Overview of Mechanisms & Models for Liquid Metal Embrittlement and Future Directions
It has been known for more than a century that metals that are ductile in air may become brittle in contact with certain liquids. Whether LME occurs and to what extent depends on the solid/liquid couple. Heavy liquid metals (HLM) such as lead and lead-bismuth eutectic are known to induce LME in steels, and LME is therefore a key challenge that must be addressed in order to ensure safety of HLM cooled nuclear reactors. There has been significant research devoted to liquid-metal embrittlement (LME) in the last six decades with the objective to understand the basic mechanisms and to develop mechanistic and engineering-based models in order to avoid LME in engineering designs.
Unfortunately there are still gaps in the understanding of LME and there is still no consensus on the best assessment methods and design is essentially based on experimental correlations. This is perhaps not surprising given the complexity where the properties of the solid and the liquid, their interaction, the temperature and the stress interact in a complex way. For a complete analysis two coupled problems need to be addressed: i) the interaction between the atoms in the liquid and solid and transport of the embrittler; ii) the associated transition from ductile to brittle fracture.
This report presents LME degradation mechanism and associated models that have been proposed in the last decades as well as some possible new developments. The models are discussed with respect to their strengths and weaknesses and applicability to support the design and assessment of HLM cooled nuclear reactors
NILSSON Karl-Fredrik;
HOJNA Anna;
2018-12-19
Publications Office of the European Union
JRC113457
978-92-79-97249-2 (online),
1831-9424 (online),
EUR 29437 EN,
OP KJ-NA-29437-EN-N (online),
https://publications.jrc.ec.europa.eu/repository/handle/JRC113457,
10.2760/017392 (online),
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