The direct ZnAl layered double hydroxide growth on AA2024 is a fast-occurring reaction,
18 yet is characterized by an inhomogeneous film thickness. It has been shown that at the periphery
19 of Cu-rich intermetallic, the flakes tend to be larger and denser. A combination of in situ and
20 ex situ measurements were used to monitor the changes in the layered double hydroxide film
21 grown on the regions of intermetallics. Immediately after immersion, an activation of the
22 intermetallics is observed due to the dealloying process with an almost immediate film growth.
23 Dealloying is followed by trenching of the adjacent Al matrix leading to an excessive
24 production of large and dense layered double hydroxide flakes at the periphery of the
25 intermetallic. However, the scanning electron microscopy cross-section images revealed that
26 the trenching process leads to defects in the area surrounding the intermetallic. This could
27 weaken the corrosion resistance performance of the layered double hydroxide conversion
28 coating and lead to adhesion failure of consecutive polymer coatings. Nevertheless, this work
29 highlights a few advantages and drawbacks of the layered double hydroxide conversion
30 coatings and pathways to its potential optimization and improvement.publishe
