Microchemistry of Proton-Irradiated Austenitic Alloys Under Conditions Relevant to Lwr Core Components

1998 ◽  
Vol 540 ◽  
Author(s):  
G. S. Was ◽  
T. R. Allen ◽  
J. T. Busby ◽  
J. Gan ◽  
D. Damcott ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Composition Dependence ◽  
Alloy Composition ◽  
Dose Range ◽  
Boundary Segregation ◽  
Dose Dependence ◽  
Composition Analysis ◽  
Boundary Composition ◽  
Austenitic Alloys ◽  
Core Components

AbstractOver 1200 measurements of grain boundary composition and microstructure have been made on 14 different austenitic Fe-Cr-Ni alloys following proton irradiation in the temperature range 200-600°C and in the dose range 0.1-3.0 dpa. Grain boundary composition measurements revealed that Cr depletes at grain boundaries, Ni enriches and Fe can either enrich or deplete depending on alloy composition. Analysis of temperature and composition dependence of RIS revealed that the magnitude and direction of grain boundary segregation depends on alloy composition because the value of migration enthalpy differs among the alloy constituents, and diffusivities of the alloy constituents are composition-dependent. The dose dependence of segregation revealed ordering in Ni-base alloys and temperature dependence was used to show that RIS occurs by vacancy exchange rather than an interstitial binding mechanism. The dependence of segregation on composition is consistent with all known, relevant neutron data.

Proton Irradiation Induced Grain Boundary Segregation in Austenitic Stainless Steels

1994 ◽  
Vol 373 ◽  
Author(s):  
D.L. Damcott ◽  
G.S. Was ◽  
S.M. Bruemmer
Keyword(s):  
Grain Boundary ◽  
Proton Irradiation ◽  
Boundary Segregation ◽  
Reactor Core ◽  
Austenitic Stainless Steels ◽  
Sharp Decrease ◽  
Diffusion Parameters ◽  
Core Components ◽  
Radiation Induced ◽  
Higher Temperature

AbstractRadiation induced segregation (RIS) has been implicated as a mechanism for irradiationassisted stress corrosion cracking (IASCC) in reactor core components. Proton irradiation has been shown to be useful in creating grain boundary chemistries similar to those found in neutron and charged particle irradiated materials for accelerated testing of IASCC susceptibility. This work quantifies grain boundary RIS as a function of proton irradiation dose (0.1-3.0 dpa), temperature (200°−600°C), and alloy composition (20Cr-9Ni, 24Cr-19Ni, and xCr-24Ni, x=16, 20,24). Auger electron spectroscopy revealed Cr depletion and Ni enrichment under all irradiation conditions. As a function of dose, the degree of segregation increased rapidly to near saturation prior to 1 dpa, with a boundary composition of 12.1 at.% Cr and 36.0 at.% Ni at 1 dpa. Segregation peaked at approximately 500°C with 13.0 at.% Cr and 38.6 at.% Ni at the grain boundary at 0.5 dpa; very little segregation was observed at or below 300°C or at 600°C. The trends in segregation as a function of dose agreed well with the Perks' model predictions with the exception of the measurement at 600°C, which showed the sharp decrease in segregation predicted for a higher temperature (700°C-800°C). For alloys containing constant bulk Cr but varying Ni, the Perks' model agreed well with the observed segregation trend; however, for alloys containing constant bulk Ni and varying Cr, agreement was achieved only through the use of composition dependent diffusion parameters.

Influence of Initial Grain Boundary Composition on the Evolution of Radiation-Induced Segregation Profiles

1998 ◽  
Vol 540 ◽  
Author(s):  
J.T. Busby ◽  
G.S. Was ◽  
S.M. Bruemmer ◽  
D. J. Edwards ◽  
E.A. Kenik
Keyword(s):  
Grain Boundary ◽  
Stainless Steels ◽  
Boundary Segregation ◽  
Reactor Core ◽  
Austenitic Stainless Steels ◽  
Central Peak ◽  
Boundary Composition ◽  
Radiation Induced ◽  
The Impact ◽  
Profile Development

AbstractRadiation-induced segregation (RIS) has been identified as a potential contributor to irradiation-assisted stress corrosion cracking (IASCC) of austenitic stainless steels in reactor core components. The occurrence of grain boundary segregation prior to irradiation influences both the shape and magnitude of RIS profile development during subsequent irradiation. In an effort to better understand the impact of this pre-irradiation enrichment on RIS profile development, the evolution of grain boundary Cr segregation profiles with irradiation dose has been characterized. Commercial purity and high-purity austenitic stainless steels with different initial levels of grain boundary Cr have been irradiated with neutrons (at 275°C) or protons (at 360-400°C) to doses up to ∼5 dpa. Grain boundary composition profiles were measured before and after irradiation using scanning transmission electron microscopy with energy dispersive xray spectroscopy (STEM-EDS). The initial enrichment of Cr is shown to delay radiation-induced Cr depletion and produce a “W-shaped” profile at low irradiation doses. Further irradiation causes the central peak of the W to decrease, eventually resulting in the classical “V-shaped” depletion profile. Possible mechanisms for the pre-irradiation enrichment and its evolution into a “W-shaped” profile will be discussed.

Grain boundary segregation in metals

1992 ◽  
Vol 50 (2) ◽  
pp. 1204-1205
Author(s):  
C.L. Briant
Keyword(s):  
Fracture Surface ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Material Properties ◽  
Electron Spectroscopy ◽  
High Vacuum ◽  
Boundary Segregation ◽  
Grain Boundary Segregation ◽  
Local Concentration ◽  
The One

Grain boundary segregation is the process by which solute elements in a material diffuse to the grain boundaries, become trapped there, and increase their local concentration at the boundary over that in the bulk. As a result of this process this local concentration of the segregant at the grain boundary can be many orders of magnitude greater than the bulk concentration of the segregant. The importance of this problem lies in the fact that grain boundary segregation can affect many material properties such as fracture, corrosion, and grain growth.One of the best ways to study grain boundary segregation is with Auger electron spectroscopy. This spectroscopy is an extremely surface sensitive technique. When it is used to study grain boundary segregation the sample must first be fractured intergranularly in the high vacuum spectrometer. This fracture surface is then the one that is analyzed. The development of scanning Auger spectrometers have allowed researchers to first image the fracture surface that is created and then to perform analyses on individual grain boundaries.

An atom probe tomography study of grain boundary segregation in nanocrystalline Ni-W

2005 ◽  
Vol 903 ◽  
Author(s):  
Andrew Detor ◽  
Michael K. Miller ◽  
Christopher A. Schuh
Keyword(s):  
Grain Boundary ◽  
Atom Probe Tomography ◽  
Boundary Segregation ◽  
Atom Probe ◽  
Solute Segregation ◽  
Grain Boundary Segregation ◽  
Distribution Analysis ◽  
Grain Sizes ◽  
Composition Fluctuations ◽  
20 Nm

AbstractAtom probe tomography is used to observe the solute distribution in electrodeposited nanocrystalline Ni-W alloys with three different grain sizes (3, 10, and 20 nm) and the results are compared with atomistic computer simulations. The presence of grain boundary segregation is confirmed by detailed analysis of composition fluctuations in both experimental and simulated structures, and its extent quantified by a frequency distribution analysis. In contrast to other nanocrystalline alloys, the present Ni-W alloys exhibit only a subtle amount of solute segregation to the intergranular regions. This finding is consistent with quantitative predictions for these alloys based upon a thermodynamic model of grain boundary segregation.

scholarly journals Grain Boundary Segregation in UFG Alloys Processed by Severe Plastic Deformation

2012 ◽  
Vol 14 (11) ◽  
pp. 968-974 ◽  
Author(s):  
Xavier Sauvage ◽  
Artur Ganeev ◽  
Yulia Ivanisenko ◽  
Nariman Enikeev ◽  
Maxim Murashkin ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Grain Boundary ◽  
Severe Plastic Deformation ◽  
Boundary Segregation ◽  
Grain Boundary Segregation

Boron Grain Boundary Segregation in a Heat Treatable Steel

2015 ◽  
Vol 160 (5) ◽  
pp. 204-208 ◽  
Author(s):  
Phillip Haslberger ◽  
Christoph Turk ◽  
Katharina Babinsky ◽  
Devrim Caliskanoglu ◽  
Helmut Clemens ◽  
...  
Keyword(s):  
Grain Boundary ◽  
Boundary Segregation ◽  
Grain Boundary Segregation
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