scholarly journals A grain boundary model considering the grain misorientation within a geometrically nonlinear gradient-extended crystal viscoplasticity theory

2020 ◽  
Vol 476 (2235) ◽  
pp. 20190581
Author(s):  
Atefeh Alipour ◽  
Stefanie Reese ◽  
Bob Svendsen ◽  
Stephan Wulfinghoff
Keyword(s):  
Free Energy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Nonlinear Crystal ◽  
Geometrically Nonlinear ◽  
Two Dimensional ◽  
Boundary Model ◽  
Grain Misorientation ◽  
Dislocation Density Tensor ◽  
Boundary Strength

The main goal of the current work is to present a grain boundary model based on the mismatch between adjacent grains in a geometrically nonlinear crystal viscoplasticity framework including the effect of the dislocation density tensor. To this end, the geometrically nonlinear crystal viscoplasticity theory by Alipour et al. (Alipour A et al . 2019 Int. J. Plast. 118 , 17–35. ( doi:10.1016/j.ijplas.2019.01.009 )) is extended by a more complex free energy and a geometrical transmissibility parameter is used to evaluate the dislocation transmission at the grain boundaries which includes the orientations of slip directions and slip plane normals. Then, the grain boundary strength is evaluated based on the misorientation between neighbouring grains using the transmissibility parameter. In some examples, the effect of mismatch in adjacent grains on the grain boundary strength, the dislocation transmission at the grain boundaries and the Hall–Petch slope is discussed by a comparison of two-dimensional random-oriented polycrystals and textured polycrystals under shear deformation.

Research on Micro-Mechanism of Nanocomposite Ceramic in Two-Dimensional Ultrasound Grinding

2007 ◽  
Vol 359-360 ◽  
pp. 344-348 ◽  
Author(s):  
Bo Zhao ◽  
Yan Wu ◽  
Guo Fu Gao ◽  
Feng Jiao
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Deformation Mechanism ◽  
Ground Surface ◽  
Grain Boundary Sliding ◽  
Second Phase ◽  
Two Dimensional ◽  
Composite Ceramics ◽  
Nano Composite ◽  
Boundary Sliding

Surface microstructure of nano-composite ceramics prepared by mixed coherence system and machined by two-dimensional ultrasonic precision grinding was researched using TEM, SEM, XRD detector and other equipments. Structure, formation mechanism and characteristic of metamorphic layer of ground surface of nano-composite ceramics were researched. The experiment shows micro deformation mechanism of ceramic material in two-dimensional ultrasound grinding is twin grain boundary and grain-boundary sliding for Al2O3, and it is crystal dislocation of enhanced phase, matrix grain boundary sliding, coordination deformation of intergranular second phase as well as its deformation mechanism for nano-composite ceramics. The fracture surfaces of nano-composite materials with different microscopic structure were observed using TEM and SEM. Research shows that ZrO2 plays an important influence on the generation and expansion of crack, and enhances the strength of grain boundaries. When grain boundaries is rich in the ZrO2 particles, the crack produced in grinding process will be prevented, and the surface with plastic deformation will be smooth. The results shows nanoparticles dispersed in grain boundary prevents crack propagation and makes materials fracture transgranularly which makes the processed surface fine.

Competitive Motions of Grain-Boundary and Free Surface in Selecting Thin Film Morphology

1996 ◽  
Vol 441 ◽  
Author(s):  
B. Sun ◽  
Z. Suo ◽  
W. Yang
Keyword(s):  
Thin Film ◽  
Free Energy ◽  
Free Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Analytic Solutions ◽  
Film Morphology ◽  
Polycrystalline Thin Film ◽  
Continuous Film

AbstractDuring annealing of a polycrystalline thin film, grain-boundaries and film surfaces move. If the grain-boundaries move faster, the grains having the lowest free energy grow at the expense of others, resulting in a continuous film with large grains. If the film surfaces move faster, they groove along their junctions with the grain-boundaries, breaking the film to islands. This paper describes analytic solutions for steady surface motions, and discusses the morphology selection.

Computational and theoretical aspects of a grain-boundary model that accounts for grain misorientation and grain-boundary orientation

2016 ◽  
Vol 111 ◽  
pp. 443-459 ◽  
Author(s):  
D. Gottschalk ◽  
A. McBride ◽  
B.D. Reddy ◽  
A. Javili ◽  
P. Wriggers ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Orientation ◽  
Boundary Model ◽  
Grain Misorientation

Grain Boundary and Misorientation Angle Dependent Thermal Transport in Single-layer MoS2

Nanoscale ◽  
2022 ◽  
Author(s):  
Ke Xu ◽  
Ting Liang ◽  
Zhisen Zhang ◽  
Xuezheng Cao ◽  
Meng Han ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Misorientation Angle ◽  
Thermal Transport ◽  
Single Layer ◽  
Large Area ◽  
Grain Misorientation

Grain boundaries (GBs) are inevitable defects in large-area MoS2 samples but play a key role in their properties, however, the influence of grain misorientation on thermal transport remains largely unknown...

Crystallinity Dependence of Grain and Grain Boundary Strength of a Bicrystal Structure of Copper

2020 ◽  
Author(s):  
Ken Suzuki ◽  
Yiqing Fan ◽  
Yifan Luo
Keyword(s):  
Thin Films ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Defect Density ◽  
Volume Ratio ◽  
Md Simulations ◽  
Atomic Diffusion ◽  
Strength And Deformation ◽  
Electroplated Copper ◽  
Boundary Strength

Abstract Electroplated copper thin films often contain porous grain boundaries and the volume ratio of porous grain boundaries in the copper thin films is much larger than that in bulk copper. Thus, the lifetime of the interconnection components fabricated by electroplating is strongly dominated by the strength of grain boundaries because final fracture caused by the acceleration of atomic diffusion during electromigration (EM) occurs at grain boundaries in polycrystalline interconnections. It is important, therefore, to quantitatively evaluate the grain boundary strength of electroplated copper films for estimating the lifetime of the interconnection in order to assure the product reliability. In this study, relationship between the strength and crystallinity of electroplated copper thin films was investigated experimentally and theoretically. In order to investigate the relationship between the strength and grain boundary quality, molecular dynamics (MD) simulations were applied to analyze the deformation behavior of a bicrystal sample and its strength. The variation of the strength and deformation property were attributed to the higher defect density around grain boundaries.

Correlation between structure, energy, and ideal cleavage fracture for symmetrical grain boundaries in fcc metals

1990 ◽  
Vol 5 (8) ◽  
pp. 1708-1730 ◽  
Author(s):  
D. Wolf
Keyword(s):  
Phase Space ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Cleavage Fracture ◽  
Good Description ◽  
Random Boundary ◽  
Free Surfaces ◽  
Symmetrical Tilt ◽  
Boundary Model ◽  
Twist Boundaries

The misorientation phase space for symmetrical grain boundaries is explored by means of atomistic computer simulations, and the relationship between the tilt and twist boundaries in this three-parameter phase space is clucidated. The so-called random-boundary model (in which the interactions of atoms across the interface are assumed to be entirely random) is further developed to include relaxation of the interplanar spacings away from the grain boundary. This model is shown to include fully relaxed free surfaces naturally, thus permitting a direct comparison of the physical properties of grain boundaries and free surfaces, and hence the determination of ideal cleavage-fracture energies of grain boundaries. An extensive comparison with computer-simulation results for symmetrical tilt and twist boundaries shows that the random-boundary model also provides a good description of the overall structure-energy correlation for both low- and high-angle tilt and twist boundaries. Finally, the role of the interplanar spacing parallel to the grain boundary in both the grain-boundary and cleavage-fracture energies is elucidated.

scholarly journals Diffusion-Accommodated Grain Boundary Sliding in a Polycrystal

1990 ◽  
Vol 196 ◽  
Author(s):  
P. M. Hazzledine ◽  
J. H. Schneibel
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Grain Boundary Sliding ◽  
Diffusional Creep ◽  
Two Dimensional ◽  
Dimensional Model ◽  
Material Deposition ◽  
Two Dimensional Model ◽  
Boundary Sliding ◽  
Coble Creep

ABSTRACTA two-dimensional model for diffusional creep (Coble creep) and diffusionaccommodated grain boundary sliding in polycrystals has been developed. The results obtained for small symmetrical clusters of grains reproduce Spingam and Nix's work [Acta Metall. 2M, 1389 (1978)]. For clusters of irregularly shaped grains the material deposition and removal rates, the fluxes along the grain boundaries, the grain boundary tractions as well as the grain boundary sliding rates are irregular and can all be calculated.

Diffusion-accommodated sliding of irregularly shaped grain boundaries

1990 ◽  
Vol 5 (3) ◽  
pp. 563-569 ◽  
Author(s):  
J. H. Schneibel ◽  
P. M. Hazzledine
Keyword(s):  
Free Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Diffusion ◽  
Periodic Case ◽  
Shear Stresses ◽  
Two Dimensional ◽  
Stress Distributions ◽  
Normal Stresses ◽  
Random Size

The diffusion-accommodated sliding of irregularly shaped grain boundaries in two-dimensional bicrystals is considered. The following assumptions are made: the grains adjoining the boundaries are rigid, the boundaries do not support any shear stresses, sliding displacements are infinitesimal, and sliding is accommodated only by grain boundary diffusion. The solution to this problem is illustrated for a bicrystal with a grain boundary consisting of three segments. The results of calculations involving up to 35 segments agree with Raj and Ashby's theory for the sliding of periodic boundaries. The influence of boundary conditions on the normal stress distributions along grain boundaries is examined. Zero-flux conditions at the intersection of a grain boundary with a free surface, which correspond to low surface diffusivities, can lead to high normal grain boundary stresses. The stress distributions and sliding rates of boundaries containing randomly spaced equisized bumps or equispaced bumps of random size are compared to the periodic case (i.e., equispaced equisized bumps). Substantial normal stresses can build up at such nonperiodic grain boundaries.

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