Fig. 4.

Turning corroded Mg alloy surface into protective coating. a As-FIBed ZK 60 Mg alloy pillar and the corresponding selected area electron diffraction (SADP). b After immersion in deionized water for 1 min, some fluffy Mg(OH)₂ &(MgO) corrosion product grew on the pillar’s surface. Note the top part was bare. c After the corroded pillar was exposed in CO₂ and the e-beam irradiation atmosphere for 20 min (only the part with fluffy corrosion product was irradiated by e-beam), the newly formed MgCO₃ covered the bottom part of the pillar. d After water immersion, only the top part of the pillar was corroded. The region covered with MgCO₃ remained unchanged. e The top part was further corroded, and the protected part remained intact after exposure in humid air (relative humidity: 65–80%, temperature:18–26 °C) for 20 days. Scale bar, 200 nm