Corrosion of ultra-high-purity Mg in 3.5% NaCl solution saturated with Mg(OH)2

Corrosion was evaluated for ultra-high-purity magnesium (Mg) immersed in 3.5% NaCl solution saturated with Mg(OH)2. The intrinsic corrosion rate measured with weight loss, PW = 0.25 ± 0.07 mm y−1, was slightly smaller than that for high-purity Mg. Some specimens had somewhat higher corrosion rates attributed to localised corrosion. The average corrosion rate measured from hydrogen evolution, PAH, was lower than that measured with weight loss, PW, attributed to dissolution of some hydrogen in the Mg specimen. The amount of dissolution under electrochemical control was a small amount of the total dissolution. A new hydride dissolution mechanism is suggested.