期刊
出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.msea.2015.10.042
关键词
Hydrogen embrittlement; Grain boundaries; Fracture; Molecular dynamics
类别
资金
- Laboratory Directed Research and Development program at Sandia National Laboratories
- U.S. Department of Energy's National Nuclear Security Administration [DE-AC04-94AL85000]
- National Science Foundation [0722625, 0959124, 0918970]
A statistical approach combined with molecular dynamics simulations is used to study the influence of hydrogen on intergranular decohesion. This methodology is applied to a Ni Sigma 3(112)[1 (1) over bar0] symmetric tilt grain boundary. Hydrogenated grain boundaries with different H concentrations are constructed using an energy minimization technique with initial H atom positions guided by Monte Carlo simulation results. Decohesion behavior is assessed through extraction of a traction-separation relationship during steady-state crack propagation in a statistically meaningful approach, building upon prior work employing atomistic cohesive zone volume elements (CZVEs). A sensitivity analysis is performed on the numerical approach used to extract the traction-separation relationships, clarifying the role of CZVE size, threshold parameters necessary to differentiate elastic and decohesion responses, and the numerical averaging technique. Results show that increasing H coverage at the Ni Sigma 3(112)[1 (1) over bar0] grain boundary asymmetrically influences the crack tip velocity during propagation, leads to a general decrease in the work of separation required for crack propagation, and provides a reduction in the peak stress in the extracted traction-separation relationship. The present framework offers a meaningful vehicle to pass atomistically derived interfacial behavior to higher length scale formulations for intergranular fracture. (C) 2015 Elsevier B.V. All rights reserved.
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