Correlation between the corrosion behavior and corrosion films formed on the surfaces of Mg_82-xNi₁₈Nd_x (x = 0, 5, 15) amorphous alloys

This study deals with the characterization of the corrosion films formed on the surfaces of amorphous Mg_82-xNi₁₈Nd_x (x = 0, 5, 15) alloys in 3% NaCl solution saturated with Mg(OH)₂. Hydrogen evolution test revealed that the addition of Nd has a beneficial effect to reduce the dissolution rate of Mg_82-xNi₁₈Nd_x alloys. SEM showed that the least severe corrosion occurred for the Mg₆₇Ni₁₈Nd₁₅ alloy which has the highest Nd concentration. XPS revealed that the corrosion film formed on Mg₆₇Ni₁₈Nd₁₅ is the least hydroxidized among the amorphous Mg_82-xNi₁₈Nd_x (x = 0, 5, 15) alloys. The improved corrosion resistance of Mg₆₇Ni₁₈Nd₁₅ is attributed to the high content of oxidized Nd in the corrosion film preventing the detrimental Cl^- and CO₃^2- anions from penetrating.