The effect of the β phase and heat treatment on the corrosion behavior of magnesium AZ91 alloy

One of the major causes for corrosion deterioration is the presence of impurities, non-metallic inclusions and intermetallic phases. Some of these phases may be more cathodic comparing to the Mg matrix and hence it is important to understand their effect on the corrosion mechanism of the magnesium alloys. In order to understand the effect of the beta (Mg17Al12) phase, the corrosion performance of Mg AZ91 alloy in as cast (F), homogenized (T4) and artificially-aged (T6) conditions were evaluated under immersion test conditions and potentiodynamic polarization analysis in NaCl and Mg(OH)(2) electrolyte.