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.

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.

Cr-Vacancy Elastic and Chemical Interactions in Irradiated Stainless Steels

1998 ◽  
Vol 540 ◽  
Author(s):  
E. P. Simonen ◽  
S. M. Bruemmer
Keyword(s):  
Grain Boundary ◽  
Point Defects ◽  
Stainless Steels ◽  
Austenitic Stainless Steels ◽  
Solution Annealing ◽  
Chemical Interactions ◽  
Radiation Induced ◽  
Solute Interactions ◽  
Present Evaluation ◽  
Nonequilibrium Segregation

AbstractInteractions between point defects and major solute strongly influence grain boundary concentrations during heat treatment, irradiation and annealing of austenitic stainless steels. Previous approaches to nonequilibrium segregation emphasize only elastic defect-solute interactions. The present evaluation of nonequilibrium concentrations at grain boundaries indicates chemical interactions unique to solution annealing and cooling during thermal nonequilibrium segregation (TNES). Subsequent to TNES, radiation-induced segregation and post-irradiation annealing are modeled and compared with measured changes in grain boundary composition. The latter two mechanisms are controlled by exchanges between vacancies and major solute such as Cr.

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.

Comparison Of Thermally- And Irradiation-Induced Grain Boundary Segregation In Austenitic Stainless Steels

1991 ◽  
Vol 238 ◽  
Author(s):  
Edward A. Kenik
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Stainless Steels ◽  
Analytical Electron Microscopy ◽  
Boundary Segregation ◽  
Austenitic Stainless Steels ◽  
Chromium Depletion ◽  
Thermal Sensitization ◽  
The Matrix ◽  
Radiation Induced

ABSTRACTSegregation at grain boundaries in austenitic stainless steels sensitized by either thermal annealing or irradiation was studied by analytical electron microscopy. Characterization of grain boundary compositions in both types of materials was performed by high spatial resolution (≥2 nm) X-ray microanalysis. Whereas similar chromium depletion is observed in both processes, there are differences in the behavior of the other alloying elements and in the mechanisms responsible for the segregation. In thermal sensitization, the nickel/iron ratio and the silicon level observed at grain boundaries are similar to those for the matrix. In cases where little or no precipitation occurs, co-segregation of phosphorus, chromium, and molybdenum occurs at boundaries and interfaces. For radiation sensitization, radiation-induced segregation (RIS) results in enrichment of nickel, silicon, and, in certain cases, phosphorus and in depletion of iron at grain boundaries. There appears to be some synergism between segregation of nickel and silicon, which increases the magnitude of RIS effects. Grain boundary precipitation is often observed in both thermally- and irradiation-sensitized materials. However, the nature and origins of the two types of precipitation are different. The formation of chromium-enriched grain boundary carbides is the cause of the chromium depletion in thermal sensitization. In contrast, the precipitates produced by irradiation are enriched in nickel and silicon and depleted in chromium relative to the matrix and therefore are the result of RIS. Results for thermal- and radiation-induced segregation in manganese-stabilized austenites are compared to that for nickel-stabilized austenites.

Sign in / Sign up

Export Citation Format

Share Document