Microstructure Effects on Corrosion Behavior of Mg-Zn-Zr-Nd ZM6 magnesium Alloy

The effect of microconstituents on the corrosion and electrochemical behavior ofMg-Zn-Zr-Nd ZM6 magnesium alloy prepared by die-casting and ingot casting route has been investigated in 3.5Wt%NaCl solution. The experimental techniques used include long term immersion test and potentiodynamic polarization experiments. Surface examination and analytical studies were carried out using optical(OM) and scanning electron microscopy(SEM) and X-ray diffraction(XRD). Die-cast ZM6 magnesium alloy with smaller grain size offered marginally lower corrosion rate. In die-cast and ingot, corrosion attack took place preferentially on alpha-Mg phase. XRD patterns of non-corroded surface revealed a-Mg and Mg12Nd phases. The corrosion products for ZM6 ingot consisted of Mg(OH)(2) together with alpha-Mg and Mg12Nd phases. The corrosion resistance of ingot is higher than diecast sample.