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Title: INTERACTION OF INTERSTITIAL CLUSTERS WITH RHENIUM, OSMIUM, AND TANTALUM IN TUNGSTEN

Abstract

In the previous semi annual report, we explored the stability of interstitial clusters in W up to size seven. In this report, we study the binding of those clusters to Re, Os, and Ta atoms. For each cluster size, the three most stable configurations are considered to average the binding property. The average binding energy to a Re decreases from 0.79 eV for a size-1 cluster (a [111] dumbbell) to 0.65 eV for a size-7 cluster. For Os, the binding decreases from 1.61 eV for a [111] dumbbell to 1.34 eV for a size-7 cluster. Tantalum is repulsive to interstitial clusters with binding energy ranges from -0.61 eV for a [111] dumbbell to -0.5 eV for a size-7 cluster.

Authors:
; ;
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1327156
Report Number(s):
PNNL-SA-120032
AT2030110
DOE Contract Number:
AC05-76RL01830
Resource Type:
Book
Resource Relation:
Related Information: Fusion Reactor Materials Semiannual Progress Report for the Period Ending June 30, 2016, DOE/ER-0313/60, 60:183-187
Country of Publication:
United States
Language:
English
Subject:
Fusion Materials; Interstitial cluster; Rhenium Osmium Tantalum; tungsten alloys

Citation Formats

Setyawan, Wahyu, Nandipati, Giridhar, and Kurtz, Richard J. INTERACTION OF INTERSTITIAL CLUSTERS WITH RHENIUM, OSMIUM, AND TANTALUM IN TUNGSTEN. United States: N. p., 2016. Web.
Setyawan, Wahyu, Nandipati, Giridhar, & Kurtz, Richard J. INTERACTION OF INTERSTITIAL CLUSTERS WITH RHENIUM, OSMIUM, AND TANTALUM IN TUNGSTEN. United States.
Setyawan, Wahyu, Nandipati, Giridhar, and Kurtz, Richard J. Thu . "INTERACTION OF INTERSTITIAL CLUSTERS WITH RHENIUM, OSMIUM, AND TANTALUM IN TUNGSTEN". United States. doi:.
@article{osti_1327156,
title = {INTERACTION OF INTERSTITIAL CLUSTERS WITH RHENIUM, OSMIUM, AND TANTALUM IN TUNGSTEN},
author = {Setyawan, Wahyu and Nandipati, Giridhar and Kurtz, Richard J.},
abstractNote = {In the previous semi annual report, we explored the stability of interstitial clusters in W up to size seven. In this report, we study the binding of those clusters to Re, Os, and Ta atoms. For each cluster size, the three most stable configurations are considered to average the binding property. The average binding energy to a Re decreases from 0.79 eV for a size-1 cluster (a [111] dumbbell) to 0.65 eV for a size-7 cluster. For Os, the binding decreases from 1.61 eV for a [111] dumbbell to 1.34 eV for a size-7 cluster. Tantalum is repulsive to interstitial clusters with binding energy ranges from -0.61 eV for a [111] dumbbell to -0.5 eV for a size-7 cluster.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 2016},
month = {Thu Sep 01 00:00:00 EDT 2016}
}

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  • Density functional theory was employed to explore the energetic properties of clusters up to size 2 of Re in W. While WW<111> is the most stable intrinsic dumbbell, ReW<110> is more stable than ReW<111>. However, when they are trapped by a substitutional Re (Re_s), ReW<111> becomes more stable than ReW<110>. In this case, the most stable configuration forms a ReWRe crowdion with the W atom in between the Re atoms. Simulations of a ReW[111] (dumbbell’s vector is from Re to W) approaching a Re_s along [111] indicate that the binding energy decreases from 0.83 eV at the first nearest neighbormore » (NN1) to 0.10 eV at NN3 and ~0 at NN4. In addition, while ReW<111> and ReW<110> are stable near a Re_s at NN1, the ReW<100> instantaneously rotates toward ReW<111>.« less
  • Density functional theory was employed to explore the stability of interstitial clusters in W up to size seven. For each cluster size, the most stable configuration consists of parallel dumbbells. For clusters larger than size three, parallel dumbbells prefer to form in a multilayer fashion, instead of a planar structure. For size-7 clusters, the most stable configuration is a complete octahedron. The binding energy of a [111] dumbbell to the most stable cluster increases with cluster size, namely 2.49, 3.68, 4.76, 4.82, 5.47, and 6.85 eV for clusters of size 1, 2, 3, 4, 5, and 6, respectively. For amore » size-2 cluster, collinear dumbbells are still repulsive at the maximum allowable distance of 13.8 Å (the fifth neighbor along [111]). On the other hand, parallel dumbbells are strongly bound together. Two parallel dumbbells in which the axis-to-axis distance is within a cylindrical radius of 5.2 Å still exhibit a considerable binding of 0.28 eV. The most stable cluster in each size will be used to explore interactions with transmutation products.« less
  • Segregation under irradiation in austenitic steels is due to a permanent flux of vacancies and interstitials produced by irradiation towards sinks like surfaces and interfaces. A model based on a mean field lattice rate theory is proposed where kinetics and thermodynamics are treated in a mutually consistent way. For a Fe-Ni-Cr ternary alloy, the 15 parameters defining the jump frequencies of vacancies were fitted on equilibrium properties including ordering energies and tracer diffusion experiments with no use of segregation data. Measurements of RIS by Auger Electron Spectroscopy (AES) were used in the last step of the fitting procedure in ordermore » to choose the best set of the 27 interstitial jump frequencies. This fitting procedure strongly supports the idea that the interstitials are contributing to RIS in Fe-Cr-Ni alloys. The authors also simulate the trapping of interstitials by an impurity model and reproduce the total inhibition of RIS by this impurity as observed experimentally.« less