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In this research work, binary Al-25Zn and ternary Al-25Zn-3Cu alloys were fabricated using stir casting process. Microstructure and mechanical properties of as-cast alloys were foundout and the composition of the alloys was validated using energy dispersive X-ray analysis (EDX). The fabricated alloys were solution treated at 450 °C for 10 hours and then artificially aged at different temperatures (100 °C, 150 °C and 200 °C), each at 1 hour, 2 hours, 3 hours and4 hours. The microstructure after heat treatment was compared with the as-cast microstructure. Hardness and tensile properties were investigated for both as-cast and heat-treated alloys. Al-25Zn-3Cu alloy exhibits superior strength (hardness and tensile) when compared to Al-25Zn alloy in both as-cast and heat-treated conditions. Higher hardness and tensile strength were obtained at the aging temperature of 100 °C for 1 hour, for both alloys. The results were validatedusing scanning electron microscope (SEM) microstructures and X-ray diffraction (XRD). [ABSTRACT FROM AUTHOR]

Ferum-nickel-chromium (Fe-Ni-Cr) alloy is a family of Ni-based alloy which is generally utilized in elevated temperature applications with excellent oxidation resistance properties. In this study, Fe-33Ni-19Cr alloy underwent a heat treatment procedure at 1000°C and 1100°C for 3 hours soaking time, and then rapidly cooled by water quench. The heat- treated alloys were then subjected to a cyclic oxidation test at 900°C for 150 cycles in air. The oxidized alloys were characterized in terms of weight change per surface area as a function of cycles and oxide scale behavior in plan and cross- sectional view using a scanning electron microscope outfitted with an energy dispersive x-ray spectrometer. It was found that the low heat treatment temperature, which is 1000°C, produced fine grain structure. Whereas, heat-treated alloy at 1100°C produced coarse grain structure. On the other hand, cyclic oxidation of both heat-treated oxidized alloys recorded a weight gain pattern. Various oxide phases were formed on the oxidized alloys surface, namely Cr-rich and Cr-Mn rich oxides. The surface morphology analysis exhibited an uninterrupted oxide layer established on the oxidized alloys surface, with fine grain heat-treated alloy forming a uniform oxide layer. However, oxide exfoliation has been recorded on coarse grain heat-treated alloys. [ABSTRACT FROM AUTHOR]