Microstructure and corrosion behavior of die-cast AM60B magnesium alloys in a complex salt solution: A slow positron beam study

• Usefulness of positron beam measurement for characterization of corrosion layer.
• The calcium carbonate was deposited on the surface of both HPDC and SVDC alloys.
• Larger volume fraction of eutectic phase in SVDC alloy than HPDC alloy.
• Higher corrosion resistance of SVDC alloy than HPDC alloy.

The microstructure and corrosion behavior of high pressure die-cast (HPDC) and super vacuum die-cast (SVDC) AM60B magnesium alloys were investigated in a complex salt solution using slow positron beam technique and potentiodynamic polarization tests. The experiments revealed that a CaCO3 film was formed on the surface of the alloys and that the rate of CaCO3 formation for the SVDC alloy with immersion time was slower than that of the HPDC alloy. The larger volume fraction of β-phase in the skin layer of the SVDC alloy than that of the HPDC alloy was responsible for the better corrosion resistance.