Effect of Al/Mn ratio on corrosion behavior of lean Mg-Zn-Ca-Al-Mn alloy processed by twin-roll casting. (March 2023)

• Record Type: Journal Article
• Authors: Wang, Bing-Yu; Li, Mei-Xuan; Li, Yi-Jia; Wang, Yu-Fei; Gao, Yipeng; Wang, Hui-Yuan
• Is Part Of: Corrosion science. Volume 212(2023)
• Publication Date: 2023-03
• Subjects: A. Magnesium -- A. Alloy -- A. intermetallics -- C. passive films -- C. Pitting corrosion; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2022.110938
• Languages: English
• ISSNs: 0010-938X

Abstract

Abstract: Adopting twin-roll casting (TRC) technique, lean Mg-1.2Zn-0.3Ca-0.3Al-xMn (x = 0.25, 0.38, 0.5 wt%) alloys with different Al/Mn ratio were prepared. The stoichiometric ratio of Al8 Mn5 is taken as dividing line. Under Al/Mn > 1.6, rhombohedral Al8 Mn5 is formed, while under Al/Mn ≤ 1.6, cubic β-Mn is generated. Because of lower Volta potential of Al8 Mn5 than β-Mn, the alloy with Al/Mn > 1.6 shows the lowest average corrosion rate (4.55 mm y −1 ). The formation of fine rather than coarse Al8 Mn5 weakens micro-galvanic corrosion and relieves stress concentration, thus simultaneously endowing the alloy (Al/Mn > 1.6) with admirable corrosion resistance and mechanical properties (UTS:∼266 MPa, YS:∼193 MPa, EF:∼20 %). Graphical Abstract: ga1 Highlights: Effect of Al/Mn atomic ratio on corrosion behavior of Mg-Zn-Ca-Al-Mn alloy is studied. Rhombohedral Al8 Mn5 is formed (Al/Mn>1.6), while cubic β-Mn is formed (Al/Mn ≤ 1.6). Fine Al-Mn phase are obtained by twin-roll casting and multi-pass rolling. β-Mn is nobler than Al8 Mn5 and larger Al/Mn ratio leads to less film breakdown. Alloy with Al/Mn> 1.6 shows good corrosion resistance and mechanical property synergy.