Locally Condensed Water as a Solution for In Situ Wet Corrosion Electron Microscopy

Area of Science:

• Materials Science
• Corrosion Science
• Electron Microscopy

Background:

• Understanding nanoscale corrosion initiation is crucial for materials science.
• In situ transmission electron microscope (TEM) studies are limited by liquid scattering in nanoreactors (NRs).
• Efficient liquid removal or thickness control is needed for high-resolution wet corrosion studies.

Purpose of the Study:

• To demonstrate local sample wetting in a TEM liquid cell nanoreactor.
• To enable in situ observation of nanoscale corrosion initiation.
• To overcome image blurring caused by liquid layers in wet TEM studies.

Main Methods:

• Utilized a microelectromechanical system (MEMS) Peltier device with planar Sb/BiSb thermoelectric materials for localized cooling.
• Prepared TEM samples using a dual-beam focused ion beam scanning electron microscope.
• Introduced water vapor and carrier gas into the nanoreactor chamber to create a liquid layer on the sample.

Main Results:

• Achieved a localized temperature decrease of 10 ± 2°C on the nanoreactor membrane.
• Demonstrated quick formation of water layers/droplets on the TEM sample.
• Ex situ TEM analysis revealed the onset and progression of O2 and H2S corrosion on AA2024-T3 alloy and HCT980X steel lamellae.

Conclusions:

• The developed Peltier-controlled nanoreactor facilitates in situ observation of nanoscale corrosion.
• This method addresses challenges of liquid scattering in wet TEM corrosion studies.
• Provides a pathway for detailed investigation into the initiation and progression of microstructural corrosion.