Effect of Nonessential Alloying Elements and Solution pH on Corrosion Behavior of Al-Mg Alloys Fabricated by Cold Spray Deposition

This paper highlights the difference in corrosion behavior of cold spray (CS) deposited AA5083 and Al-5.0 wt% Mg alloys with an emphasis on the effect of nonessential alloying elements and solution pH. CS process is an emerging technology for repairing damaged structures via solid-state deposition. While recent works have focused on CS Al alloys, less attention has been paid to CS Al binary alloys in comparison to Al engineering alloys, which have important implications for the integrity of structural components repaired by the CS process. Herein, the microstructure of CS AA5083 and Al-5.0 wt% Mg binary alloy was analyzed using various microstructure characterization techniques. Corrosion behavior was assessed using electrochemical and immersion tests in 0.6 M NaCl (pH 8.3 and 11.5) solution. Intermetallic phases, such as Fe- and Si-containing phases, in CS AA5083 decreased corrosion resistance by increasing cathodic kinetics in a near-neutral solution. In addition, immersion tests demonstrated lower corrosion resistance in CS AA5083 than in CS Al-5.0 wt% Mg, whereas an alkaline environment showed the presence of a secondary passive layer on CS AA5083, providing higher corrosion resistance compared to CS Al-5.0 wt% Mg.