Atomistic process on hydrogen embrittlement of a single crystal of nickel by the embedded atom method

Xu, Xuejun; Wen, Mei; Hu, Zhong; Fukuyama, Seiji; Yokogawa, Kiyoshi

doi:10.1016/s0927-0256(01)00217-8

Cited by 25 publications

(7 citation statements)

References 21 publications

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“…Although experiments clearly demonstrate embrittlement, the microscopic 5 processes are not established nor does a comprehensive and predictive theory for this phenomenon yet exist. Atomic-scale simulations are thus increasingly being used to test possible embrittlement concepts [7,8,9,10,11,12,13,14,15,16], within the limitations of such modeling. Since embrittlement is often accompanied by a change from ductile fracture to intergranular cleavage, mechanisms involving H segregation at grain boundaries would seem to be of particular importance.…”

Section: Introductionmentioning

confidence: 99%

Atomistic study of hydrogen embrittlement of grain boundaries in nickel: II. Decohesion

Tehranchi

2017

Modelling Simul. Mater. Sci. Eng.

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Abstract. Atomistic simulations of bicrystal samples containing a grain boundary are used to examine the effect of hydrogen atoms on the nucleation of intergranular cracks in Ni. Specifically, the theoretical strength is obtained by rigid separation of the two crystals above and below the GB and the yield strength (point of dislocation emission) is obtained by standard tension testing normal to the GB. These strengths are computed in pure Ni and Ni with H segregated to the grain boundaries under conditions typical of H embrittlement in Ni, and in highly-H-saturated states. In all GBs studied here, the theoretical strengthσ is not significantly reduced by the presence of the hydrogen atoms. Similarly, with the exception of the NiΣ27(115) 110 boundary, the yield strength σy is not significantly altered by the presence of segregated H atoms. In all cases, the theoretical strengths are ∼25 GPa and the yield strengths are ∼10 GPa, so that (i) the theoretical strength is always well above the yield strength, with or without H, and (ii) both strengths are far above the bulk plastic flow stress, σ B y of Ni and Ni alloys. Complementing recent work showing that H does not change the ability of GB cracks to emit dislocations and blunt, the present work indicates that hydrogen atoms segregated to the GB have little effect on lowering the GB strength and so do not significantly facilitate nucleation of intergranular cracks.

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Section: Introductionmentioning

confidence: 99%

Atomistic study of hydrogen embrittlement of grain boundaries in nickel: II. Decohesion

Tehranchi

2017

Modelling Simul. Mater. Sci. Eng.

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“…[1,[7][8][9] Fundamental issues in understanding H-enhanced dislocation mobility and dislocation nucleation are still a work in progress. In the past few decades, these fundamental issues have been studied theoretically using various modeling techniques such as quantum mechanics/first principal, [35] atomistic, [36][37][38][39] continuum phenomenological material models. [34] Different experimental techniques have also been employed to describe underlying mechanisms related to H solute interaction with material microstructure under various stresses and their subsequent effect on material engineering properties.…”

Section: Introductionmentioning

confidence: 99%

A Nanoscale Study of Dislocation Nucleation at the Crack Tip in the Nickel-Hydrogen System

Solanki

Ward

Bammann

2010

Metall Mater Trans A

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Strengthening and embrittlement are controlled by the interactions between dislocations and hydrogen (H)-induced defect structures that can inversely affect the deformation mechanisms in materials. Here we present a simulation framework to understand fundamental issues associated with H-assisted dislocation nucleation and mobility using Monte Carlo (MC) and molecular dynamics (MD). In order to study the interaction between H and dislocations and its effect on material failure, we extensively examined mode I loading of an edge crack using MD simulations. The MD calculations of the total structural energy in the nickel (Ni)-H system shows that H atoms prefer to occupy octahedral interstitial sites in the fcc Ni lattice. As H concentration is increased, the Young's modulus and the energy required to create free surface decreased, resulting in H-enhanced localized plasticity. The MD simulations also indicate that H not only facilitates dislocation emission from the crack tip but also enhances dislocation mobility, leading to softening of the material ahead of the crack tip. While the decrease in surface energy suggests H embrittlement, the increase in local plasticity induces crack blunting and prohibits crack propagation. The mechanisms responsible for transitioning from a ductile to brittle crack behavior clearly depend on the H concentration and its proximity to the crack tip. Enhanced plasticity will occur within a general field of H atoms that results in lower stacking fault and surface energies, yet H interstitials on preferential slip planes can inhibit dislocation nucleation.

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“…Moreover, 250, 500, and 1000 H atoms were initially introduced into octahedral (O) sites because it is the preferred site in fcc Fe, which was named FeH 0.0625 , FeH 0.125 , and FeH 0.25 (Figure 1D). 17,18 MD simulations were performed using a canonical ensemble (NVT), where the constant temperature was maintained through the Nose–Hoover method. Atomic interactions were described using the modified embedded atom method, which could describe the physical properties of Fe–H alloys over the entire composition range, from pure Fe to pure H, and both in bcc (body‐centered cubic) and fcc Fe 19–23 …”

Section: Simulation Detailsmentioning

confidence: 99%

Avoiding glass spot defect arising from roller hydrogen embrittlement via regulating protective atmosphere distribution

Tong

Wang

Zhang

et al. 2022

Int J of Appl Glass Sci

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A kind of float glass spot defect, characterized by small size, metallic luster, and difficult to clean, adheres only to the lower surface (contacts with molten tin) of the float glass ribbon. This defect causes serious production loss. Therefore, determining the precise source of this spot defect and the effective prevention of its occurrence is vital in the scientific interest and technological significance. Herein, we report a new idea for preventing glass spot defect resulting from roller hydrogen embrittlement (HE) via regulating protective atmosphere distribution. We also reveal its formation mechanism. The generation mechanism of this spot defect shows that the protective atmosphere in the tin bath diffuses into the annealing lehr. However, the annealing lehr does not effectively discharge it (particularly H2). Thus, roller HE occurs. Opening the vent decreases the H2 concentration around the roller. In addition, the vent is moved by ∼1 m in the original position toward the exit of the annealing lehr, which is most conducive to H2 discharge. This optimization measure reduces or eliminates the spot defect caused by the HE of the roller. Moreover, it has great application potential in the design of float glass annealing lehr.

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Atomistic process on hydrogen embrittlement of a single crystal of nickel by the embedded atom method

Cited by 25 publications

References 21 publications

Atomistic study of hydrogen embrittlement of grain boundaries in nickel: II. Decohesion

Atomistic study of hydrogen embrittlement of grain boundaries in nickel: II. Decohesion

A Nanoscale Study of Dislocation Nucleation at the Crack Tip in the Nickel-Hydrogen System

Avoiding glass spot defect arising from roller hydrogen embrittlement via regulating protective atmosphere distribution

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