Microgalvanic activity of an Mg–Al–Ca-based alloy studied by scanning Kelvin probe force microscopy

An Mg–Al–Ca based alloy was investigated by scanning electron microscopy, energy dispersive spectroscopy and scanning Kelvin probe force microscopy following extrusion. The investigations revealed two main intermetallics, i.e. Al–Ca(Sn,Sr) and Al–Mn–Fe, both distributed along the extrusion direction and having distinctive morphology. The microgalvanic couples, i.e. Al–Ca(Sn,Sr)/α-Mg and Al–Mn–Fe/α-Mg showed positive Volta potential differences with the Al–Mn–Fe intermetallic being the noblest (i.e. 262 ± 18 mV vs 62 ± 7 mV).