Critical concentration for hydrogen bubble formation in metals.
Lu Sun1, Shuo Jin, Hong-Bo Zhou
1School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, People's Republic of China.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|September 11, 2014
Summary
This study models hydrogen behavior in tungsten and molybdenum, predicting critical concentrations for hydrogen bubble formation. Understanding these limits is crucial for materials science applications.
Area of Science:
- Materials Science
- Physical Chemistry
- Computational Materials Science
Background:
- Hydrogen embrittlement is a critical issue in metals like tungsten and molybdenum.
- Understanding hydrogen's interaction with vacancies is key to predicting material failure.
- Previous models lacked precise predictions for critical hydrogen concentrations leading to bubble formation.
Purpose of the Study:
- To determine hydrogen concentration at interstitial and monovacancy sites in tungsten and molybdenum.
- To predict the critical hydrogen concentration for hydrogen bubble formation under varying temperatures and pressures.
- To establish a generalizable approach for predicting hydrogen bubble formation in metals.
Main Methods:
- Utilized a thermodynamic model incorporating first-principle energetics.
- Calculated hydrogen concentration dependence on temperature and pressure.
- Defined and calculated critical hydrogen concentration for monovacancy-hydrogen complexes.
Main Results:
- Determined critical hydrogen concentrations for tungsten (24 ppm/7.3 GPa) and molybdenum (410 ppm/4.7 GPa) at 600 K.
- Identified critical concentration as the point where interstitial and monovacancy hydrogen concentrations equalize.
- Observed rapid growth of hydrogen-vacancy complexes beyond critical concentrations, indicating bubble formation initiation.
Conclusions:
- The study provides critical hydrogen concentration thresholds for bubble formation in tungsten and molybdenum.
- The developed thermodynamic model offers a predictive tool for hydrogen behavior in metals.
- This approach is expected to be broadly applicable for assessing hydrogen bubble formation risks in various metallic materials.
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