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

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.

The Effect of Alloying, Processing and Heat Treatment on the Wear Resistance of Al-Cu-Mg-Ag Alloys

“…The wear test is carried out at two levels of loads and application time. This paper is an extension research for pervious published paper in reference [11], [21].…”

“…The significance of Mg and Ag interaction clears this correlation. Peak-aging mechanism increases the mechanical properties in terms of yield strength and hardness which in turn enhances the wear resistance and reduce the weight loss due to the friction tests [11].…”

“…E. Scharifi et al [10] investigated the effect of hot tensile deformation for heat treated AA7075 alloy and found that the aging time increased the hardness. A. Al-Obaisi et al [11] investigated the effect of alloying elements (Cu, Mg, and Ag) and aging conditions (under-aged and peak-aged) on the mechanical properties at different testing temperatures. The peak-aged conditions produced higher yield and tensile strength compared to the under-aged conditions at different testing temperatures.…”