EFFECTS OF Al₂O_3np AND Mg ADDITION ON THE PROPERTIES OF THE Al–Zr–Ce NANOCOMPOSITE PRODUCED BY STIR CASTING, AS ALUMINIUM CONDUCTOR

Abstract

Aluminum has long been used as conductor in high-voltage electric transmission due to its economic value and high conductivity. By adding nanosized ceramic particles such as Al₂O₃ and also alloying elements such as zirconium (Zr), cerium (Ce), and magnesium (Mg), the aluminum performance in strength could be improved without compromising much of its electrical conductivity. The purpose of this research is to investigate the mechanical, electrical, and physical properties of Al–0.12% Zr–0.015% Ce reinforced with different volume fraction (from 0.5 to 1.5%) Al₂O₃ nanoparticles with addition of 3 and 5 wt.% Mg produced by stir casting route. A master alloy, which consists of aluminum alloyed with Zr and Ce, was produced. The master alloy was then melted and Mg along with the reinforcement was blended inside the molten metal by stirrer with rotational speed of 500 rpm at 850 ^oC in an inert gas environment. The molten composites were casted into plate and tensile test sample molds. The tensile strength of the nano composite was optimal at 1.0 and 1.2 vol.% Al₂O_3np with addition of 3 and 5 wt.% Mg, respectively. Higher Mg content produced nanocomposites with better strength and elongation. It was found that the conductivity of the nanocomposites is generally decreased with addition of reinforcement because of isolator particles and increasing of Mg content leads to further decrease in conductivity. It was found that the coefficient of thermal expansion could be decreased by adding more Al₂O_3np. However, adding more Mg generally increases the nanocomposite CTE value. The microstructure observations showed that the composites yield finer grains and more pores, than the unreinforced alloy.