Traction–separation relationships for hydrogen induced grain boundary embrittlement in nickel via molecular dynamics simulations

Journal Article · Mon Oct 19 00:00:00 EDT 2015 · Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing

DOI:https://doi.org/10.1016/j.msea.2015.10.042· OSTI ID:1236488

Barrows, Wesley ^[1]; Dingreville, Rémi ^[2]; Spearot, Douglas ^[1]

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1. Univ. of Arkansas, Fayetteville, AR (United States)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

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 Σ3(112)[11¯0] 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 Σ3(112)[11¯0] 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. Furthermore the present framework offers a meaningful vehicle to pass atomistically derived interfacial behavior to higher length scale formulations for intergranular fracture.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1236488
• Alternate ID(s): OSTI ID: 1556184
• Report Number(s): SAND-2015-10405J; PII: S0921509315305086
• Journal Information: Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing, Vol. 650, Issue C; ISSN 0921-5093
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
hydrogen embrittlement
grain boundaries
fracture
molecular dynamics