Role of alloyed Al on the microstructure and corrosion behavior of as-cast dilute Mg-2Zn-xAl-0.5Ca alloys. (February 2023)

• Record Type: Journal Article
• Authors: Li, Yi-Jia; Li, Mei-Xuan; Hua, Zhen-Ming; Wang, Bing-Yu; Gao, Yipeng; Wang, Hui-Yuan
• Is Part Of: Corrosion science. Volume 211(2023)
• Publication Date: 2023-02
• Subjects: A. Magnesium -- A. Alloy -- A. Intermetallics -- B. SEM -- B. Weight loss -- C. Pitting corrosion; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110861
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: Effect of Al on microstructure and corrosion behaviors of cast Mg-2Zn- x Al-0.5Ca ( x = 0, 0.5, 1.0, 2.0 wt%) alloys is investigated. The 0.5Al specimen shows the lowest corrosion rate (4 mm/y) because appropriate Al doping into Ca2 Mg6 Zn3 decreases cathodic activity of this phase and Al alloying significantly refines intermetallics, both of which contribute to reducing pitting corrosion. Moreover, finer grains enhance barrier effect of continuous net-like phases at grain boundaries, effectively confining the corrosion propagation. The formation of Al2 O3 reinforces the surface film. Optimum Al content is determined as 0.5–1.0%, which endows alloy with admirable corrosion resistance and high ultimate tensile strength. Graphical Abstract: ga1 Highlights: Micro-galvanic process dominates corrosion behavior of cast Mg-2Zn-xAl-0.5Ca alloys. 0.5–1 wt% Al addition refines microstructure, while 2 wt% Al reverses the effect. Less-Al-rich Ca2 Mg6 Zn3 shows small VPD, but excess-Al-rich shows larger VPD. Corrosion barrier effect enhances at 0.5–1 wt% Al and disappears at 2 wt% Al. Optimal Al content is 0.5–1 wt% with high anti-corrosion and strength concurrently.