An additively manufactured magnesium-aluminium alloy withstands seawater corrosion

• Published in: Npj Materials degradation Vol. 6; no. 1; pp. 1 - 10
• Main Authors: Zeng, Zhuoran, Choudhary, Sanjay, Esmaily, Marco, Benn, Felix, Derra, Thomas, Hora, Yvonne, Kopp, Alexander, Allanore, Antoine, Birbilis, Nick
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 20.04.2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/1023/1026; 639/638/542; Additive manufacturing; Alloying additive; Alloys; Aluminum base alloys; Chemistry and Materials Science; Corrosion and Coatings; Corrosion resistance; Corrosion resistant alloys; Corrosion tests; Electrochemistry; Magnesium; Magnesium base alloys; Marine corrosion; Materials Science; Phosphoric acid; Powder beds; Room temperature; Sea water corrosion; Seawater; Structural Materials; Submerging; Tribology
• ISSN: 2397-2106; 2397-2106
• DOI: 10.1038/s41529-022-00241-5

Magnesium, the lightest structural metal, has inherently poor corrosion resistance. In this study, we developed a magnesium-aluminium Mg-10.6Al-0.6Zn-0.3Mn alloy, additively manufactured by laser powder bed fusion. We reveal that this alloy has a record low degradation rate amongst all magnesium alloys in practically relevant corrosive solutions, and it even withstands seawater corrosion. As tested by a number of methods, the alloy shows even more enhanced passivation with longer immersion periods. The alloy surface following immersion maintained a nearly corrosion-free appearance and was determined to have a thin aluminium-containing surface film, due to surface enrichment of aluminium from the supersaturated matrix. Aluminium enrichment near the sample surface was also observed when the sample is immersed in phosphoric acid or exposed to atmosphere at room temperature. This study demonstrates the prospects for additively manufactured ultra-lightweight magnesium structure with outstanding corrosion resistance.