INVESTIGATION OF COPPER ADDITION ON THE MECHANICAL PROPERTIES AND CORROSION RESISTANCE OF COMMERCIALLY PURE ALUMINUM

Aluminum and its alloys normally solidify in columnar structure with large grain size which results in deterioration of their surface quality and mechanical strength. In this work, the influence of Cu addition to commercially pure aluminum on microstructure, microhardness, grain size, impact energy, flow stress at 0.2 strain, mechanical behavior and corrosion resistance was studied. Three different Al-Cu alloys of 3,6 and 9 wt. % Cu content were prepared and experimentally tested both mechanically and chemically. The addition of Cu resulted in a linear increase of the hardness, and substantial reduction in the grain size, slight reduction the impact energy, substantial increase in the flow stress at 0.2 strains, and improve in the mechanical characteristics. The Potentiostatic measurements showed that the susceptibility of the samples towards corrosion decreases in the order: Al>Al-3 wt % Cu>Al-9 wt % Cu>Al-6 wt % Cu. The corrosion rates of the 3,6 and 9 wt % Cu alloys in HCl were found to be 0.29, 0.13 and 0.21 nm/s, respectively. The different properties, i.e. impact energy, flow stress at 0.2 strain, mechanical characteristics and corrosion resistance, showed that the 6 wt. % Cu is an optimal composition