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

• DOI: 10.1007/s11771-016-3368-6
• Publication Date: 2017-01-25T01:38:45Z
• Authors: Jing-wei Zhao; Bing-hui Luo; Ke-jian He; Zhen-hai Bai; Bin Li; Wei Chen
• Keywords: 0205 materials engineering; 02 engineering and technology

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 (Mg32 (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 (Al3Mg2), 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.