3D study of intermetallics and their effect on the corrosion morphology of rheocast aluminium alloy

•T6.1 spheroidizes Si, strengthens the matrix and modifies the intermetallics.•Electrochemical behaviour of untreated and heat-treated alloys is similar.•3D SEM-Tomography provides additional information on the corrosion morphology.•Corrosion advances as paths between intermetallics with little influence of Si.

In the present study, the effect of heat treatment T6.1 on the microstructure and corrosion behaviour of rheocast aluminium alloy A356 is investigated on the basis of 2D/3D characterization techniques and electrochemical and SKPFM measurements. Heat treatment strengthens the α-Al matrix, modifies the intermetallic particles and spheroidizes eutectic Si. These changes do not modify significantly the corrosion behaviour of the alloy.3D SEM-Tomography clearly shows that the corrosion advances in the shape of narrow paths between closely spaced intermetallics without a major influence of eutectic Si.