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

Abstract

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.

Authors:

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

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+ Show Author Affiliations

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

Publication Date:

Mon Oct 19 00:00:00 EDT 2015

Research Org.:

Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA)

OSTI Identifier:

1236488

Alternate Identifier(s):

OSTI ID: 1556184

Report Number(s):

SAND-2015-10405J
Journal ID: ISSN 0921-5093; PII: S0921509315305086

Grant/Contract Number:  

AC04-94AL85000

Resource Type:

Accepted Manuscript

Journal Name:

Materials Science and Engineering. A, Structural Materials: Properties, Microstructure and Processing

Additional Journal Information:

Journal Volume: 650; Journal Issue: C; Journal ID: ISSN 0921-5093

Publisher:

Elsevier

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; hydrogen embrittlement; grain boundaries; fracture; molecular dynamics