Second phase effect on corrosion of nanostructured Mg-Zn-Ca dual-phase metallic glasses

Abstract Dual-phase metallic glasses (DP-MGs), a special member of the MGs family, often reveal unusual strength and ductility, yet, their corrosion behaviors are not understood. Here, we developed a nanostructured Mg57Zn36Ca7 (at.%) DP-MG and uncovered its corrosion mechanism in simulated body fluid (SBF) at the near-atomic scale utilizing transmission electron microscope (TEM) and atom probe tomography (APT). The 10-nm-wide Ca-rich amorphous phases allow oxygen propagation into the DP-MG, resulting in a micrometer thick hydroxides/oxides layer. This dense corrosion layer protects the DP-MG from further corrosion, enabling a corrosion rate that is 77% lower than that of Mg (99.99% purity).