Joined Numerical and Observational Study of Complex Tilt Grain Boundaries Structures at the Atomic Level in Nickel

2005 ◽  
pp. 231-236 ◽  
Author(s):  
O. Hardouin Duparc ◽  
A. Larere ◽  
S. Poulat ◽  
L. Priester ◽  
J. Thibault
Keyword(s):  
Observational Study ◽  
Grain Boundaries ◽  
Atomic Level

scholarly journals Atomic level characterization in corrosion studies

2017 ◽  
Vol 375 (2098) ◽  
pp. 20160414 ◽  
Author(s):  
Philippe Marcus ◽  
Vincent Maurice
Keyword(s):  
Grain Boundaries ◽  
Density Functional ◽  
Three Dimensional ◽  
Atomic Level ◽  
Passive Films ◽  
Localized Corrosion ◽  
Ex Situ ◽  
Tunnelling Microscopy ◽  
Surface Hydroxylation ◽  
Fundamental Insight

Atomic level characterization brings fundamental insight into the mechanisms of self-protection against corrosion of metals and alloys by oxide passive films and into how localized corrosion is initiated on passivated metal surfaces. This is illustrated in this overview with selected data obtained at the subnanometre, i.e. atomic or molecular, scale and also at the nanometre scale on single-crystal copper, nickel, chromium and stainless steel surfaces passivated in well-controlled conditions and analysed in situ and/or ex situ by scanning tunnelling microscopy/spectroscopy and atomic force microscopy. A selected example of corrosion modelling by ab initio density functional theory is also presented. The discussed aspects include the surface reconstruction induced by hydroxide adsorption and formation of two-dimensional (hydr)oxide precursors, the atomic structure, orientation and surface hydroxylation of three-dimensional ultrathin oxide passive films, the effect of grain boundaries in polycrystalline passive films acting as preferential sites of passivity breakdown, the differences in local electronic properties measured at grain boundaries of passive films and the role of step edges at the exposed surface of oxide grains on the dissolution of the passive film. This article is part of the themed issue ‘The challenges of hydrogen and metals’.

The anatomy of grain boundaries: Their structure and atomic-level solute distribution

2013 ◽  
Vol 69 (8) ◽  
pp. 622-625 ◽  
Author(s):  
L. Yao ◽  
S.P. Ringer ◽  
J.M. Cairney ◽  
M.K. Miller
Keyword(s):  
Grain Boundaries ◽  
Atomic Level ◽  
Solute Distribution

scholarly journals In2O3 Nanocrystals for CO2 Fixation: Atomic-Level Insight into the Role of Grain Boundaries

iScience ◽  
2019 ◽  
Vol 16 ◽  
pp. 390-398 ◽  
Author(s):  
Lirong Wang ◽  
Jinyan Cai ◽  
Yangcenzi Xie ◽  
Jiasheng Guo ◽  
Lingxiao Xu ◽  
...  
Keyword(s):  
Grain Boundaries ◽  
Co2 Fixation ◽  
Atomic Level ◽  
Insight Into

Grain boundaries as heterogeneous systems: atomic and continuum elastic properties

1992 ◽  
Vol 339 (1655) ◽  
pp. 555-586 ◽  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Elastic Properties ◽  
Discrete Model ◽  
Continuum Model ◽  
Elastic Moduli ◽  
Atomic Level ◽  
Upper And Lower Bounds ◽  
Effective Moduli ◽  
The Continuum

The relation between atomic structure and elastic properties of grain boundaries is investigated theoretically from both atomistic and continuum points of view. A heterogeneous continuum model of the boundary is introduced where distinct phases are associated with individual atoms and possess their atomic level elastic moduli determined from the discrete model. The effective elastic moduli for sub-blocks from an infinite bicrystal are then calculated for a relatively small number of atom layers above and below the grain boundary. These effective moduli can be determined exactly for the discrete atomistic model, while estimates from upper and lower bounds are evaluated in the framework of the continuum model. The complete fourth-order elastic modulus tensor is calculated for both the local and the effective properties. Comparison between the discrete atomistic results and those for the continuum model establishes the validity of this model and leads to criteria to assess the stability of a given grain boundary structure. For stable structures the continuum estimates of the effective moduli agree well with the exact effective moduli for the discrete model. Metastable and unstable structures are associated with a significant fraction of atoms (phases) for which the atomic-level moduli lose positive definiteness or even strong ellipticity. In those cases, the agreement between the effective moduli of the discrete and continuum systems breaks down.

Enhanced ionic conductivity in electroceramics by nanoscale enrichment of grain boundaries with high solute concentration

Nanoscale ◽  
2017 ◽  
Vol 9 (44) ◽  
pp. 17293-17302 ◽  
Author(s):  
William J. Bowman ◽  
Madeleine N. Kelly ◽  
Gregory S. Rohrer ◽  
Cruz A. Hernandez ◽  
Peter A. Crozier
Keyword(s):  
Ionic Conductivity ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Solute Concentration ◽  
Atomic Level ◽  
Oxygen Ionic Conductivity ◽  
Boundary Composition ◽  
High Solute Concentration

The enhancement of grain boundary oxygen ionic conductivity by four orders of magnitude in an electroceramic is explicitly shown to result from modulation of local grain boundary composition at the atomic level.

Atomic-Level and Effective Elastic Moduli at Grain Boundaries

1991 ◽  
Vol 229 ◽  
Author(s):  
I. Alber ◽  
J. L. Bassani ◽  
M. Khantha ◽  
V. Vitek ◽  
G. J. Wang
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Elastic Properties ◽  
Fourth Order ◽  
Continuum Model ◽  
Elastic Moduli ◽  
Atomic Level ◽  
Upper And Lower Bounds ◽  
Atomistic Model ◽  
The Continuum

AbstractThe relationship between atomic structure and elastic properties of grain boundaries is investigated from both discrete and continuum points of view. A heterogeneous continuum model of the boundary is introduced where distinct phases are associated with individual atoms and possess their atomic level elastic moduli determined from the atomistic model. The complete fourth-order tensors of both the atomic-level and the effective elastic moduli are determined, where the latter are defined for sub-blocks from an infinite bicrystal and are calculated here for a relatively small number of atom layers above and below the grain boundary. These effective moduli are determined exactly for the discrete atomistic model, while only estimates from upper and lower bounds can be determined for the continuum model. Comparison between the atomistic results and those for the continuum model establishes the validity of this definition of elastic properties for heterogeneous structures at these scales. Furthermore, these comparisons as well as algebraic properties of the fourth-order tensor of moduli lead to criteria to assess the stability of a given grain boundary structure.

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