Abstract: The weak corrosion resistance of magnesium and its alloys greatly limited the industrial application. Though functional self-healing coatings have been proposed as countermeasures, repeated damages on coatings under practical installation and complex external environments could require self-adaptive corrosion protection against multiple abrasions. In this study, an ultra-high corrosion-resistant Mg-1Zn-1Sc (wt.%) alloy with a corrosion rate of 0.087 mm/y has been designed and prepared, which has fine grains and uniform structure of a nano-scale ScZn phase with low potential. A unique and dense corrosion product film with a three-layered structure was found and studied on Mg-1Zn-1Sc alloy, providing excellent corrosion protection. In addition, the formation and protection mechanisms of the three-layered corrosion product film on Mg-1Zn-1Sc alloy have been discussed and proposed. The growth behavior of protective corrosion product film could be driven by the synergy of Sc and Zn elements. Furthermore, with the increase of Sc content, the strength, plasticity, and corrosion resistance of Mg-1Zn-xSc (x = 0, 0.2, 0.6, 1.0, in wt.%) alloys increased simultaneously. The high corrosion resistance and moderate mechanical performance qualify Mg-1Zn-1Sc alloy as a promising candidate for diverse industrial applications.

Key words: High corrosion resistance, Mechanical performance, Mg-Zn-Sc alloy, Corrosion product film, Three-layer structure, SKPFM