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

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:650

Article

Barrows, Wesley¹  Dingreville, Remi²  Spearot, Douglas¹ 

[1] Univ Arkansas, Dept Mech Engn, Fayetteville, AR 72701 USA

[2] Sandia Natl Labs, Albuquerque, NM 87185 USA

关键词: Hydrogen embrittlement;    Grain boundaries;    Fracture;    Molecular dynamics;   

DOI  :  10.1016/j.msea.2015.10.042

来源: Elsevier

【 摘 要 】

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.

【 授权许可】

Free