期刊
ACTA MATERIALIA
卷 59, 期 8, 页码 2969-2980出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.actamat.2011.01.037
关键词
Hydrogen embrittlement; Modeling; Monte Carlo technique; Ab initio electron theory
资金
- Interdisciplinary Centre for Materials Simulation (ICAMS)
- Thyssen Krupp AG
- Bayer Material Science AG
- Salzgitter Mannesmann Forschung GmbH
- Robert Bosch GmbH
- Benteler Stahl/Rohr GmbH
- Bayer Technology Services GmbH
- European Commission
The effect of H on the stress-mediated dislocation-dislocation interaction in face-centered cubic metals is studied by a hierarchical approach combining ab initio electronic structure calculations, semi-empirical embedded atom method potentials and a lattice-gas Hamiltonian, using the NiH system as a model system. The H distribution around edge dislocations is found to depend critically on H-H interactions within the metal matrix. In the absence of these interactions a dilute H distribution is obtained at realistic bulk H concentrations. In contrast, our calculations show that even a weakly attractive interaction between interstitial H atoms in the host matrix dramatically increases the local H concentration in the tensile strain field of the dislocation, resulting in the formation of a local hydride phase along the dislocation line. While in the absence of any H-H interactions huge bulk H concentrations of the order of 10 at.% are required to induce the stress shielding effect underlying the hydrogen-enhanced local plasticity (HELP) mechanism, the presence of even weak H-H interactions dramatically reduces the onset H concentration of HELP. As a consequence bulk H concentrations as low as 1.6 x 10(-2) at.% (160 ppm) may result in embrittlement. The formation of a local hydride induces a strong, short-range shielding effect along the slip plane of the dislocation, while normal to the glide plane the shear stress is predominantly increased. The stress shielding effect is correlated with a reduced dislocation separation at dislocation pile-up tips, which may result in the nucleation of microcracks and hence the onset of embrittlement. (C) 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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