Journal
NATURE MATERIALS
Volume 12, Issue 2, Pages 145-151Publisher
NATURE PUBLISHING GROUP
DOI: 10.1038/NMAT3479
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Funding
- US Office of Naval Research [N00014-05-1-0504]
- General Motors/Brown Collaborative Research Lab on Computational Materials
- NSERC Discovery grant [RGPIN 418469-2012]
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Hydrogen embrittlement in metals has posed a serious obstacle to designing strong and reliable structural materials for many decades, and predictive physical mechanisms still do not exist. Here, a new H embrittlement mechanism operating at the atomic scale in alpha-iron is demonstrated. Direct molecular dynamics simulations reveal a ductile-to-brittle transition caused by the suppression of dislocation emission at the crack tip due to aggregation of H, which then permits brittle-cleavage failure followed by slow crack growth. The atomistic embrittlement mechanism is then connected to material states and loading conditions through a kinetic model for H delivery to the crack-tip region. Parameter-free predictions of embrittlement thresholds in Fe-based steels over a range of H concentrations, mechanical loading rates and H diffusion rates are found to be in excellent agreement with experiments. This work provides a mechanistic, predictive framework for interpreting experiments, designing structural components and guiding the design of embrittlement-resistant materials.
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