Faceting of Ʃ3 Grain Boundaries in Cu: Three-Dimensional Wulff Diagrams

2005 ◽  
Vol 237-240 ◽  
pp. 584-592 ◽  
Author(s):  
Yaroslav Kucherinenko ◽  
Svetlana Protasova ◽  
Boris B. Straumal
Keyword(s):  
Surface Energy ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Melting Temperature ◽  
Convenient Method ◽  
Three Dimensional ◽  
Diffusional Growth ◽  
3 Dimensional ◽  
Thermal Groove

Diffusional growth of the grain boundary (GB) groove permits one to measure the ratio between GB energy sGB and surface energy ssur. The faceting of twin tilt grain boundaries in Cu has been studied using the GB thermal groove method. No rough facet edges were observed. It means that melting temperature is lower than the roughening temperature for the observed facets in Cu. The influence of orientation and misorientation deviation Dq = ½q – qS½ from coincidence misorientation qS has been studied. By increase of Dq the energy of (100)CSL facet increases. The convenient method for construction 3D three-dimensional Wulff diagrams was found. The 3- dimensional Wulff diagrams were constructed using this method and measured sGB / ssur values.

Inhomogeneous Swelling Near Grain Boundaries in Irradiated Materials: Cavity Nucleation and Growth Saturation Effects

2000 ◽  
Vol 650 ◽  
Author(s):  
S. L. Dudarev
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Nucleation And Growth ◽  
Homogeneous Distribution ◽  
Rate Theory ◽  
Diffusional Growth ◽  
Standard Rate ◽  
Saturation Effects ◽  
Kinetics Of ◽  
Cascade Damage

ABSTRACTThe effect of inhomogeneous nucleation and growth of cavities near grain boundaries illustrates the failure of the standard rate theory to describe the kinetics of phase transformations in irradiated materials under cascade damage conditions. The enhanced swelling observed near grain boundaries is believed to result from the competition between the diffusional growth of cavities and their shrinkage due to the interaction with mobile interstitial clusters. Swelling rates associated with the two processes behave in a radically different way as a function of the size of growing cavities. For a spatially homogeneous distribution of cavities this gives rise to the saturation of swelling in the limit of large irradiation doses.We investigate the evolution of the population of cavities nucleating and growing near a planar grain boundary. We show that a cavity growing near the boundary is able to reach a size that is substantially larger than the size of a cavity growing in the interior region of the grain. For a planar grain boundary the magnitude of swelling at maximum is found to be up to eight times higher than the magnitude of swelling in the grain interior.

Grain Boundary-Dependent Selection Criteria for Nucleation of Gamma-Massive Grains in TiAl-Based Alloys

2010 ◽  
Vol 654-656 ◽  
pp. 2338-2341 ◽  
Author(s):  
A. Sankaran ◽  
Emmanuel Bouzy ◽  
Matthew R. Barnett ◽  
Alain Hazotte
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Selection Criteria ◽  
Three Dimensional ◽  
Massive Transformation ◽  
Three Dimensions ◽  
Variant Selection ◽  
Electron Backscattered Diffraction ◽  
Resolution Electron ◽  
Nucleation Mechanisms

Rapid cooling of TiAl-based alloy from α phase (disordered hexagonal, A3) generates  phase (ordered tetragonal, L1o) grains through massive transformation nucleating mostly over the α/α grain boundaries. This current work deals with the identification and the validation of different nucleation mechanisms during  massive transformation in TiAl-based alloys. Special attention has been given to the variant selection criteria for the nucleation of the massive structures along different types of α/α grain boundaries. The  massive domains formed along the grain boundaries were analysed using high resolution electron backscattered diffraction (EBSD). Statistical studies were made on different nucleation sites and different mechanisms are proposed. Two–dimensional studies of the nucleation mechanism suggest that the minimization of the interfacial energy could be the predominant criteria during the grain boundary nucleation. In order to verify this nucleation criterion in three-dimensions, serial sections were made and EBSD maps were taken and analysed in each section. The variant selection observed during the nucleation and the growth of the  massive grains is further discussed after getting a broader view under three-dimensional investigations.

Atomic Scale Characterisation of Electrodeposited Nanocrystalline Ni-P Alloys

1999 ◽  
Vol 581 ◽  
Author(s):  
Matthias Abraham ◽  
Mattias Thuvandert ◽  
Helen M. Lane ◽  
Alfred Cerezo ◽  
George D.W. Smith
Keyword(s):  
Heat Treatment ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Boundary Segregation ◽  
Atom Probe ◽  
Atomic Scale ◽  
Grain Boundary Segregation ◽  
P Concentration

ABSTRACTNanocrystalline Ni-P alloys produced by electrodeposition have been characterised by three-dimensional atom probe (3DAP) analysis. In the as-deposited materials, there are indications of some variation in P concentration between grains and segregation to grain boundaries. After heat treatment however, strong grain boundary segregation and the formation of Ni3P precipitates have been observed.

Effect of Grain Boundary Characteristics on Lattice Orientations

2007 ◽  
Vol 26-28 ◽  
pp. 1003-1006 ◽  
Author(s):  
Jae Hyung Cho
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Three Dimensional ◽  
Microstructural Characterization ◽  
Grain Boundary Character Distribution ◽  
Average Scheme ◽  
Plane Normal ◽  
Grain Boundary Characteristics ◽  
Correlation Parameters ◽  
Boundary Characteristics

Grain boundary characteristics are defined by five parameter, grain boundary plane normal and misorientation angle/axis between two adjacent grains. The influence of the grain boundary character distribution on lattice evolution during deformation was investigated using three-dimensional crystal plasticity finite element method (CPFEM). Various combinations of grain boundaries were modeled systematically. In analyzing the numerical microstructural characterization obtained by the simulation, orientation average scheme and correlation parameters between misorientation and its special distribution are used. Inter- and intra-grain structures were investigated using the spatial distribution of lattice orientation. Main emphasis was placed on misorientation distributions around grain boundaries, where grain interaction mainly occurred.

Influence of Grain Boundary Mobility on Microstructure Evolution during Recrystallisation

2012 ◽  
Vol 715-716 ◽  
pp. 191-196
Author(s):  
Myrjam Winning ◽  
Dierk Raabe
Keyword(s):  
Grain Boundary ◽  
Cellular Automaton ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Microstructure Evolution ◽  
Texture Evolution ◽  
Three Dimensional ◽  
Boundary Mobility ◽  
Metallic Materials ◽  
Grain Boundary Mobility

The paper introduces first investigations on how low angle grain boundaries can influence the recrystallisation behaviour of crystalline metallic materials. For this purpose a three-dimensional cellular automaton model was used. The approach in this study is to allow even low angle grain boundaries to move during recrystallisation. The effect of this non-zero mobility of low angle grain boundaries will be analysed for the recrystallisation of deformed Al single crystals with Cube orientation. It will be shown that low angle grain boundaries indeed influence the kinetics as well as the texture evolution of metallic materials during recrystallisation.

THEORETICAL AND COMPUTER MODELS OF 3-DIMENSIONAL GRAIN BOUNDARY MIGRATION WITH MOBILE PARTICLES

2022 ◽  
Author(s):  
Carlos Leonardo Di Prinzio ◽  
Pastor Ignacio Achaval
Keyword(s):  
Grain Size ◽  
Analytical Solution ◽  
Grain Boundary ◽  
Boundary Migration ◽  
Three Dimensional ◽  
Monte Carlo Algorithm ◽  
3 Dimensional ◽  
Particle Mobility ◽  
Size Evolution ◽  
Computational Data

In this work, the migration of a three-dimensional (3D) spherical crystal in the presence of mobile particles using a Monte Carlo algorithm was studied. Different concentrations of particles (<i>f</i>) and different particle mobility (<i>M<sub>p</sub></i>) were used. It was found that the grain size reaches a critical radius (<i>R<sub>c</sub></i>) which depends exclusively on <i>f</i>. This dependence can be written as: <i>R<sub>c</sub></i>∝<i>f</i><sup>1/3</sup>. The dynamic equation of grain size evolution and its analytical solution were also found. The analytical solution proposed fits successfully the simulation results. The particle fraction in the grain boundary was also found analytically and it fits the computational data.

Behavior of Basal Plane Dislocations and Low Angle Grain Boundary Formation in Hexagonal Silicon Carbide

2007 ◽  
Vol 556-557 ◽  
pp. 231-234 ◽  
Author(s):  
Yi Chen ◽  
Govindhan Dhanaraj ◽  
William M. Vetter ◽  
Rong Hui Ma ◽  
Michael Dudley
Keyword(s):  
Silicon Carbide ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Basal Plane ◽  
Opposite Sign ◽  
Three Dimensional ◽  
Cross Slip ◽  
X Ray ◽  
Tilt Boundaries ◽  
Edge Dislocations

The interactions between basal plane dislocations (BPDs) and threading screw and edge dislocations (TSDs and TEDs) in hexagonal SiC have been studied using synchrotron white beam x-ray topography (SWBXT). TSDs are shown to strongly interact with advancing basal plane dislocations (BPDs) while TEDs do not. A BPD can cut through an individual TED without the formation of jogs or kinks. The BPDs were observed to be pinned by TSDs creating trailing dislocation dipoles. If these dipoles are in screw orientation segments can cross-slip and annihilate also potentially leaving isolated trailing loops. The three-dimensional (3D) distribution of BPDs can lead to aggregation of opposite sign edge segments leading to the creation of low angle grain boundaries (LAGBs) characterized by pure basal plane tilt of magnitude determined by the net difference in densities of the opposite sign dislocations. Similar aggregation can also occur against pre-existing prismatic tilt boundaries made up of TED walls with the net difference in densities of the opposite sign dislocations contributing some basal plane tilt character to the LAGB.

Interplay between Surface and Grain Boundary in Sintering

2007 ◽  
Vol 558-559 ◽  
pp. 1029-1034
Author(s):  
Fumihiro Wakai
Keyword(s):  
Numerical Simulation ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Coordination Number ◽  
Particle Motion ◽  
Center Of Mass ◽  
Three Dimensional ◽  
Vector Sum

Three-dimensional numerical simulation of sintering was performed to illustrate the interplay between surface and grain boundary in particle scale. The shrinkage during sintering can be described as a motion of the center of mass by the force acting between particles, that is, the sintering force. When a particle interacts with several neighbor particles, the sintering force on the particle is a vector sum of forces acting through grain boundaries with neighbors. A particle changes its own shape through interaction with neighbor particles, then, the coordination number affects particle motion.

Process and Device Considerations for Small Grain Polysilicon Transistors

1985 ◽  
Vol 53 ◽  
Author(s):  
H. Shichijo ◽  
S.D.S. Malhi ◽  
R. Sundaresan ◽  
S.K. Banerjee ◽  
H.W. Lam
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Layer Thickness ◽  
3 Dimensional

ABSTRACTPolysilicon transistors offer the first entry into 3-dimensional ICs. This paper reviews some process and device considerations in using these devices in VLSI environments. The process issues include the choice of polysilicon grain size, layer thickness, doping, and methods of grain boundary passivation. The device considerations are closely related to the effects of grain boundaries in modifying the device characteristics. Three specific application examples are reviewed. It is concluded that polysilicon transistors offer new possibilities to enhance the performance of bulk technologies without resorting to any recrystallization techniques.

scholarly journals Strengthening Effect of Nb on Ferrite Grain Boundary in X70 Pipeline Steel

Materials ◽  
2020 ◽  
Vol 14 (1) ◽  
pp. 61
Author(s):  
Zhongyi Li ◽  
Zhipeng Li ◽  
Wenhuai Tian
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Pipeline Steel ◽  
Three Dimensional ◽  
Strengthening Effect ◽  
Electronic Density ◽  
First Principle Calculation ◽  
Before And After ◽  
Probe Test ◽  
Microalloying Elements

Understanding the strengthening effect of niobium on ferrite grain boundaries from the perspective of valence electron structures will help to use niobium and other microalloying elements more effectively to improve the performance of steel materials. In this paper, the effect of niobium element on ferrite grain boundary strengthening is studied based on microstructure analysis at the nanometer scale. The enrichment of niobium in pipeline steel at ferrite boundary was observed by a three-dimensional atomic probe test. Segregation of Nb is observed in the ferrite grain boundaries of X70 steel, and its maximum concentration is 0.294–0.466 at.%. The charges in the occupancy of the Fe 3d state in grain and grain boundary were 7.23 and 7.37, respectively, based on quantitative analysis of electron energy loss spectra (EELS). The first-principle calculation suggests that the charges in the occupancy of 3d state for grain boundary iron are 6.57 and 6.68, respectively, before and after the Nb doping (with an increase of 1.67%), which reveals a similar trend to that of the EELS results. Through Nb alloying, the 3d valence electronic density of the state of Fe in grain boundary moves to a lower energy, which can reduce the total energy of the system and make the grain boundary more stable. Meanwhile, the charges in the occupancy of the 3d state for Fe in the grain boundary increases, providing more electrons for grain boundary bonding. These improve the strength and toughness of the material. This work provides a fundamental understanding for pipeline steel strengthening by element alloying.

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