The effect of the local microstructure of MRI 201S magnesium alloy on its corrosion rate

• Corrosion of die-cast MRI magnesium alloys was studied.
• The periphery and the central part of 3 mm die-cast sheets may have different microstructures.
• The coarser the grains of alpha-phase the faster the corrosion process.
• Sealing of the side surfaces of a specimen may significantly lower the corrosion process.

The corrosion rates of High Density Die Cast MRI 201S and three other magnesium alloys in 3% NaCl were measured.The side surfaces of some specimens were insulated by a polymer, while the other specimens had all the surfaces open to the corrosive media. No difference between the two types of specimens for was observed for AZ91D, MRI 153M and MRI 202S alloys, while for MRI 201S alloy the corrosion of the samples of the 1st type was significantly slower than of the 2nd type. For all the alloys studied, the coarser the grains the higher the corrosion rate.