Effects of minor Zn content on microstructure and corrosion properties of Al−Mg alloy

• Published in: Journal of Central South University Vol. 23; no. 12; pp. 3051 - 3059
• Main Authors: Zhao, Jing-wei, Luo, Bing-hui, He, Ke-jian, Bai, Zhen-hai, Li, Bin, Chen, Wei
• Format: Journal Article
• Language: English
• Published: Changsha Central South University 01.12.2016; Springer Nature B.V
• Subjects: Aluminum; Beta phase; Chemical and Environmental Engineering; Corrosion effects; Corrosion resistance; Corrosion resistant alloys; Corrosion tests; Engineering; Exfoliation corrosion; Grain boundaries; Magnesium base alloys; Materials; Metallic Materials; Metallurgy; Microstructure; Zinc; Al−Mg alloy; ); Al, Zn; corrosion; Zn addition; phase (Mg
• ISSN: 2095-2899; 2227-5223
• DOI: 10.1007/s11771-016-3368-6

The effects of different Zn contents in Al−Mg alloy on the microstructure characterizations were observed by advanced electron microscopy and the corrosion properties were investigated by the inter-granular corrosion tests, the exfoliation corrosion tests, and the Potentiodynamic polarizaion tests. The τ phase (Mg 32 (Al, Zn) 49 ) forms on the pre-existing Mn-rich particles and at the grain boundaries. According to the theory of binding energy, the formation of τ phase is much easier than that of β phase (Al 3 Mg 2 ), somehow replacing β phase and reducing the possibility of β phase precipitation. This change dramatically decreases the susceptibility of corrosion. The Zn addition increases the corrosion resistance of Al−Mg alloy with an optimal value of 0.31%. When the Zn addition is increased to 0.78%, however, the corrosion resistance of alloy decreases once again but it is still better than that of the alloy without Zn addition.