Diffusion in the Presence of Grain Boundaries: a Variable Length Scale Simulation Method

2001 ◽  
Vol 677 ◽  
Author(s):  
Irina V Belova ◽  
Graeme E Murch
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Numerical Data ◽  
Simulation Method ◽  
Tracer Diffusion ◽  
Boundary Plane ◽  
Length Scale ◽  
Grain Boundary Plane ◽  
Variable Mesh ◽  
Boundary Diffusivity

ABSTRACTIn this paper we introduce a Monte Carlo method for numerical analysis of the problem of tracer diffusion in the presence of isolated grain boundaries with a variable mesh in the direction perpendicular to the grain boundary plane. A number of isoconcentration contour profiles were studied. Two different expressions for the angle between the isoconcentration contours and the grain boundary were derived for the instantaneous tracer source following procedures analogous to Fisher's and Whipple's approximations for the constant tracer source. Comparison with the numerical data was made. Both these approximations overestimate the grain boundary diffusivity.

The structure of a near Σ=27 tilt grain boundary in Ge

1992 ◽  
Vol 50 (1) ◽  
pp. 214-215
Author(s):  
Stuart McKernan ◽  
C. Barry Carter
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Structural Unit ◽  
Perfect Crystal ◽  
Boundary Plane ◽  
Boundary Structure ◽  
Structural Units ◽  
Grain Boundary Plane ◽  
Grain Boundary Structure ◽  
Complex Structural

The modeling of tilt grain boundaries in terms of repeating structural units of varying separation is now a well established concept. High-resolution electron microscope (HREM) images of different tilt grain boundaries in many materials display a qualitative similarity of atomic configurations of the grain boundary structure. These boundaries are frequently described in terms of characteristic structural units, which may be separated from each other by regions of ‘perfect’ crystal (as, for example, in low-angle grain boundaries), or may be contiguous, forming ordered arrays of the structural units along the boundary. In general there will be a different arrangement of the structural units or an arrangement of different structural units, according to the precise geometry of the particular grain boundary. The structure of some special grain boundaries has been examined and these are found to exist in several different configurations, depending on the orientation of the grain boundary plane among other parameters. Symmetry-related symmetric tilt grain boundaries and asymmetric tilt grain boundaries with one grain having a prominent, low-index facet, are commonly observed, low-energy configurations. Structural multiplicity of these configurations along the same grain boundary has been observed in some systems. Defects in the perfect ordering of the structural units may be caused by deviations of the grain boundary plane away from the perfect tilt orientation. Deviations of grain boundary structure away from the exact orientation will also produce defects in the repeating structural unit configuration. These deviations may have a regular and well-defined structure, producing a more complex structural unit.

Variant Selection in Fcc-to-Bcc Precipitation at Grain Boundaries in Ni-43Cr Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 305-308 ◽  
Author(s):  
Yoshitaka Adachi ◽  
Fu Xing Yin ◽  
Kazunari Hakata ◽  
Kaneaki Tsuzaki
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Tilt Angle ◽  
Boundary Plane ◽  
Variant Selection ◽  
Orientation Relationships ◽  
Boundary Misorientation ◽  
Grain Boundary Plane ◽  
Grain Boundary Misorientation ◽  
Selection Of

Variant selection of bcc-Cr at the grain boundaries in a supersaturated fcc matrix was studied using a Ni-43Cr alloy. The preferentially selected variant was examined as a function of the grain boundary misorientation, the tilt angle between the {111}fcc plane and the grain boundary plane, and the orientation relationships with respect to both of the adjacent matrix grains.

scholarly journals Structural and electronic properties of defects at grain boundaries in CuInSe2

2017 ◽  
Vol 19 (22) ◽  
pp. 14770-14780 ◽  
Author(s):  
R. Saniz ◽  
J. Bekaert ◽  
B. Partoens ◽  
D. Lamoen
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Electronic Properties ◽  
Boundary Plane ◽  
Rule Violation ◽  
Grain Boundary Plane ◽  
Structural And Electronic Properties ◽  
Octet Rule

Octet rule violation near the grain boundary plane is common in Σ3 grain boundaries, with important structural and electronic implications.

Statics and Dynamics of Grain Boundaries in Ni3Al

1988 ◽  
Vol 133 ◽  
Author(s):  
Diana Farkas
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Cluster Variation Method ◽  
Boundary Region ◽  
Boundary Plane ◽  
Variation Method ◽  
Boundary Misorientation ◽  
Grain Boundary Plane ◽  
Alloy Properties ◽  
Experimental Findings

ABSTRACTVarious modeling techniques have been used to study the structure of grain boundaries in ordered compounds, particularly Ni3Al. The techniques include computer simulation, group theoretical analysis and the cluster variation method for high temperature effects. A multiplicity of possible grain boundary structures was analyzed for different misorientations and grain boundary plane location. 1The influence of several alloy properties like atomic size differences and deviation from stochiometry on the occurrence of these different structures is analyzed. The implications of these results for grain boundary misorientation distribution, grain boundary plane location and faceting behavior are discussed and compared to experimental findings. The possibility of orderdisorder transitions in the grain boundary region is also discussed.

Structure and segregation of dopant–defect complexes at grain boundaries in nanocrystalline doped ceria

2015 ◽  
Vol 17 (23) ◽  
pp. 15375-15385 ◽  
Author(s):  
Pratik P. Dholabhai ◽  
Jeffery A. Aguiar ◽  
Longjia Wu ◽  
Terry G. Holesinger ◽  
Toshihiro Aoki ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Plane ◽  
Doped Ceria ◽  
Defect Complexes ◽  
Grain Boundary Plane

Σ5 twist grain boundary plane in doped ceria with dopant–defect complexes.

scholarly journals Reconstruction of α–Iron 〈100〉 Symmetric Tilt Grain Boundaries Σ17(410) and Σ13(510)

2016 ◽  
Vol 67 (6) ◽  
pp. 427-432
Author(s):  
Eva Vitkovská ◽  
Peter Ballo
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Numerical Experiments ◽  
Numerical Study ◽  
Boundary Plane ◽  
Atomic Density ◽  
Grain Boundary Plane ◽  
Symmetric Tilt ◽  
Boundary Reconstruction

Abstract A detailed numerical study on structure of symmetric tilt grain boundaries in α-iron is presented. The study is focused on structural and energetic optimization of 〈100〉 grain boundaries Σ5(210), Σ5(310), Σ17(410) and Σ13(510). Particular attention is given to grain boundary reconstruction, which is characterized by increased atomic density in grain boundary plane compared to bulk. The results of our numerical experiments significantly improved our knowledge about the migration of atoms between planes perpendicular as well as parallel to GB plane as an essential part of grain boundary reconstruction.

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