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.

Grain Boundary Characteristics Evaluation by Atomistic Investigation Methods

2009 ◽  
Vol 1215 ◽  
Author(s):  
Yoshiyuki Kaji ◽  
Tomohito Tsuru ◽  
Yoji Shibutani
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Density Functional ◽  
Coincidence Site Lattice ◽  
Individual Characteristics ◽  
Material Strength ◽  
Investigation Methods ◽  
Grain Boundary Characteristics ◽  
The Individual ◽  
Boundary Characteristics

AbstractThe grain boundary has been recognized for one of the major defect structures in determining the material strength. It is increasingly important to understand the individual characteristics of various types of grain boundaries due to the recent advances in material miniaturization technique.In the present study three types of grain boundaries of coincidence site lattice (CSL), small angle (SA), and random types are considered as the representative example of grain boundaries. The grain boundary energies and atomic configurations of CSL are first evaluated by first-principle density functional theory (DFT) and the embedded atom method (EAM) calculations. SA and random grain boundaries are subsequently constructed by the same EAM and the fundamental characteristics are investigated by the discrete dislocation mechanics models and the Voronoi polyhedral computational geometric method. As the result, it is found that the local structures are well accorded with the previously reported high resolution-transmission electron microscope (HR-TEM) observations, and that stress distributions of CSL and SA grain boundaries are localized around the grain boundary core. The random grain boundary shows extremely heterogeneous core structures including a lot of pentagon-shaped Voronoi polyhedral resulting from the amorphous-like structure.

Grain-Boundary Characteristics in Austenitic Steel

1996 ◽  
Vol 54 ◽  
pp. 344-345
Author(s):  
M.D. Caul ◽  
V. Randle
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Austenitic Steel ◽  
Material Properties ◽  
Degrees Of Freedom ◽  
Precipitate Formation ◽  
Grain Boundary Characteristics ◽  
Boundary Geometry ◽  
Individual Grains ◽  
Boundary Characteristics

Grain boundaries are an active area of research interest due to their effect on material property and structure relationships. In order to discuss material properties with regard to grain boundaries it is necessary to know the boundary type. The optimum technique for performing this task is Electron Backscatter Diflfraction (EBSD) in concert with the Scanning Electron Microscope (SEM). By collecting texture measurements in the form of individual orientations from grains it is possible to obtain misorientation measurements from grain boundaries. These measurements are three of the five degrees of freedom necessary to geometrically describe a grain boundary. The other two can be obtained by a serial sectioning technique.Grain boundaries in austenitic steel specimens, isothermally aged at either 700°C or 800°C, have been evaluated with the aim of relating boundary geometry to Cr2N precipitate formation. Samples were analysed using SEM and EBSD in order to obtain orientation measurements of individual grains to misorientations at grain boundaries and to Cr2N precipitates. These precipitates are detrimental to room temperature properties of high nitrogen stainless steels, so a reduction in their formation at grain boundaries would be advantageous. The steel is therefore an ideal candidate material for relating boundaries to material properties. The 700°C isothermally aged sample induces precipitate formation at grain boundaries whereas precipitation by cellular decomposition of austenite occurs in the 800 CC sample. The 700°C sample was used to categorise boundary types using the CSL model and relate this to Cr2N formation. The 800°C sample was used to examine the effect of aging temperature on boundary inclination. Therefore all five degrees of freedom in grain boundary geometry were obtained.

Grain Boundary Characteristics and Stress-induced Damage Morphologies in Sputtered and Electroplated Copper Films

2003 ◽  
Vol 766 ◽  
Author(s):  
Hyun Park ◽  
Soo-Jung Hwang ◽  
Kyu Hwan Oh ◽  
Young-Chang Joo
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Morphological Difference ◽  
High Energy ◽  
Triple Junctions ◽  
Boundary Area ◽  
Boundary Triple ◽  
Surface Damages ◽  
Grain Boundary Characteristics ◽  
Boundary Characteristics

AbstractVarious Cu films were fabricated using sputtering and electroplating with and without additive, and their surface damages after annealing were investigated. After annealing at 435°C, the difference between damage morphologies of the films was observed. In some films stressinduced grooves along the grain boundaries were observed, while in the others voids at the grain boundary triple junctions were observed. It was also observed that the stress-induced groove was formed along the high energy grain boundaries. To explain the morphological difference of surface damages, a simple parameter considering the contributions of grain structures and grain boundary characteristics to surface and grain boundary diffusions is suggested. The effective grain boundary area, which is a function of grain size, film thickness and the fraction of high energy grain boundaries, played a key role in the morphological difference.

Defect-Solute Interactions Near Irradiated Grain Boundaries

1993 ◽  
Vol 319 ◽  
Author(s):  
E. P. Simonen ◽  
J. S. Vetrano ◽  
H. L. Heinisch ◽  
S. M. Bruemmer
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Austenitic Stainless Steels ◽  
Back Diffusion ◽  
Metallic Materials ◽  
Grain Boundary Characteristics ◽  
Radiation Induced ◽  
Composition Profiles ◽  
Solute Interactions ◽  
Boundary Characteristics

AbstractDefect-solute interactions control radiation-induced segregation (RIS) to interfacial sinks, such as grain boundaries, in metallic materials. The best studied system in this regard has been austenitic stainless steels. Measurements of grain boundary composition indicate that RIS of major alloying elements is in reasonable agreement with inverse-Kirkendall predictions. The steep and narrow composition profiles are shown to result from limited back diffusion near the boundary. Subsequently, defect-solute interactions that affect the near-boundary defect concentrations strongly affect RIS. The variability in measured RIS may in part be caused by grain boundary characteristics.

Grain Boundary Characteristics Optimization of 90Cu–10Ni Copper-Nickel Alloy for Improving Corrosion Resistance

CORROSION ◽  
10.5006/2690 ◽  
2018 ◽  
Vol 74 (7) ◽  
pp. 819-828 ◽  
Author(s):  
Zhigang Wang ◽  
Xingyu Feng ◽  
Qiongyu Zhou ◽  
Hang Wang ◽  
Yinghui Zhang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Grain Boundary ◽  
Coincidence Site Lattice ◽  
Rolling Reduction ◽  
Grain Boundary Character Distribution ◽  
Triple Junctions ◽  
Electrochemical Testing ◽  
Grain Boundary Characteristics ◽  
Copper Nickel Alloy ◽  
Boundary Characteristics

The grain boundary character distribution and corrosion resistance of a 90% Cu 10% Ni alloy were investigated. When the rolling reduction was increased, the fraction of coincidence site lattice (CSL) grain boundaries with low-Σ index increased initially, and decreased thereafter. The highest fraction of low-Σ CSL boundaries (70%) was obtained through 9% secondary rolling reduction. Electrochemical testing indicated that the corrosion resistance improved significantly after intermediate deformation (7% and 9% reduction ratios) and high-temperature annealing. This improvement was attributed to an increase in the fraction of low-Σ CSL boundaries and the formation of triple junctions during recrystallization.

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.

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