the Mg2Si⁎ electrode changes
fromanode to cathode during the corrosion process, resulting in the anodic
dissolution (α(Al)) and corrosion of the Al matrix with the formation
of corrosion pits (Fig. 7c). For the microstructure of corroded Al–
20%Mg2Si alloy with/without Al–P master alloy, coexistence of Si-rich
remnants (Mg2Si⁎) and corrosion pits is due to the electrochemical polarity
conversion (Mg2Si⁎ and α(Al)), as shown in Figs. 4 and 5.