Effect of rare earth and Mn elements on the corrosion behavior of extruded AZ61 system in 3.5 wt% NaCl solution and salt spray test

In this study, multiple addition of rare earth (RE) and manganese (Mn) to AZ61 was conducted aiming to find out the influence to corrosion resistance. AZ61 containing different amounts of RE and Mn was investigated by electrochemical measurement in condition of 3.5 wt% NaCl solution at 25 °C. Gravimetric measurement was conducted in 5 wt% salt spray at 35 °C and 3.5 wt% NaCl solution at 25 °C. Samples were characterized by SEM, EDS, OM and XRD. The result shows that with RE addition Al8Mn5 in AZ61 changed into Al10RE2Mn7. The quantity of β phase is reduced significantly. The multiple addition of RE and Mn improved the corrosion resistance of AZ61. When the ratio of Mn and RE is 0.3, alloy has the best property of corrosion resistance. In addition, the composite addition removed the impurity elements in AZ61 especially Fe.