The role of β(Al12Mg17) phase on corrosion behavior of the AZ91 alloy in NaCl aqueous solution

The effect of the β phase (Al12Mg17) on the corrosion resistance in a NaCl solution was investigated by electro chemical methods.Volume fraction of β phase in each specimen was controlled systematically by isothermal annealing at 473 K as 0%, 4%, 22% and 100 %, respectively. Although α phase shows lower corrosion current density than that of β phase, the α/β mixed phase specimen showed higher corrosion current density than that of α phase.It strongly suggests that β phase act as cathodic electrode in the alloys