Corrosion behavior of AZ91 magnesium alloys in harsh marine atmospheric environment in South China Sea
Hao Liu, Lihui Yang, Mengqi Wang, Congtao Sun, Xiutong Wang, Jiarun Li, Jingying Li
Abstract
This study investigated the two-year corrosion behavior of AZ91 magnesium alloys in the marine environments of NanSha Islands and Sanya by microscopic morphology observation, electrochemical analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. The results indicated that the corrosion rate of AZ91 magnesium alloy exposed in NanSha Islands was significantly higher than that in Sanya. The corrosion rate of AZ91 magnesium alloy exposed to the Nansha environment initially increased and subsequently decreased. After six months of exposure, the corrosion rate reached a peak value of 25.05 μm/year. Following 24 months of exposure, the corrosion rate decreased to 9.54 μm/year, with the maximum corrosion depth attaining 188 μm. The primary constituents of the corrosion products were: MgCO 3 ·xH 2 O(x = 3,5), Mg 2 Cl(OH) 3 ·4H 2 O, Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O and Mg (OH) 2 . The long-term corrosion behavior can be accurately predicted, and the power function relationship between the loss weight and time of the test magnesium alloys is obtained, which is expressed as NanSha Islands: ln W L = 14.098ln t - 8.529; SanYa: ln W L = 3.434ln t - 2.153.