Abstract

An ultrahigh corrosion resistance of Mg-Er alloys was achieved via a simple method by forming an Er2O3 oxide film using a high temperature treatment. The corrosion rate of Mg-8.1 wt% Er alloy with oxide film is only 0.12 mm/y in 3.5 wt% NaCl solution, even lower than that of high-purity magnesium. The triangular prism-like Mg(OH)2 was observed for the first time in corrosion field of Mg alloys, which was terrific compact and effectively hindered the further corrosion. A mechanism of two-layer barrier coming from the oxide film and triangular prism-like Mg(OH)2 was proposed to contribute the outstanding corrosion resistance.