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Title: Dependence of Grain Boundary Structure on Radiation Induced Segregation and Void Denuded Zones in a Model Ni-Cr Alloy.

Abstract

Abstract not provided.

Authors:
;  [1]; ;  [2];  [1];  [3];  [4]
  1. (University of Wisconsin)
  2. (Oak Ridge National Laboratory)
  3. (Drexel University)
  4. (Drexel)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1399305
Report Number(s):
SAND2016-10004C
648047
DOE Contract Number:
AC04-94AL85000
Resource Type:
Conference
Resource Relation:
Conference: Proposed for presentation at the The Rio Grande Symposium on Advanced Materials held October 3, 2016 in Albuquerque, NM, United States of America.
Country of Publication:
United States
Language:
English

Citation Formats

Barr, Christopher Michael, Barnard, Leland, Hattar, Khalid Mikhiel, Kinga Unocic, Morgan, Dane, Taheri, Mitra, and Barr, Christopher. Dependence of Grain Boundary Structure on Radiation Induced Segregation and Void Denuded Zones in a Model Ni-Cr Alloy.. United States: N. p., 2016. Web.
Barr, Christopher Michael, Barnard, Leland, Hattar, Khalid Mikhiel, Kinga Unocic, Morgan, Dane, Taheri, Mitra, & Barr, Christopher. Dependence of Grain Boundary Structure on Radiation Induced Segregation and Void Denuded Zones in a Model Ni-Cr Alloy.. United States.
Barr, Christopher Michael, Barnard, Leland, Hattar, Khalid Mikhiel, Kinga Unocic, Morgan, Dane, Taheri, Mitra, and Barr, Christopher. 2016. "Dependence of Grain Boundary Structure on Radiation Induced Segregation and Void Denuded Zones in a Model Ni-Cr Alloy.". United States. doi:. https://www.osti.gov/servlets/purl/1399305.
@article{osti_1399305,
title = {Dependence of Grain Boundary Structure on Radiation Induced Segregation and Void Denuded Zones in a Model Ni-Cr Alloy.},
author = {Barr, Christopher Michael and Barnard, Leland and Hattar, Khalid Mikhiel and Kinga Unocic and Morgan, Dane and Taheri, Mitra and Barr, Christopher},
abstractNote = {Abstract not provided.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month =
}

Conference:
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  • The appearance of denuded zones following low stress creep in particle-containing crystalline materials is both a microstructural prediction and observation often cited as irrefutable evidence for the Nabarro-Herring mechanism of diffusional creep. The denuded zones are predicted to be at grain boundaries that are orthogonal to the direction of the applied stress. Furthermore, their dimensions should account for the accumulated plastic flow. In the present paper, the evidence for such denuded zones is critically examined. These zones have been observed during creep of magnesium, aluminum, and nickel-base alloys. The investigation casts serious doubts on the apparently compelling evidence for themore » link between denuded zones and diffusional creep. Specifically, denuded zones are clearly observed under conditions that are explicitly not diffusional creep. Additionally, the denuded zones are often found in directions that are not orthogonal to the applied stress. Other mechanisms that can account for the observations of denuded zones are discussed. It is proposed that grain boundary sliding accommodated by slip is the rate-controlling process in the stress range where denuded zones have been observed. It is likely that the denuded zones are created by dissolution of precipitates at grain boundaries that are simultaneously sliding and migrating during creep.« less
  • Ferritic/Martensitic (F/M) steels with high Cr content posses the high temperature strength and low swelling rates required for advanced nuclear reactor designs. Radiation induced segregation (RIS) occurs in F/M steels due to solute atoms preferentially coupling to point defect fluxes to defect sinks, such as grain boundaries (GBs). The RIS response of F/M steels and austenitic steels has been shown to be dependent on the local structure of GBs but has only been demonstrated in ion irradiated specimens. A 9 wt. % Cr model alloy steel was irradiated to 3 dpa using neutrons at the Advanced Test Reactor (ATR) tomore » determine the effect of neutron radiation environment on the RIS-GB structure dependence. This investigation found the relationship between GB structure and RIS is also active for F/M steels irradiated using neutrons. The data generated from the neutron irradiation is also compared to RIS data generated using proton irradiations on the same heat of model alloy.« less
  • Metallographic studies were made of Mg-1/2 wt.% Zr alloy. It was found that very heavy precipitation took place during creep testing and that denuded zones developed at grain boundaries. The precipitate was identified as ZrH/sub 2/ . Grain growth was isotropic and ceased after about 200 hr, so that during creep tests of more than 1000 hr duration the grain morphology was stabie for most of the time. It was concluded that a possible explanation of the denuded zones is that during deformation a form of directi onal diffusion was occurring that had some similarities with that involved in Nabarro-Herringmore » creep. It was therefore suggested that the zirconium hydride precipitate acts as a marker, and that magnesium atoms diffuse into the grain boundaries that lie at right angles to the applied stress. (M.C.G.)« less
  • Grain boundary radiation-induced segregation (RIS) in Fe-Ni-Cr stainless alloys has been measured and modelled as a function of irradiation temperature and dose. Heavy-ion irradiation was used to produce damage levels from 1 to 20 displacements per atom (dpa) at temperatures from 175 to 550{degrees}C. Measured Fe, Ni, and Cr segregation increased sharply with irradiation dose (from 0 to 5 dpa) and temperature (from 175 to about 350{degrees}C). However, grain boundary concentrations did not change significantly as dose or temperatures were further increased. Impurity segregation (Si and P) was also measured, but only Si enrichment appeared to be radiation-induced. Grain boundarymore » Si levels peaked at an intermediate temperature of {approximately}325{degrees}C reaching levels of {approximately}8 at. %. Equilibrium segregation of P was measured in the high-P alloys, but interfacial concentration did not increase with irradiation exposure. Examination of reported RIS in neutron-irradiated stainless steels revealed similar effects of irradiation dose on grain boundary compositional changes for both major alloying and impurity element`s. The Inverse Kirkendall model accurately predicted major alloying element RIS in ion- and neutron-irradiated alloys over the wide range of temperature and dose conditions. In addition, preliminary calculations indicate that the Johnson-Lam model can reasonably estimate grain boundary Si enrichment if back diffusion is enhanced.« less