Fig. 11
a Bivariate scatter plot of ƒCu versus XSn,a, in alloy-layer A and alloy-layer B [2] based on atomic fraction of Cu and Sn measured with SEM–EDS technique; b Cu-Sn–O ternary diagram based on atomic fraction showing the relationships between Cu, Sn, and O of the external and internal corrosion layers (A, B, C and D) in the corrosion crusts for samples in M1 and M2 morphologies, measured with SEM–EDS technique [17]