Bode plots of (a, c) impedance magnitude and (b, d) phase angle as a function of frequency recorded in artificial seawater for Al-Si9-Cu3 samples coated with (a, b) MMT and (c, d) ZG before immersion in the Adriatic Sea and after 1, 3, and 8 months immersion. Before electrochemical measurements, the samples were sonicated to remove the biofilm formed during immersion in the seawater.