Initiation and Propagation of Localized Corrosion on Cold-Sprayed Aluminum Alloy 2024 and 7075

This paper investigates the initiation and propagation of localized corrosion on cold-sprayed (CS) aluminum alloy 2024 and 7075 deposits. CS deposits on AA2024-T351 and AA7075-T651 substrates were produced with commercially available AA2024 and AA7075 powders using helium as carrier gas. Electrochemical and immersion tests in 0.6 M NaCl and ASTM G110 test were used to evaluate the corrosion properties of CS AA2024 and AA7075 deposits. For analysis, optical microscopy, scanning electron microscopy, energy dispersive x-ray spectroscopy, and x-ray diffraction were utilized before and after the experiment. The results indicated that the initiation and propagation of localized corrosion highly depend on microstructural characteristics, such as the distribution and chemical composition of intermetallic networks with the matrix and propagated along these networks and prior particle boundaries, where an ultrafine grain structure is present. Accelerated localized corrosion tests generated deep penetration as well as a large area of defects owing to the coalescence of fissures.