scholarly journals A three-dimensional study of coupled grain boundary motion with junctions

2015 ◽  
Vol 471 (2178) ◽  
pp. 20150127 ◽  
Author(s):  
Anup Basak ◽  
Anurag Gupta
Keyword(s):  
Grain Boundary ◽  
Three Dimensional ◽  
Continuum Theory ◽  
Coupling Factor ◽  
Polycrystalline Materials ◽  
Triple Junctions ◽  
Kinetic Coefficients ◽  
And Migration ◽  
Grain Boundary Motion

A novel continuum theory of incoherent interfaces with triple junctions is applied to study coupled grain boundary (GB) motion in three-dimensional polycrystalline materials. The kinetic relations for grain dynamics, relative sliding and migration of the boundary and junction evolution are developed. In doing so, a vectorial form of the geometrical coupling factor, which relates the tangential motion at the GB to the migration, is also obtained. Diffusion along the GBs and the junctions is allowed so as to prevent nucleation of voids and overlapping of material near the GBs. The coupled dynamics has been studied in detail for two bicrystalline and one tricrystalline arrangements. The first bicrystal consists of two cubic grains separated by a planar GB, whereas the second is composed of a spherical grain embedded inside a larger grain. The tricrystal has an arbitrary-shaped grain embedded inside a much larger bicrystal made of two cubic grains. In all these cases, analytical solutions are obtained wherever possible while emphasizing the role of various kinetic coefficients during the coupled motion.

Dynamics of grain boundary motion at the atomic level

2004 ◽  
Vol 819 ◽  
Author(s):  
K. L. Merkle ◽  
L. J. Thompson ◽  
F. Phillipp
Keyword(s):  
Grain Boundary ◽  
Elevated Temperatures ◽  
High Resolution Electron Microscopy ◽  
Collective Effects ◽  
Polycrystalline Materials ◽  
Grain Boundary Engineering ◽  
Triple Junctions ◽  
Resolution Electron ◽  
Curvature Driven ◽  
Grain Boundary Motion

AbstractGrain boundaries (GBs) in polycrystalline materials play a pivotal role in controlling their mechanical and physical behavior. High-resolution electron microscopy (HREM) was used to study thermally activated GB migration in thin films of Al and Au at elevated temperatures (T > 0.5 Tm). Grain boundary engineering via epitaxial templating allowed the manufacture of well-defined grain and interfacial geometries. These techniques enabled the observation of tilt, but also twist and general GBs at atomic resolution in-situ at high temperatures. Surface-energy driven GB migration occurred in general GBs, whereas tilt GB motion was curvature driven. Digital analysis of HREM video recordings have given considerable insight in the dynamics of GB motion at elevated temperatures. It is not surprising that the complex and diverse migration mechanisms depend on GB geometry as well as on interatomic interactions. The results provide, among others, direct evidence for collective effects by concerted atomic shuffles, ledge propagation in (113) symmetric tilt GBs, and motions of triple junctions at elevated temperatures.

Atomistic Modeling of Grain Boundaries and Dislocation Processes in Metallic Polycrystalline Materials

2009 ◽  
Vol 131 (4) ◽  
Author(s):  
Douglas E. Spearot ◽  
David L. McDowell
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Boundary Behavior ◽  
Complex Stress ◽  
Boundary Structure ◽  
Polycrystalline Materials ◽  
Atomistic Modeling ◽  
Triple Junctions

The objective of this review article is to provide a concise discussion of atomistic modeling efforts aimed at understanding the nanoscale behavior and the role of grain boundaries in plasticity of metallic polycrystalline materials. Atomistic simulations of grain boundary behavior during plastic deformation have focused mainly on three distinct configurations: (i) bicrystal models, (ii) columnar nanocrystalline models, and (iii) 3D nanocrystalline models. Bicrystal models facilitate the isolation of specific mechanisms that occur at the grain boundary during plastic deformation, whereas columnar and 3D nanocrystalline models allow for an evaluation of triple junctions and complex stress states characteristic of polycrystalline microstructures. Ultimately, both sets of calculations have merits and are necessary to determine the role of grain boundary structure on material properties. Future directions in grain boundary modeling are discussed, including studies focused on the role of grain boundary impurities and issues related to linking grain boundary mechanisms observed via atomistic simulation with continuum models of grain boundary plasticity.

Comparison of Experimental and Computational Aspects of Grain Growth in Al-Foil

2000 ◽  
Vol 652 ◽  
Author(s):  
Melik C. Demirel ◽  
Andrew P. Kuprat ◽  
Denise C. George ◽  
Bassem S. El-Dasher ◽  
Neil N. Carlson ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Three Dimensional ◽  
Interface Energy ◽  
Grain Structure ◽  
Electron Backscattered Diffraction ◽  
Boundary Properties ◽  
Ebsd Technique ◽  
Columnar Grain ◽  
Grain Boundary Motion

ABSTRACTGrain boundary and crystallographic orientation information of an Al-foil with a columnar grain structure is characterized by Electron Backscattered Diffraction (EBSD) technique. The starting microstructure and grain boundary properties are implemented as an input for the three- dimensional grain growth simulation. In the computational model, minimization of the interface energy is the driving force for the grain boundary motion. The computed evolved microstructure is compared with the final experimental microstructure, after annealing at 550 °C. Good agreement is observed between the experimentally obtained microstructure and the simulated microstructure. The constitutive description of the grain boundary properties was based on a 1- parameter characterization of the variation in mobility with misorientation angle.

COMPUTATIONAL HOMOGENIZATION OF POLYCRYSTALLINE MATERIALS WITH PORES: A THREE-DIMENSIONAL GRAIN BOUNDARY FORMULATION

2012 ◽  
Vol 04 (03) ◽  
pp. 1250012 ◽  
Author(s):  
F. TRENTACOSTE ◽  
I. BENEDETTI ◽  
M. H. ALIABADI
Keyword(s):  
Grain Boundary ◽  
Mechanical Model ◽  
Volume Fraction ◽  
Effective Properties ◽  
Three Dimensional ◽  
Boundary Integral ◽  
Elastic Problem ◽  
Polycrystalline Materials ◽  
Effective Material Properties ◽  
Boundary Integral Representation

In this study, the influence of porosity on the elastic effective properties of polycrystalline materials is investigated using a 3D grain boundary micro mechanical model. The volume fraction of pores, their size and distribution can be varied to better simulate the response of real porous materials. The formulation is built on a boundary integral representation of the elastic problem for the grains, which are modeled as 3D linearly elastic orthotropic domains with arbitrary spatial orientation. The artificial polycrystalline morphology is represented using 3D Voronoi Tessellations. The formulation is expressed in terms of intergranular fields, namely displacements and tractions that play an important role in polycrystalline micromechanics. The continuity of the aggregate is enforced through suitable intergranular conditions. The effective material properties are obtained through material homogenization, computing the volume averages of micro-strains and stresses and taking the ensemble average over a certain number of microstructural samples. The obtained results show the capability of the model to assess the macroscopic effects of porosity.

Three-Dimensional Simulation of Coarsening and Grain Growth in Sintering

2007 ◽  
Vol 539-543 ◽  
pp. 2359-2364 ◽  
Author(s):  
Fumihiro Wakai
Keyword(s):  
Grain Boundary ◽  
Grain Growth ◽  
Boundary Energy ◽  
Three Dimensional ◽  
Grain Boundary Energy ◽  
Surface Evolver ◽  
Grain Boundary Mobility ◽  
Surface Mobility ◽  
Dimensional Simulation ◽  
Grain Boundary Motion

The interparticle mass transport causes the larger particles to grow at the expense of the smaller particles in the process of sintering. Coarsening during sintering results from surface motion, while grain growth results from grain boundary motion. The three-dimensional simulation was performed to study coarsening and grain growth during sintering by using the Surface Evolver program. The coarsening and grain growth were affected by the ratio of grain boundary energy to surface energy, the ratio of grain boundary mobility to surface mobility, the size of a particle, and its coordination number.

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