The Influence of Alloying Elements (Al, Ni and Zn) on the Corrosion Resistance of Some Cu-Ternary Alloys in Na2SO4 Solutions

In this research, the corrosion behavior of Cu–10Al–10Zn, Cu–10Al–10Ni and Cu–10Ni–10Zn alloys was investigated in sulfate solutions. The effects of alloying elements, immersion time, and sulfate ions concentration were also studied. Different electrochemical methods such as open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS) were used. Polarization measurements reveal that Cu–10Al–10Ni alloy possess lower corrosion rate than both Cu–10Al–10Zn and Cu–10Ni–10Zn alloys in this solution. The EIS measurements have shown that a more thicker and resistant passive layer is formed on the Cu–10Al–10Ni alloy surface. Also, the corrosion current density (icorr) decreases with increasing $$ {\text{SO}}_{4}^{ - } $$ ion concentration especially at concentration higher than 0.1 M Na2SO4 solution. The surface analysis (SEM/EDX) has shown the participation of the different alloying elements in the protection according to the alloy constituents. It turned out that presence of Al and Ni increase the corrosion resistance. For industrial applications, the results lead to the recommendation of the Cu–10Al–10Ni alloy for applications in the production of Na2SO4. The stability of the Cu-ternary alloys in SO42− solutions depends on the presence of the alloying elements Al, Ni and Zn.