Hydrogen-induced microstructural evolution in a nickel-based alloy under high-temperature and high-pressure...

Area of Science:

• Materials Science
• Metallurgy
• Chemical Engineering

Background:

• Carbon neutrality goals necessitate advanced hydrogen-based industrial processes.
• The long-term stability of structural materials in high-temperature, high-pressure hydrogen environments is critical for these technologies.

Purpose of the Study:

• To visualize and understand the hydrogen-induced microstructural evolution in Inconel 600 under extreme conditions.
• To elucidate the mechanisms of hydrogen embrittlement in Ni-based alloys for future material design.

Main Methods:

• In situ high-energy X-ray diffraction
• Transmission electron microscopy
• Electron backscatter diffraction

Main Results:

• Hydrogen absorption caused pressure-dependent lattice expansion, hydride formation, and dislocation multiplication.
• Cracking occurred along grain boundaries and slip bands at 400°C, while voids formed within grains at 800°C.
• Dislocation slip bands acted as pathways for crack propagation, leading to embrittlement.

Conclusions:

• Microstructural evolution under extreme hydrogen is a sequential process.
• Hydrogen desorption and carbide gasification were observed.
• Mechanistic insights are provided for designing durable Ni-based alloys for hydrogen-utilizing carbon-neutral technologies.