THE ROLE OF β(Al12Mg17) PHASE ON CORROSION BEHAVIOR OF THE AZ91 ALLOY IN NaCl AQUEOUS SOLUTION.

The effect of the βphase (Al₁₂Mg₁₇) on the corrosion resistance in a NaCl solution was investigated by electro chemical methods.Volume fraction of βphase 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 βphase, the α /βmixed phase specimen showed higher corrosion current density than that of α phase.It strongly suggests that βphase act as cathodic electrode in the alloys. [ABSTRACT FROM AUTHOR]