Role of microalloyed Sm in enhancing the corrosion resistance of hot-rolled Mg–8Sn–1Al–1Zn alloy

• Published in: Corrosion science 2021-06, Vol.185, p.109425, Article 109425
• Main Authors: Kwon, Jaeho, Baek, Soo-Min, Jung, Hoseok, Kim, Jong Chan, Lee, Si-Young, Park, Sung Soo
• Format: Article
• Language: English
• Subjects: Alloys; Corrosion rate; Corrosion resistance; Corrosion resistant alloys; Hot rolling; Hydrogen evolution; Magnesium base alloys; Mg alloy; Microalloying; Microgalvanic corrosion; Phase; Rolling resistance; Volta potential
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2021.109425

•Effect of Sm microalloying on the corrosion resistance of Mg–8Sn–1Al–1Zn alloy was investigated.•Microalloying with 0.02 wt% Sm resulted in the formation of Al8Fe4Sm instead of nobler Al5Fe2.•Sm microalloying led to about six times improved corrosion resistance in 0.6 M NaCl solution.•The role of the microstructural changes in enhancing corrosion resistance is discussed. We report that the corrosion resistance of hot-rolled Mg–8Sn–1Al–1Zn alloy was significantly enhanced by Sm microalloying. Corrosion rates, measured after immersion for 72 h in 0.6 M NaCl solution, were found to be 2.7 and 19 mm y−1 for the alloys with and without an addition of 0.02 wt% Sm, respectively. Electrochemical and microstructural analyses revealed that the enhanced corrosion resistance achieved by Sm microalloying is mainly a result of a reduced H2 evolution rate owing to the presence of Al8Fe4Sm particles instead of nobler Al5Fe2 particles, which highly accelerate microgalvanic corrosion in the alloy without Sm microalloying.