Synthesis and Characterization of Al7075 Microcomposites with MgO/Mn

The evaluation of corrosion resistance, hardness, and tensile strength of the stir-casted Al7075 alloy and Al7075 with 4%MgO and 4%MgO/1.5%Mn has been done via salt spray analysis, Rockwell’s hardness machine, and universal testing machine. Al7075 alloy was melted at 700 °C with reinforcements added, and the mixture was then poured into sand molds. The microstructure of the casted samples of compositions Al7075 + 4%MgO and Al7075 + 4%MgO + 1.5%Mn was studied using scanning electron microscope (SEM) which shows the presence and even distribution of the reinforcements added. Hardness test was conducted on all the compositions of the casted and heat-treated samples prepared with a steel tip indenter of diameter 10 mm. Tensile test was conducted at an ambient temperature of 27 °C. The yield stress, percent elongation, and ultimate tensile strength were determined for the cast and heat-treated samples. The corrosion test was conducted in a salt spray chamber within temperature range of 35–37 °C. A fog containing 5% NaCl solution in distilled water (pH 6.8) was sprayed onto the samples for a period of 8 h. It was observed that the heat-treated samples of Al7075 + 4%MgO and Al705 + 4%MgO + 1.5%Mn did not undergo corrosion at the end of eight hours, whereas non-heat-treated samples had white corrosion and plain Al7075 displayed red corrosion.