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The interaction of dislocations and hydrogen-vacancy complexes and its importance for deformation-induced proto nano-voids formation in alpha-Fe

: Li, S.Z.; Li, Y.G.; Lo, Y.C.; Neeraj, T.; Srinivasan, R.; Ding, X.D.; Sun, J.; Qi, L.; Gumbsch, P.; Li, J.

Postprint urn:nbn:de:0011-n-3694015 (1.3 MByte PDF)
MD5 Fingerprint: e566ad1b96bc3926c721e40913a01c4d
Created on: 18.05.2017

International Journal of Plasticity 74 (2015), No.11, pp.175-191
ISSN: 0749-6419
National Science Foundation NSF
National Science Foundation NSF
Journal Article, Electronic Publication
Fraunhofer IWM ()

By using molecular dynamics and cluster dynamics simulations, we probed the role of hydrogen-vacancy complexes on nucleation and growth of proto nano-voids upon dislocation plasticity in alpha-Fe. Our atomistic simulations reveal that, unlike a lattice vacancy, a hydrogen-vacancy complex is not absorbed by dislocations sweeping through the lattice. Additionally, this complex has lower lattice diffusivity; therefore, it has a lower probability of encountering and being absorbed by various lattice sinks. Hence, it can exist metastably for a rather long time. Our large-scale molecular dynamics simulations show that when metals undergo plastic deformation in the presence of hydrogen at low homologous temperatures, the mechanically driven out-of-equilibrium dislocation processes can produce extremely high concentrations of hydrogen-vacancy complex (10(-5) similar to 10(-3)). Under such high concentrations, these complexes prefer to grow by absorbing additional vacancies and act as the embryos for the formation of proto nano-voids. The current work provides one possible route for the experimentally observed nano-void formation in hydrogen embrittlement of steels and bridges atomic-scale events and damage with macroscopic failure.