Understanding the corrosion behaviour of the magnesium alloys EV31A, WE43B, and ZE41A

The corrosion rates of the Mg alloys immersed in 3.5 wt% NaCl solution saturated with Mg(OH)(2) were in the following increasing order: WE43B (0.23 mm/y) < EV31A (0.88 mm/y) < pure-Mg (1.6 mm/y) < ZE41A (8.5 mm/y). The average corrosion rate for WE43B was somewhat lower than the intrinsic corrosion rate of Mg as shown by high-purity Mg, attributed to (a) no corrosion acceleration by the small second phase particles, and (b) a more protective surface film. The high corrosion rates of ZE41A were attributed to the presence of a coarse semicontinuous T-phase, which served as strong cathodic sites.