperature, aging time, and copper, magnesium, and silver contents. It was shown that the copper content had a great effect on mechanical properties. Also, more than 80% of the variation of the high-temperature data was explained through the generated statistical models.